Histological and intraoperative evaluations of the arachnoid in patients with Chiari I malformation

BACKGROUND

Arachnoid dissection for decompression of Chiari I malformation is controversial. Whether arachnoid changes have an impact on the clinical course is not established. This paper documents the histological spectrum of arachnoid changes and evaluates correlations with preoperative, intraoperative, and postoperative data.

METHOD

Arachnoid samples of 162 consecutive foramen magnum decompressions from 2006 to 2016 were studied. Arachnoid thickness and degrees of fibrosis and cellularity were determined with the examiner blinded for clinical data. Based on 145 first time decompressions, a histological classification for arachnoid features was developed.

RESULTS

The arachnoid was thicker in secondary compared with primary decompressions (176.1 ± 158.2 μm vs. 35.9 ± 43.5 μm; p = 0.0026) and in adults compared to children (37.3 ± 45.3 μm vs. 21.8 ± 7.7 μm; p = 0.0007). In primary decompressions, arachnoid thickness, degrees of fibrosis, and cellularity followed a normal distribution with all features shifted significantly to higher grades in secondary decompressions. The histological classification correlated with the preoperative severity of gait ataxia, motor weakness, and sensory deficits, whereas it had no predictive power for postoperative short- or long-term results. By comparison, the intraoperative evaluation of arachnoid changes accounting for relationships between arachnoid and surrounding tissues showed higher correlations with preoperative symptoms and had significant predictive power for postoperative short- and long-term results.

CONCLUSIONS

Histological changes of the arachnoid correlate with preoperative symptoms. Relationships between arachnoid and surrounding tissues show even higher correlations with predictive power for short- and long-term outcomes. These findings suggest a pathophysiological role for the arachnoid in Chiari I malformation.

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.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Emergency Department Visits Following Suboccipital Decompression for Adult Chiari Malformation Type I

BACKGROUND

Postoperative emergency department (ED) visits following suboccipital decompression in Chiari malformation type I (CM-1) patients are not well described. We sought to evaluate the magnitude, etiology, and significance of postoperative ED service utilization in adult CM-1 patients at a tertiary referral center.

METHODS

A prospectively maintained database of CM-1 patients seen at our institution between January 1, 2006 and December 31, 2019 was used. ED visits occurring within 30 days after surgery were tracked for postoperative patients, while comparing clinical, imaging, and operative characteristics between patients with and without an ED visit. Clinical improvement at last follow-up was also compared between both groups of patients in a univariable and multivariable analysis using the Chicago Chiari Outcome Scale (CCOS).

RESULTS

In 175 surgically treated patients, 44 (25%) visited an ED in the 1-month period after surgery. The most common reason for seeking care was isolated headache (41%), and concentration disturbance at presentation was the only factor significantly associated with a postoperative ED visit (P = 0.023). The occurrence of a postoperative ED visit was independently associated with a lower chance of clinical improvement at last follow-up (adjusted odds ratio of CCOS ≥13 = 0.35, P = 0.021; adjusted odds ratio of CCOS ≥14 = 0.38, P = 0.016).

CONCLUSIONS

Adult CM-1 patients undergoing surgery at a tertiary referral center have an elevated rate of postoperative ED visits, which are mostly due to pain-related complaints. Such visits are hard to predict but are associated with worse long-term clinical outcome. Interventions that decrease the magnitude of postoperative ED service utilization are warranted.

The Perplexity Surrounding Chiari Malformations - Are We Any Wiser Now?

Chiari malformations are a diverse group of abnormalities of the brain, craniovertebral junction, and the spine. Chiari 0, I, and 1.5 malformations, likely a spectrum of the same malformation with increasing severity, are due to the inadequacy of the para-axial mesoderm, which leads to insufficient development of occipital somites. Chiari II malformation is possibly due to nonclosure of the caudal end of the neuropore, with similar pathogenesis in the rostral end, which causes a Chiari III malformation. There have been significant developments in the understanding of this complex entity owing to insights into the pathogenesis and advancements in imaging modalities and neurosurgical techniques. This article aims to review the different types and pathophysiology of the Chiari malformations, along with a description of the various associated abnormalities. We also highlight the role of ante- and postnatal imaging, with a focus on the newer techniques in the presurgical evaluation, with a brief mention of the surgical procedures and the associated postsurgical complications.

Intradural Pathology Causing Cerebrospinal Fluid Obstruction in Syringomyelia and Effectiveness of Foramen Magnum and Foramen of Magendie Dredging Treatment

OBJECTIVE

This article discusses the procedure of foramina magnum and Magendie dredging, summarizing the pathologic changes in the intradural region of the craniocervical junction in patients with syringomyelia and the pathophysiologic mechanism of cerebrospinal fluid (CSF) circulation obstruction.

METHODS

Clinical data from 50 adult patients with syringomyelia treated at Xuanwu Hospital from July 2018 to January 2019 were collected and retrospectively analyzed. All operations were performed with foramina magnum and Magendie dredging, and all intradural factors that may have induced the obstruction of CSF circulation were recorded.

RESULTS

Intradural pathology was found in all patients. The pathologic changes that may have caused obstruction of the CSF circulation include tonsil occupying the foramen magnum and overlying foramen of Magendie in 88% (44/50), intertonsillar arachnoid adhesions in 36% (18/50), tonsil to medulla arachnoid adhesions in 18% (9/50), medialized tonsils in 70% (35/50), vermian branch of posterior inferior cerebellar artery in 22% (11/50), arachnoid veil in 16% (8/50), cisterna magna cyst in 4% (2/50), and tonsil to dura mater arachnoid adhesions in 8% (4/50). Mean duration of follow-up was 13.3 months. The long-term effective rate was 96.0%. Postoperative magnetic resonance imaging revealed that the size of the syringomyelia was reduced or completely resolved in 88% of patients. The mean preoperative Japanese Orthopaedic Association score was 12.9 ± 3.1, which improved to 14.7 ± 3.2 (P < 0.05) at last clinical follow-up.

