Chiari type 1 deformity case series

Using our database from 2007-2016, we studied 72 CM-I patients and 30 age-matched healthy control subjects. 4th and lateral ventricle volumes and posterior fossa volumes (PFV) were assessed and correlated with clinical signs and symptoms. Statistical analysis was performed.

RESULTS: CM-I patients had larger 4th ventricle volumes compared to control subjects (1.31mL vs 0.95, p = 0.012). There were no differences in lateral ventricle volume or PFV. CM-I 4th ventricle volume was associated with tonsillar descent (p = 0.030). CM-I 4th ventricle volume variance was larger than healthy controls (F71,29 = 8.33, p < 0.0001). CM-I patients with severe signs and symptoms had a significantly larger 4th ventricle than CM-I patients with mild signs and symptoms (1.565 mL vs 1.015 mL, p = 0.0002).

CONCLUSION: The 4th ventricle can be enlarged in CM-I independent of lateral ventricle size and is associated with greater tonsillar descent. Most importantly, 4th ventricle enlargement was associated with a worse clinical and radiographic presentation independent of posterior fossa volume. 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 1).

Children between the ages of 6 and 17 years who were evaluated and diagnosed with CM1 at the University of Chicago, Illinois, were identified. Eighty-six participants were recruited for this study with an average age of 11 years. Parents of participants completed a pediatric medical history questionnaire and a semistructured interview regarding the child's psychiatric, developmental, medical, and family history. A review of medical records was completed to complement interview data. Elevated rates of psychiatric diagnoses, including attention deficit hyperactivity disorder (ADHD) (22.1%), anxiety (12.8%), and depression (10.5%), were identified in the study population when compared to published norms in the general population documented by the American Psychiatric Association in 2013. In addition, elevated rates of psychiatric diagnoses in first-degree relatives of study participants were also identified. A 2-step binary logistic regression analysis revealed that maternal complications during pregnancy (Wald = 6.52, p = 0.01) increased the risk of a psychiatric diagnosis 9-fold. Premature birth (Wald = 6.79, p = 0.01) also significantly predicted a psychiatric diagnosis amongst participants. The current findings suggest a high prevalence of psychiatric illness in children with CM1. Pregnancy complications were associated with a high risk of a psychiatric diagnosis. Early CNS developmental disturbance may explain this relationship. Prematurity only slightly improved the prediction model. Limitations and future directions are discussed, including the cross-sectional nature of the present study, possible self-selection bias, and the importance of future investigation of other causative and/or associative factors of CM1, such as cognitive, psychiatric, and medical influences on health status 2).

Chotai et al. conducted a retrospective review at a single tertiary center for children undergoing Posterior fossa decompression (PFD) with untreated scoliosis, and identified 17 patients with complete follow-up data and imaging.

Overall, scoliosis improved in 7 (41.2%) patients, worsened in 9 (52.9%), and remained unchanged in 1 (5.9%) after PFD (mean follow-up of 7.8 ± 4.1 months). We found that 3 of the 8 (38%) children with early-onset scoliosis eventually needed scoliosis corrective surgery, which was needed in 7 of the 9 (78%) patients with adolescent-onset scoliosis. In addition, only 1 patient (17%) with a preoperative scoliosis curve <35 degrees and 9 patients (82%) with a curve ≥35 degrees required surgery for scoliosis correction despite PFD (p = 0.018).

In certain patients, PFD for CM-I may lead to improvement or stabilization of scoliosis 3).

Brock et al., analyzed prospectively 49 patients with CM operated at the Hospital das Clinicas, College of Medicine, University of São Paulo. Patients underwent decompressive surgery with or without opening of the duramater after intraoperative ultrasonography measuring flow rate. A value of 3cm/s was considered a cut-off. Quality of life before and after surgery and the improvement of neck pain and headache were evaluated.

