Tonsillar pulsatility before and after surgical decompression for children with Chiari malformation type 1: an application for true fast imaging with steady state precession

Chiari I Deformity: Beyond 5 mm below the Foramen Magnum

Although originally described as a consecutive series of pathologic changes, Chiari syndrome represents a spectrum of disease divided into two subsets: development deformities of the paraxial mesoderm manifesting after birth (types 0-1.5) and true congenital malformations due to failure of neural tube closure present in utero (types 2-5). Heterogeneity among patients with a Chiari deformity and incomplete understanding of its pathophysiologic characteristics have led to inconsistency in radiologic reporting and difficulty in defining appropriate management strategies tailored to an individual patient's condition. The radiologist is tasked with going beyond the criteria for cerebellar tonsillar herniation to define an individual patient's disease state, determine candidacy for surgery, and assist in selecting the proper surgical approach. In addition, the radiologist must be able to identify conditions that result in cerebellar tonsillar herniation that are not related to Chiari deformity to avoid inappropriate surgery. Last, the radiologist must be able to interpret postoperative imaging examinations to assess for adequacy of treatment and complications. The authors summarize recent literature regarding the pathophysiologic basis of Chiari 1 and related deformities and detail the ideal morphologic and physiologic imaging assessment, focusing on Chiari 1 and related deformities (Chiari 0, 0.5, and 1.5). Also discussed are surgical techniques and "pearls" of postsurgical imaging, including complications that must be recognized. This review provides clarity to a commonly encountered but less understood condition to optimize outcomes for patients with Chiari 1 and related deformities. ©RSNA, 2024 Supplemental material is available for this article. See the invited commentary by Huisman in this issue.

Predictors of syrinx presentation and outcomes in pediatric Chiari malformation type I: a single institution experience of 218 consecutive syrinx patients

PURPOSE

Chiari I malformation (CM-I) in pediatric patients can impose substantial neurologic and functional impairment. Additionally, the presence of syrinx is often a harbinger of clinical compromise, but little attention has been devoted to identifying features associated with syrinx development and the clinical impact of syrinx resolution. Therefore, this study aims to identify clinical and radiographic variables associated with preoperative syrinx presence and postoperative syrinx reduction in pediatric patients with CM-I and determine the relationship between postoperative syrinx reduction and clinical symptom improvement.

METHODS

The authors performed a retrospective analysis of 435 consecutive pediatric patients who underwent surgical treatment of CM-I from 2001 to 2021 at a single tertiary pediatric medical center. All patients underwent pre- and postoperative MRI, and clinical and radiographic variables were recorded and subject to inferential analysis.

RESULTS

Syrinx at presentation was independently associated with symptoms of spinal cord dysfunction at presentation (OR 2.17 (95% CI 1.05-4.48); p = 0.036), scoliosis (OR 5.33 (2.34-10.86); p = 0.001), and greater pB-C2 (posterior basion to C2 distance) measurement length (OR 1.14 (95% CI 1.01-1.30); p = 0.040). Syrinx at presentation was inversely associated with tussive headaches at presentation (OR 0.27 (95% CI 0.16-0.47); p = 0.001) and cranial nerve deficits at presentation (OR 0.49 (95% CI 0.26-0.92); p = 0.025). Postoperatively, patients with radiographic evidence of syrinx improvement had greater rates of symptom improvement (93.1% vs 82.1%; p = 0.049), better CCOS scores (15.4 vs 14.2; p = 0.001), and decreased rates of readmission (6.0% vs 25.0%, p = 0.002) and reoperation (0.5% vs 35.7%; p = 0.001). The difference in syrinx resolution was similar but not statistically significant (10.3% vs 16.7%; p = 0.251). AO joint anomaly (OR 0.20, 95% CI 0.04-0.95; p = 0.026) and foramen magnum diameter (OR 1.12, 95% CI 1.00-1.25; p = 0.049) were the only independent predictors of syrinx improvement, and surgical technique was the only predictor for syrinx resolution (OR 2.44, 95% CI 1.08-5.50; p = 0.031). Patients that underwent tonsil reduction surgery whose syrinx improved had a wider foramen magnum diameter than those whose did not improve (34.3 vs 31.7; p = 0.028).