CONCLUSIONS

Intradural pathology that causes CSF circulation obstruction exists in many forms. Relieving the obstruction of the foramen magnum and foramen of Magendie is key to surgical treatment.

Atlantoaxial fixation for failed foramen magnum decompression in patients with Chiari formation

Background:

Relationship of atlantoaxial instability with Chiari formation is further analyzed in the report.

Objective:

The outcome of 25 patients who had failed conventional treatment for Chiari formation that included foramen magnum decompression surgery and were treated by atlantoaxial fixation is analyzed.

Materials and Methods:

During the period January 2010 to November 2019, we treated 25 patients who had undergone conventionally described surgical procedures; all included foramen magnum decompression for Chiari formation. None of the patients had any craniovertebral junction anomaly. All patients had syringomyelia. All patients had worsened in their neurological condition following surgery either in the immediate or in the delayed postoperative phase. Atlantoaxial instability was diagnosed on the basis of facetal alignment and on the basis of direct observation of joint status by bone manipulation during surgery. The patients were treated by atlantoaxial fixation. Goel clinical grading scale and Japanese Orthopedic Association Score assessed the clinical status both before and after surgery.

Results:

Following surgery, all patients improved in the clinical condition. The improvement began in the immediate postoperative period and progressed. During the follow-up period that ranged from 4 to 123 months, “significant” neurological recovery and amelioration of presenting symptoms were observed. During the period of follow-up, reduction in the size of syrinx was observed in 14 out of 18 cases where postoperative magnetic resonance imaging was possible.

Conclusions:

Clinical results reinforce the belief that atlantoaxial instability is the nodal point of pathogenesis of Chiari formation. Atlantoaxial fixation is the treatment.

Minimally invasive foramen magnum durectomy and obexostomy for treatment of craniocervical junction-related syringomyelia in adults: case series and midterm follow-up

OBJECTIVE

Craniocervical junction-related syringomyelia (CCJS) is the most common form of syringomyelia. Approximately 30% of patients treated with foramen magnum decompression (FMD) will show persistence, recurrence, or progression of the syrinx. The authors present a pilot study with a new minimally invasive surgery technique targeting the pathophysiology of CCJS in adult patients.

METHODS

The authors retrospectively analyzed the clinical and radiological features of a consecutive series of patients treated for CCJS. An FMD and FM durectomy were performed through a 1.5- to 2-cm skin incision. Then arachnoid adhesions were cleared, creating a permanent communication from the fourth ventricle to the new paraspinal extradural cavity (obexostomy) and with the spinal subarachnoid space. The hypothesis was that the new CSF pouch acts like a pressure leak, interrupting the CCJS pathogenesis.

RESULTS

Twenty-four patients (13 female, 21-61 years old) were treated between 2014 and 2018. The etiology of CCJS was Chiari malformation type I (CM-I) in 20 patients (83.3%), Chiari malformation type 0 (CM-0) in 2 patients (8.3%), and CCJ arachnoiditis in 2 patients (8.3%). Two patients underwent reoperations after failed FMD for CM-I at other institutions. No major surgical complication occurred. One patient had postoperative meningitis with no CSF fistula. On postoperative MRI, shrinkage of the syrinx was seen in all patients. No patients experienced recurrence of the CCJS. No patient required a subsequent operation. The mean duration of surgery was 72 ± 11 minutes (mean ± SD), and blood loss was 35-80 ml (mean 51 ml). Follow-up ranged from 12 to 58 months. The average overall improvement in modified Japanese Orthopaedic Association scores was 10% (p < 0.001). The Odom scale showed that 19 patients (79.1%) were satisfied, 4 (16.7%) remained the same, and 1 (4.2%) reported a poor outcome. All patients experienced postoperative improvement in perception of quality of life (p < 0.001).

CONCLUSIONS

Minimally invasive FM durectomy and obexostomy is a safe and effective treatment for CCJS and for patients who have not responded to other treatment.

Operative findings and surgical outcomes in patients undergoing Chiari 1 malformation decompression: relationship to the extent of tonsillar ectopia

BACKGROUND

The diagnosis of Chiari 1 malformation is based on the extent of tonsillar ectopia.

OBJECTIVE

To examine the relationship between the extent of tonsillar ectopia and the intra-operative findings and clinical outcome following Chiari decompression surgery.

METHODS

Patients were divided into four groups depending on the position of the cerebellar tonsil (T): group 1: 0 < T < 3; group 2: 3 ≤ T ≤ 5; group 3: 5 < T ≤ 10; and group 4: T > 10. Intra-operative observations were recorded with regard to compression of the brain stem by posterior inferior cerebellar artery (pica), neuroma formation along the first cervical (C1), and accessory spinal nerves (XI), and pallor of the cerebellar tonsils. Brain stem auditory evoked potentials, (BAEP), were monitored in each case. One hundred sixty-eight patients accrued between 2009 and 2013 agreed to participate in an outcome study to determine the effectiveness of foramen magnum decompression. Findings across the four groups were compared using one-way ANOVA. Observed differences were further subjected to paired analysis. Intra-group comparisons were made using the paired t test. A P value less than 0.05 was considered statistically significant.

