Relevance of surgical strategies for the management of pediatric Chiari type I malformation

T-shaped myofascial incision for Chiari I malformation surgery without dural closure in children: Technical note

BACKGROUND

Like in all posterior fossa surgeries the avoidance of cerebrospinal fluid (CSF) leaks is of paramount importance for foramen magnum decompression in Chiari I malformation in children. The present technical note decribes the experience with the creation of a T-shaped myofascial cuff to reduce the risk of postoperative CSF leaks.

METHODS

The medical records of 98 children were evaluated. They underwent foramen magnum decompression without dural closure using a T-shaped myofascial cuff whose incision lines run completely within the fascia and the muscles not extending beyond their attachment line to the bone.

RESULTS

There were 2 CSF leaks and no infections in 98 operated patients. The follow-up was between 4 and 48 months.

CONCLUSIONS

The placement of a T-shaped myofascial cuff allows for watertight closure of the muscles and the fascia which is likely to reduce the rate of CSF leaks in pediatric Chiari I patients operated on without closure of the dura.

The Surgical Strategy Cerebrospinal Fluid Decompression Facilitates Outcomes of Adults with Chiari Malformation Type I: An Observational, Real-World, Single-Center Study of 528 Patients

OBJECTIVE

We designed this study to introduce the surgical strategy cerebrospinal fluid (CSF) decompression in treatment of Chiari malformation type I and compared CSF decompression with other surgical strategies to provide a solid basis for patient counseling.

METHODS

The study enrolled 528 consecutive patients with CMI who underwent surgical interventions from 2012 to 2022. The surgical strategy for these patients was bony and dural decompression, anatomical reduction of herniated tonsils, or CSF decompression. Short-term results were determined after 3 months; long-term outcomes were evaluated at last follow-up (at least 18 months).

RESULTS

CSF decompression was independently associated with better long- or short-term primary outcomes than anatomical reduction of herniated tonsils or bony and dural decompression (P < 0.001). Compared with short-term, the long-term outcomes were better in patients who underwent CSF decompression (P = 0.035), but were worse in patients with bony and dural decompression (P = 0.03). Specific surgical techniques cannot affect the long- and short-term outcomes of patients with Chiari malformation type I. CSF decompression provided better long-term syringomyelia improvement than short-term (181/218, 83% vs. 169/218, 77.5%; P < 0.001).

CONCLUSIONS

CSF decompression, but not a specific surgical technique or operative method, was associated with favorable neurological outcomes in ADULT patients with Chiari malformation type I. The surgical technique and operative method should be selected according to the characteristics of each patient and the intraoperative condition to normalize CSF circulation at the craniovertebral junction area. The intraoperative target, smooth CSF flow out from the fourth ventricle and in to the bilateral Luschka foramina, could be observed.

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.

Evaluating the Need for Durotomy and Duraplasty in Adults Undergoing Suboccipital Craniectomy for Chiari Decompression: A Case Series Analysis of Radiographic and Clinical Outcomes

Background Suboccipital craniectomy (SOC) in conjunction with dura opening and duraplasty for posterior fossa decompression is an effective treatment for symptomatic Chiari 1 malformations (CM1), primarily carried out in the pediatric population. However, dural opening and reconstruction are associated with an increased risk of complications, and their necessity in the adult population has not yet been robustly demonstrated. Given differences in clinical presentation and disease severity between the pediatric and adult patients, we aimed to identify if SOC alone with intraoperative ultrasound confirmation of adequate restoration of pulsatile motion of cerebellar tonsil is sufficient to treat symptomatic CM1 while mitigating surgical risks. Methods We identified a retrospective, institutional cohort of adult patients who underwent SOC for Chiari decompression between 2014 and 2023. Demographic, clinical, and radiographic features were extracted for each patient. Clinical outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS) and Motor-Sensory-Sphincter signs score (Clinical Sign Score (CSS)). Radiographic outcomes assessed cerebellar ectopia and associated syrinx characteristics. Results A total of 15 patients were identified, with an average follow-up period of three years. Eight patients underwent SOC with duraplasty, whereas seven patients underwent SOC only without duraplasty. Both groups of patients were of similar age at surgery and had similar nature and duration of symptoms prior to surgery. On pre-operative radiographic evaluation, both groups of patients had similar lengths of cerebellar ectopia (9.9±11.0 mm to 11.1±5.7 mm, p=0.591), and associated syrinxes (75% vs. 42.9%, p=0.205). Intraoperatively, both groups had similar estimated blood losses, though the length of surgery was significantly shorter when durotomy was spared (202±58.3 minutes to 116.3±47.8 minutes, p=0.011). The length of ICU stay was also significantly longer in the durotomy group (1.1±0.6 days to 0.0 days, p<0.001). Neither group reported any post-operative complications. On follow-up, both groups demonstrated similar reductions in cerebellar ectopia and syrinx characteristics. Clinically, the CCOS and CSS scores were similar between the two cohorts at follow-up, with no repeat surgery required in either group. Conclusion Our cohort suggests that for adult CM1 patients, SOC decompression alone without dural reconstruction might lead to comparable clinical and radiographic outcomes to SOC decompression with durotomy/duraplasty, especially if intraoperative ultrasound confirms good cerebrospinal fluid (CSF) flow after SOC. Notably, sparing durotomy and duraplasty is also associated with decreased operative time and decreased ICU stay.

Clinical and Radiological Outcomes of Dura-Splitting versus Duraplasty Techniques in Pediatric Chiari I Malformation: A Systematic Review and Meta-Analysis

Type I Chiari malformation is a developmental anomaly with various proposed surgical techniques for its management. The dura-splitting technique is a less invasive approach and involves the resection of the outer layer of the dura while sparing the internal layer. While this less-known approach may minimize the complication rates, there are concerns about its efficacy and outcome. Therefore, we have performed a systematic review and meta-analysis of available data on clinical and radiological outcomes of this technique in the pediatric population and compared them to the foramen magnum decompression and duraplasty technique. We have followed the Meta-analysis Of Observational Studies in Epidemiology guidelines in this review. Based on our predefined search strategy, we performed a systematic database search. Subsequently, the article screening process was done based on defined inclusion/exclusion criteria. Following the quality assessment of included studies, two authors performed data extraction. Finally, the extracted data were summarized and presented in form of tables. Forest plots were used to demonstrate the results of the meta-analysis. A review of 8 included studies consisting of 615 patients revealed the significant advantage of the dura-splitting technique in terms of shorter operation duration and hospital stay. The recurrence rate and clinical and radiological outcomes were almost similar between the two surgical techniques. Complication rates were significantly lower in the dura-splitting technique. Dura-splitting can be an effective and safe approach for the management of pediatric Chiari I malformation. However, these results are mostly extracted from observational studies and future randomized controlled trials are recommended.

Individualized surgical treatment of Chiari 1 malformation: A single-center experience

OBJECTIVE

To present our experience with an individualized surgical approach to treat Chiari malformation type 1.

METHODS

Based on (1) neurological symptoms, (2) the existence and extent of a syrinx and (3) the degree of the tonsillar descent we performed four types of approaches on a case-by-case basis in 81 patients: (1) foramen magnum decompression (FMD) with dura splitting (FMDds); (2) FMD with duraplasty (FMDdp); (3) FMD with duraplasty and tonsillar manipulation (FMDao); and (4) tonsillar resection/reduction (TR). Patient characteristics, Chiari Severity Index (CSI), fourth ventricular roof angle (FVRA) and Chicago Chiari Outcome Scale (CCOS) were analyzed.