Among 49 patients enrolled, 36 patients (73%) had CSF flow above 3 cm/s and did not undergo duraplasty. In 13 (27%) patients with initial flow <3 cm/s, a dural opening was performed together with duraplasty. All patients improved comparing pre and post operative scores and all clinical parameters evaluated did not differ between both surgical groups. Patients submitted to bone decompression alone had fewer complication rate.

Intraoperative USG with measurement of CSF allows the proper selection of patients with CM that can have a less invasive surgery with bone decompression without duraplasty 4).


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 (Pin = 0.05, Pout = 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 5)

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.

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 6).

Thirty-nine cases of CM-1 with and without syringomyelia (SM) were included. There were 18 patients in the nonduraplasty and 21 in the duraplasty group. Syringomyelia, tonsillar herniation (TH), preoperative symptom duration, and postoperative SM size were compared.

No significant difference was found between improvement in the duraplasty group (81%) and the non-duraplasty group (61.1%). In cases whose symptom duration was 0-36 months, improvement in the duraplasty group (93%) was significantly better than in the nonduraplasty group (50%) (p < 0.01). The rate of syrinx regression was 92.3% in the duraplasty group and 12.5% in the non-duraplasty group (p < 0.05). In cases with SM, the improvement was 21.4% in the non-duraplasty group compared to 78.6% in the duraplasty group (p=0.056). In cases with TH greater than 10 mm, the improvement was 66.7% in the non-duraplasty group, whereas all six cases (100%) in the duraplasty group had improved.

In SM associated cases, cases with TH greater than 10 mm, and whose symptom duration is less than 36 months, duraplasty is a more reliable choice despite a slightly higher rate of complications 7).


In 21 patients, 12 cases had osteo-compression on the cerebellar hemisphere, 18 cases had thickened adhered fabric ring that stretched from arachnoid membrane to cerebellar hemisphere, and 15 cases with syringomyelia. The patients were followed up for 6 months to 3 years after the surgery. All patients showed a remarkable recovery of syringomyelia. There were no morbidity or death related to the surgery. Most of ACM-1 patients, the osteo- and membrane compression on cerebellar hemisphere and tonsil were observed during the operation. Therefore, decompression of foramen magnum and posterior craniocervical combined with the removal of cerebellomedullary fissure arachnoid membrane and placement of an artificial dural graft should be considered as a comprehensive option of minimally invasive surgery and rational and radical treatment of ACM-1. Our experience showed that, by using our procedure, shunting becomes no longer necessary in the treatment of ACM-1-associated syringomyelia 8).


Of the 25 patients who presented with spinal symptoms, 23 (92%) proved to have a syrinx at MR imaging. When the syrinx extended into the medulla (n = 3), however, brain stem symptoms predominated. Patients with objective brain stem or cerebellar signs had the largest mean tonsillar herniations. Patients with tonsillar herniations greater than 12 mm were invariably symptomatic, but approximately 30% of patients with tonsils herniating 5-10 mm below the foramen magnum were asymptomatic at MR imaging. “Incidental” Chiari I malformations are thus much more common than previously recognized, and careful clinical assessment remains the cornerstone for proper diagnosis and management 9).


In a series of 71 patients, pain was the commonest symptom (69% of patients); other symptoms included weakness (56%), numbness (52%), and unsteadiness (40%). The presenting physical signs consisted of a foramen magnum compression syndrome (22%), central cord syndrome (65%), or a cerebellar syndrome (11%). Myelography was performed in 69 patients, and was the most useful investigation. Only 23% of plain radiographs were abnormal. In addition to tonsillar descent, the operative findings included arachnoid adhesions (41%) and syringomyelia (32%). All patients underwent suboccipital craniectomy and C1-3 laminectomy. Respiratory depression was the most frequent postoperative complication (14%), and one patient died from sleep apnea. Early postoperative improvement of both symptoms (82%) and signs (70%) was followed by later relapse in 21% of patients, showing an initial benefit following surgery. None of the patients with a cerebellar syndrome deteriorated, whereas 56% of patients with evidence of foramen magnum compression and 66% of those with a central cord syndrome maintained their initial improvement. The authors conclude that posterior fossa decompression appears to benefit some patients, although a significant proportion might be expected to relapse within 2 to 3 years after operation, depending upon the presenting syndrome 10).