RESULTS

There were 98 patients in group 1, 147 patients in group 2, 180 patients in group 3, and 63 patients in group 4. The mean extent of tonsillar ectopia was 0.4, 4.0, 7.1, and 14.3 mm in the four groups respectively. The prevalence of tonsillar pallor was greatest in group 4. Otherwise, there was no difference observed in the operative findings. A reduction of > 0.1 msec in the wave III-wave V latency of the BAEP was noted in all four groups with equal frequency. One hundred ten patients complied with at least 6 months follow-up. There was no difference in the prevalence of symptoms between the four groups at the time of initial evaluation and at 6 weeks and 6 months following surgery. There was a statistically significant reduction in the intensity of individual symptoms 6 months following surgery regardless of the extent of tonsil ectopia.

CONCLUSION

Other than the finding of tonsillar pallor, there was no relationship between the extent of tonsillar ectopia and the intraoperative anatomical and physiological observations, nor was there any relationship to the likelihood of symptomatic improvement following surgery. These observations call into question the focus on the extent of tonsillar of ectopia in assessing the patient who presents with symptoms of the Chiari malformation.

Chiari type 1-a malformation or a syndrome? A critical review

OBJECTIVE

As the understanding of pathophysiology behind Chiari malformation still is limited, the treatment of Chiari malformation type 1 remains rather empirical. This may result in suboptimal treatment strategy and outcome in many cases. In this review, we critically address whether the condition known today as Chiari malformation type I should rather be denoted Chiari syndrome.

METHODS

The current knowledge of Chiari malformation type 1 is summarized from the historical, etymological, genetic, clinical, and in particular pathophysiological perspectives.

RESULTS

There are several lines of evidence that Chiari malformation type 1 represents a condition significantly different from types 2 to 4. Unlike the other types, the type 1 should rather be considered a syndrome, thus supporting the reasons to reappraise the traditional classification of Chiari malformations.

CONCLUSION

We propose that Chiari malformation type 1 should rather be denoted Chiari syndrome, while the notation malformation is maintained for types 2-4.

The SHORE Score: A Novel Predictive Tool for Improvement After Decompression Surgery in Adult Chiari Malformation Type I

BACKGROUND

A practical scoring system predicting significant improvement after surgical decompression in adult Chiari malformation type I (CM-1) based on validated outcome measures is lacking. We aimed to develop a simple score and improvement calculator to facilitate the decision making process in symptomatic CM-1 patients.

METHODS

We evaluated adult CM-1 patients who presented to our institution between September 2006 and September 2018 and underwent surgical decompression. Previously treated patients were excluded. Univariable analysis and multivariable logistic regression were conducted to derive an optimal model predictive of improvement on last follow-up as measured by the Chicago Chiari Outcome Scale. A score was derived using the beta coefficients of the model, and predictive performance was assessed using receiver operating curves with bootstrap validation. Finally, a web-based improvement calculator was deployed.

RESULTS

The surgical cohort consisted of 149 adult CM-1 patients, of which 100 (67%) experienced significant clinical improvement (Chicago Chiari Outcome Scale ≥14) after a mean follow-up of 1.9 years. The final model predictive of significant clinical improvement consisted of headache with Valsalva (odds ratio [OR] = 2.39; P = 0.030), nonwhite race (OR = 2.57; P = 0.041), absence of visual symptoms (OR = 2.59; P = 0.015), syrinx absence (OR = 1.59; P = 0.315), and increased odontoid retroflexion (OR = 2.82; P = 0.009). The score was termed SHORE, which summarizes the model's predictive factors, each assigned 1 point. The model had an area under the curve of 0.754 with an optimism-correct value of 0.721. A calculator was deployed under: https://jhuspine2.shinyapps.io/SHORE_score/.

CONCLUSIONS

The score and calculator can serve as supplements to clinical decision making by providing realistic and personalized expectations of postoperative outcome.

Outcomes of dura-splitting technique compared to conventional duraplasty technique in the treatment of adult Chiari I malformation: a systematic review and meta-analysis

Chiari malformation type I is a developmental abnormality with an array of surgical techniques introduced for the management of it. The most common technique is foramen magnum decompression with duraplasty. Dura-splitting technique as one of the non-dura-opening techniques is a less known procedure that spares the internal layer of the dura and can theoretically result in fewer complications compared to duraplasty. So, we performed a review of literature and meta-analysis on different clinical and radiological aspects of this technique and compared its outcomes to duraplasty. MOOSE guidelines were followed. A systematic search of three databases based on predefined search strategy and inclusion/exclusion criteria was performed. After quality assessment and data extraction by two authors, summarized data were presented in form of tables, and meta-analysis results were illustrated in forest plots. A review of 10 included studies consisting of 370 patients revealed significantly shorter operation duration and less intraoperative blood loss in the dura-splitting technique compared to duraplasty. Interestingly, there was no significant difference between these two techniques in terms of clinical and radiological outcomes. Overall complication rate and incidence of CSF-related complications or infections were significantly in favor of the dura-splitting technique. Dura-splitting technique can be considered as a safe and effective surgical procedure for Chiari I malformation with comparable outcomes and fewer complications compared to duraplasty, although this interpretation is derived from retrospective observational studies and lack of a prospective clinical trial is evident.

Chiari 1 Formation Redefined-Clinical and Radiographic Observations in 388 Surgically Treated Patients

OBJECTIVE

The subject of Chiari formation is revisited and redefined. Results of surgical treatment of patients with Chiari formation by atlantoaxial fixation are presented.

METHODS

Results were analyzed of 388 patients with Chiari formation surgically treated during 2010 to June 2019.