CONCLUSIONS

Radiographic syrinx improvement is associated with greater rates of symptom improvement and less readmissions and reoperations for CM-I. AO joint anomalies and narrower foramen magnums were independent risk factors for the lack of syrinx improvement. These novel insights will help guide preoperative patient counseling, pre- and intraoperative surgical decision-making, and postoperative clinical prognostication in the treatment of pediatric CM-I.

Surgical Management of Chiari Malformation Type I in the Pediatric Population: A Single-Center Experience

Background: Chiari malformation type 1 (CM-1) involves the cerebellar tonsils' descent below the foramen magnum. In Chiari malformation type 1.5 (CM-1.5), both the cerebellar tonsils and the brainstem are herniated. Common symptoms include headaches and cervical pain, often associated with conditions like syringomyelia and hydrocephalus. Surgical treatment is not performed in asymptomatic patients, while the presence of syringomyelia represents an indication for surgery. Methods: This study retrospectively examined pediatric patients with CM-1 and CM-1.5 at Giannina Gaslini Hospital from 2006 to 2020, analyzing demographics, radiological findings, surgical interventions, and outcomes. Results: Out of 211 patients who underwent surgery, 83.9% were diagnosed with CM-1 and 16.1% with CM-1.5. Headaches were prevalent (69%) and cerebellar signs were noted in 29% of patients. Syringomyelia and hydrocephalus were present in 28.4% and 8% of cases, respectively. Intraoperative ultrasonography guided interventions, with 59.8% requiring bony and ligamentous decompression, and 27.1% undergoing duraplasty. Conclusions: The surgical treatment of CM-1/CM-1.5 involves posterior cranial fossa decompression. Choosing between bony decompression alone and its combination with duraplasty has always been controversial in the pediatric population. If we consider as surgical endpoint the restoration of cerebrospinal fluid (CSF) flux, intraoperative ultrasound may be a real-time helpful tool in orienting the surgical strategy, yet refinement with quantitative measures is needed.

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

BACKGROUND

Chiari I malformation (CIM) is characterized by descent of the cerebellar tonsils through the foramen magnum, potentially causing symptoms from compression or obstruction of the flow of cerebrospinal fluid. Diagnosis and treatment of CIM is varied, and guidelines produced through systematic review may be helpful for clinicians.

OBJECTIVE

To perform a systematic review of the medical literature to answer specific questions on the diagnosis and treatment of CIM.

METHODS

PubMed and Embase were queried between 1946 and January 23, 2021, using the search strategies provided in Appendix I of the full guidelines.

RESULTS

The literature search yielded 567 abstracts, of which 151 were selected for full-text review, 109 were then rejected for not meeting the inclusion criteria or for being off-topic, and 42 were included in this systematic review.

CONCLUSION

Three Grade C recommendations were made based on Level III evidence. The full guidelines can be seen online at https://www.cns.org/guidelines/browse-guidelines-detail/1-imaging .

Insights on the Hydrodynamics of Chiari Malformation

Background: We propose that the appearance of a ptosis of the cerebellar tonsils and syringomyelia is linked to its own hemohydrodynamic mechanisms. We aimed to quantify cerebrospinal fluid (CSF) and cerebral blood flow to highlight how neurofluid is affected by Chiari malformations type 1(CMI) and its surgery. Methods: We retrospectively included 21 adult patients with CMI who underwent pre- and postoperative phase contrast MRI (PCMRI) during the period from 2001 to 2017. We analyzed intraventricular CSF, subarachnoid spaces CSF, blood, and tonsils pulsatilities. Results: In preoperative period, jugular venous drainage seems to be less preponderant in patients with syringomyelia than other patients (venous correction factor: 1.49 ± 0.4 vs. 1.19 ± 0.1, p = 0.05). After surgery, tonsils pulsatility decreased significantly (323 ± 175 μL/cardiac cycle (CC) vs. 194 ± 130 μL/CC, p = 0.008) and subarachnoid CSF pulsatility at the foramen magnum increased significantly (201 ± 124 μL/CC vs. 363 ± 231 μL/CC, p = 0.02). After surgery, we found a decrease in venous flow amplitude (5578 ± 2469 mm3/s vs. 4576 ± 2084 mm3/s, p = 0.008) and venous correction factor (1.98 ± 0.3 vs. 1.20 ± 0.3 mm3/s, p = 0.004). Conclusions: Phase-contrast MRI could be a useful additional tool for postoperative evaluation and follow-up, and is complementary to morphological imaging.

