Treatment of Chiari type I malformation in patients with and without syringomyelia: a consecutive series of 66 cases

Predictors of poor functional outcomes in adults with type I Chiari Malformation: Clinical and surgical factors assessed with the Chicago Chiari Outcome Scale over long-term follow-up

OBJECTIVE

This study aimed to identify clinical and surgical features associated with poor long-term postoperative outcomes in patients diagnosed with Type I Chiari Malformation (CMI) treated with posterior fossa decompression with duroplasty (PFDD), with or without tonsillar coagulation.

METHODS

This retrospective, single-center study included 107 adult patients with CMI surgically treated between 2010 and 2021. The surgical technique involved a midline suboccipital craniectomy, C1 laminectomy, durotomy, arachnoid dissection, duroplasty, and tonsillar coagulation until 2014, after which tonsillar coagulation was discontinued. Postoperative outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS) at a median follow-up of 35 months. Clinical, surgical, and neuroimaging data were analyzed using the Wilcoxon signed-rank test, Cox regression analysis, and Kaplan-Meier survival curves to identify predictors of poor functional outcomes.

RESULTS

Of the 107 patients (mean age 43.9 years, SD 13), 81 (75.5 %) showed functional improvement, 25 (23.4 %) remained unchanged, and 1 (0.9 %) experienced worsened outcomes. Cephalalgia, bilateral motor weakness, and bilateral paresthesia were the most frequent initial symptoms. Tonsillar coagulation was performed in 31 cases (28.9 %) but was clinically associated with higher rates of unfavorable outcomes. The Wilcoxon signed-rank test indicated that long-term follow-up CCOS was significantly higher than postoperative CCOS (Z = -7.678, p < 0.000). Multivariate Cox analysis identified preoperative bilateral motor weakness (HR 6.1, 95 % CI 1.9-18.9; p = 0.002), hydrocephalus (HR 3.01, 95 % CI 1.3-6.9; p = 0.008), and unilateral motor weakness (HR 2.99, 95 % CI 1.1-8.2; p = 0.033) as significant predictors of poor outcomes on a long-term follow-up.

CONCLUSION

This study highlights the high rate of functional improvement in CMI patients following PFDD. Preoperative motor weakness and hydrocephalus were significant predictors of poor long-term outcomes. Tonsillar coagulation did not demonstrate a clear clinical benefit and may be associated with worse outcomes. Our findings suggest that careful preoperative assessment and selection of surgical techniques are crucial for optimizing patient outcomes.

Long-term outcome of operated Chiari I patients between 2005 and 2020 in Eastern Finland

PURPOSE

The purpose of our study was to examine the long-term outcomes of operated Chiari malformation type 1 (CM1) patients and evaluate whether different duraplasty techniques affected outcome after surgery in Kuopio University Hospital catchment area.

METHODS

In this retrospective study, a total of 93 patients were diagnosed with CM1 and underwent posterior fossa decompression surgery with or without duraplasty between 2005 and 2020. All patients' medical records were examined for baseline characteristics, surgical details, and long-term follow-up data after operation.

RESULTS

The mean age of CM1 patients was 25.9 years (SD 19.2 years), with female preponderance 69/93 (73.4%). The mean clinical follow-up time was 26.5 months (SD 33.5 months). The most common presenting symptoms were headache, symptoms of extremities, and paresthesia. Posterior fossa decompression with duraplasty was performed in 87 (93.5%) patients and bony decompression in 6 (6.5%) patients. After surgery, preoperative symptoms alleviated in 84.9% (79/93) and the postoperative syringomyelia regression rate was 89.2% (33/37) of all patients. The postoperative complication rate was 34.4% (32/93), with aseptic meningitis being the most common, 25.8% (24/93). Revision surgery was required in 14% (13/93) of patients. No significant correlation between postoperative outcome and extent of dural decompression, or type of duraplasty performed was found.

CONCLUSION

This is the largest reported series of surgically treated CM1 patients in Finland. Posterior fossa decompression is an effective procedure for CM1 symptomology. Duraplasty technique had no significant difference in complication rate or long-term outcomes.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines for Patients With Chiari Malformation: Surgical Interventions

BACKGROUND

Chiari malformation type I (CIM) diagnoses have increased in recent years. Controversy regarding the best operative management prompted a review of the literature to offer guidance on surgical interventions.

OBJECTIVE

To assess the literature to determine (1) whether posterior fossa decompression or posterior fossa decompression with duraplasty is more effective in preoperative symptom resolution; (2) whether there is benefit from cerebellar tonsillar resection/reduction; (3) the role of intraoperative neuromonitoring; (4) in patients with a syrinx, how long should a syrinx be observed for improvement before additional surgery is performed; and 5) what is the optimal duration of follow-up care after preoperative symptom resolution.

METHODS

A systematic review was performed using the National Library of Medicine/PubMed and Embase databases for studies on CIM in children and adults. The most appropriate surgical interventions, the use of neuromonitoring, and clinical improvement during follow-up were reviewed for studies published between 1946 and January 23, 2021.

RESULTS

A total of 80 studies met inclusion criteria. Posterior fossa decompression with or without duraplasty or cerebellar tonsil reduction all appeared to show some benefit for symptom relief and syrinx reduction. There was insufficient evidence to determine whether duraplasty or cerebellar tonsil reduction was needed for specific patient groups. There was no strong correlation between symptom relief and syringomyelia resolution. Many surgeons follow patients for 6-12 months before considering reoperation for persistent syringomyelia. No benefit or harm was seen with the use of neuromonitoring.

CONCLUSION

This evidence-based clinical guidelines for the treatment of CIM provide 1 Class II and 4 Class III recommendations. In patients with CIM with or without syringomyelia, treatment options include bone decompression with or without duraplasty or cerebellar tonsil reduction. Improved syrinx resolution may potentially be seen with dural patch grafting. Symptom resolution and syrinx resolution did not correlate directly. Reoperation for a persistent syrinx was potentially beneficial if the syrinx had not improved 6 to 12 months after the initial operation. The full guidelines can be seen online at https://www.cns.org/guidelines/browse-guidelines-detail/3-surgical-interventions .

The Chiari Malformations: A Bibliometric Analysis of the 100 Most Cited Articles

OBJECTIVE

The Chiari malformations present heterogeneous entities, raising many questions regarding their natural history, pathophysiology, treatment options, and prognosis. Bibliometric analyses have emerged as a method to assess the impact of articles in current clinical practice.

METHODS

The most cited articles were identified via Scopus Library by using the keywords "Chiari," "Arnold-Chiari," and "Chiari malformation." The 100 most cited articles were then assembled and analyzed in detail.

RESULTS

The top 100 articles yielded a mean of 155,28 citations per article, ranging from 87 to 896 citations, and from 1.63 to 38.96 per year. Years of publications ranged from 1950 to 2015. Oakes was the most cited author (n = 7), followed by Tubbs and Milhorat. The country with the highest cited articles was the United States (n = 63), followed by the United Kingdom (n = 6), Italy (n = 5), Spain (n = 5), Japan (n = 4), and Germany (n = 3). Neurosurgery is the journal with the most highly cited articles (n = 21), followed by Journal of Neurosurgery (n = 19). Most articles focused on Chiari malformation type I (n = 83). The topic discussed most often was imaging (n = 63), followed by the evaluation of treatment outcome (n = 58), clinical signs and symptoms (n = 57), and the role of surgery (n = 56).

CONCLUSIONS

The present bibliometric analysis provides a succinct appraisal of the most cited articles concerning Chiari malformation, allowing a deeper insight in this area and its main influential articles with their impact on current clinical practice and future research.

Long-term outcome and prognostic factors of syringo-subarachnoid shunt for syringomyelia

BACKGROUND

Syringo-subarachnoid shunt (SSS) is often considered a rescue procedure or a second-line treatment option for syringomyelia. However, the clinical efficacy of SSS in treating this condition remains controversial.

OBJECTIVE

To evaluate the long-term outcome of the SSS and its relationship with the syrinx area, as well as to investigate the factors that influence the prognosis.

METHODS

This retrospective study included twenty-seven consecutive patients who underwent SSS between 2014 and 2020. The study evaluated several independent variables such as age, sex, duration of progressive symptoms, morphological characteristics of the syrinx, changes in the syrinx area, and Chiari malformation. The long-term follow-up (>2 years) Japanese Orthopaedic Association (JOA) score was used to assess neurological function and outcome. Statistical analysis was performed using a stepwise logistic regression test.

RESULTS

All patients were followed up for an average of 48.6 ± 14.8(26.8 to 78.0) months. Follow-up magnetic resonance imaging showed syrinx collapse to different degrees occurred in 96.3% (26 of 27) patients. The JOA score was improvedinonly6patients (22.2%), remained stable in 5 patients (18.5%),and deteriorated in 16 patients(59.3%).A logistic regression test showed that the tension syrinx (odds ratio 0.111) and early shunting intervention (odds ratio 0.138) were favorable independent prognostic factors.

CONCLUSIONS

It is important to note that the shrinkage of the syrinx does not necessarily translate to an improvement in clinical outcomes. Therefore, the decision to perform SSS should be made with caution and considered as a last resort.

Exploring the Pathogenesis of Atlanto-Occipital Instability in Chiari Malformation With Type II Basilar Invagination: A Systematic Morphological Study

BACKGROUND

Our previous study suggested that atlanto-occipital instability (AOI) is common in patients with type II basilar invagination (II-BI).