RESULTS

Two hundred and sixty-six patients had syringomyelia. Two hundred and three patients had no craniovertebral bone abnormality and 74 patients had group A and 111 patients had group B basilar invagination. Twenty-nine patients had been earlier treated by foramen magnum decompression surgery with or without duroplasty. Clinical parameters, analysis of video recordings both before and after surgery, and patient self-assessment were included in the analysis of outcome. Immediate postoperative and sustained clinical improvement was observed in 385 patients (99.4%).

CONCLUSIONS

Satisfactory clinical outcome in most patients after atlantoaxial fixation and without any manipulation of neural structures, dura, or bone in the region of foramen magnum consolidates the viewpoint that atlantoaxial instability is the nodal point of pathogenesis of Chiari 1 formation. The study suggests that Chiari 1 formation may be a secondary natural neural alteration in the face of atlantoaxial instability. The role of foramen magnum decompression surgery needs to be reassessed.

Epidemiology of Symptomatic Chiari Malformation in Tatarstan: Regional and Ethnic Differences in Prevalence

BACKGROUND

Epidemiology can assess the effect of Chiari I malformation (CM1) on the neurological health of a population and evaluate factors influencing CM1 development.

OBJECTIVE

To analyze the regional and ethnic differences in the prevalence of CM1.

METHODS

The population of the Republic of Tatarstan (RT) in the Russian Federation was evaluated for patients with CM1 symptoms over an 11-yr period. Typical symptoms of CM1 were found in 868 patients. Data from neurological examination and magnetic resonance imaging (MRI) measurement of posterior cranial fossa structures were analyzed.

RESULTS

MRI evidence of CM1, defined as cerebellar tonsils lying at least 5 mm inferior to the foramen magnum, was found in 67% of symptomatic patients. Another 33% of symptomatic patients had 2 to 4 mm of tonsillar ectopia, which we defined as "borderline Chiari malformation type 1 (bCM1)." The period prevalence in the entire RT for symptomatic CM1 was 20:100 000; for bCM1 was 10:100 000; and for CM1 and bCM1 together was 30:100 000. Prevalence of patients with CM1 symptoms was greater in the northern than southern districts of Tatarstan, due to a high prevalence (413:100 000) of CM1 in the Baltasy region in one of the northern districts.

CONCLUSION

One-third of patients with typical symptoms of CM1 had less than 5 mm of tonsillar ectopia (bCM1). Assessments of the health impact of CM1-type symptoms on a patient population should include the bCM1 patient group. A regional disease cluster of patients with Chiari malformation was found in Baltasy district of RT and needs further study.

Radiological outcome after surgical treatment of syringomyelia-Chiari I complex in adults: a systematic review and meta-analysis

Foramen magnum decompression (FMD) is widely accepted as the standard treatment for syringomyelia associated with Chiari type I malformation (CMI). Despite extensive clinical investigations, relevant surgical details are still matter of debate. The authors performed a systematic review and meta-analysis of the literature examining the radiological outcome of syringomyelia in adult patients with CMI after different surgical strategies. PRISMA guidelines were followed. A systematic search of three databases was performed for studies published between 1990 and 2018. Our systematic review included 13 studies with a total of 276 patients with CMI associated with syringomyelia. Overall, the rate of post-operative radiological improvement at last follow-up was 81.1% (95% CI 73.3-88.9%; p < 0.001; I² = 71.4%). The rate of post-operative syrinx shrinkage did not differ significantly among both groups of decompression with the extra-arachnoidal technique and arachnoid dissection (90%, 95% CI 85.1-94.8%, I² = 0% vs 79.8%, 95% CI 61.7-98%, I² = 85.5%). A lower rate of post-operative radiological syrinx shrinkage was observed after decompression with splitting of the outer layer of the dura (55.6% 95% CI 40.5-70.8%, I² = 0%). CSF-related complications and infections were similar among the different groups. Our meta-analysis found that FMD with the extra-arachnoidal technique and arachnoid dissection provides similar results in terms of post-operative shrinkage of syringomyelia. Patients undergoing decompression with splitting of the dura presented the lower rate of syrinx reduction. These data should be considered when choosing the surgical approach in adult patients with CMI associated with syringomyelia.

Multidimensional, patient-reported outcome after posterior fossa decompression in 79 patients with Chiari malformation type I

Background:

We studied patient-reported outcome among patients who underwent posterior fossa decompression (PFD) for Chiari malformation type I (CM-I).

Methods:

We interviewed patients who underwent PFD for CM-I from 1995 to 2016.

Results:

A total of 79 patients were interviewed. The median age at surgery was 30 years (range 5–72 years) with 27 pediatric patients. Forty-six patients had syringomyelia (36 adults and 10 pediatric patients). Fifty-four patients (68%) reported at least some improvement, 46 (58%) important improvement, 13 (16%) worsening, and 12 stabilization (15%). Any improvement as well as important improvement were significantly more often reported in the nonsyringomyelia group (85% vs. 57%, P = 0.01 and 76% vs. 46%, P = 0.01, respectively). Of the 47 patients reporting preoperative neck pain, 31 (66%) reported at least some improvement after surgery and 9 (19%) worsening after surgery. Of the 59 patients experiencing headaches before surgery, 45 (76%) reported at least some improvement after surgery and 4 (7%) worsening. Quality of life was mostly affected by pain and discomfort in all groups. Sixty-two patients (78%) were satisfied or very satisfied with the results of surgery and 8 (11%) were unsatisfied or very unsatisfied. Up to 71 patients (90%) would consent to surgery again.