Seaman SC, Dawson JD, Magnotta V, Menezes AH, Dlouhy BJ. Fourth ventricle enlargement in Chiari malformation type I. World Neurosurg. 2019 Sep 9. pii: S1878-8750(19)32397-6. doi: 10.1016/j.wneu.2019.08.230. [Epub ahead of print] PubMed PMID: 31513955.
Lacy M, DeDios-Stern S, Fredrickson S, Parikh S, Nader T, Frim DM. Prevalence of Psychiatric Diagnoses in Pediatric Chiari Malformation Type 1. Pediatr Neurosurg. 2018 Aug 27:1-8. doi: 10.1159/000488460. [Epub ahead of print] PubMed PMID: 30149388.
Chotai S, Basem J, Gannon S, Dewan M, Shannon CN, Wellons JC, Bonfield CM. Effect of Posterior Fossa Decompression for Chiari Malformation-I on Scoliosis. Pediatr Neurosurg. 2018 Jan 4. doi: 10.1159/000485254. [Epub ahead of print] PubMed PMID: 29298440.
Brock RS, Taricco MA, de Oliveira MF, de Lima Oliveira M, Teixeira MJ, Bor-Seng-Shu E. Intra Operative Ultrasonography for Definition of Less Invasive Surgical Technique in Patients with Chiari Type I Malformation. World Neurosurg. 2017 Feb 9. pii: S1878-8750(17)30152-3. doi: 10.1016/j.wneu.2017.02.003. [Epub ahead of print] PubMed PMID: 28192262.
Stanko KM, Lee YM, Rios J, Wu A, Sobrinho GW, Weingart JD, Jackson EM, Ahn ES, Chaichana KL, Jallo GI. Improvement of syrinx resolution after tonsillar cautery in pediatric patients with Chiari Type I malformation. J Neurosurg Pediatr. 2015 Oct 30:1-8. [Epub ahead of print] PubMed PMID: 26517059.
Kennedy BC, Kelly KM, Phan MQ, Bruce SS, McDowell MM, Anderson RC, Feldstein NA. Outcomes after suboccipital decompression without dural opening in children with Chiari malformation Type I. J Neurosurg Pediatr. 2015 May 1:1-9. [Epub ahead of print] PubMed PMID: 25932779.
Gurbuz MS, Karaaslan N, Caliskan T, Unal E, Berkman MZ. Comparison of the Surgical Results for Foramen Magnum Decompression with and without Duraplasty in Chiari Malformation Type 1. Turk Neurosurg. 2015;25(3):419-24. doi: 10.5137/1019-5149.JTN.11235-14.1. PubMed PMID: 26037182.
Liang CJ, Dong QJ, Xing YH, Shan M, Wen LX, Qiang ZY, Ping ZQ, Tao PZ, Ping HX. Posterior fossa decompression combined with resection of the cerebellomedullary fissure membrane and expansile duraplasty: a radical and rational surgical treatment for Arnold-Chiari type I malformation. Cell Biochem Biophys. 2014 Dec;70(3):1817-21. doi: 10.1007/s12013-014-0135-x. PubMed PMID: 25018150.
Elster AD, Chen MY. Chiari I malformations: clinical and radiologic reappraisal. Radiology. 1992 May;183(2):347-53. PubMed PMID: 1561334.
Paul KS, Lye RH, Strang FA, Dutton J. Arnold-Chiari malformation. Review of 71 cases. J Neurosurg. 1983 Feb;58(2):183-7. PubMed PMID: 6848674.
  • chiari_type_1_deformity_case_series.txt
  • Last modified: 2019/09/13 20:58
  • by administrador