OBJECTIVE

To further understand the pathogenesis of AOI in Chiari malformations (CM) and CM + II-BI through systematic measurements of the bone structure surrounding the craniocervical junction.

METHODS

Computed tomography data from 185 adults (80 controls, 63 CM, and 42 CM + II-BI) were collected, and geometric models were established for parameter measurement. Canonical correlation analysis was used to evaluate the morphological and positional relationships of the atlanto-occipital joint (AOJ).

RESULTS

Among the 3 groups, the length and height of the condyle and superior portion of the lateral masses of the atlas (C1-LM) were smallest in CM + II-BI cases; the AOJ had the shallowest depth and the lowest curvature in the same group. AOJs were divided into 3 morphological types: type I, the typical ball-and-socket joint, mainly in the control group (100%); type II, the shallower joint, mainly in the CM group (92.9%); and type III, the abnormal flat-tilt joint, mainly in the CM + II-BI group (89.3%). Kinematic computed tomography revealed AOI in all III-AOJs (100%) and some II-AOJs (1.5%) but not in type I-AOJs (0%). Morphological parameters of the superior portion of C1-LM positively correlated with those of C0 and the clivus and significantly correlated with AOI.

CONCLUSION

Dysplasia of the condyle and superior portion of C1-LM exists in both CM and II-BI cases yet is more obvious in type II-BI. Unstable movement caused by AOJ deformation is another pathogenic factor in patients with CM + II-BI.

Management of Adult Chiari I Patients Based on CSF Flow Magnetic Resonance Imaging: Experience of Two Neurosurgical Centers

BACKGROUND AND STUDY AIMS

 Chiari malformation type 1 (CM1) is one of the most discussed neurosurgical disorders. No consensus exists how to manage adult CM1 patients. We aimed to evaluate all adult CM1 patients consecutively managed at our institutions and discuss our approach based on the phase-contrast (PC) magnetic resonance imaging (MRI).

PATIENTS AND METHODS

 The medical charts of adult patients diagnosed with CM1 at two referral neurosurgical centers between 2010 and 2017 were reviewed. The patients were either managed conservatively or surgically. We evaluated the patients clinically with the Chicago Chiari Outcome Scale (CCOS). The radiologic diagnosis was based on both craniocervical and PC-MRI.

RESULTS

 Ninety adult CM1 patients were managed conservatively. Conservative treatment failed in 5 of these 90 patients. Seventy-two patients (including those 5 patients who did not benefit from conservative treatment) underwent posterior fossa decompression with duraplasty. Eighty-five patients (94.4%) from the conservative group and 61 patients (84.7%) from the surgical group were treated successfully. An aqueductal stroke volume (ASV) value of 12 µL was found as the cutoff value for surgical candidates. A strong positive correlation between the increase in ASV values and clinical improvement was observed.

CONCLUSIONS

 PC-MRI can help in the management and follow-up of adult CM1 patients. Conservative management is possible in selected symptomatic CM1 patients with a high ASV (ASV > 15 µL). Surgery should be considered in patients with an ASV ≤ 12 µL. CM1 patients with ASV ≤12 to >15 μL require close follow-up. Long-standing symptoms, severe sleep apnea, symptoms influencing functionality, and syrinx are factors that affected outcomes negatively.

Full-endoscopic technique for posterior fossa decompression in Chiari malformation type I: An anatomical feasibility study in human cadavers

Although endoscope-assisted techniques have been described, a full-endoscopic approach is yet to be performed for posterior fossa decompression (PFD) in Chiari malformation type I (CM-I). This study aims to describe the full-endoscopic PFD technique and evaluate its feasibility. Five fresh-frozen anonymized adult human cadavers were operated on using an endoscope with an oval shaft cross-section with a diameter of 9.3 mm, a working length of 177 mm, and a viewing angle of 20°. It also had an eccentric working channel with a diameter of 5.6 mm, a light guide, a sheath for continuous irrigation, and a rod lens system. The instruments were introduced from the working channel. Posterior craniocervical structures were dissected, and PFD was achieved. The planned steps were performed in all five cadavers. The endoscope was introduced to the posterior craniocervical region, dissecting the structures to easily expose the suboccipital bone and C1 posterior arch. Important structures, such as the C1 posterior tubercle, rectus capitis posterior minor muscles, and posterior atlantooccipital membrane, were used as landmarks. PFD was feasible even with the dural opening. Using the full-endoscopic approach, posterior craniocervical structures can be reached, and PFD can be performed successfully. The instruments used are well-defined for spinal usage; thus, this full-endoscopic technique can be widely used in the surgical treatment of patients with CM-I.

Association between synthetic sealants and increased complication rates in posterior fossa decompression with duraplasty for Chiari malformations regardless of graft type

OBJECTIVE

Dural sealants are commonly used in posterior fossa decompression with duraplasty (PFDD) for Chiari malformation type I (CMI). Prior evidence suggests that combining certain sealants with some graft material is associated with an increased rate of complications. In 2018, the authors noted an increased rate of symptomatic pseudomeningocele and aseptic meningitis after PFDD in CMI patients. The authors utilized retrospective and prospective analyses to test the hypothesis that complication rates increase with the use or combination of certain sealants and grafts.

METHODS

The analysis was split into 2 periods. The authors retrospectively reviewed patients who underwent PFDD for CMI at their center between August 12, 2011, and December 31, 2018. The authors then eliminated use of DuraSeal on the basis of the retrospective analysis and prospectively examined complication rates from January 1, 2019, to August 4, 2021. The authors defined a complication as symptomatic pseudomeningocele, bacterial or aseptic meningitis, cerebrospinal fluid leak, subdural hygroma, hydrocephalus, surgical site infection, or wound dehiscence.

RESULTS

From 2011 to 2018, complications occurred in 24.5% of 110 patients. Sealant choice was correlated with complication rates: no sealant (0%), Tisseel (6%), and DuraSeal (15.3%) (p < 0.001). No difference in complication rate was noted on the basis of choice of graft material (p = 0.844). After eliminating DuraSeal, the authors followed 40 patients who underwent PFDD after 2018. The complication rate decreased to 12.5%. All complications after 2018 were associated with Tisseel.

CONCLUSIONS

At the authors' single center, use of sealants in PFDD surgery for CMI, especially DuraSeal, was correlated with a higher complication rate. Eliminating DuraSeal led to a significant decrease in the rate of symptomatic pseudomeningocele and aseptic meningitis.

Possible predictive clinical and radiological markers in decision making for surgical intervention in patients with Chiari Malformation type 1

BACKGROUND

The first aim of this study was to compare the clinical data and posterior fossa morphometry obtained during the admission to the hospital between control group individuals (who had not Chiari Malformation (CM) type 1) and CM type 1 patients treated surgically or not. The second aim was to create a valid and reliable scale that can predict the decision-making for surgical intervention simply and easily in these patients.

MATERIALS

Medical data and radiological images of 70 CM type 1 patients during their admission to the hospital were compared with the data of 69 control group individuals.

RESULTS

Conservative treatment and/or follow-up was applied to 58 (82.9%) patients, and 12 (17.1%) patients underwent surgery. ROC analysis showed that the presence of myelopathy, tonsillar herniation >8 mm, Chamberlain line >84 mm, McRae line >44.50 mm, and odontoid process-McRae line angle <10.50 degrees could be used as predictive markers in decision-making for surgical intervention (p < 0.05). Logistic Regression analysis revealed that symptoms severity, and McRae line value would be the 'best parameters' in decision-making for surgical intervention (p < 0.05). A scale named the CHIASURG scale developed using this study's parameters showed that the parameters of 'depth of tonsillar herniation', 'Chamberlain line', and 'McRae line' could predict the surgical intervention risk.

CONCLUSION

It was found that symptoms severity and McRae line value could be used as predictive markers in decision-making for surgical intervention. Additionally, it was concluded that a new scale called CHIASURG could predict surgical intervention risk validly and reliably.

Comparison of Clinical and Radiologic Outcomes between Dural Splitting and Duraplasty for Adult Patients with Chiari Type I Malformation

Background The most used surgical procedure in the treatment of patients with Chiari type I malformation (CIM) is posterior fossa decompression. However, no consensus has been reached regarding the superiority of either dural splitting or duraplasty. Thus, the aim of this study was to compare clinical and radiologic outcomes between the two techniques used in consecutive patients.

Methods We retrospectively reviewed 74 adult patients with CIM who were diagnosed and treated surgically between 2015 and 2020 at our neurosurgery department. The patients were divided into two groups: dural splitting in group 1 and duraplasty in group 2. Clinical outcomes based on Chicago Chiari Outcome Scale (CCOS) scores at the last control visits were compared between the groups. Radiologic outcomes were compared in terms of tonsillar regression rate based on 12-postoperative-month magnetic resonance images.

Results Overall improved, unchanged, and worsened neurologic statuses were observed in 75.6% (n = 56), 17.5% (n = 13), and 6.7% (n = 5) of our patients, respectively. The mean last visit CCOS scores in groups 1 and 2 were 12.3 ± 2.1 and 13.5 ± 1.7, respectively. The difference between the groups was statistically significant (p < 0.01). The mean tonsillar regression rates were 34.7 ± 17.0% and 52.1 ± 15.3% in groups 1 and 2, respectively, with a statistically significant difference (p < 0.001).