Conclusion:

In CM-I patients, PFD offers symptom improvement in about two-thirds of patients with high patient satisfaction. Symptom improvement is significantly higher in patients without associated syringomyelia, but patient satisfaction is similar. Symptom worsening is more frequent in the adult than in the pediatric population, with similar rates of postoperative improvement and patient satisfaction.

Chiari malformation and syringomyelia

Chiari malformation was first described over a century ago, and consists of posterior fossa anomalies that generally share the feature of cerebellar tonsillar descent through the foramen magnum. Our understanding of this disorder was initially based on autopsy studies, and has been greatly enhanced by the advent of MRI. The surgical management of Chiari anomalies has also evolved in a parallel fashion. Although the exact surgical technique varies among individual surgeons, the goals of surgery remain constant and consist of relieving brainstem compression and cranial nerve distortion, restoring the normal flow of CSF across the foramen magnum, and reducing the size of any associated syrinx cavity. Syrinx cavities are most commonly associated with Chiari anomalies, yet primary spinal syringomyelia (PSS) can be caused by traumatic, infectious, degenerative, and other etiologies that cause at least a partial CSF flow obstruction in the spinal subarachnoid space. As with syringomyelia associated with Chiari anomalies, the main goal of PSS surgery is to reestablish CSF flow across the area of obstruction. In addition to MRI, myelography with CT can be very helpful in the evaluation and management of these patients by identifying focal regions of CSF obstruction that may be amenable to surgical intervention. Future directions for the treatment of Chiari anomalies and syringomyelia include the application of advanced imaging techniques, more widespread use of genetic evaluation, large-scale outcome studies, and the further refinement of surgical technique.

Fourth Ventricle Enlargement in Chiari Malformation Type I

OBJECTIVE

How Chiari malformation type I (CM-I) affects posterior fossa brain structures and produces various symptoms remains unclear. The fourth ventricle is surrounded by critical structures required for normal function. The foramen of Magendie can be obstructed in CM-I; therefore, fourth ventricle changes may occur. To test this hypothesis, we assessed fourth ventricle volume in CM-I compared with healthy controls.

METHODS

Using our database from 2007-2016, we studied 72 patients with CM-I and 30 age-matched healthy control subjects. Fourth and lateral ventricle volumes and posterior fossa volumes (PFV) were assessed and correlated with clinical signs and symptoms. Statistical analysis was performed.

RESULTS

Patients with CM-I had larger fourth ventricle volumes compared with control subjects (1.31 vs. 0.95 mL; P = 0.012). There were no differences in lateral ventricle volume or PFV. CM-I fourth ventricle volume was associated with tonsillar descent (P = 0.030). CM-I fourth ventricle volume variance was larger than healthy controls (F_71,29 = 8.33; P < 0.0001). Patients with CM-I with severe signs and symptoms had a significantly larger fourth ventricle than patients with CM-I with mild signs and symptoms (1.565 vs. 1.015 mL; P = 0.0002).

CONCLUSIONS

The fourth ventricle can be enlarged in CM-I independent of lateral ventricle size and is associated with greater tonsillar descent. Most importantly, fourth ventricle enlargement was associated with a worse clinical and radiographic presentation independent of PFV. Fourth ventricle enlargement can affect critical structures and may be a mechanism contributing to symptoms unexplained by tonsil descent. Fourth ventricle enlargement is a useful adjunct in assessing CM-I.

The influence of concomitant syringomyelia on patient reported outcome following hind brain decompression

Objectives: To evaluate the impact of concomitant syringomyelia and self-reported complications on patient reported outcome measures in patients undergoing hindbrain decompression for a Chiari 1 malformation.Methods: Prospective data collection of 95 patients who underwent Foramen magnum decompression between March 2011 and March 2015. Outcome evaluation was performed using the Core Outcome Measure Index questionnaire for neck (COMI-neck) and Gestalt impression (to assess improvement of headaches). Patients were split into two cohorts, those with and those without syringomyelia. Both cohorts were compared in all domains of the COMI neck questionnaires, headache, and complications. Non-parametric data were analysed with Wilcoxon signed rank, Mann-Whitney U and Fisher exact tests. Parametric data were analysed with Student T-test. SPSS Software was used for analysis.Results: 79 patients returned 1 year follow-up COMI-neck questionnaires. Thirty three had concomitant syringomyelia and 46 had no syringomyelia present. There was no statistically significant difference in patient reported outcomes (COMI-neck index median 4.5 +/- 3.3 vs 4.2+/-3.2; p = .376) between the syrinx and non-syrinx cohorts. However postoperative neck pain (median 4 +/- 3.35 vs 1 +/- 3.17; p 0.041) and arm/shoulder pain scores (2 +/- 3.38 vs. 0+/- 2.628; p 0.049) were significantly lower in the non-syrinx cohort. In both cohorts 57% patients had an improvement in headache. 92% patients were 'satisfied' with treatment and 63% stated that the operation 'helped'. 54% patients in the syrinx and 59% in the non-syrinx cohort self-reported complications. There was no statistical difference in outcomes of the patients with and without self-reported complications (p = .121).Conclusions: This study demonstrates that the clinical effectiveness of FMD is lower and reported complications are higher when evaluated by patient reported outcome measures as opposed to surgeon reported complications. Patients with and without concomitant syringomyelia showed equal overall outcomes, although neck and arm pain was worse in syrinx patients.

Posterior fossa decompression for Chiari malformation type I: clinical and radiological presentation, outcome and complications in a retrospective series of 105 procedures

OBJECTIVE

Determining clinical and radiological characteristics, complication rates and outcome for patients undergoing posterior fossa decompression (PFD) and duraplasty for Chiari malformation type I (CM-I).