RESULTS

CCOS was between 13 and 16 points in 8/11 (73 %) patients after FMDds, 38/45 (84 %) patients after FMDdp, and 24/24 (100 %, one patient lost to follow-up) patients after TR. We experienced an overall complication rate of 13.6 % (11/81) in this series, whereas seven of these eleven complications (64 %) occurred in the FMDao group and the complication rate increased with the invasiveness of the approach (0 % FMDds; 4 % FMDdp; 12 % TR).

CONCLUSION

Given the clear correlation between the extend of the approach and the complication rate the least invasive approach necessary to achieve clinical improvement should be selected. Due to the high complication rates, FMDao should not be used as a treatment option. The severity of the tonsillar descent, basilar invagination and current CM1 scores could be used to aid in the approach selection.

Transient meningism in children after non-autologous duraplasty for Chiari Malformation surgery: A case series

BACKGROUND

Increasing the posterior fossa volume is the mainstay of treatment for Chiari type 1 Malformation (C1M) and type 1.5 (C1.5M). Different options to restore CSF flow have been described but no consensus has been reached yet. Bony decompression of posterior cranial fossa with dural opening provides good results but at the price of complications such as pseudomeningocele and aseptic meningitis. A single center retrospective analysis was conducted to find any relationships between outcome and perioperative factors. As a second goal a specific analysis was conducted on the complications and their hypothetical causes.

METHODS

All the pediatric patients who underwent to posterior fossa bony decompression and dural opening for C1M or C1.5M in the period 2008-2020 were included in the study. A minimum period of three-months follow-up was considered among the inclusion criteria.

RESULTS

A population of fifty-three consecutive patients was collected. Pseudomeningocele and a mild meningeal irritation resulted the most frequent complications. Considering preoperative and intraoperative factors, the type of dural graft showed a relatively strong correlation (P<.01) with pseudomeningocele appearance and the development of meningism. In the latter case, a short course of steroids was the only treatment required to control symptoms.

CONCLUSIONS

Different factors could influence the outcome in Chiari Malformation surgery and eventually the development of complications. An adequate dural graft selection is of paramount importance when a dural opening for posterior fossa augmentation is planned. In case of mild meningeal irritation, a trial with short course steroids could avoid revision surgery.

Effectiveness of C1 Laminectomy for Chiari Malformation Type 1: Posterior Fossa Volume Expansion and Syrinx-Volume Decrease Rate

PURPOSE

This study aimed to analyze the effect of foramen magnum decompression with C1 laminectomy (C1L) for Chiari malformation type 1 (CM-1) in terms of improving clinical symptoms, expanding posterior fossa volume, and decreasing syrinx volume.

MATERIALS AND METHODS

Between January 2007 and June 2019, 107 patients with CM-1 were included. The median patient age was 13±13 years (range: 9 months-60 years), female-to-male ratio was 1:1, and average length of tonsil herniation was 13±5 mm (range: 5-24 mm). Surgical techniques were divided into four groups based on duraplasty or C1L usage. Among the study subjects, 38 patients underwent duraplasty and had their syrinx volumes measured separately on serial magnetic resonance imaging. A three-dimensional visualization software was used to evaluate the syrinx-volume decrease rate.

RESULTS

Bony decompression exhibited a mere 20% volume expansion of the lower-half posterior fossa. C1L offered a 3% additional volume expansion, which rose to 5% when duraplasty was added (p=0.029). There were no significant differences in complication rate when C1L was combined with duraplasty (p=0.526). Syrinx volumes were analyzed in 38 patients who had undergone duraplasty. Among them, 28 patients who had undergone duraplasty without C1L demonstrated a 5.9% monthly decrease in syrinx volume, which was 7.5% in the remaining 10 patients with C1L (p=0.040).

CONCLUSION

C1L was effective in increasing posterior fossa volume expansion, both with and without duraplasty. A more rapid decrease in syrinx volume occurred when C1L was combined with duraplasty.

Exploring the prognostic differences in patients of Chiari malformation type I with syringomyelia undergoing different surgical methods

Background

The best surgical treatment of Chiari malformation patients with syringomyelia remains controversial, and whether cerebellar tonsillectomy should be performed has not been decided.

Objective

To evaluate the efficacy of posterior fossa decompression with duraplasty (PFDD) and Posterior fossa decompression with resection of tonsils (PFDRT) in patients of Chiari malformation type I (CM-I) with syringomyelia and explore relevant factors affecting prognosis.

Patients and methods

We retrospectively analyzed 182 adult patients of CM-I with syringomyelia who underwent PFDD or PFDRT over a 6-year period, and analyzed their clinical manifestations, imaging features, and follow-up data. Clinical outcomes were assessed using the Chicago Chiari Outcome Scale (CCOS), and imaging outcomes were assessed using the syrinx remission rate. Difference comparisons were performed to compare the differences between different surgical groups. Influencing factors associated with outcome were investigated using bivariate analysis and multiple linear regression analysis.

Results

There were statistically significant differences in CCOS score (p = 0.034) and syrinx remission rates (p = 0.046) between the PFDRT group and the PFDD group after surgery. Regression analysis showed that preoperative motor dysfunction, cerebellar-related symptoms and different surgical methods may have influenced the CCOS score and that brainstem-related symptoms and age may have influenced the syrinx remission rates in the total patient group (p < 0.05). Regression analysis showed that the duration of symptoms, cerebellar-related symptoms and preoperative syrinx diameter may have influenced the CCOS score and that the preoperative cerebellar tonsillar hernia distance may have influenced the postoperative syrinx remission rate in the PFDRT group (p < 0.05). Age and length of hospital stay may have influenced the CCOS score, and brainstem-related symptoms and age may have influenced the syrinx remission rates in the PFDD group (p < 0.05).

Conclusion

This study showed that the CCOS score in the PFDRT group was better than that in the PFDD group. Preoperative motor dysfunction, cerebellar-related symptoms, and different surgical methods in patients of CM-I with syringomyelia affected postoperative CCOS score. Both the duration of symptoms and the age of the patients should be actively considered as factors influencing prognosis. Symptomatic CM-I patients with syringomyelia should undergo surgical treatment as early as possible.

Prevalence and treatment of typical and atypical headaches in patients with Chiari I malformation: A meta-analysis and literature review

OBJECTIVE

A meta-analysis was conducted to analyze the incidence of typical and atypical headaches and outcomes following various treatments in patients with Chiari I malformation.

BACKGROUND

Headache is the most common symptom of Chiari malformation, which can be divided into typical and atypical subgroups to facilitate management. Much controversy surrounds the etiology, prevalence and optimal therapeutic approach for both types of headaches.

METHOD

We identified relevant studies published before 30 July 2022, with an electronic search of numerous literature databases. The results of this study were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

RESULT

A total of 1913 Chiari malformation type I CIM patients were identified, 78% of whom presented with headache, within this group cephalgia was typical in 48% and atypical in 29% of patients, and migraine was the most common type of atypical headache. The ratio of typical/atypical headaches with international classification of headache disorders diagnosis was 1.53, and without international classification of headache disorders diagnosis was 1.56, respectively. The pooled improvement rates of typical headaches following conservative treatment, extradural decompression and intradural decompression were 69%, 88%, and 92%, respectively. The corresponding improvement rates for atypical headaches were 70%, 57.47%, and 69%, respectively. The complication rate in extradural decompression group was significantly lower than in intradural decompression group (RR, 0.31; 95% CI: 0.06-1.59, I² = 50%, P = 0.14). Low reoperation rates were observed for refractory headaches in extradural decompression and intradural decompression groups (1%).