Comparison between Dura-Splitting Technique with Duraplasty in Symptomatic Patients with Chiari Malformation Type I: A Systematic Review and Meta-analysis

BACKGROUND: There are many surgical procedures for CIM patients, posterior fossa decompression with fibrous band excision, with additional duraplasty, or syringosubdural shunt for syringomyelia related CIM. Prospective studies have been carried out but yet no conclusion, on which one is the best option. The objective of this study was to assess qualitatively the outcome of posterior fossa decompression with dura-splitting (PFDDS) technique compared to posterior fossa decompression with duraplasty (PFDDP) for treating CIM patients. AIM: This study aimed to give us a preference while conducting surgery in a patient with Chiari malformation type I (CIM) between posterior fossa decompression with incision of the fibrous band of the dura (dura-splitting/DS) technique and duraplasty (DP) technique. METHODS: The analysis conducted using PRISMA flowchart with PICO framework (Patient: Chiari malformation type I patient over preschool age; Intervention: Dura-splitting; Comparison: Duraplasty; and Outcome: Complication rate, length of stay, reoperation rate, syrinx reduction, symptomatic improvement, and operation time) and already registered for meta-analysis study with database searching from PubMed, the Cochrane Library, and Google Scholar that following inclusion criteria: (1) Original study; (2) study that compares DS and DP in CM- I; and (3) patient age over preschool age. RESULTS: A review of five included studies involving 458 patients met the inclusion criteria, in which 319 patients treated with DS surgery and 139 for DP surgery for this study. Significantly DS technique correlated lower rate of complication (RR = 0.20; p < 0.0001), shorter length of stay (MD = −3.53; p = 0.0002), and shorter operation time (MD = −58.59; p = 0.0004). No significant differences in reoperation rate (RR = 1.90; p = 0.22), symptom improvement (RR = 1.12; p = 0.44), and syrinx reduction (RR = 1.11; p = 0.56) were noted. CONCLUSIONS: Posterior fossa decompression using the DS technique is associated with a lower rate of complication, shorter length of stay, and shorter operation time. However, no significant differences were found in the reoperation rate, symptom improvement, and syringomyelia reduction between these two techniques.

Fourth ventricle roof angle as a measure of fourth ventricle bowing and a radiographic predictor of brainstem dysfunction in Chiari malformation type I

OBJECTIVE

Chiari malformation type I (CM-I) is a congenital and developmental abnormality that results in tonsillar descent 5 mm below the foramen magnum. However, this cutoff value has poor specificity as a predictor of clinical severity. Therefore, the authors sought to identify a novel radiographic marker predictive of clinical severity to assist in the management of patients with CM-I.

METHODS

The authors retrospectively reviewed 102 symptomatic CM-I (sCM-I) patients and compared them to 60 age-matched normal healthy controls and 30 asymptomatic CM-I (aCM-I) patients. The authors used the fourth ventricle roof angle (FVRA) to identify fourth ventricle "bowing," a configuration change suggestive of fourth ventricle outlet obstruction, and compared these results across all three cohorts. A receiver operating characteristic (ROC) curve was used to identify a predictive cutoff for brainstem dysfunction. Binary logistic regression was used to determine whether bowing of the fourth ventricle was more predictive of brainstem dysfunction than tonsillar descent, clival canal angle, or obex position in aCM-I and sCM-I patients.

RESULTS

The FVRA had excellent interrater reliability (intraclass correlation 0.930, 95% CI 0.905-0.949, Spearman r2 = 0.766, p < 0.0001). The FVRA was significantly greater in the sCM-I group than the aCM-I and healthy control groups (59.3° vs 41.8° vs 45.2°, p < 0.0001). No difference was observed between aCM-I patients and healthy controls (p = 0.347). ROC analysis indicated that an FVRA of 65° had a specificity of 93% and a sensitivity of 50%, with a positive predictive value of 76% for brainstem dysfunction. FVRA > 65° was more predictive of brainstem dysfunction (OR 5.058, 95% CI 1.845-13.865, p = 0.002) than tonsillar herniation > 10 mm (OR 2.564, 95% CI 1.050-6.258, p = 0.039), although increasing age was also associated with brainstem dysfunction (OR 1.045, 95% CI 1.011-1.080, p = 0.009). A clival canal angle < 140° (p = 0.793) and obex below the foramen magnum (p = 0.563) had no association with brainstem dysfunction.