METHODS AND MATERIALS

Retrospective, single-university hospital study of all PFDs for CM-I between January 1995 and December 2016.

RESULTS

PFD was performed in 105 patients with CM-I (n = 105), of whom 62 suffered from associated syringomyelia and 37 were pediatric cases. There was a female preponderance in the syringomyelia, non-syringomyelia, pediatric and adult groups (62.9%, 65.1%, 54.1% and 69.1%, respectively). Mean age at diagnosis was higher in the syringomyelia group (32.3 versus 26.9 years, p = 0.06) and in both groups delay for diagnosis was long (33.4 and 47.1 months, p = 0.50). Headache during Valsalva maneuver and on exertion was significantly more present in the non-syringomyelia group (27.9% versus 16.1%, p < 0.0001 and 39.5% versus 11.3%, p = 0.0009); cranial nerve dysfunction and cerebellar signs did not differ significantly (p = 0.07 and p = 0.53). Spinal cord syndrome was significantly more present in the syringomyelia group (72.6% versus 25.6%, p < 0.0001). Scoliosis was present in five patients, of whom four had syringomyelia. Duraplasty was performed in 101 surgeries. For 100 patients, PFD was the primary treatment of CM-I; 2 patients had previously undergone syrinx drainage and 3 ventriculoperitoneal shunting for hydrocephalus. Only one patient presented with hydrocephalus. Duraplasty (n = 101) was complicated by CSF leak in 4.0% (n = 4), symptomatic pseudomeningocele in 4.0% (n = 4), aseptic meningitis in 2.0% (n = 2) and hydrocephalus in 1.0% (n = 1). Osseous decompression without duraplasty was performed in only four highly selected patients, not allowing a comparative analysis with duraplasty. Post-operative symptom improvement is reported for 67.3% of all patients and stabilization of symptoms in 23.9%. Symptom improvement was significantly more frequent in the non-syringomyelia group (p = 0.03). Outcome seemed similarly good in the pediatric and the adult groups.

CONCLUSION

PFD performed with duraplasty is a safe procedure. The majority of patients do report symptom stabilization or improvement. Non-syringomyelia patients reported significantly more frequent improvement of clinical symptoms.

Minimally invasive posterior fossa decompression with duraplasty in Chiari malformation type I with and without syringomyelia

Background:

Posterior fossa decompression (PFD), with and without duraplasty, represents a valid treatment in Chiari malformation Type I (CM-I) with and without syringomyelia. Despite a large amount of series reported in literature, several controversies exist regarding the optimal surgical approach yet. In this study, we report our experience in the treatment of CM-I, with and without syringomyelia, highlighting how the application of some technical refinements could lead to a good outcome and a lesser rate of complications.

Methods:

Twenty-six patients with CM-I, with and without syringomyelia, underwent PFD through a 3 cm × 3 cm craniectomy with the removal of the most median third of the posterior arch of C1 and duraplasty. Signs and symptoms included sensory deficits, motor deficits, neck pain, paresthesias, headache, dizziness, lower cranial nerve deficits, and urinary incontinence. Postoperative magnetic resonance (MR) was performed in all patients.

Results:

Signs and symptoms improved in 76.9% of cases. Postoperative MR revealed a repositioning of cerebellar tonsils and the restoration of cerebrospinal fluid circulation. In our experience, the rate of complication was 23% (fistula, worsening of symptoms, and respiratory impairment).

Conclusion:

PFD through a 3 cm × 3 cm craniectomy and the removal of the most median third of posterior arch of C1 with duraplasty represents a feasible and valid surgical alternative to treat patients with CM-I, with and without syringomyelia, achieving a good outcome and a low rate of complications.

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

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

Analysis of Clinical and Radiographic Outcomes of the Angle between Clivus and Supraocciput in Patients with Chiari's Malformation Type I Following Surgical Decompression

Background  The objective of this study was to investigate whether different angles between the clivus and supraocciput (C-SO angle) in patients with Chiari's malformation type I (CMI) after posterior fossa decompression lead to different clinical and radiographic outcomes. Methods  A total of 73 patients who underwent surgical decompression at our institution between 2010 and 2016 were retrospectively divided into two groups: group A, with an angle less than 96 degrees, and group B, with an angle ≥ 96 degrees. Patient clinical outcomes were determined using the Chicago Chiari Outcome Scale (CCOS), and radiographic outcomes were determined by changes in the syrinx size before and after surgery. Direct comparisons were made between the two groups. Results  There were no statistically significant differences between the two groups regarding demographics, preoperative symptoms or radiographic characteristics ( p  > 0.05), except for the cerebellar tonsillar descent ( p ≤ 0.001). The mean overall CCOS score was 13.11 ± 1.99. The total CCOS score was significantly different between the two patient groups ( p  < 0.05). Moreover, group A demonstrated significantly better postoperative improvements than group B in clinical outcome measures based on the CCOS system ( p  = 0.035). For radiographic outcomes, the change in the syrinx between the two groups was also significantly different, with a value p =  0.024. Conclusions  A direct comparison between the two groups revealed that a smaller C-OS angle (< 96 degrees) was related to unsatisfactory clinical and radiographic outcomes. Thus, the C-OS angle may emerge as a predictor of clinical or radiographic outcomes following surgical decompression in patients with CMI.