Conclusion Adult patients undergoing duraplasty had better clinical and radiologic outcomes than those treated with dural splitting. Therefore, we recommend decompression with duraplasty for adult CIM patients.

Conservative Treatment of Chiari Malformation Type I Based on the Phase-Contrast MRI: A Retrospective Study

BACKGROUND

The phase-contrast magnetic resonance image (PC-MRI) use is interestingly increased in diagnosis and follow-up patients with Chiari Type I Malformation (CM1). The current study aimed to elaborate the benefits of conservative treatment by evaluating consecutively treated adult patients with CM1 who were selected on basis of the PC-MRIs.

METHODS

Medical records of patients diagnosed with CM1 were retrospectively reviewed at two neurosurgical centers spanning eight years (2010-2017). Adult patients with CM1, who were treated conservatively and met study criteria, were selected to be the core sample for this study. Between-groups (benefited vs non-benefited) comparisons were performed to understand the factors that may affect the outcomes.

RESULTS

Ninety (68 females and 22 males) adult patients received conservative treatment for CM1. The mean age was 40.6. Headaches and pinprick loss were the most commonly recorded symptoms and clinical findings which were recorded in 58 (64.4%) and 31 (34.4%) patients, respectively. Eleven patients were presented with a syrinx. The mean aqueductal stroke volume (ASV) was 16.5 μl. The conservative treatment failed in treating five (5.6%) patients who underwent surgical intervention. The means of ASV in the benefited and non-benefited groups were 16.7 and 13.2 μl, respectively (p=0.004).

CONCLUSION

Conservative approaches (prescriptive medications, physical therapy, Pilates, and swimming) can improve the life quality of non-surgical candidate adult patients with CM1. Conservative treatment can be useful in selected patients with variably CM1 (ASV=16.7 μl). The presence of heavy sleep apnea or/and functional symptoms were prognostic factors that were affected the conservative treatment negatively.

The factors affecting the outcomes of conservative and surgical treatment of chiari i adult patients: a comparative retrospective study

BACKGROUND

The prognosis of the Chiari malformation type 1 (CM1) demonstrates a variant spectrum that varies from full recovery to complicated worse neurological disability.

OBJECTIVE

To investigate the factors affecting the outcomes of conservative and surgical treatment for CM1 by evaluating adult patients consecutively managed at our institutions.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of patients diagnosed with CM1 at two reference neurosurgical centers for eight years (2010-2017). We selected all CM1 adult patients who managed conservatively or surgically as the core sample for this study. For clinical evaluation, we used a Chicago Chiari Outcome Scale (CCOS). For radiological assessment, we adopted both craniocervical and contrast-phase MRIs. We investigate factors such as age, sex, pretreatment symptoms, symptoms duration, and radiological findings in both groups.

RESULTS

Ninety patients were treated conservatively. After a progression, five of them were treated surgically later and included in a total of 72 patients who underwent decompressive surgery. We successfully managed 85 patients (94.4%) of the conservative group and 64 patients (88.9%) of the surgical group. We found that patients with aqueductal stroke volume (ASV) of 12 µl are surgical candidates. We observed a strong positive correlation between clinical improvement and the increase in ASV values.

CONCLUSIONS

ASV≤12 µl is a significant predictor for surgical intervention. The presence of heavy sleep apnea or/and functional symptoms, tonsillar herniation >13.4 mm on coronal images, low ASV, long symptom durations, and a syrinx are the independent prognostic factors that affected outcomes negatively.

Foramen magnum decompression in adults with Chiari type 1 malformation: use of intraoperative ultrasound to guide extent of surgery

BACKGROUND

Foramen magnum decompression (FMD) is an established technique for patients with Chiari-1 malformation. However, the extent of decompressive surgery is controversial, in particular whether dural opening is undertaken.

OBJECTIVE

In this study, we report outcomes with our technique utilising intraoperative ultrasound (iOU) findings. Decision to proceed for further decompression was based on CSF flow around foramen magnum and visualisation of tip of tonsils.

METHODS

Review of adults with CM-1 undergoing FMD 2013-2018. Patients underwent a suboccipital craniectomy ± partial C1 superior laminectomy ± duraplasty in a stepwise manner. Favourable iOU findings of CSF flow around the foramen magnum and pulsation of the tonsillar tips were sought at each step. Post-operative outcomes were assessed using the Chicago Chiari Outcome Score (CCOS).

RESULTS

Fifty-seven patients were included. The mean age was 47 years (range 18-77 years). There was a strong female preponderance (48 females to nine males). The mean follow-up was 3.2 years (range 1-5 years). Surgery included: suboccipital craniectomy (52/57, 91%), plus partial C1 superior laminectomy (2/57, 4%), and plus duraplasty (3/57, 6%). Redo surgery was undertaken in 7/57 patients (12%). At final follow-up, 56/57 (98%) patients achieved a good (CCOS 13-16) or satisfactory (CCOS 9-12) outcome based on COSS.

CONCLUSIONS

A patient centred approach to surgery utilising findings from iOU can achieve favourable outcomes. Dural opening is not routinely required.

Long-term surgical outcome of Chiari type-I malformation-related syringomyelia: an experience of tertiary referral hospital

OBJECTIVE

Syringomyelia is a common condition seen in patients with Chiari type-I malformation (CM1). The purpose of this retrospective study was to evaluate the long-term clinical and radiological outcomes of posterior fossa decompression with duraplasty (PFDD) with coagulation of tonsillar ectopia in consecutive surgically treated adult patients with CM1-related syringomyelia (CRS).

METHODS

Over 9 years' duration (1993-2001), medical charts of diagnosed patient with CM1 at our neurosurgical center were reviewed retrospectively. This study included adult patients with CM1 who had syringomyelia and underwent PFDD with coagulation of tonsillar ectopia surgery. The differences between the pre- and postoperative syrinx/cord ratio (S/C), the syrinx length, and the regression of herniated cerebellar tonsils on coronal and midsagittal MRIs were evaluated.

RESULTS

A total of 87 surgical procedures (46 primary operations, 7 ventriculoperitoneal shunts, and 34 additional operations) for CRS were performed on 24 males and 22 females. The mean preoperative S/C was 0.59 ± 0.12. The means of regression in herniated cerebellar tonsils on mid-sagittal and coronal images were 11.8 ± 2.3 mm and 10.2 ± 2.2 mm (p < 0.0001), respectively. 35 (76.1%) patients were discharged after showing signs of recovery or improvement. Different complications occurred in 16 (34.8%) patients. Negative correlations were noticed between postoperative recovery/improvement and the long symptoms' duration, the herniated tonsils' extent, S/C, and the persistence of the herniated tonsils on the coronal images.

CONCLUSION

Early diagnosis of patients with CRS can improve surgical outcomes. Due to its efficacy in resolving clinical symptoms and syrinx cavities, PFDD is still an optimal surgical approach for CRS.

Nonoperative management of enlarging syringomyelia in clinically stable patients after decompression of Chiari malformation type I

OBJECTIVE

The authors aimed to describe the natural history and optimal management of persistent syringomyelia after suboccipital craniectomy for Chiari malformation type I (CM-I).

METHODS

A cohort of all patients who presented to a tertiary pediatric hospital with newly diagnosed CM-I between 2009 and 2017 was identified. Patients with persistent or worsened syringomyelia were identified on the basis of a retrospective review of medical records and imaging studies. The management of these patients and their clinical courses were then described.

RESULTS

A total of 153 children with CM-I and syringomyelia were evaluated between 2009 and 2017. Of these, 115 (68.8%) patients underwent surgical intervention: 40 patients underwent posterior fossa decompression (PFD) alone, 43 underwent PFD with duraplasty, and 32 underwent PFD with duraplasty and fourth ventricle stent placement. Eleven (7.19%) patients had increased syringomyelia on subsequent postoperative imaging. Three of these patients underwent revision surgery because of worsening scoliosis or pain, 2 of whom were lost to follow-up, and 4 were managed nonoperatively with close surveillance and serial MRI evaluations. The syringes decreased in size in 3 patients and resolved completely in 1 patient.

CONCLUSIONS

Persistent or worsened syringomyelia after CM-I decompression is uncommon. In the absence of symptoms, nonoperative management with close observation is safe for patients with persistent syrinx.

Comparison of two surgical techniques in Chiari Malformation Type 1 Patients: Duraplasty alone vs duraplasty with arachnoid dissection

OBJECT

Optimal surgical technique to restore the cerebrospinal fluid flow through the foramen magnum remains to be debated in Chiari malformation type 1 (CM-1) patients.

METHOD

This study included 46 patients with CM-1 who underwent surgical treatment by one of two methods: posterior fossa bone decompression (BD) with arachnoid preserving duraplasty (Group 1) and BD with duraplasty and arachnoid dissection (Group 2). Complaints of the patient population and neurological findings were assessed with Neck Disability Index (NDI) and Europe Quality of Life 5 Dimensions (EQ-5D) in pre- and postoperative periods.

RESULTS

NDI and EQ-5D scores improved in overall patient population and in each individual surgical group. Both groups showed a significant decrease in size of syringomyelia cavity. Complications resulting in recurrent treatments and re-operations occurred in 15% of patients (n = 7); six of them were from Group 2.

CONCLUSION

CM-1 patients benefit significantly from surgical treatment. Duraplasty should be included to surgical technique. Avoiding arachnoid dissection may lead to better results regarding complication rates.