CONCLUSIONS

The authors identified a novel radiographic measure, the FVRA, that can be used to assess fourth ventricular bowing in CM-I and is more predictive of brainstem dysfunction than tonsillar herniation. The FVRA is easy to measure, has excellent interrater variability, and can be a reliable universal radiographic measure. The FVRA will be useful in further describing CM-I radiographically and clinically by identifying patients more likely to be symptomatic as a result of brainstem dysfunction.

Utility of True Fast Imaging with Steady-State Precession in Detecting Arachnoid Veils of the Posterior Fossa

INTRODUCTION

Arachnoid membranes are well recognized as a cause of cerebrospinal fluid (CSF) flow impairment in disorders such as obstructive hydrocephalus and syringohydromyelia, but can be difficult to detect with standard noninvasive imaging techniques. True fast imaging with steady-state precession (TrueFISP) can exhibit brain pulsations and CSF dynamics with high spatiotemporal resolution. Here, we demonstrate the utility of this technique in the diagnosis and management of arachnoid membranes in the posterior fossa.

CASE PRESENTATIONS

Three symptomatic children underwent cine TrueFISP imaging for suspicion of CSF membranous obstruction. Whereas standard imaging failed to or did not clearly visualize the site of an obstructive lesion, preoperative TrueFISP identified a membrane in all 3 cases. The membranes were confirmed intraoperatively, and postoperative TrueFISP helped verify adequate marsupialization and recommunication of CSF flow. Two out of the 3 cases showed a decrease in cerebellar tonsillar pulsatility following surgery. All children showed symptomatic improvement.

CONCLUSION

TrueFISP is able to detect pulsatile arachnoid membranes responsible for CSF outflow obstruction that are otherwise difficult to visualize using standard imaging techniques. We advocate use of this technology in pre- and postsurgical decision-making as it provides a more representative image of posterior fossa pathology and contributes to our understanding of CSF flow dynamics. There is potential to use this technology to establish prognostic biomarkers for disorders of CSF hydrodynamics.

Bony decompression vs duraplasty for Chiari I malformation: does the eternal dilemma matter?

PURPOSE

The management of Chiari I malformation (CIM) still raises the problem of the optimal surgical treatment, with special regard to the "eternal dilemma" of the posterior fossa bony decompression alone (PFBD) or with duraplasty (PFBDD). The goal of the present review is to update the results (outcome and complications) of both techniques to better understand the correct indication for each of them.

METHODS

A review of the literature has been performed, focusing on the articles and the meta-analyses specifically addressing the problem of PFBD vs PFBDD. Also, the personal authors' experience is briefly discussed.

RESULTS

PFBD (usually with C1 laminectomy, often with delamination of the external dural layer) is the most commonly used technique in children, especially if syringomyelia is absent. It ensures a high success rate, with > 80% clinical improvement and about 75% reduction of the syringomyelia, and a very low risk of complications, hospital stay, and costs. A certain risk of recurrence is present (2-12%). PFBDD (with autologous tissues or dural substitutes), on the other hand, is mostly used not only in adults but also in children with large syringomyelia. It is burdened by a higher risk of complications (namely, the CSF-related ones), longer hospital stay, and higher costs; however, it warrants a better clinical improvement (> 85%) and a lower risk of reoperation (2-3.5%). Eight meta-analyses of the literature (three on pediatric series and five in adult series) and one prospective study in children, published in the last decade, largely confirm these findings.

CONCLUSION

PFBD and PFBDD are different techniques that are indicated for different types of patients. In children, PFBD has been demonstrated to represent the best choice, although some patients may require a more aggressive treatment. Therefore, the success in the management of CIM, with or without syringomyelia, depends on the correct indication to surgery and on a patient-tailored choice rather than on the surgical technique.

