Degree Of Tonsillar Herniation Research Articles

Multi-parameter-based radiological diagnosis of Chiari Malformation using Machine Learning Technology.

The known primary radiological diagnosis of Chiari Malformation-I (CM-I) is based on the degree of tonsillar herniation (TH) below the Foramen Magnum (FM). However, recent data also shows the association of such malformation with smaller posterior cranial fossa (PCF) volume and the anatomical issues regarding the Odontoid. This study presents the achieved result regarding some detected potential radiological findings that may aid CM-I diagnosis using several machine learning (ML) algorithms. Midsagittal T1-weighted MR images were collected in 241 adult patients diagnosed with CM, eleven morphometric measures of the posterior cerebral fossa were performed. Patients whose imaging was performed in the same centre and on the same device were included in the study. By matching age and gender, radiological exams of 100 clinically/radiologically proven symptomatic CM-I cases and 100 healthy controls were assessed. Eleven morphometric measures of the posterior cerebral fossa were examined using 5 designed ML algorithms. The mean age of patients was 29.92±15.03years. The primary presenting symptoms were headaches (62%). Syringomyelia and retrocurved-odontoid were detected in 34% and 8% of patients, respectively. All of the morphometric measures were significantly different between the groups, except for the distance from the dens axis to the posterior margin of FM. The Radom Forest model is found to have the best 1.0 (14 of 14) ratio of accuracy in regard to 14 different combinations of morphometric features. Our study indicates the potential usefulness of ML-guided PCF measurements, other than TH, that may be used to predict and diagnose CM-I accurately. Combining two or three preferable osseous structure-based measurements may increase the accuracy of radiological diagnosis of CM-I.

Long-term outcomes for children with an incidentally discovered Chiari malformation type 1: what is the clinical significance?

Chiari malformation type 1 (CM1) is an increasingly common incidental finding on magnetic resonance imaging (MRI). The proportion of children with an incidentally discovered CM1 who upon further evaluation require operative intervention for previously unrecognized signs and symptoms of neurological compromise or significant radiographic findings (syringomyelia) is unclear. An extensive long-term single-institution patient series was evaluated to better clarify the likelihood of surgery in patients who present with an incidentally discovered CM1. This study was conducted using prospective data for patients up to 18years old that were evaluated for a CM1 at a large tertiary pediatric neurosurgery clinic between February 2009 and June 2019. Patients were excluded if they did not have an incidentally discovered CM1 and at least 12months of clinical follow-up. A total of 218 consecutive patients were included in this study. The mean age at the initial neurosurgical evaluation was 6.5years (range 5months to 18.4years), and the mean duration of clinical follow-up was 40.6months (range 12 to 114months). Initial MR imaging was most commonly obtained for the evaluation of seizures (15.1%), nonspecific headaches (not occipital or tussive) (14.7%), trauma (9.6%), and developmental delay (7.8%). Of the patients studied that eventually required surgery, we identified two groups: those operated before 6months since presentation and those operated after 6months. A total of 36 patients (16.5%) underwent a decompression with 22 patients (61.1%) receiving surgery within 6months and the remaining 14 patients (38.9%) beyond 6months. Patients undergoing early surgery (10.1%) initially presented with a significant syrinx or were noted to have an occult neurological dysfunction, whereas a smaller subset of patients (6.4%) eventually required surgery over time due to the development of new symptoms or a de novo syrinx. Only the presence of syringomyelia was statistically significant for the need of a surgical intervention, while age, sex and degree of tonsillar herniation were not. Evaluation of a large group of patients with an incidentally discovered Chiari malformation demonstrated that most patients may be managed conservatively, especially in the absence of syringomyelia. However, there is a subset of patients who will go on to develop a de novo syrinx or neurological symptoms that are new or progressive during follow-up, which should be evaluated by imaging of the brain and spinal cord. The presence of syringomyelia was associated with need for early surgical intervention. However, for patients without syringomyelia, surgical intervention is uncommon but may be delayed up to several years after presentation; therefore, long-term clinical follow-up is recommended.

Soft tissue density within the foramen magnum, a predictor for surgical intervention in pediatric patients with Chiari malformation type I.