CONCLUSION

The International Classification of Headache Disorders can assist in screening atypical headaches. extradural decompression is preferred for typical headaches, while conservative therapy is optimal for atypical headaches. A definite correlation exists between atypical headaches and Chiari Malformation Type I patients with higher prevalence than in the general population. Importantly, decompression is effective in relieving headaches in this particular patient population.

Chiari Type 1 Malformation and Syringomyelia in Children: Classification and Treatment Options

Chiari type 1 malformation (CIM) is defined as tonsillar ectopia of >5 mm, while syringomyelia (SM) is defined as a cerebrospinal fluid (CSF)-filled cavity larger than 3 mm dissecting the spinal cord. Over the last decades, our understanding of these pathologies has grown; however, many controversies still exist almost in every aspect of CIM and SM, including etiology, indication for treatment, timing of treatment, surgical technique, follow-up regime, and outcome. This chapter provides a comprehensive overview on different aspects of CIM and SM and on the still existing controversies, based on the evidence presently available. Future directions for clinical research concerning CIM and SM treatment and outcome are elaborated and discussed as well.

Outcome evaluation of decompression surgery combined with cerebellar tonsillectomy compared without cerebellar tonsillectomy for Chiari type I malformation patients

BACKGROUND

Surgical intervention is an important treatment option to improve the prognosis for Chiari type I malformation (CM-I) patients. However, there is no consensus about surgical strategies. The article intends to evaluate the effect of decompression combined with or without cerebellar tonsillectomy in the treatment of CM-I.

METHOD

Following PRISMA's principles, Embase, PubMed, Web of Science, and Cochrane databases and references to relevant articles were searched to include only original articles on decompression combined with or without cerebellar tonsillectomy in CM-I patients. Through meta-analysis, the data on clinical improvement, radiological improvement, and complications were pooled.

RESULTS

Nine articles, including 399 CM-I patients undergoing decompression alone and 343 undergoing decompression with cerebellar tonsillectomy, meet the inclusion standard. In comparison, the improvement rate of clinical symptoms or signs in patients with cerebellar tonsillectomy is higher and statistically significant (RR: 0.85, 95% CI: 0.75-0.95; P = 0.006). However, decompression with cerebellar tonsillectomy is also significantly higher in the incidence of postoperative complications (RR: 0.54, 95% CI: 0.36-0.80; P = 0.002). No statistical difference is discovered between the two groups in the improvement rate of syringomyelia (RR: 0.77, 95% CI: 0.57-1.03; P = 0.08).

CONCLUSIONS

Although decompression with cerebellar tonsillectomy is superior than decompression alone in clinical improvement for CM-I patients, it also faces a higher risk of postoperative complications. The reduction of syringomyelia in the two groups can be considered equally effective without significant differences. In the future, the results of the research require multicenter and large-scale randomized controlled trials to verify in clinical practice.

TRIAL REGISTRATION

CRD42022321750 (PROSPERO).

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.

The management of Chiari malformation type 1 and syringomyelia in children: a review of the literature

In anticipation of the "Chiari and Syringomyelia Consensus Conference" held in Milan in 2019, we performed a systematic literature review on the management of Chiari malformation type 1 (CM1) and syringomyelia (Syr) in children.We aimed to summarize the available evidence and identify areas where consensus has not been reached and further research is needed.In accordance with PRISMA guidelines, we formulated seven questions in Patients-Interventions-Comparators-Outcomes (PICO) format. Six PICOs concerned CM1 children with/without additional structural anomalies (Syr, craniosynostosis, hydrocephalus, tethered cord, and cranio-vertebral junction anomalies), and one PICO Syr without CM1. We searched Medline, Embase, Cochrane, and NICE databases from January 1, 1999, to May 29, 2019. Cohort studies, controlled and randomized clinical trials (CCTs, RCTs), and systematic reviews were included, all pertinent only to patients ≤ 18 years of age.For CM1, 3787 records were found, 460 full texts were assessed and 49 studies (46 cohort studies, one RCT, and two systematic reviews) were finally included. For Syr, 376 records were found, 59 full texts were assessed, and five studies (one RCT and four cohort studies) were included. Data on each PICO were synthetized narratively due to heterogeneity in the inclusion criteria, outcome measures, and length of follow-up of the included studies.Despite decades of experience on CM1 and Syr management in children, the available evidence remains limited. Specifically, there is an urgent need for collaborative initiatives focusing on the adoption of shared inclusion criteria and outcome measures, as well as rigorous prospective designs, particularly RCTs.

Inpatient outcomes of posterior fossa decompression with or without duraplasty for Chiari malformation type I

OBJECTIVE

Chiari malformation type 1 (CM-1) is a congenital neurologic condition in which the cerebellar tonsils herniate below the foramen magnum, resulting in symptoms such as headache and neck pain. Two common surgical treatment approaches are posterior fossa decompression with (PFDD) and without duraplasty (PFD). Previous single-center studies have demonstrated increased neurologic complications after PFDD compared to PFD. The goal of this study is to determine differences in inpatient complications and hospitalization data among patients treated with these surgical techniques using a nationwide sample.

METHODS

The National Inpatient Sample (NIS) was queried for years 2012-2015 for all patients with a primary diagnosis of CM-1 who underwent PFD or PFDD. Differences in baseline demographics and comorbidities were accounted for in subsequent analysis using propensity score matching. Hospitalization measures and inpatient complications of the two cohorts were compared using Chi-squared tests and t-tests when appropriate.

RESULTS

A total of 2395 patients with CM-1 were included in this study, with 750 (31.3%) undergoing PFD and 1645 (68.7%) undergoing PFDD. PFDD was associated with higher total hospital costs than PFD. There were no significant differences in other hospitalization or discharge data, non-neurologic complications, or CNS complications (CSF leak, pseudomeningocele, abscess, meningitis, stroke) between the two surgical groups.

CONCLUSIONS

This study represents the largest national analysis to date of adult CM-1 patients undergoing PFD or PFDD. Our findings suggest that whether the decision is made to perform the less invasive PFD or more invasive PFDD, inpatient complications and hospitalization data will not significantly differ.

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.

Posterior fossa decompression with duraplasty in Chiari malformation type 1: a systematic review and meta-analysis

BACKGROUND

Surgery for symptomatic Chiari type I malformation (CM-I) patients include posterior fossa decompression (PFD) involving craniectomy with or without dural opening, and posterior fossa decompression with duraplasty (PFDD). This review aims to examine the evidence to aid surgical decision-making.

METHODS

A medical database search was expanded to include article references to identify all relevant published case series. Animal studies, editorials, letters, and review articles were excluded. A systemic review and meta-analysis were performed to assess clinical and radiological improvement, complications, and reoperation rates.