Cerebellar Tissue Strain in Chiari Malformation with Headache

OBJECTIVE

The pathogenesis of Chiari malformation type 1 (CM-1)-associated Valsalva headache is unknown, but it may be caused by abnormal cerebellar tonsil tissue strain. Advances in cardiac-gated magnetic resonance imaging (MRI) techniques such as balanced fast-field echo (bFFE) allow quantification of the motion of anatomic structures and can be used to measure tissue strain. The current study investigated the relationship between Valsalva heachache and tonsillar motion in patients with CM-1.

METHODS

A retrospective review of patients with CM-1 who had undergone cardiac-gated bFFE MRI was performed. Headache symptoms were retrieved from the medical records. Anatomic landmarks were manually selected on the cine bFFE, and a validated motion-tracking software was used to assess motion over the cardiac cycle in patients at rest. For each patient, displacement, strain, and strain rate were calculated for 3 anatomic segments. Patients undergoing surgery were examined before and after surgery.

RESULTS

From 88 patients, a total of 108 bFFE sequences were analyzed. Valsalva headache was present in 50% of patients. Cerebellar tonsil displacement (P = 0.003), strain (P = 0.012), and maximum strain rate (P = 0.04) were reduced after surgery (n = 20). There was no statistically significant association between tissue motion and headache symptoms.

CONCLUSION

The results of this study do not support a relationship between cardiac cycle cerebellar strain and Valsalva headache in patients with CM-1. It is possible that cerebellar strain related to respiratory maneuvers is associated with headache in Chiari patients. Further investigation of tissue strain is warranted because it represents a potential biomarker for outcomes after surgery.

Dynamic cerebellar herniation in Chiari patients during the cardiac cycle evaluated by dynamic magnetic resonance imaging

PURPOSE

Cerebellar herniation in Chiari patients can be dynamic, following the cerebrospinal fluid pulsatility during the cardiac cycle. We present a voxel intensity distribution method (VIDM) to automatically extract the pulsatility-dependent herniation in time-resolved MRI (CINE MRI) and compare it to the simple linear measurements. The degree of herniation is furthermore compared on CINE and static sequences, and the cerebellar movement is correlated to the presence of hydrocephalus and syringomyelia.

METHODS

The cerebellar movement in 27 Chiari patients is analyzed with VIDM and the results were compared to linear measurements on an image viewer (visual inspection, VI) using a paired t test. Second, an ANOVA test is applied to compare the degree of herniation on static 3D MRI and CINE. Finally, the Pearson's correlation coefficient is calculated for the correlation between cerebellar movement and the presence of hydrocephalus and syringomyelia.

RESULTS

VIDM showed significant movement in 85% of our patients. Assuming that movement < 1 mm cannot be detected reliably on an image viewer, VI identified movement in 29.6% of the patients (p = 0.002). The herniation was greater on static sequences than on CINE in most cases, but this was not statistically significant. The cerebellar movement was not correlated with hydrocephalus or syringomyelia (Pearson's coefficient < 0.3).

CONCLUSIONS

VIDM is a sensitive method to detect tissue movement on CINE MRI and could be used for Chiari patients, but also for the evaluation of cyst membranes, ventriculostomies, etc. The cerebellar movement appears not to correlate with hydrocephalus and syringomyelia in Chiari patients.

Cerebellar tonsil ectopia measurement in type I Chiari malformation patients show poor inter-operator reliability

Background

Type 1 Chiari malformation (CM-I) has been historically defined by cerebellar tonsillar position (TP) greater than 3–5 mm below the foramen magnum (FM). Often, the radiographic findings are highly variable, which may influence the clinical course and patient outcome. In this study, we evaluate the inter-operator reliability (reproducibility) of MRI-based measurement of TP in CM-I patients and healthy controls.

Methods

Thirty-three T2-weighted MRI sets were obtained for 23 CM-I patients (11 symptomatic and 12 asymptomatic) and 10 healthy controls. TP inferior to the FM was measured in the mid-sagittal plane by seven expert operators with reference to McRae’s line. Overall agreement between the operators was quantified by intraclass correlation coefficient (ICC).