Outcomes for various dural graft materials after posterior fossa decompression with duraplasty for Chiari malformation type I: a systematic review and meta-analysis

OBJECTIVE

Posterior fossa decompression with duraplasty (PFDD) is often used for Chiari malformation type I (CM-I), but outcomes associated with different dural graft materials are not well characterized. In this meta-analysis, the authors examined complication rates and outcomes after PFDD for CM-I for autografts and four types of nonautologous grafts.

METHODS

A literature search of numerous electronic databases (Ovid Medline, Embase, Scopus, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Database of Abstracts of Reviews of Effects, Health Technology Assessment Database, NHS Economic Evaluation Database, and ClinicalTrials.gov) was performed to identify articles detailing complications for dural graft materials after PFDD. Whenever available, data were also extracted regarding the need for revision surgery, symptom changes after PFDD, and syrinx size changes after PFDD. All searches were compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), Institute of Medicine, Standards for Systematic Reviews, Cochrane Handbook for Systematic Reviews of Interventions, and Peer Review of Electronic Search Strategies guidelines. There were no exclusion criteria based on patient age or presence or absence of syringomyelia.

RESULTS

The current evidence surrounding outcomes for various dural graft materials was found to be of low or very low quality. Twenty-seven studies were included, encompassing 1461 patients. Five types of dural graft materials were included: autograft (n = 404, 27.6%), synthetic (n = 272, 18.6%), bovine pericardium (n = 181, 12.4%), collagen-based (n = 397, 27.2%), and allograft (n = 207, 14.2%). Autograft was associated with a significantly lower rate of pseudomeningocele compared to collagen-based grafts, allografts, and nonautologous grafts in aggregate. Autograft was also associated with the lowest rates of aseptic meningitis, infectious meningitis, and need for revision PFDD, though these associations did not reach statistical significance. No other graft comparisons yielded significant results. Autograft and nonautologous graft materials yielded similar rates of revision surgery and produced similar improvements in postoperative symptoms and syrinx size.

CONCLUSIONS

Autograft was the dural graft material that most frequently had the lowest rate of complications and was associated with significantly lower rates of pseudomeningocele compared to collagen-based graft, allograft, and nonautologous graft materials. Autografts and nonautologous grafts yielded similar outcomes for revision surgery, symptoms, and syrinx size. Large prospective studies comparing different graft materials are needed to accurately and precisely characterize outcomes for individual graft types.

Preoperative Acetazolamide Challenge in Pediatric Chiari I Malformation

PURPOSE

In patients who present with headaches and Chiari 1 malformation without cranial nerve or brainstem dysfunction or syrinx formation, the decision to decompress can be difficult to make. We present a case series examining the use of acetazolamide as a diagnostic aid to determine candidacy for decompression.

METHODS

A single pediatric neurosurgeon's (M.M.H.) experience from 2003 to 2018 was retrospectively reviewed. All cases evaluated in the clinic for CPT code of Chiari 1 malformation were analyzed. Inclusion criteria were patients with diagnosis of Chiari 1 malformation and headache-predominant symptoms who underwent an acetazolamide challenge test. Exclusion criteria included age over 18, syrinx, or significant clinical evidence of brainstem compression or cranial nerve dysfunction. Data were recorded with respect to response to acetazolamide. Surgical outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS) pain category and the improve/same/worse (IWS) scale. Overall satisfaction from surgery was also recorded.

RESULTS

Forty-five patients met inclusion criteria and underwent acetazolamide challenge. Thirty-three (73.3%) patients showed improvement of their symptoms with acetazolamide challenge (responders). Of the 33 responders, 25 (75.8%) underwent Chiari decompression. The remaining 8 (24.2%) responders experienced persistent improvement of their symptoms after the acetazolamide trial and did not require intervention. Twelve (26.7%) patients did not improve with acetazolamide (nonresponders) of which 11 (91.7% of nonreponders) never required intervention. One nonresponder eventually underwent Chiari decompression due to progressively worsening and debilitating headaches. All twenty-five (100%) responders improved after surgery and 24 (96%) were satisfied with the outcome of surgery. The average responder CCOS pain score was 3.52 out of 4. The nonresponder who did not improve with acetazolamide had persistent severe headaches after decompression. The CCOS pain score for this nonresponder was 2 out of 4.

CONCLUSION

Pediatric headache-predominant Chiari 1 malformation presents a difficult diagnostic dilemma. The authors describe a trial of acetazolamide as a preoperative diagnostic tool to aid the decision to decompress. Further studies will need to be performed to determine the effectiveness of preoperative acetazolamide in identifying which patients may benefit from surgical decompression.

The 270° Circumferential Microsurgical Decompression of the Foramen Magnum in Adult Chiari Malformation Type I: Single Surgeon Series of 130 Patients with Syringomyelia, Neurologic, and Headache Outcomes

OBJECTIVE

Chiari malformation type I (CM-I) is a craniocervical junction disorder associated with descent of the cerebellar tonsils >5 mm. The prevalence of CM-I is common, including 0.5%-3.5% in the general population, 0.56%-0.77% on magnetic resonance imaging, and 0.62% in anatomic dissection studies. We sought to measure our surgical outcomes related to resolution/improvement of headaches, neurologic outcomes, and syringomyelia compared with reported adult CM-I studies from 2000-2019.

METHODS

From December 2003 to June 2018, the first author (K.I.A.) performed 270° circumferential decompression on adult (>18 years) patients with CM-I. At admission and follow-up, all parameters were numerically evaluated; headaches were self-reported on the visual analog scale, neurologic condition was evaluated using Karnofsky Performance Status and European Myelopathy Score, and syrinx width (if present) was measured on magnetic resonance imaging by grades I-IV. All parameters were analyzed, compared, and statistically tested. We compared results with our previously reported and updated systematic review of operative adult CM-I studies (studies from 2000 to 2019).

RESULTS

In our series, 118/121 (98%) experienced headache improvements and 100% experienced neurologic improvements. Complete syrinx resolution was experienced by 35/43 (81%); 8 (19%) showed significant improvement. In data from reported studies (2000-2019), only 79% experienced headache resolution, 77% improvement of neurologic status, and 74% resolution/improvement of syrinx (mean).

CONCLUSIONS

Our modified 270° circumferential microsurgical foramen magnum decompression for adult CM-I appears to be beneficial in improvement of outcomes, namely in resolution of the syrinx, neurologic symptoms, and headaches. We also confirm the association of body mass index with CM-I. Further studies are needed to confirm our results.

Clinical and radiological evaluation of treated Chiari I adult patients: retrospective study from two neurosurgical centers

Chiari malformation type I (CM1) is a common neurosurgical disorder. It often causes debilitation in the affected patients. CM1 is a herniation of the caudal cerebellum into the spinal canal. This study aimed to evaluate the clinical and radiological outcomes of posterior fossa decompression and duraplasty (PFDD) in treated CM1 patients. In retrospective design, we reviewed the medical records of diagnosed patients with CM1 at two neurosurgical centers spanning 8 years from 2010 to 2017. We selected all CM1 patients who underwent PFDD surgery (n = 72) as the core sample for this study. We used the Chicago Chiari Outcome Scale (CCOS) to evaluate clinical outcomes. Pre- and postoperatively, we assessed the syrinx/cord ratio, the syrinx length, and the improvement of aqueductal stroke volume (ASV) on CSF flow MRIs. The mean value of CCOS was 14.1 ± 2.1. On midsagittal MRIs, the mean regression in ectopia tonsils was 9.4 ± 1.9 mm (i.e., mean pre- and postoperative tonsil herniation was 13.1 ± 3.1 mm and 4.0 ± 1.6 mm, respectively; p < 0.001). On coronal MRIs, the mean regression in ectopia tonsils was 8.4 ± 1.5 mm (i.e., mean pre- and postoperative tonsil herniation was 13.9 ± 2.4 mm and 5.8 ± 1.0 mm, respectively; p < 0.001). A strong positive correlation was observed between clinical improvement and the increase in ASV values. CSF flow MRIs can help in the surgical decision and follow-up of CM1 patients. ASV ≤ 12 μl is a significant predictor for surgical intervention. Full clinical and radiological evaluation utilizing CSF flow MRI are essential. Most syrinx cavities have regressed following PFDD.

Tonsillectomy with modified reconstruction of the cisterna magna with and without craniectomy for the treatment of adult Chiari malformation type I with syringomyelia

BACKGROUND

In light of the controversies regarding the surgical treatment of adult Chiari malformation type I (CM-I) with syringomyelia, a retrospective study was conducted to evaluate the safety and efficacy of tonsillectomy followed by modified reconstruction of the cisterna magna with or without craniectomy.

METHODS

Between 2008 and 2017, 78 adult CM-I patients (36 males and 42 females, mean age 40.6 years old) with syringomyelia were treated with posterior fossa decompression (PFD) with tonsillectomy and modified reconstruction of the cisterna magna. Patients were divided into two study groups: group A (n = 40) underwent cranioplasty with replacement of the bone flap; group B (n = 38) underwent suboccipital craniectomy. Neurological outcomes were evaluated by traditional physician assessment (improved, unchanged, and worsened) and the Chicago Chiari Outcome Scale (CCOS). Syringomyelia outcomes were assessed radiologically.