RESULTS

Seventeen articles, containing data on 3618 paediatric and adult participants, met the inclusion criteria. In the group, 5 papers included patients that had the dura left open. PFDD is associated with better clinical outcomes (RR 1.24, 95% CI, 1.07 to 1.44; P = 0.004), but has a higher complication rate (RR 4.51, 95% CI, 2.01 to 10.11; P = 0.0003). In adults, clinical outcomes differences did not reach statistical significance (P = 0.07) but re-operation rates were higher with PFD (RR 0.17, 95% CI 0.03 to 0.86; P = 0.03), whilst in children re-operation rates were no different (RR 0.97, 95% CI 0.41 to 2.30; P = 0.94). Patients with a syrinx did better with PFDD (P = 0.02). No significant differences were observed concerning radiological improvement.

CONCLUSIONS

In the absence of hydrocephalus and craniocervical region instability, PFDD provides better clinical outcomes but with higher risk. The use of PFD may be justified in some cases in children, and in the absence of a syrinx. To help with future outcome assessments in patients with a CM-I, standardization of clinical and radiological grading systems are required.

TRIAL REGISTRATION

not required.

Syringomyelia Resolution Following Chiari Surgery: A Novel Scale for Communication and Research

BACKGROUND

The pathophysiological connection between Chiari malformation and syringomyelia is accepted. Debate remains, however, how can we best define changes in syringomyelia following surgery.

OBJECTIVE

To introduce a grading system focusing on syrinx reduction based on routinely and reproducible radiological information, and provide a suggestion of the application of this scale for prediction of patient's prognoses.

METHODS

Data from 48 patients with Chiari malformation and syringomyelia were compiled. We calculated syrinx cross-sectional area by approximating an ellipse in the largest axial plane. We compared the percentage of reduction or enlargement following surgery. The percentage change was grouped into four grades: Grade 0 = Increasing size, grade I ≤ 50% reduction, grade II = 50% to 90% reduction, grade III ≥ 90% reduction.

RESULTS

A total of 89.6% of patients had syrinx improvement after surgery. A total of 5 patients were grade 0, 14 were grade I, 20 patients were grade II, and 9 patients met criteria for grade III. The mean postoperative syrinx area was 24.1 mm2 (0-169 mm2) with a mean syrinx reduction of 62.7%.

CONCLUSION

Radiological improvement of syringomyelia can be mathematically defined and standardized to assist in communication in outcome-based trials. Radiological resolution is expected most patients.

Outcomes of Dura Splitting Decompression Versus Posterior Fossa Decompression With Duraplasty in the Treatment of Chiari I Malformation: A Systematic Review and Meta-analysis

BACKGROUND

Surgery is the definitive treatment option for symptomatic Chiari malformation I (CMI), but there is no clear consensus as to the preferred surgical method. This study aimed to quantitatively assess and compare the effect and safety of dura splitting decompression (DSD) and posterior fossa decompression with duraplasty (PFDD) in treating patients with CMI.

METHODS

A literature search of EMBASE, MEDLINE, PubMed, Cochrane Library, and Web of Science databases was conducted. References from January 1990 to September 2020 were retrieved. We only included papers containing original data, comparing the use of DSD and PFDD in CMI patients.

RESULTS

Overall, 11 relevant studies were identified, wherein 443 patients treated for CMI by DSD were compared with 261 patients treated by PFDD. No difference was observed between PFDD and PFD in terms of clinical improvement (P = 0.69), syringomyelia improvement (P = 0.90), or reoperation (P = 0.22). DSD was associated with shorter operation durations (P = 0.0007), shorter length of stay (P = 0.0007), and shorter overall postoperative complications (P < 0.0001) (especially cerebrospinal fluid [CSF] leak [P = 0.005], meningitis [P = 0.002], and pseudomeningocele [P = 0.002]), as compared with PFDD.

CONCLUSIONS

This study confirmed that dura splitting decompression has clinical and syringomyelia improvement outcomes comparable to posterior fossa decompression with duraplasty. Compared with PFDD, DSD not only significantly shortened the operation time and length of stay, but also significantly reduced the overall complication rate, especially those related to incidence of CSF-related complications. More evidence from advanced multicenter studies are needed to require to validate the findings.

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.

CSF goes astray no matter what is in the way: occipital intradiploic pseudomeningocele and de novo syringomyelia following foramen magnum decompression for Chiari I malformation in a pediatric patient

Nontraumatic intradiploic pseudomeningoceles and de novo syringomyelia formation are very rare entities. The authors have previously reported the case of a 4-year-old girl who underwent foramen magnum decompression without dural closure for Chiari I malformation. Three years after the operation an intradiploic pseudomeningocele was documented, but the patient was lost to follow-up without undergoing revision surgery. Four years later, at the age of 11 years, the patient returned for treatment of intensifying symptoms. Radiological imaging then showed an increase in the size of the intradiploic pseudomeningocele and a new cervical syrinx. The patient underwent a first revision surgery in which a part of the internal layer of the occipital bone was removed and arachnoid scar lysis was performed. Two months later the syrinx had worsened, and in a second revision surgery a pseudomeningocele-peritoneal shunt was placed. Here, the authors describe what is to their knowledge the first case of an intradiploic pseudomeningocele and de novo syringomyelia formation following Chiari I decompressive surgery.

Ventrolateral Tonsillar Position Defines Novel Chiari 0.5 Classification

BACKGROUND

Cervicomedullary compression in young children has been described in the context of Chiari type 1 malformation, with symptoms associated with the extent of tonsillar herniation below McRae line. Historically, Chiari type 1 malformation has been defined by tonsillar herniation of at least 5 mm. However, in certain populations, including very young children, Chiari symptoms may be present without this finding. A new Chiari classification is thus necessary.

METHODS

Cases involving patients up to 5 years of age evaluated for possible posterior fossa decompression were retrospectively reviewed. Preoperative symptoms, magnetic resonance imaging findings, surgical management, and short- and long-term outcome and follow-up were recorded. Tonsillar descent and presence of ventral herniation (VH) were recorded. We define VH as the tonsils crossing a line that bisects the caudal medulla at the level of the foramen magnum, thus creating a novel entity, Chiari type 0.5 malformation. Patients with ventrally herniated tonsils were compared with patients exhibiting more typical Chiari morphology.

RESULTS

Of 41 cases retrospectively reviewed, 20 met criteria for VH. These differed from cases without VH because of the predominance of medullary symptoms. In the VH cohort, 11 patients underwent surgical decompression with symptom resolution; 9 were initially managed conservatively, but 3 subsequently required surgery.

CONCLUSIONS

We define a novel Chiari entity, Chiari type 0.5 malformation, characterized by ventral tonsillar wrapping around the medulla in young children in the absence of classic Chiari type 1 malformation imaging findings. These patients are more likely to present with medullary symptoms than patients without VH. They are also more likely to require surgical decompression and respond favorably to intervention.

Persistent Syringomyelia After Posterior Fossa Decompression for Chiari Malformation

BACKGROUND

Chiari malformation (CM) is often comorbid with syringomyelia. The treatment of CM via posterior fossa decompression (PFD) may not improve syringomyelia in up to 40% of patients, based on historical cohorts. Management of these patients is problematic, as both reoperation and syrinx shunting have high failure rates in the long term.

METHODS

We retrospectively reviewed our cases in which patients with CM type 1 or 1.5 and syringomyelia underwent PFD without postoperative improvement in syringomyelia. Symptomatology and radiographic measurements were collected at presentation and on the first and latest available postoperative scans and analyzed. We present 2 cases to illustrate the challenges in the management of these patients.