Prophylactic enlargement of the thecal sac volume by spinal expansion duroplasty in patients with unresectable malignant intramedullary tumors and metastases prior to radiotherapy

Unresectable malignant intramedullary tumors and metastases usually require radiotherapy which intensifies spinal cord edema and might result in neurological decline. Spinal expansion duroplasty before radiotherapy enlarges the intrathecal volume and might thus prevent neurological deficits. The study aims to evaluate the clinical course of patients undergoing expansion duroplasty. This retrospective analysis (2007-2016) included all patients with unresectable intramedullary tumors who underwent spinal expansion duroplasty. To assess the degree of preoperative cord enlargement, we calculated the "diameter ratio": diameter of the spinal cord below and above the tumor / diameter of the tumor × 2. The presence of perimedullary cerebrospinal fluid (CSF) at the affected levels was analyzed on the preoperative magnetic resonance imaging (MRI). We recorded the occurrence of neurological deficits, wound breakdown, and CSF fistula. We screened 985 patients, 11 of which were included. Eight patients had an intramedullary metastasis, three patients a spinal malignant glioma. A diameter ratio ≤ 0.8 representing a significant preoperative intramedullary enlargement was seen in 10 cases (90.9%). Postoperative imaging was available in 9 patients, demonstrating successful decompression in 8 of the 9 patients (88.9%). The postoperative course was uneventful in 9 patients (81.8%). Mean overall survival was 13.4 (SD 16.2) months. Spinal expansion duroplasty prior to radiotherapy is a previously undescribed concept. Despite neoadjuvant radiation, no wound breakdown or CSF fistula occurred. In unresectable intramedullary tumors and metastases, spinal expansion duroplasty seems to be a safe procedure with the potential to prevent neurological decline due to radiation-induced cord swelling.

Dura-splitting versus a combined technique for Chiari malformation type I complicated with syringomyelia

BACKGROUND

Surgical approaches for Chiari malformation type I (CM-I) complicated with syringomyelia (SM) are controversial, so we assessed the efficacy and safety of two widely used procedures.

METHODS

We retrospectively analyzed results from posterior fossa decompression (PFD) using bony decompression with dura-splitting or a combined technique (duraplasty with arachnoid dissection and coagulation of the herniated tonsils) for CM-I associated with SM between Jan 2008 and Feb 2016. Patients were followed up for at least one year. General data, primary outcomes (symptom improvement, syrinx reductions, and complications) and secondary outcomes (operating time, blood loss, postoperative hospital stay) for each procedure were compared.

RESULTS

Of the 49 patients treated, 17 had dura-splitting decompression and 32 had the combined technique. There were no significant differences in general data. The combined technique was significantly superior to dura-splitting for long-term syrinx reductions (length, 100.03 ± 44.79 vs 72.73 ± 34.79 mm, p = 0.040; diameter, 8.09 ± 3.46 vs 5.73 ± 3.02 mm, p = 0.026) and symptom improvement (75.00% vs 47.06%, p = 0.036). No postoperative complications occurred during dura-splitting cases; however, complications occurred in 9 combined technique cases (31.25%, p = 0.010) and surgical time was longer for the combined technique (248.03 ± 60.12 vs 167.94 ± 60.11 min, p < 0.001).

CONCLUSIONS

The combined technique improved long-term symptoms and reduced syringes compared to dura-splitting; however, postoperative complications are more likely.

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.

Cisterna magna arachnoid membrane suturing decreases incidence of pseudomeningocele formation and incisional CSF leakage

OBJECTIVE

A pseudomeningocele and an incisional cerebrospinal fluid leak are considered frequent complications following neurosurgical operations. The rate of these complications especially increases following neurosurgical procedures on the posterior cranial fossae. According to some publications, the rate of pseudomeningoceles has been reported as high as 40%, whereas that of incisional cerebrospinal fluid leaks is up to 17%. For the purposes of reducing the risk of these complications after a midline suboccipital craniotomy, we propose suturing the arachnoid membrane of the cisterna magna. In this paper, we present a retrospective analysis of arachnoid membrane suturing.

METHODS

Seventy patients underwent midline suboccipital craniotomy by the first author between 2012 and 2016 at Burdenko Neurosurgery Institute. In this group was included a consecutive group of patients with posterior fossae tumors where the approach was performed through the cisterna magna arachnoid membrane following midline suboccipital craniotomy and dural opening. The patients were divided into two groups. Group 1 included 38 patients to whom cisterna magna arachnoid membrane suturing was performed with monofilament nonabsorbable suture 7.0., and additionally, the suture was sealed with fibrin adhesive sealant TachoComb®. Group 2 included 32 patients without arachnoid membrane suturing. There was no other significant difference in terms of clinical signs and surgical procedures between these groups. In the postoperative period, the frequency of developing a pseudomeningocele and an incisional cerebrospinal fluid leak was assessed in these two groups. The results were evaluated on the basis of clinical, CT, and MRI data performed in the postoperative period.

RESULTS

In the patients who underwent arachnoid membrane suturing (group I), pseudomeningocele formation was observed in one (2.6%) and CSF leak in one (2.6%) of the 38 patients. In group II, in which patients had no arachnoid membrane suturing, we observed pseudomeningocele formation in 11 (34.4%) patients and a CSF leak in 7 (25.0%) out of 28 patients with known follow-up. Statistical analysis of the data indicates a significantly higher risk of postoperative pseudomeningocele formation and/or an incisional cerebrospinal fluid leak in a group of patients who did not undergo arachnoid membrane suturing (p < 0.05).