RESULTS

The procedure was successfully performed in all patients, and restoration of normal cerebrospinal fluid (CSF) flow was confirmed by intraoperative ultrasonography. The median postoperative follow-up was 20.3 months (range 18-60 months). Clinical improvement was evident in 66 (84.6%) patients, with no significant differences between the two groups (85.0% vs. 84.2%, P = 0.897). According to the CCOS, 36 patients (90.0%) in group A were labeled as "good" outcome, compared with that of 34 (86.8%) in group B (P = 0.734). Improvement of syringomyelia was also comparable between the groups, which was observed in 35 (87.5%) vs. 33 (86.8%) patients (P = 0.887). The postoperative overall (7.5% vs. 23.7%, P = 0.048) and CSF-related (2.5% vs. 18.4%, P = 0.027) complication rates were significantly lower in group A than group B.

CONCLUSIONS

Tonsillectomy with modified reconstruction of the cisterna magna without craniectomy seems to be a safe and effective surgical option to treat adult CM-I patients with syringomyelia, though future well-powered prospective randomized studies are warranted to validate these findings.

Chiari malformation type I and basilar invagination originating from atlantoaxial instability: a literature review and critical analysis

Introduction

Recently, a novel hypothesis has been proposed concerning the origin of craniovertebral junction (CVJ) abnormalities. Commonly found in patients with these entities, atlantoaxial instability has been suspected to cause both Chiari malformation type I and basilar invagination, which renders the tried and tested surgical decompression strategy ineffective. In turn, C1-2 fusion is proposed as a single solution for all CVJ abnormalities, and a revised definition of atlantoaxial instability sees patients both with and without radiographic evidence of instability undergo fusion, instead relying on the intraoperative assessment of the atlantoaxial joints to confirm instability.

Methods

The authors conducted a comprehensive narrative review of literature and evidence covering this recently emerged hypothesis. The proposed pathomechanisms are discussed and contextualized with published literature.

Conclusion

The existing evidence is evaluated for supporting or opposing sole posterior C1-2 fusion in patients with CVJ abnormalities and compared with reported outcomes for conventional surgical strategies such as posterior fossa decompression, occipitocervical fusion, and anterior decompression. At present, there is insufficient evidence supporting the hypothesis of atlantoaxial instability being the common progenitor for CVJ abnormalities. Abolishing tried and tested surgical procedures in favor of a single universal approach would thus be unwarranted.

Comparison of surgical outcomes in patients with Chiari Type I malformation receiving posterior fossa decompression with and without duraplasty

PURPOSE

The goals of this study were to compare clinical outcomes in patients with Chiari Malformation Type I (CMI) receiving posterior fossa decompression with (PFDD) or without duraplasty (PFD).

METHODS

We conducted a retrospective analysis of 178 consecutive cases of 157 patients undergoing PFDD or PFD for CMI at Cohen Children's Medical Center between 2007 and 2017. Clinical improvement was defined as a clear reduction of preoperative symptoms after surgery as reported by patients and parents. An improvement of syrinx was derived from radiologic comparison of pre- and postoperative MR imaging. Chi-square analysis was performed to analyze the association between duraplasty and clinical parameters (alpha = 0.05).

RESULTS

The primary presenting complaint was headache (142/178; 80%), followed by neck, back, and upper extremity pain, and numbness or tingling (49/178; 28%). Seventy patients (78/178; 44%) underwent PFD, and 100 patients (100/178; 56%) underwent PFDD. Overall, 143 patients (143/178; 80%) experienced subjective improvement with no statistically significant difference between the two surgical techniques (p = 0.705). The number of patients receiving PFDD with syrinx improvement or stabilization (55/59; 93%) was statistically larger than those that received PFD (8/13; 62%) (p = 0.008). PFDD was associated with greater complications than PFD alone. There were 35 cases of reoperation overall (35/178; 19%), and there was no statistically significant difference in reoperation rate between PFD and PFDD (p = 0.255).

CONCLUSIONS

There appears to be a role for PFDD in patients with severe syringomyelia, but overall, PFD alone may be safely offered as the initial surgical intervention for symptomatic CMI patients.

Chiari I malformations with syringomyelia: long-term results of neurosurgical decompression

STUDY DESIGN

Retrospective case series.

OBJECTIVES

The objective was to assess the long-term outcomes on scoliosis following Chiari-I (CM-I) decompression in patients with CM-I and syringomyelia (SM). A secondary objective was to identify risk factors of scoliosis progression.

BACKGROUND

The association between CM-I with SM and scoliosis is recognized, but it remains unclear if CM-I decompression alters the long-term evolution of scoliosis in patients with associated syringomyelia.

METHODS

A retrospective review of children with scoliosis, CM-I, and SM during 1997-2015 was performed. Congenital, syndromic, and neuromuscular scoliosis were excluded. Clinical and radiographic characteristics were recorded at presentation, pre-decompression, after 1-year, and latest follow-up. A scale to measure syringomyelia area on MRI was used to evaluate SM changes post-decompression.

RESULTS

65 children with CM-I, SM, and scoliosis and a mean age of 8.9 years (range 0.7-15.8) were identified. Mean follow-up was 6.9 years (range 2.0-20.4). Atypical curves were present in 28 (43%) children. Thirty-eight patients (58%) underwent decompression before 10 years. Syringomyelia size reduced a mean of 70% after decompression (p < 0.001). Scoliosis improved in 26 (40%), stabilized in 17 (26%), and progressed in 22 (34%) cases. Early spinal fusion was required in 7 (11%) patients after a mean of 0.5 ± 0.37 years and delayed fusion in 16 (25%) patients after 6.0 ± 3.24 years. The remaining 42 (65%) patients were followed for a median of 6.1 years (range 2.0-12.3) without spine instrumentation or fusion. Fusion patients experienced less improvement in curve magnitude 1-year post-decompression (p < 0.001) and had larger curves at presentation (43° vs. 34°; p = 0.004).

CONCLUSIONS

Syringomyelia size decreased by 70% after CM-I decompression and scoliosis stabilized or improved in two-thirds of patients. Greater curve improvement within the first year post-decompression and smaller curves at presentation decreased the risk of spinal fusion. Neurosurgical decompression is recommended in children with CM-I, SM, and scoliosis with the potential to treat all three conditions.

LEVEL OF EVIDENCE

Level IV.

Factors associated with syrinx size in pediatric patients treated for Chiari malformation type I and syringomyelia: a study from the Park-Reeves Syringomyelia Research Consortium

OBJECTIVE

Factors associated with syrinx size in pediatric patients undergoing posterior fossa decompression (PFD) or PFD with duraplasty (PFDD) for Chiari malformation type I (CM-I) with syringomyelia (SM; CM-I+SM) are not well established.

METHODS

Using the Park-Reeves Syringomyelia Research Consortium registry, the authors analyzed variables associated with syrinx radiological outcomes in patients (< 20 years old at the time of surgery) with CM-I+SM undergoing PFD or PFDD. Syrinx resolution was defined as an anteroposterior (AP) diameter of ≤ 2 mm or ≤ 3 mm or a reduction in AP diameter of ≥ 50%. Syrinx regression or progression was defined using 1) change in syrinx AP diameter (≥ 1 mm), or 2) change in syrinx length (craniocaudal, ≥ 1 vertebral level). Syrinx stability was defined as a < 1-mm change in syrinx AP diameter and no change in syrinx length.

RESULTS

The authors identified 380 patients with CM-I+SM who underwent PFD or PFDD. Cox proportional hazards modeling revealed younger age at surgery and PFDD as being independently associated with syrinx resolution, defined as a ≤ 2-mm or ≤ 3-mm AP diameter or ≥ 50% reduction in AP diameter. Radiological syrinx resolution was associated with improvement in headache (p < 0.005) and neck pain (p < 0.011) after PFD or PFDD. Next, PFDD (p = 0.005), scoliosis (p = 0.007), and syrinx location across multiple spinal segments (p = 0.001) were associated with syrinx diameter regression, whereas increased preoperative frontal-occipital horn ratio (FOHR; p = 0.007) and syrinx location spanning multiple spinal segments (p = 0.04) were associated with syrinx length regression. Scoliosis (HR 0.38 [95% CI 0.16-0.91], p = 0.03) and smaller syrinx diameter (5.82 ± 3.38 vs 7.86 ± 3.05 mm; HR 0.60 [95% CI 0.34-1.03], p = 0.002) were associated with syrinx diameter stability, whereas shorter preoperative syrinx length (5.75 ± 4.01 vs 9.65 ± 4.31 levels; HR 0.21 [95% CI 0.12-0.38], p = 0.0001) and smaller pB-C2 distance (6.86 ± 1.27 vs 7.18 ± 1.38 mm; HR 1.44 [95% CI 1.02-2.05], p = 0.04) were associated with syrinx length stability. Finally, younger age at surgery (8.19 ± 5.02 vs 10.29 ± 4.25 years; HR 1.89 [95% CI 1.31-3.04], p = 0.01) was associated with syrinx diameter progression, whereas increased postoperative syrinx diameter (6.73 ± 3.64 vs 3.97 ± 3.07 mm; HR 3.10 [95% CI 1.67-5.76], p = 0.003), was associated with syrinx length progression. PFD versus PFDD was not associated with syrinx progression or reoperation rate.

CONCLUSIONS

These data suggest that PFDD and age are independently associated with radiological syrinx improvement, although forthcoming results from the PFDD versus PFD randomized controlled trial (NCT02669836, clinicaltrials.gov) will best answer this question.