RESULTS

Our cohort consisted of 48 consecutive patients with CM and syringomyelia who underwent PFD. Of these, 41 patients had postoperative improvement in or resolution of syringomyelia. We subsequently studied the cohort of 7 patients who underwent PFD with (n = 5) or without (n = 2) durotomy and demonstrated worsening of syringomyelia following surgery. This cohort had mean (±SEM) preoperative syrinx area of 23.9 ± 10.0 mm². Postoperatively, the mean syrinx area increased to 40.5 ± 9.6 mm² and 57.3 ± 12.5 mm² on the first and latest postoperative scans available (P = 0.02), for an increase of 106.9% ± 94.4% and 186.0% ± 107.4% (P = 0.04). Presenting symptoms included occipital headache, paresthesias, visual deterioration, and paraspinal pain. On last follow-up (mean 13.9 ± 4.9 months), the majority of symptoms were resolved in this cohort, despite persistence of syringomyelia.

CONCLUSIONS

In this small cohort of unique patients, syrinx resolution was not achieved via decompression surgery. Despite "radiographic failure," good symptom control was achieved, with most patients remaining or becoming asymptomatic postoperatively, thus supporting our rationale for what has largely been a conservative approach in this population.

Outcomes and complications for individual neurosurgeons for the treatment of Chiari I malformation at a children's hospital

PURPOSE

The aim of this study was to evaluate the outcomes and complications for individual surgeons at British Columbia Children's Hospital for the treatment of Chiari I Malformation (CMI) in children.

METHODS

This was a retrospective review of patients with CMI who had surgery from 1986 to 2015. We assessed the Chicago Chiari Outcome Scores (CCOS) and complication rates by surgeon.

RESULTS

Seventy patients, 38 males and 32 females, underwent posterior fossa decompression including 14 extradural and 56 intradural approaches. Syringomyelia was present in 74.3%. Most syringomyelia improved with no difference between intradural and extradural surgeries. After initial surgery, 13 patients (18.6%) had complications including 2/14 (14.3%) of extradural and 11/56 (19.6%) of intradural surgeries. Two patients required surgical intervention for complications whereas 11 had transient complications. The complication rate by surgeon ranged from 11 to 20% for extradural (2 surgeons only) and 10.5 to 40% for intradural surgeries (4 surgeons). The CCOS ranged from 12 to 15 for extradural and 6 to 16 for intradural. The CCOS ranges for surgeons 1 and 2 were 12-15 and 13-15 respectively for extradural. The CCOS ranges for surgeons 1, 2, 3, and 4 were 12-16, 6-15, 12-16, and 12-16 respectively for intradural. Thirteen patients had a second surgery for CMI. The final CCOS was good in 86% and moderate in 14%.

CONCLUSION

There was variability in surgeries performed at BCCH by different surgeons, with variations in CCOS and complication rates. This information is important during decision making, consent process, and for quality improvement.

Opinion for different centers: surgical experience with Chiari malformation type I in children at Xuanwu Hospital, China

PURPOSE

To evaluate the presenting symptoms, surgical strategy, and outcome in children with Chiari malformation type I (CM-I).

METHODS

The medical records of children who were diagnosed with CM-I under 14 years old and subsequently underwent surgery for CM-I between 2014 and 2018 were reviewed. The medical records for presentation, radiological image, surgical intervention, and outcome were evaluated.

RESULTS

Twelve children with CM-I and syringomyelia were included. All of the children were symptomatic. The most common presenting symptom was weakness, followed by scoliosis. All of them underwent posterior fossa decompression with/without duraplasty. Relief of preoperative pathologies and syringomyelia was experienced by all of them.

CONCLUSIONS

The presenting symptoms of CM-I in children may be neurological deficits and scoliosis, which have a relationship with syringomyelia. Early recognition and a tailored operative procedure of CM-I in children could lead to good outcomes. Additional therapies for syringomyelia and scoliosis could be avoided.

Decompressive surgery for Chiari I malformation in children without dural repair: a still effective and safe procedure?

PURPOSE

There are numerous publications about the technical aspects of decompressive surgery for Chiari I malformation highlighting many variations of this procedure. Each approach has its followers. Bony decompression of the foramen magnum alone or with the removal of a portion of the posterior arch of C1, dural splitting with keeping arachnoid intact, and durotomy are described. Dural closure is done with various materials. We retrospectively reviewed foramen magnum decompression without dural repair (FMDWDR) following the technique used by Gardener and Williams as an option in pediatric patients with Chiari I malformation in terms of complication rate and clinical outcome.

METHODS

The surgical database of our unit identified 65 consecutive children who underwent FMDWDR surgery for Chiari I malformation between 2009 and 2016. The retrospective assessment included patient demographics, clinical data, surgical technique, revision rate, complications, and clinical outcome.

RESULTS

Durotomy without repair was performed in 65 patients. Complications included aseptic meningitis and subdural hematoma respectively in three cases, intradiploic CSF collections in three patients, and CSF leaks in six children. The CSF leak rate has reduced dramatically after introducing a technical modification. Revision surgery was performed in seven cases. None of the patients was identified with postoperative hydrocephalus or infection. There was no mortality and no long-term surgical morbidity. In terms of clinical outcome, 52 patients reported postoperative improvement, 10 were clinically unchanged, and three noticed worsening of symptoms.

CONCLUSION

Applying a "T"-shaped fascial incision which allows a watertight closure of the fascia FMDWDR is still a safe and effective treatment option for Chiari I malformation in children.

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.

Surgical Treatment in Symptomatic Chiari Malformation Type I: A Series of 25 Adult Patients Treated with Cerebellar Tonsil Shrinkage

BACKGROUND

The variety of symptoms and radiological findings in patients with Chiari malformation type I makes both the indication for surgery and the technical modality controversial. We report our 5-year experience, describing our technique and critically evaluating the clinical results.

METHODS

Between 2012 and 2016, 25 patients (15 female and 10 male; mean age 39.2 years) underwent posterior fossa decompression for Chiari malformation type I. Their clinical complaints included headache, nuchalgia, upper limb weakness or numbness, instability, dizziness and diplopia. Syringomyelia was present in 12 patients (48%). Suboccipital craniectomy was completed in all cases with C1 laminectomy and shrinkage of the cerebellar tonsils by bipolar coagulation; duraplasty was performed with a suturable dura substitute.

RESULTS

Gratifying results were observed in our series. Symptoms and signs were resolved in 52% of patients, and 20% of patients had an improvement in their preoperative deficits. The symptoms of six patients (24%) were essentially unchanged, and one patient (4%) deteriorated despite undergoing surgery. Generally, patients with syringomyelia on magnetic resonance imaging (MRI) showed less symptomatic improvement after surgery. The syrinx disappeared in seven of 12 patients, and complications occurred in three patients (12%).

CONCLUSION

Cerebellar tonsil reduction and restoration of cerebrospinal fluid (CSF) circulation provided clinical improvement and a stable reduction in the syrinx size in the vast majority of treated patients, with a low rate of complications.

Time to Resolution of Symptoms After Suboccipital Decompression with Duraplasty in Children with Chiari Malformation Type I

BACKGROUND

Duraplasty is a technique successfully used to treat Chiari malformation type I (CM-I). This study describes the timely manner of clinical outcomes and the postoperative course after craniectomy and duraplasty for the treatment of symptomatic CM-I in children.