Results

The mean and standard deviation of cerebellar TP measurements for asymptomatic (CM-Ia) and symptomatic (CM-Is) patients in mid-sagittal plane was 6.38 ± 2.19 and 9.57 ± 2.63 mm, respectively. TP measurements for healthy controls was 0.48 ± 2.88 mm. The average range of TP measurements for all data sets analyzed was 7.7 mm. Overall operator agreement for TP measurements was relatively high with an ICC of 0.83.

Conclusion

The results demonstrated a large average range (7.7 mm) of measurements among the seven expert operators and support that, if economically feasible, two radiologists should make independent measurements before radiologic diagnosis of CM-I and surgery is contemplated. In the future, an objective diagnostic parameter for CM-I that utilizes automated algorithms and results in smaller inter-operator variation may improve patient selection.

Cardiac-Related Spinal Cord Tissue Motion at the Foramen Magnum is Increased in Patients with Type I Chiari Malformation and Decreases Postdecompression Surgery

OBJECTIVE

Type 1 Chiari malformation (CM-I) is a craniospinal disorder historically defined by cerebellar tonsillar position greater than 3-5 mm below the foramen magnum (FM). This definition has come under question because quantitative measurements of cerebellar herniation do not always correspond with symptom severity. Researchers have proposed several additional radiographic diagnostic criteria based on dynamic motion of fluids and/or tissues. The present study objective was to determine if cardiac-related craniocaudal spinal cord tissue displacement is an accurate indicator of the presence of CM-I and if tissue displacement is altered with decompression.

METHODS

A cohort of 20 symptomatic patients underwent decompression surgery. Fifteen healthy volunteers were recruited for comparison with the CM-I group. Axial phase-contrast magnetic resonance imaging (PC-MRI) measurements were collected before and after surgery at the FM with cranial-caudal velocity encoding and 20 frames per cardiac cycle with retrospective reconstruction. Spinal cord motion (SCM) at the FM was quantified based on the peak-to-peak integral of average spinal cord velocity.

RESULTS

Tissue motion for the presurgical group was significantly greater than controls (P = 0.0009). Motion decreased after surgery (P = 0.058) with an effect size of -0.151 mm and a standard error of 0.066 mm. Postoperatively, no statistical difference from controls in bulk displacement at the FM was found (P = 0.200) after post hoc testing using the Tukey adjustment for multiple comparisons.

CONCLUSIONS

These results support SCM measurement by PC-MRI as a possible noninvasive radiographic diagnostic for CM-I. Dynamic measurement of SCM provides unique diagnostic information about CM-I alongside static quantification of tonsillar position and other intracranial morphometrics.

Management of parturients in active labor with Arnold Chiari malformation, tonsillar herniation, and syringomyelia

BACKGROUND

Arnold-Chiari malformation Type 1 (ACM-1) in parturients is a topic of ongoing discussion between obstetricians and anesthesiologists. The primary unanswered question remains; How should the anesthesia provider proceed with labor analgesia and anesthesia for cesarean section when confronted with an advanced, asymptomatic, or minimally symptomatic case of ACM-1 during labor?

CASE DESCRIPTION

A 24-year-old, ASA II, G1P0 full-term parturient presented to Labor and Delivery for vaginal delivery. A diagnosis of ACM-1 was made 12 years ago when a brain magnetic resonance imaging (MRI) was performed for right-sided numbness following a rear-end motor vehicle collision. The patient had been asymptomatic since then and had been seen by an outside neurologist frequently for the past 10 years. During the anesthesia evaluation, it was noted that she had an exaggerated patellar reflex, and a questionable left-sided Babinski; subsequently, an MRI study was requested. Review of a brain MRI demonstrated an advanced form of ACM with a 1.7 cm transtonsillar herniation and a large syrinx extending from C1 down to C5. Following a discussion with the patient, family, and primary OB team, a plan for elective cesarean section was made per neurosurgical recommendations. This was conducted uneventfully under general anesthesia. The patient had no complaints in the post-anesthesia care unit.

CONCLUSION

Unfamiliarity of health care providers with regards to ACM-1 parturients can be countered by increasing awareness of this condition throughout medical specialties involved in their care. The Ghaly Obstetric Guide to Arnold-Chiari malformation Type 1, along with proper training of anesthesia care providers regarding the specificities of ACM-1 parturients aids in better management and understanding of this complex condition.

"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.