Management of Chiari I malformations: a paradigm in evolution

PURPOSE

Despite decades of experience and research, the etiology and management of Chiari I malformations (CM-I) continue to raise more questions than answers. Controversy abounds in every aspect of management, including the indications, timing, and type of surgery, as well as clinical and radiographic outcomes. This review aims to outline past experiences, consolidate current evidence, and recommend directions for the future management of the Chiari I malformation.

METHODS

A review of recent literature on the management of CM-I in pediatric patients is presented, along with our experience in managing 1073 patients who were diagnosed with CM-I over the past two decades (1998-2018) at Children's National Medical Center (CNMC) in Washington DC.

RESULTS

The general trend reveals an increase in the diagnosis of CM-I at younger ages with a significant proportion of these being incidental findings (0.5-3.6%) in asymptomatic patients as well as a rise in the number of patients undergoing Chiari posterior fossa decompression surgery (PFD). The type of surgical intervention varies widely. At our institution, 104 (37%) Chiari surgeries were bone-only PFD with/without outer leaf durectomy, whereas 177 (63%) were PFD with duraplasty. We did not find a significant difference in outcomes between the PFD and PFDD groups (p = 0.59). An analysis of failures revealed a significant difference between patients who underwent tonsillar coagulation versus those whose tonsils were not manipulated (p = 0.02).

CONCLUSION

While the optimal surgical intervention continues to remain elusive, there is a shift away from intradural techniques in favor of a simple, extradural approach (including dural delamination) in pediatric patients due to high rates of clinical and radiographic success, along with a lower complication rate. The efficacy, safety, and necessity of tonsillar manipulation continue to be heavily contested, as evidence increasingly supports the efficacy and safety of less tonsillar manipulation, including our own experience.

Response of Syrinx Associated with Chiari I Malformation to Posterior Fossa Decompression with or without Duraplasty and Correlation with Functional Outcome: A Prospective Study of 22 Patients

Background

The aim of the study is to correlate the surgical outcome with radiological changes in patients with Chiari I malformation (CMI) with syrinx. We also compared long-term functional and radiographic outcome in CM1 patients treated with posterior fossa decompression (PFD) with or without duroplasty.

Patients and Methods

From December 2013 to October 2015, 22 patients who underwent surgery with the diagnosis of CMI and syrinx were included in the study. Measurements were performed on preoperative and postoperative magnetic resonance (MR) scans using the same software. All patients underwent PFD with or without duroplasty. Clinical results were evaluated on the basis of the Chicago Chiari Outcome Scale (CCOS). We assessed the degree of resolution of syrinx and outcome of Chiari decompression with PFD versus PFD with duroplasty. Mean duration of follow-up was 12.4 ± 5.37 months (range: 6-24 months).

Results

Out of 19 patients in whom syrinx diameter decreased on postoperative MR imaging, 17 (89.5%) improved based on CCOS and 2 (10.5%) were unchanged while out of three patients in whom syrinx worsened, 2 (66.7%) improved and 1 (33.3%) was unchanged (P = 0.37). The cord diameter was found to have decreased in 12 patients and of these 11 (91.7%) improved. The cord diameter increased in 10 patients, but 8 (80%) improved (P = 0.57). The mean changes in syrinx, cord, and syrinx/cord ratio were studied in both groups with and without duroplasty, were not statistically significant. In this study, radiological parameters failed to predict functional outcome.

Conclusions

The outcome does not correlate with change in any of the syrinx-related factors. Surgical decompression with or without duroplasty does not have a statistically significant relationship in the degree of syrinx resolution. Surgical decompression without duroplasty provides the benefits of surgical decompression while avoiding the complications of intradural techniques.

Surgical Experience in Pediatric Patients with Chiari-I Malformations Aged ≤18 Years

Objective:

The objective of this study was to retrospectively study Chiari I malformation patients (<18 years) treated surgically.

Materials and Methods:

Chiari I malformation patients (<18 years) treated surgically at our institute were retrospectively studied.

Results:

During the study period between January 1999 and June 2011, fifty patients, aged ≤18 years with Chiari malformation, were treated surgically and formed the basis for this series. There were 21 female children (42%) and 29 male children (58%), with a female-to-male ratio of 1:1. At the last follow-up, oropharyngeal symptoms were improved in 33% (n = 3/9). Headache/neck/back pain improved in 69.56% of children (n = 16/23). Upper-extremity pain/weakness/numbness improved in 73.91% of children (n = 17/23). Ataxia improved in 66.66% of children (n = 4/6). Lower-limb weakness/hyperreflexia improved in 83.33% of children (n = 5/6). At follow-up, magnetic resonance imaging for patients with syrinx was available for 75% of patients (n = 30/50) and not available for 25% of patients (n = 10/40). Syrinx was diminished in size or resolved in 66.33% of patients (n = 19/30) and the remaining was same for 36.66% of patients (n = 11/30).

Conclusions:

The main goal of surgery is to arrest the progression of neurological deficits. Foramen magnum decompression with a lax duroplasty is the surgical procedure of choice.

Hydrocephalus after foramen magnum decompression for Chiari I malformation successfully treated with the aspiration of pseudomeningocele: a case report

Background

Pseudomeningocele or cerebrospinal fluid leakage is one of the most common complications of foramen magnum decompression with duraplasty for Chiari I malformation. Usually, cerebrospinal fluid leakage is treated with lumbar drainage and/or secondary suture. However, if hydrocephalus occurs, spinal drainage may cause brain herniation.

Case presentation

A 54-year-old Japanese woman presented to our hospital with a 10-month history of bilateral finger extension weakness and clumsiness. Magnetic resonance imaging showed displacement of her cerebellar tonsils below the foramen magnum level, with syringomyelia presenting from the C4 to T8 level. Suboccipital craniectomy and C1 laminectomy with duraplasty were performed under general anesthesia. At 1 month after discharge, she again presented to our hospital due to severe headache and nausea. Magnetic resonance imaging of her cervical spine showed pseudomeningocele compressing her cerebellum and spinal cord. Magnetic resonance imaging of her brain also showed ventriculomegaly. Pseudomeningocele aspiration was performed, with 25 ml of fluid removed under X-ray control. Immediately after aspiration her headache and nausea decreased, and she reported improvement in her symptoms with increasing bilateral finger extension strength and decreasing bilateral upper extremity numbness at her 1-year follow-up.

Conclusions

Although there is a considerable risk of meningitis with the aspiration procedure of pseudomeningocele, an aspiration procedure may be an easy and effective treatment option for postoperative hydrocephalus after suboccipital craniotomy with duraplasty in a patient treated for Chiari I malformation.

Predictive value of posterior cranial fossa morphology in the decompression of Chiari malformation type I: A retrospective observational study

Posterior fossa decompression (PFD) is the standard procedure for the treatment of Chiari malformation type I (CMI). Although most patients have satisfactory surgical outcomes, some show no improvement or even a worsening of symptoms. Patient selection is thought to account for these different surgical outcomes. Our aim was to evaluate the predictive value of the preoperative posterior cranial fossa (PCF) morphology on the efficacy of PFD.Data from 39 CMI patients with CMI-related symptoms who underwent occipital foramen enlargement + C-1 laminectomy + enlarged duraplasty were retrospectively collected from January 2011 to May 2018. The patients were divided into improved and unimproved groups according to the modified Chicago Chiari Outcome Scale. Demographic information and clinical history, including preoperative comorbidities and clinical manifestations, were recorded for the 2 groups and compared. PCF morphology was assessed based on 13 linear, 8 angular, 4 areal parameters and 4 ratios related to these liner and areal parameters. The data were then analyzed statistically.Of the 39 patients with CMI, 24 showed improvement after PFD (61.5%), whereas the remaining 15 patients showed no improvement (38.5%). The preoperative symptoms lasted 1 to 240 months, with a median of 24 months. The follow-up period ranged from 2 to 82 months, with a median of 27 months. The improved and unimproved groups differed significantly with regard to upper limb numbness (OR = 10, P = .02) and upper limb weakness (OR = 4.86, P = .02). The 2 groups did not differ significantly with regard to any morphological parameters such as tonsillar descent, syrinx size.Preoperative upper limb numbness and upper limb weakness are unfavorable factors that influence the outcome of PFD in patients with CMI. However, the morphology of PCF cannot predict the response to PFD in patients with CMI.

Treatment of Holocord Syringomyelia-Chiari Complex by Posterior Fossa Decompression and a Syringosubarachnoid Shunt in a Single-Stage Single Approach

BACKGROUND

Posterior fossa decompression with expansive duraplasty is the first-line surgical approach for the treatment of symptomatic syringomyelia associated with Chiari malformation. Despite good decompression, the clinical failure rate is reported to be up to 26%. A syringosubarachnoid (S-S) shunt may be used as a secondary option.

METHODS

In this paper we describe a single-institution experience of three cases of holocord syringomyelia-Chiari complex treated with foramen magnum decompression, expansive duraplasty and an S-S shunt carried out in a single-stage single approach. Following a standard suboccipital craniectomy, patients were submitted to syrinx fenestration and simultaneous insertion of an S-S shunt through a 1-mm posterior midline myelotomy at the C2 level prior to expansive dural reconstruction.