METHODS

A retrospective chart review was performed in 105 consecutive children who underwent surgical decompression of symptomatic CM-I with dural opening by a single surgeon between 1999 and 2015.

RESULTS

In 16 of 28 children (57%) with typical Valsalva-related/tussive and mixed headaches, the symptoms resolved before discharge; by 6 months, all children were headache-free. Two of 28 children (7%) had recurrent headaches 9 months after surgery. Among the 78 children with syrinx, syrinx resolved or decreased in 68 (87%), recurred in 8 (10%), and was stable in 2 children (3%). Syrinx was resolved or decreased by 3 months in 51 children (65%) and by 6 months in 62 children (79%). Complications included aseptic meningitis requiring reoperation in 3 children (3%) and infection in one child (1%). Twelve children underwent reoperation, none within the first 30 days. No child had a major morbidity or mortality.

CONCLUSIONS

In carefully selected children with CM-I, a high success rate can be achieved with suboccipital decompression and duraplasty. Valsalva-related/tussive headaches resolved by the time of discharge from the hospital in the majority of children, and syrinx resolved or decreased in two-thirds of the children by 3 months. By 6 months, headaches were resolved in all cases, and syrinx was resolved or decreased in 79% of cases.

[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.

Comparison of Results Between Posterior Fossa Decompression with and without Duraplasty for the Surgical Treatment of Chiari Malformation Type I: A Systematic Review and Meta-Analysis

BACKGROUND

Posterior fossa decompression without (PFD) or with duraplasty (PFDD) for the treatment of type 1 Chiari malformation (CM-1) is controversial. We thus performed a systematic review and meta-analysis of studies to assess the effect on clinical and imaging improvement, operative time, complications, and recurrence rate between PFD and PFDD in patients with CM-1.

METHODS

We systematically searched PubMed, Embase, Cochrane, Web of Knowledge, and ClinicalTrials.gov for retrospective or prospective studies comparing PFD with PFDD. Our main end points were clinical and imaging improvement, operative time, complications, and recurrence rate. We assessed pooled data by use of a fixed-effects or random-effects model according to the between-study heterogeneity.

RESULTS

Of 214 identified studies, 13 were eligible and were included in our analysis (N = 3481 patients). Compared with PFD, PFDD led to a mean greater increase in operative time than did PFD [standardized mean difference, -2.35; 95% confidence interval [CI], (-2.70 to -1.99)], a higher likelihood of clinical improvement in patients with syringomyelia (relative risk [RR], 0.70; 95% CI, 0.49-0.98), no increased RR of clinical improvement in patients without syringomyelia, no increased RR of imaging improvement, but an increased RR of cerebrospinal fluid-related complications (RR, 0.29; 95% CI, 0.15-0.58), cerebrospinal fluid leak, aseptic meningitis, pseudomeningocele, and a decreased likelihood of recurrence rate.

CONCLUSIONS

PFDD can be an optimal surgical strategy because of its higher clinical improvement and lower recurrence rate in the patients with syringomyelia. In patients without syringomyelia, PFD can be a preferred choice because of its similar clinical improvement and lower costs. Future randomized studies with large numbers and the power to provide illumination for surgical decision making in CM-1 are warranted.

The addition of duraplasty to posterior fossa decompression in the surgical treatment of pediatric Chiari malformation Type I: a systematic review and meta-analysis of surgical and performance outcomes

OBJECTIVE Surgery is the definitive treatment of Chiari malformation Type I (CM-I). It involves posterior fossa decompression, which can be performed along with C-1 laminectomy, reconstructive duraplasty, or tonsil shrinkage. The aim of this study was to provide an updated systematic review and meta-analysis of the latest available evidence regarding posterior fossa decompression only (PFDO) versus posterior fossa decompression with duraplasty (PFDD) in the treatment of CM-I in children. METHODS A literature search was performed in compliance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for article identification, screening, eligibility, and inclusion. Relevant articles were identified from 6 electronic databases from their inception to April 2016. These articles were screened against established criteria for inclusion into this study. RESULTS From 12 relevant studies identified, 1492 pediatric patients treated via PFDD were compared with 1963 pediatric patients treated by PFDO for CM-I. PFDD was associated with greater overall clinical improvement (p = 0.009), along with longer length of stay (p < 0.0001) and more postoperative complications (p = 0.0001) compared with PFDO. No difference was observed between PFDD and PFDO in terms of revision surgery incidence (p = 0.13), estimated blood loss (p = 0.14), syrinx improvement (p = 0.09), or scoliosis improvement (p = 0.95). CONCLUSIONS It appears that the addition of duraplasty to posterior decompression in the definitive treatment of CM-I in children may alter surgical and performance outcomes. In particular, parameters of overall clinical improvement, length of stay, and postoperative complication may differ between children undergoing PFDD and those undergoing PFDO. Current evidence in the literature is of low to very low quality that, as of yet, has not been able to completely control for inherent selection bias both in study design and surgeon preference. Future, large prospective registries and randomized controlled trials are warranted to validate the findings of this study.

Trends in surgical treatment of Chiari malformation Type I in the United States

OBJECTIVE The goal of this analysis was to define temporal and geographic trends in the surgical treatment of Chiari malformation Type I (CM-I) in a large, privately insured health care network. METHODS The authors examined de-identified insurance claims data from a large, privately insured health care network of over 58 million beneficiaries throughout the United States for the period between 2001 and 2014 for all patients undergoing surgical treatment of CM-I. Using a combination of International Classification of Diseases (ICD) diagnosis codes and Current Procedural Terminology (CPT) codes, the authors identified CM-I and associated diagnoses and procedures over a 14-year period, highlighting temporal and geographic trends in the performance of CM-I decompression (CMD) surgery as well as commonly associated procedures. RESULTS There were 2434 surgical procedures performed for CMD among the beneficiaries during the 14-year interval; 34% were performed in patients younger than 20 years of age. The rate of CMD increased 51% from the first half to the second half of the study period among younger patients (p < 0.001) and increased 28% among adult patients between 20 and 65 years of age (p < 0.001). A large sex difference was noted among adult patients; 78% of adult patients undergoing CMD were female compared with only 53% of the children. Pediatric patients undergoing CMD were more likely to be white with a higher household net worth. Regional variability was identified among rates of CMD as well. The average annual rate of surgery ranged from 0.8 surgeries per 100,000 insured person-years in the Pacific census division to 2.0 surgeries per 100,000 insured person-years in the East South Central census division. CONCLUSIONS Analysis of a large nationwide health care network showed recently increasing rates of CMD in children and adults over the past 14 years.

External validity of the chiari severity index and outcomes among pediatric chiari I patients treated with intra- or extra-Dural decompression

INTRODUCTION

Chiari malformation type-1 (CM-1) may be treated by intradural (ID) or extradural (ED) posterior fossa decompression, although the optimal approach is debated. The Chiari Severity Index (CSI) is a pre-operative metric to predict patient-defined improvement after CM-1 surgery. In this study, we evaluate the results of ID versus ED decompression and assess the external validity of the CSI.

METHODS

We performed a retrospective cohort study of pediatric CM-1 patients undergoing decompression at a single academic children's hospital. Characteristics of headache, syrinx, and myelopathy were collected to derive CSI grade. The primary outcome measure was pre-operative symptom resolution. The proportion of patients with favorable outcome was tabulated for each of the three CSI grades and compared to previously published results.