CONCLUSIONS

Suturing of the arachnoid membrane of the cisterna magna and its further sealing with fibrin adhesive sealant TachoComb® create an additional barrier for preventing cerebrospinal fluid collection in the extradural space. This technique significantly reduces the risk of postoperative pseudomeningocele formation and/or an incisional cerebrospinal fluid leak in patients with midline suboccipital craniotomy.

A Report of 2 Cases of Brainstem Hemorrhage After Suboccipital Craniectomy for Chiari Decompression

BACKGROUND AND IMPORTANCE

Decompression surgery for Chiari malformation is known to have very low procedure-related complications. There has been no report of post-Chiari malformation decompression surgery development of brainstem hemorrhage. We report 2 post-Chiari decompression surgery brainstem hemorrhage cases with 2-yr follow-up.

CLINICAL PRESENTATION

Two cases were reviewed in which patients underwent uncomplicated suboccipital craniectomy with expansive autologous pericranium duraplasty for Chiari decompression. Postoperatively, both patients awoke with hemibody sensory and motor deficits. Immediate postoperative magnetic resonance imaging revealed a small hemorrhage within the dorsal medulla in both cases. Follow-up imaging shows resolution along with near complete clinical recovery of deficits.

CONCLUSION

These cases demonstrate a rare postdecompression surgery-related complication in Chiari malformation. We hypothesize that these hemorrhages may occur from the rapid drainage of cerebrospinal fluid resulting in a loss of positive pressure, allowing a low-pressure hemorrhage to occur. Given that these hemorrhages are of low pressure, recovery is excellent.

Chiari I malformation: surgical technique, indications and limits

BACKGROUND

Chiari malformation type I (CM-I) is a rare disease characterised by herniation of cerebellar tonsils below the foramen magnum with associated anomalies of posterior fossa. We describe here the surgical technique, indications and limits of surgical treatment.

METHOD

The authors describe the surgical technique, including: posterior fossa decompression, opening of the foramen of Magendie and duraplasty in case of CM-I.

CONCLUSIONS

Posterior fossa decompression plus duraplasty is a safe and effective procedure for patients with CM-I malformation.

Intradural pathology and pathophysiology associated with Chiari I malformation in children and adults with and without syringomyelia

OBJECTIVE The pathophysiology underlying tonsillar herniation and CSF obstruction in Chiari malformation Type I (CM-I) is unclear, and the cause of CM-I-associated syringomyelia is not well understood. A better understanding of this pathophysiology is important for an improved treatment strategy. Therefore, the authors sought to identify, characterize, and examine the intradural pathology and CSF flow pathophysiology in the posterior fossa and at the level of the foramen magnum that occurs in the setting of CM-I. They determined the incidence of these intradural findings and assessed differences across age, with the degree of tonsillar herniation, and in the presence and absence of syringomyelia. METHODS A prospective database initiated in March 2003 recorded all intraoperative findings during surgical treatment of children and adults with CM-I with or without syringomyelia. A total of 389 surgeries for CM-I were performed in 379 patients between March 2003 and June 2016. A total of 109 surgeries were performed in 109 patients with CM-I (without osseoligamentous abnormalities) in whom both a posterior fossa extradural and intradural decompression with duraplasty was performed (first-time intradural procedures). Using a surgical microscope, intradural pathology and obstruction of CSF channels were identified and assessed. Student t-tests and Fisher's exact tests compared groups in a series of univariate analyses, followed by multivariate logistic regression. RESULTS The following intradural pathological entities were observed (prevalence noted in parentheses). These include those that did not obstruct CSF flow channels: opacified arachnoid (33.0%), thickened arachnoid (3.7%), ischemic and gliotic tonsils (40.4%), tonsillar cysts (0.9%), and inferior descent of the fourth ventricle and cervicomedullary junction (CMJ) (78.0%). The following intradural pathological entities were observed to obstruct CSF flow channels: medialized tonsils (100%), tonsil overlying and obstructing the foramen of Magendie (21.1%), intertonsillar and tonsil to CMJ arachnoid adhesions (85.3%), vermian posterior inferior cerebellar artery branches obstructing the foramen of Magendie (43.1%), and arachnoid veils or webs obstructing or occluding the foramen of Magendie (52.3%). Arachnoid veils varied in type and were observed in 59.5% of patients with CM-I who had syringomyelia, which was significantly greater than the 33.3% of patients with CM-I without syringomyelia who had an arachnoid veil (p = 0.018). The presence of CM-I with an arachnoid veil had 3.22 times the odds (p = 0.013, 95% CI 1.29-8.07, by multivariate logistic regression) of being associated with syringomyelia, adjusting for tonsillar herniation. The inferior descent of the fourth ventricle and CMJ occurred with a greater degree of tonsillar herniation (p < 0.001) and correlated with a cervicomedullary kink or buckle on preoperative MRI. CONCLUSIONS Intradural pathology associated with CM-I with or without syringomyelia exists in many forms, is more prevalent than previously recognized in patients of all ages, and may play a role in the pathophysiology of CM-I tonsillar herniation. Arachnoid veils appear to partially obstruct CSF flow, are significantly more prevalent in cases of CM-I with syringomyelia, and therefore may play a role in the pathophysiology of CM-I-associated syringomyelia.

Chiari malformation: Has the dilemma ended?

Chiari malformation as a clinical entity has been described more than hundred years ago. The concepts regarding pathogenesis, clinical features and management options have not yet conclusively evolved. Considering that a variety of treatment methods are being adopted to treat Chiari malformation is suggestive of the fact that confusion still reigns supreme in the minds of treating clinicians. Over the years, the understanding of Chiari malformation has changed from a disease process to a natural protective phenomenon and the treatment from decompression to fixation.