RESULTS

Postoperative imaging showed immediate reduction of the holocord cavities. Preoperative neurological deficits rapidly improved significantly and were stabilized at follow-up.

CONCLUSION

In our experience the positioning of the shunt catheter at a high level of the spinal cord (C2) did not add a significant risk of morbidity and obviated the need for a second operation and/or a separate incision in cases of clinical failure. This technique avoided the risk associated with a second surgery and its morbidity, and allowed prompt clinical recovery.

Surgical Treatment of Chiari Malformation in Adults: Comparison of Surgical Techniques Described in the Literature and Our Experience

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Chiari 1 Malformation Surgery: Comparing Non-violation of the Arachnoid versus Arachnoid Opening and Thermocoagulation of the Tonsils

OBJECTIVE

Evidence is lacking concerning the myriad surgical techniques for type 1 Chiari malformation. This study evaluated the impact of arachnoid violation with tonsil thermocoagulation during surgical craniovertebral junction decompression.

METHODS

The evaluation included aspects of the neurologic examination and parameters of cerebrospinal fluid flow on magnetic resonance imaging during preoperative and postoperative periods. All patients underwent craniovertebral junction decompression and opening of the dura mater. Patients were divided into 2 study groups. Patients in group 1 did not undergo arachnoid violation. Patients in group 2 underwent tonsil manipulation and systematic opening of the fourth ventricle outlet.

RESULTS

There were 16 patients enrolled in each group (total of 32 patients). Regarding clinical improvement, there were no significant differences between groups in the postoperative period. Group 2 had more adverse events (relative risk 2.45, 95% confidence interval 1.55-3.86). In terms of cerebrospinal fluid flow parameter analyses, patients in group 1 achieved better results (P < 0.05).

CONCLUSIONS

For treatment of symptomatic type 1 Chiari malformation, craniovertebral junction decompression with arachnoid preservation (i.e., without tonsillar manipulation) seems more suitable than the addition of arachnoid opening and thermocoagulation of the tonsils.

Management of hydrocephalus and subdural hygromas in pediatric patients after decompression of Chiari malformation type I: case series and review of the literature

OBJECTIVE

Hydrocephalus associated with subdural hygromas is a rare complication after decompression of Chiari malformation type I (CM-I). There is no consensus for management of this complication. The authors present a series of 5 pediatric patients who underwent CM-I decompression with placement of a dural graft complicated by posterior fossa hygromas and hydrocephalus that were successfully managed nonoperatively.

METHODS

A retrospective review over the last 5 years of patients who presented with hydrocephalus and subdural hygromas following foramen magnum decompression with placement of a dural graft for CM-I was conducted at 2 pediatric institutions. Their preoperative presentation, perioperative hospital course, and postoperative re-presentation are discussed with attention to their treatment regimen and ultimate outcome. In addition to reporting these cases, the authors discuss all similar cases found in their literature review.

RESULTS

Over the last 5 years, the authors have encountered 194 pediatric cases of CM-I decompression with duraplasty equally distributed at the 2 institutions. Of those cases, 5 pediatric patients with a delayed postoperative complication involving hydrocephalus and subdural hygromas were identified. The 5 patients were managed nonoperatively with acetazolamide and high-dose dexamethasone; dosages of both drugs were adjusted to the age and weight of each patient. All patients were symptom free at follow-up and exhibited resolution of their pathology on imaging. Thirteen similar pediatric cases and 17 adult cases were identified in the literature review. Most reported cases were treated with CSF diversion or reoperation. There were a total of 4 cases previously reported with successful nonoperative management. Of these cases, only 1 case was reported in the pediatric population.

CONCLUSIONS

De novo hydrocephalus, in association with subdural hygromas following CM-I decompression, is rare. This presentation suggests that these complications after posterior fossa decompression with duraplasty can be treated with nonoperative medical management, therefore obviating the need for CSF diversion or reoperation.

Duraplasty Type as a Predictor of Meningitis and Shunting After Chiari I Decompression

BACKGROUND

Expansile duraplasty is frequently performed during Chiari I decompression. Aseptic and bacterial meningitis are possible complications of this procedure. We sought to compare the rates of meningitis and subsequent need for cerebrospinal fluid (CSF) diversion with duraplasty using bovine pericardial (BPC) xenograft and allograft.

METHODS

We conducted a retrospective review of 112 patients who underwent Chiari I decompression. All patients underwent duraplasty with either allograft or BPC. Occurrence of postoperative lumbar punctures and associated data were recorded to determine rates of meningitis. Rates of subsequent shunting were also recorded.

RESULTS

Overall, 112 patients were included in the study: 30 underwent duraplasty with allograft (27%) and 82 received BPC (73%). A total of 26 patients developed postoperative meningitis (23 cases of chemical meningitis and 3 of bacterial meningitis). Rates of meningitis were higher in patients who received BPC than patients who received allograft (28% vs. 10%, respectively; P = 0.047). The rate of shunting was greater in patients with meningitis compared with patients without meningitis (56.5% vs. 5.75%, respectively; P < 0.0001). Moreover, 13 of the 15 patients (87%) in the BPC cohort who were shunted were found to have meningitis compared with 0 of the 3 shunted patients (0%) in the allograft cohort (P = 0.044).

CONCLUSIONS

We found that rates of total meningitis were greater in patients who underwent Chiari I decompression and duraplasty with BPC compared with an allograft. The rate of shunting was significantly higher for patients who developed meningitis after decompression compared with patients without meningitis.

[Posterior decompression of the craniovertebral junction in syringomyelia combined with Chiari-1 malformation in children]

OBJECTIVE

to develop the algorithm for defining the amount of posterior decompression of the craniovertebral junction in children with syringomyelia combined with Chiari-1 malformation.

MATERIAL AND METHODS

Sixty eight children with syringomyelia and Chiari-1 malformation, under age of 18 years, underwent posterior decompression of the craniovertebral junction (PDCVJ) in the period from January 2001 to June 2016. Seven (10%) patients underwent extradural decompression (EDD), 16 (24%) patients underwent extra-arachnoid duraplasty (EAD), 25 (37%) patients underwent intra-arachnoid dissection (IAD) and duraplasty, and 20 (29%) patients underwent PDCVJ and placement of a fourth ventricle-subarachnoid shunt.

RESULTS

Clinical improvement occurred in 85% of patients, and stabilization was observed in 11% of patients. Syringomyelia regressed in 78% of cases. There were no complications associated with EDD; however, re-operation was required in 3 (43%) cases. In the case of EAD, treatment results were satisfactory in 11 (79%) patients; re-operation was required in 2 (12.5%) cases; there were no complications in the early postoperative period. The highest complication rate of 6 (30%) cases was associated with shunt placement and duraplasty. However, long-term results in this group of patients were satisfactory in 16 (94%) cases, and MRI-based positive changes were observed in 100% of cases.

CONCLUSION

According to our analysis, EAD is the method of choice for PDCVJ in children with syringomyelia and Chiari-1 malformation without myelopathy symptoms. In the presence of myelopathy symptoms, intra-arachnoid dissection (with or without shunting) is an acceptable alternative. To our opinion, the use of EDD in syringomyelia is unadvisable.

Dural Repair in Cranial Surgery Is Associated with Moderate Rates of Complications with Both Autologous and Nonautologous Dural Substitutes

OBJECTIVE

Duraplasty, a common neurosurgical intervention, involves synthetic or biological graft placement to ensure dural closure. The objective of this study is to advance our understanding of the use of dural substitutes in cranial surgery.

METHODS

The PubMed database was systematically searched to identify studies published over the past decade (2007-2017) that described duraplasty procedures. Clinical data were disaggregated and analyzed for the comparisons of biological versus synthetic grafts.

RESULTS

A total of 462 cases were included in the quantitative synthesis. Overall, the most common indication for duraplasty was tumor resection (53%). Allografts were more frequently used in decompression for Chiari malformations compared with xenografts and synthetic grafts (P < 0.001). Xenografts were more frequently used in decompressive hemicraniectomy procedures for evacuation of acute subdural hematomas over allografts and synthetics (P < 0.001). Synthetic grafts were more frequently used in tumor cases than biological grafts (P = 0.002). The cumulative complication rate for dural substitutes of all types was 11%. There were no significant differences in complication rates among the 3 types of dural substitutes.

CONCLUSIONS

Dural substitutes are commonly used to ensure dural closure in a variety of cranial procedures. This study provides greater insight into duraplasty practices and highlights the moderate complication rate associated with the procedure. Future studies are needed to determine the safety and efficacy of such procedures in larger prospective cohorts.