RESULTS

From 2004 to 2014, 189 patients underwent ID (48%) or ED (52%) decompression at the Children's Hospital of Philadelphia (CHOP). Follow-up ranged from 1 to 75 months. Rates of symptom resolution (58-64%) and reoperation (8%) were similar regardless of surgical approach. Although proportions of favorable outcomes differed between the CHOP and Washington University (WU) cohorts, the difference was not related to CSI grade (p = 0.63). Furthermore, there was no difference in the proportion of favorable outcomes between the two cohorts regardless of ID (p = 0.26) or ED approach (p = 0.11).

CONCLUSIONS

Equivalent rates of symptom resolution and reoperation following ID and ED decompression support the ED approach as a first-line surgical option for pediatric CM-1 patients. In addition, our findings provide preliminary evidence supporting the generalizability of the CSI and its use in future comparative trials.

Comparison of posterior fossa decompression with and without duraplasty for the surgical treatment of Chiari malformation type I in adult patients: A retrospective analysis of 103 patients

Chiari malformation type I (CM-I) is a congenital neurosurgical disease about the herniation of cerebellar tonsil through the foramen magnum. A variety of surgical techniques for CM-I have been used, and there is a controversy whether to use posterior fossa decompression with duraplasty (PFDD) or posterior fossa decompression without duraplasty (PFD) in CM-I patients. Here, we compared the clinical results and effectiveness of PFDD and PFD in adult patients with CM-I. The cases of 103 adult CM-I patients who underwent posterior fossa decompression with or without duraplasty from 2008 to 2014 were reviewed retrospectively. Patients were divided into 2 groups according to the surgical techniques: PFDD group (n = 70) and PFD group (n = 33). We compared the demographics, preoperative symptoms, radiographic characteristics, postoperative complications, and clinical outcomes between the PFD and PFDD patients. No statistically significant differences were found between the PFDD and PFD groups with regard to demographics, preoperative symptoms, radiographic characteristics, and clinical outcomes(P > 0.05); however, the postoperative complication aseptic meningitis occurred more frequently in the PFDD group than in the PFD group (P = 0.027). We also performed a literature review about the PFDD and PFD and made a summary of these preview studies. Our study suggests that both PFDD and PFD could achieve similar clinical outcomes for adult CM-I patients. The choice of surgical procedure should be based on the patient's condition. PFDD may lead to a higher complication rate and autologous grafts seemed to perform better than nonautologous grafts for duraplasty.

Improvement of syrinx resolution after tonsillar cautery in pediatric patients with Chiari Type I malformation

OBJECT Chiari Type I malformation involves caudal displacement of the cerebellar tonsils below the foramen magnum, which obstructs normal cerebrospinal fluid flow and increases intracranial pressure. Certain aspects of its surgical treatment remain controversial. A retrospective study was conducted to assess the efficacy of tonsillar cautery on syrinx resolution among pediatric Chiari patients undergoing cervicomedullary decompression. METHODS A retrospective cohort study was performed for patients 0-18 years of age who underwent surgical correction for Chiari Type I malformation with syrinx between 1995 and 2013. Basic demographic information was collected as well as data for preoperative symptoms, prior surgical history, perioperative characteristics, and postsurgical outcomes. Descriptive statistics were performed in addition to bivariate analyses. Candidate predictor variables were identified based on an association with tonsillar cautery with p < 0.10. Forward stepwise likelihood ratio was used to select candidate predictors in a binary logistic regression model (P_in = 0.05, P_out = 0.10) most strongly associated with the outcome. RESULTS A total of 171 patients with Chiari Type I malformation with syrinx were identified, and 43 underwent tonsillar cautery. Patients who underwent tonsillar cautery had 6.11 times greater odds of improvement in their syrinx (95% CI 2.57-14.49, p < 0.001). There was no effect of tonsillar cautery on increased perioperative complications as well as the need for repeat decompressions. CONCLUSIONS Tonsillar cautery is safe and effective in the treatment of Chiari Type I malformation with syrinx and may decrease time to syrinx resolution after cervicomedullary decompression. Tonsillar cautery does not increase postoperative complications in pediatric Chiari Type I malformation patients.

Delayed resolution of syrinx after posterior fossa decompression without dural opening in children with Chiari malformation Type I

OBJECT Chiari malformation Type I (CM-I) is associated with a syrinx in 25%-85% of patients. Although posterior fossa decompression (PFD) without dural opening is an accepted treatment option for children with symptomatic CM-I, many surgeons prefer to open the dura if a syrinx exists. The purpose of this study was to investigate the frequency and timing of syrinx resolution in children undergoing PFD without dural opening for CM-I. METHODS A retrospective review of 68 consecutive pediatric patients with CM-I and syringomyelia who underwent PFD without dural opening was conducted. Patient demographics, presenting symptoms and signs, radiographic findings, and intraoperative ultrasound and neuromonitoring findings were studied as well as the patients' clinical and radiographic follow-up. RESULTS During the mean radiographic follow-up period of 32 months, 70% of the syringes improved. Syrinx improvement occurred at a mean of 31 months postoperatively. All patients experienced symptom improvement within the 1st year, despite only 26% of patients showing radiographic improvement during that period. Patients presenting with sensory symptoms or motor weakness had a higher likelihood of having radiographic syrinx improvement postoperatively. CONCLUSIONS In children with CM-I and a syrinx undergoing PFD without dural opening, syrinx resolution occurs in approximately 70% of patients. Radiographic improvement of the syrinx is delayed, but this does not correlate temporally with symptom improvement. Sensory symptoms or motor weakness on presentation are associated with syrinx resolution after surgery.

Clinical Outcome Measures in Chiari I Malformation

Chiari malformation type 1 (CM-I) is a common and often debilitating neurologic disease. Reliable evaluation of treatments has been hampered by inconsistent use of clinical outcome measures. A variety of outcome measurement tools are available, although few have been validated in CM-I. The recent development of the Chicago Chiari Outcome Scale and the Chiari Symptom Profile provides CM-I-specific instruments to measure outcomes in adults and children, although validation and refinement may be necessary.

Surgical History of Sleep Apnea in Pediatric Patients with Chiari Type 1 Malformation

Sleep apnea represents a relative indication for posterior fossa decompression in pediatric patients with Chiari malformation type 1. Duraplasty was associated with improvement of sleep apnea in 100% of patients and dural splitting with improvement in 50% of patients. Duraplasty and dural splitting were associated with a similar reduction in tonsillar herniation on radiographic imaging of 58% (37% excluding tonsillectomy) and 35%, respectively. Longitudinal follow-up studies of patients with either neurologic deficits or severe symptoms will further elucidate the natural history of Chiari malformation type 1 and more appropriately gauge the risk-benefit tradeoff of surgical intervention.

Outcomes after suboccipital decompression without dural opening in children with Chiari malformation Type I

OBJECT Symptomatic pediatric Chiari malformation Type I (CM-I) is most often treated with posterior fossa decompression (PFD), but controversy exists over whether the dura needs to be opened during PFD. While dural opening as a part of PFD has been suggested to result in a higher rate of resolution of CM symptoms, it has also been shown to lead to more frequent complications. In this paper, the authors present the largest reported series of outcomes after PFD without dural opening surgery, as well as identify risk factors for recurrence. METHODS The authors performed a retrospective review of 156 consecutive pediatric patients in whom the senior authors performed PFD without dural opening from 2003 to 2013. Patient demographics, clinical symptoms and signs, radiographic findings, intraoperative ultrasound results, and neuromonitoring findings were reviewed. Univariate and multivariate regression analyses were performed to determine risk factors for recurrence of symptoms and the need for reoperation. RESULTS Over 90% of patients had a good clinical outcome, with improvement or resolution of their symptoms at last follow-up (mean 32 months). There were no major complications. The mean length of hospital stay was 2.0 days. In a multivariate regression model, partial C-2 laminectomy was an independent risk factor associated with reoperation (p = 0.037). Motor weakness on presentation was also associated with reoperation but only with trend-level significance (p = 0.075). No patient with < 8 mm of tonsillar herniation required reoperation. CONCLUSIONS The vast majority (> 90%) of children with symptomatic CM-I will have improvement or resolution of symptoms after a PFD without dural opening. A non-dural opening approach avoids major complications. While no patient with tonsillar herniation < 8 mm required reoperation, children with tonsillar herniation at or below C-2 have a higher risk for failure when this approach is used.

Pediatric and adult Chiari malformation Type I surgical series 1965-2013: a review of demographics, operative treatment, and outcomes

OBJECT

Chiari malformation Type I (CM-I) is a hindbrain disorder associated with elongation of the cerebellar tonsils, which descend below the foramen magnum into the spinal canal. It occurs in children and adults. Clinical symptoms mainly develop from alterations in CSF flow at the foramen magnum and the common subsequent development of syringomyelia.

METHODS

The authors reviewed English-language reports of pediatric, adult, and combined (adult and pediatric) surgical series of patients with CM-I published from 1965 through August 31, 2013, to investigate the following: 1) geographical distribution of reports; 2) demographics of patients; 3) follow-up lengths; 4) study durations; 5) spectrum and frequency of surgical techniques; 6) outcomes for neurological status, syrinx, and headache; 7) frequency and scope of complications; 8) mortality rates; and 9) differences between pediatric and adult populations. Research and inclusion criteria were defined, and all series that contained at least 4 cases and all publications with sufficient data for analysis were included.

RESULTS

The authors identified 145 operative series of patients with CM-I, primarily from the United States and Europe, and divided patient ages into 1 of 3 categories: adult (>18 years of age; 27% of the cases), pediatric (≤18 years of age; 30%), or unknown (43%). Most series (76%) were published in the previous 21 years. The median number of patients in the series was 31. The mean duration of the studies was 10 years, and the mean follow-up time was 43 months. The peak ages of presentation in the pediatric studies were 8 years, followed by 9 years, and in the adult series, 41 years, followed by 46 years. The incidence of syringomyelia was 65%. Most of the studies (99%) reported the use of posterior fossa/foramen magnum decompression. In 92%, the dura was opened, and in 65% of these cases, the arachnoid was opened and dissected; tonsillar resection was performed in 27% of these patients. Postoperatively, syringomyelia improved or resolved in 78% of the patients. Most series (80%) reported postoperative neurological outcomes as follows: 75% improved, 17% showed no change, and 9% experienced worsening. Postoperative headaches improved or resolved in 81% of the patients, with a statistical difference in favor of the pediatric series. Postoperative complications were reported for 41% of the series, most commonly with CSF leak, pseudomeningocele, aseptic meningitis, wound infection, meningitis, and neurological deficit, with a mean complication rate of 4.5%. Complications were reported for 37% of pediatric, 20% of adult, and 43% of combined series. Mortality was reported for 11% of the series. No difference in mortality rates was seen between the pediatric and adult series.

CONCLUSIONS

Before undergoing surgical treatment for CM-I, symptomatic patients and their families should be given clear information about the success of treatment and potential complications. Furthermore, surgeons may benefit from comparing published data with their own. In the future, operative CM-I reports should provide all details of each case for the purpose of comparison.

National trends, complications, and hospital charges in pediatric patients with Chiari malformation type I treated with posterior fossa decompression with and without duraplasty

BACKGROUND

The treatment of type 1 Chiari malformation (CM-1) with posterior fossa decompression without (PFD) or with duraplasty (PFDD) is controversial. The authors analyze both options in a national sample of pediatric patients.

METHODS

Utilizing the Kids' Inpatient Database, CM-1 patients undergoing PFD or PFDD from 2000 through 2009 were analyzed.

RESULTS

1,593 patients with PFD and 1,056 with PFDD were evaluated. The average age was 10.3 years, slightly younger in PFD (9.8 vs. 10.9 years, p = 0.001). PFDD patients were more likely White (81.2 vs 75.6%, p = 0.04) and less likely admitted emergently (8.4 vs. 13.8%, p = 0.007). They also underwent more reoperations (2.1 vs. 0.7%, p = 0.01), had more procedure-related complications (2.3 vs. 0.8%, p = 0.003), a longer length of stay (4.4 vs. 3.8 days, p = 0.001) and higher charges (USD 35,321 vs. 31,483, p = 0.01).

CONCLUSIONS

This large national study indicates that PFDD is performed more often in Caucasians, less so emergently, and associated with significantly more complications and immediate reoperations, while PFD is more frequent in those with syringomyelia and more economical, requiring fewer hospital resources. Overall, PFD is more favorable for CM-1, though it would be prudent to conduct a prospective trial, as this analysis is limited by data on preoperative presentations and long-term outcomes.

Outcome methods used in clinical studies of Chiari malformation Type I: a systematic review

OBJECT

Chiari malformation Type I (CM-I) is a common and often debilitating neurological disease. Efforts to improve treatment of CM-I are impeded by inconsistent and limited methods of evaluating clinical outcomes. To understand current approaches and lay a foundation for future research, the authors conducted a systematic review of the methods used in original published research articles to evaluate clinical outcomes in patients treated for CM-I.

METHODS

The authors searched PubMed, Embase, the Cumulative Index to Nursing and Allied Health Literature, ClinicalTrials.gov , and Cochrane databases to identify publications between January 2003 and August 2013 that met the following criteria: 1) reported clinical outcomes in patients treated for CM-I; 2) were original research articles; 3) included at least 10 patients or, if a comparative study, at least 5 patients per group; and 4) were restricted to patients with CM-I.

RESULTS

Among the 74 papers meeting inclusion criteria, there was wide variation in the outcome methods used. However, all approaches were broadly grouped into 3 categories: 1) "gestalt" impression of overall symptomatic improvement (n=45 papers); 2) postoperative change in specific signs or symptoms (n=20); or 3) results of various standardized assessment scales (n=22). Among standardized scales, 11 general function measures were used, compared with 6 disease-specific tools. Only 3 papers used scales validated in patients with CM-I. To facilitate a uniform comparison of these heterogeneous approaches, the authors appraised articles in multiple domains defined a priori as integral to reporting clinical outcomes in CM-I. Notably, only 7 articles incorporated patient-response instruments when reporting outcome, and only 22 articles explicitly assessed quality of life.

CONCLUSIONS

The methods used to evaluate clinical outcomes in CM-I are inconsistent and frequently not comparable, complicating efforts to analyze results across studies. Development, validation, and incorporation of a small number of disease-specific patient-based instruments will improve the quality of research and care of CM-I patients.