Chiari 1 deformity in children: etiopathogenesis and radiologic diagnosis

The metamerically associated normal hindbrain and normal posterior fossa are programmed to grow together in such a way that the tonsils are located above the foramen magnum and surrounded by the cerebrospinal fluid (CSF) of the cisterna magna. This allows the pulsating CSF to move freely up and down across the craniovertebral junction (CVJ). A developmental mismatch between the rates of growth of the neural tissue and of the bony posterior fossa may result in the cerebellar tonsils being dislocated across the foramen magnum. The cause of this may be, rarely, an overgrowth of the cerebellum. More commonly, it is due to an insufficient development of the posterior fossa, possibly associated with a malformation of the craniocervical joint. When it is not due to a remediable cause, such a herniation is called a Chiari 1 deformity. This definition is anatomic (descent of the tonsils below the plane of the foramen magnum) and not clinical: many patients with the deformity are and will remain asymptomatic. Most authors consider that a descent of 5 mm or more is clinically significant but other factors, such as the diameter of the foramen magnum and the degree of tapering of the upper cervical "funnel," are likely to be as important. Morphologic markers of severity on magnetic resonance imaging are, beside the degree of descent, the peg-like deformity of the tonsils, the obstruction of the surrounding CSF spaces (at the craniocervical junction and in the whole posterior fossa), a compression of the cord, an abnormal signal of the cord, and a syringomyelia, typically cervicothoracic. The syringomyelia is assumed to be explained by the "Venturi effect" that is associated with the increased velocity of the CSF across the restricted CSF spaces. Radiologically, the etiopathogenic assessment should address the size and morphology of the posterior fossa, and the functional status of the craniocervical flexion joint. The posterior fossa is best evaluated on sagittal cuts by the posterior fossa pentagon proportionality associated with the line of Chamberlain, and on coronal cuts, by showing a possible shallowness of the posterior fossa. The functional status of the craniocervical joint is altered in case of a proatlantal hypoplasia, as this condition results in a cranial shift of the joint that brings the tip of the dens and of the flexion axis in front of the medulla, that is, in a situation of osteoneural conflict. Less commonly, similar conflicts may also occur when an abnormal craniocervical segmentation results in an instability of the joint.

Syrinx to Subarachnoid Shunting for Syringomyelia

OBJECTIVE

Surgery for syringomyelia generally aims to treat the underlying cause, if it is known. Optimal management is unclear for idiopathic syringomyelia, or when treatment of the putative cause has failed or is high risk. Syrinx to subarachnoid shunting is an option for these cases; a series is reported to assess the outcomes of this approach.

METHODS

We retrospectively analyzed the clinical and radiologic features of a consecutive series of patients with syringomyelia treated with syrinx to subarachnoid shunting.

RESULTS

Forty-one patients (19 male, 4-79 years old) were treated from 2000 to 2016, including 15 patients with idiopathic syringomyelia, 13 with spinal trauma, 5 with Chiari malformation, 4 with arachnoiditis, 3 with tethered cord, and 1 with arachnoid bands. The patients were treated with a syrinx to subarachnoid shunt, and a subset also underwent expansile duraplasty. At follow-up (3-108 months, mean 36 months) syrinx size was reduced in 37 patients, and there was improvement or stabilization of symptoms in all but 1 patient. Three patients had temporary lower limb sensory symptoms after surgery. Other complications were 2 transient cerebrospinal fluid leaks, a pseudomeningocoele, and 1 postoperative myocardial infarction. Two cases of shunt dislodgement required reoperation, and a third case required early reoperation for an enlarging syrinx. There were no cases of shunt blockage or infection.

CONCLUSIONS

Syrinx to subarachnoid shunting is a safe and effective treatment for idiopathic syringomyelia and for patients who are not suitable for, or have not responded to, other treatment.

Pediatric Craniovertebral Junction Surgery

The craniovertebral junction (CVJ) has attracted more attention in pediatric medicine in recent years due to the progress in surgical technologies allowing a direct approach to the CVJ in children. The CVJ is the site of numerous pathologies, most originating in bone anomalies resulting from abnormal CVJ development. Before discussing the surgical approaches to CVJ, three points should be borne in mind: first, that developmental anatomy demonstrates age-dependent mechanisms and the pathophysiology of pediatric CVJ anomalies; second, that CT-based dynamic simulations have improved our knowledge of functional anatomy, enabling us to locate CVJ lesions with greater certainty; and third, understanding the complex structure of the pediatric CVJ also clarifies the surgical anatomy. This review begins with a description of the embryonic developmental process of the CVJ, comprising ossification and resegmentation of the somite. From the clinical perspective, pediatric CVJ lesions can be divided into three categories: developmental bony anomalies with or without instability, stenotic CVJ lesions, and others. After discussing surgery and management based on this classification, the author describes surgical outcomes on his hands, and finally proceeds to address controversial issues specific for pediatric CVJ surgery. The lessons, which the author has gleaned from his experience in pediatric CVJ surgery, are also presented briefly in this review. Recent technological progress has facilitated pediatric surgery of the CVJ. However, it is important to recognize that we are still far from reliably and consistently obtaining satisfactory results. Further progress in this area awaits contributions of the coming generations of pediatric surgeons.

Chiari-related hydrocephalus: assessment of clinical risk factors in a cohort of 297 consecutive patients

OBJECTIVE Patients treated for Chiari I malformation (CM-I) with posterior fossa decompression (PFD) may occasionally and unpredictably develop postoperative hydrocephalus. The clinical risk factors predictive of this type of Chiari-related hydrocephalus (CRH) are unknown. The authors' objective was to evaluate their experience to identify risk factors that may predict which of these patients undergoing PFD will develop CRH after surgery. METHODS The authors performed a retrospective clinical chart review of all patients who underwent PFD surgery and duraplasty for CM-I at the Primary Children's Hospital in Utah from June 1, 2005, through May 31, 2015. Patients were dichotomized based on the need for long-term CSF diversion after PFD. Analysis included both univariate and multivariable logistic regression analyses. RESULTS The authors identified 297 decompressive surgeries over the period of the study, 22 of which required long-term postoperative CSF diversion. On multivariable analysis, age < 6 years old (OR 3.342, 95% CI 1.282-8.713), higher intraoperative blood loss (OR 1.003, 95% CI 1.001-1.006), and the presence of a fourth ventricular web (OR 3.752, 95% CI 1.306-10.783) were significantly associated with the need for long-term CSF diversion after decompressive surgery. CONCLUSIONS Younger patients, those with extensive intraoperative blood loss, and those found during surgery to have a fourth ventricular web were at higher risk for the development of CRH. Clinicians should be alert to evidence of CRH in this patient population after PFD surgery.

"Stealth cranioplasty:" A novel endeavor for symptomatic adult Chiari I patients with syringomyelia: Technical note, appraisal, and philosophical considerations

Aim and Objective:

In this article, we describe a novel technique of reconstruction of posterior fossa by cranioplasty with use of preshaped titanium mesh following posterior fossa decompression (PFD) for Chiari malformation type I (CMI) with syringomyelia (SM) in symptomatic adults.

Materials and Methods:

Eleven patients underwent limited PFD and expansive cranioplasty with preshaped titanium mesh, what we term as “Stealth Cranioplasty” (SCP), following arachnoid preserving duraplasty (APD) and hexagonal tenting of the duraplasty with the cranioplasty (HTDC) for the management of symptomatic adult CMI with SM. All these patients had syringes extending from 3 to >10 vertebral levels.

Results:

Seven male and four female symptomatic CMI adult patients, between age ranges of 22 and 44 years (mean 29.45 years), presented with different neurological symptoms related to CMI and SM for 6–84 months (mean 37.09 months). All the patients underwent PFD, APD followed by SCP and HTDC and were followed up for 7–54 months (mean 35.90 months). Of 11 patients, 8 patients improved according to the Chicago Chiari Outcome Scale (CCOS) with score of 13–15 while 3 patients remained unchanged with CCOS of 12, and there was no worsening. There was no complication related to Chiari surgery in any of the patients. All the patients had good reestablishment of cisterna magna. Two patients had marked reduction of syrinx while eight patients had moderate-to-mild reduction and one patient had no change of syrinx. None of the patients needed redo surgery.

Conclusion:

SCP is an effective, fruitful, and cost-effective technique for the management of symptomatic adult CMI with SM. This technique has the advantages of preventing complications and recurrences in addition to the improvement of symptoms by addressing the basic pathology.

Isolated thoracic syrinx in children with Chiari I malformation

INTRODUCTION

Syrinx has been reported in 25-85 % of children with Chiari malformation type I (CMI), and it is most commonly cervical in location. As a result, cervical MRI is routinely included in an evaluation for CMI. Isolated thoracic syrinx without involvement of the cervical cord in this population is uncommon but clinically important because its presence may influence the decision to operate, surgical techniques employed, or interpretation of follow-up imaging. The purpose of this study was to determine the incidence of isolated thoracic syrinx in a large group of children evaluated for CMI.

METHODS

We retrospectively reviewed all patients under 21 years of age who were evaluated for CMI at Columbia University/Morgan Stanley Children's Hospital of New York from 1998 to 2013. All patients underwent MRI of the entire spine as part of the CMI evaluation, regardless of whether surgery was planned. The proportion of patients exhibiting isolated thoracic syrinx was determined. Presenting signs, symptoms, and imaging findings were then studied in an attempt to identify any clinical features associated with isolated thoracic syrinx.

RESULTS

We identified 266 patients evaluated over the study period. One-hundred thirty-two patients (50 %) presented with a syrinx, and 12 patients (4.5 % of all patients evaluated and 9.1 % of all patients with a syrinx) had an isolated thoracic syrinx. Demographic variables, clinical presentation, and extent of tonsillar ectopia showed great heterogeneity in this group, and no factor was consistently associated with isolated thoracic syrinx.

CONCLUSIONS

Isolated thoracic syrinx is an uncommon but clinically significant finding in children with CMI. Our data demonstrate that the presence of a CMI-related thoracic syrinx cannot be reliably predicted clinically and is therefore likely to be missed in patients who do not undergo complete spinal cord imaging. MRI of the entire spinal cord should be considered for all children undergoing initial evaluation for CMI.