Chiari malformation type I (CMI) is diagnosed as herniation of the cerebellar tonsils by at least 5 mm below the foramen magnum. However, the degree of tonsillar herniation is a poor predictor of the need for decompression surgery. Exploration for an alternative morphological predictor for surgical intervention could provide greater insight into the development of an appropriate treatment plan for these patients. To investigate this issue, the authors calculated the soft tissue density within the foramen magnum as a measure of impaction of the cerebellar tonsils. Soft tissue density within the foramen magnum and degree of tonsillar herniation were then assessed for their correlation with the need for surgical intervention. The authors conducted a retrospective, longitudinal chart review of pediatric patients with CMI. Those who had undergone surgical intervention were considered symptomatic and those who had been treated conservatively, as asymptomatic. Soft tissue density was found by dividing the soft tissue occupancy of the foramen magnum (brainstem and cerebellar tonsils) by the total area of the bony foramen magnum. The predictive value of these two measurements for the need of surgery was determined. Of the 465 patients seen for CMI at the authors' institution between July 1, 2011, and May 31, 2017, 80 underwent surgical intervention and 385 were asymptomatic. The average tissue density was significantly greater in the surgical group than in the asymptomatic group (83.3% and 78.6%, respectively, p < 0.0001). The average tonsillar descent for surgical patients was 10.8 mm compared to 9.8 mm for asymptomatic patients (p = 0.140). The point-biserial correlation coefficient was assessed, and soft tissue density was found to positively correlate with the need for surgical intervention (rpb = 0.199, p = 0.0001), whereas tonsillar herniation did not correlate with the need for surgery (rpb = 0.083, p = 0.115). Additionally, the degree of tonsillar herniation did not correlate with soft tissue density (r = 0.09), indicating that soft tissue density is an independent morphological parameter. The study findings suggest that the need for surgical intervention in CMI patients is positively correlated with increasing soft tissue density within the foramen magnum, whereas the degree of tonsillar herniation did not show a correlation with the need for surgical intervention. Additionally, soft tissue density is a factor independent of the degree of tonsillar herniation. Further investigation of tissue density within the foramen magnum is needed in the hope of discovering a clinically applicable parameter that would indicate a need for surgical intervention in patients with CMI.

Retrospective Evaluuation of the Outcomes in the Patients with Chiari's Malformation Undergoing Surgical Treatment

Introduction and Objectives: We aimed at evaluating retrospectively effects of surgery on the clinical symptoms and signs and imaging parameters in the patients with Chiari's malformation undergoing surgical treatment.&#x0D; Materials and Methods: Medical charts and radiological images of the patients with Chiari's Malformation type I who had surgical treatment between January 2008 and July 2014 were reviewed retrospectively. The patients were classified as those having good (in whom the symptoms disappeared or reduced), stabilized (with preoperative symptoms persisting without any progression), or poor (with preoperative symptoms progressing in the postoperative period) outcomes.&#x0D; Findings: All patients underwent FMD, Cl laminectomy and duraplasty. Seventeen subjects underwent removal of arachnoid adhesions, 10 subjects underwent opening of the fourth ventricle, and one subject underwent subpial resection. Of the patients, 28 were female and 11 were male with ratio of females to males being 25:1. The youngest patient was 5 years old and the eldest one was 51 years old, and mean age of the patients was 3231 ± 3131 years. The subjects were divided in two groups based on presence or absence of associated syringomyelia: those with syringamyelia (Group 1, n = 15) and those without syringomyelia (Group 2, n = 24). Postoperatively, in the Group 1 (SM 1- CM) 10 (66.7%) patients had good, 3 (20%) had stabilized and 2 (133%) patients had poor surgical outcomes. In the Group 2, 23 (918%) subjects had good and 1 (4.2%) subject had stabilized outcomes. For the Group 2, rate of recovery was higher than in the Group 1 (918% and 66.7%, respectively; Pearson's chi-square test, P = 0.014). Rate of recovery in 21 subjects with degree of tonsillar herniation being more than 11 mm (95.2%) was statistically significantly higher than 18 subjects with degree of tonsillar herniation being less than 11 mm (72.2%) (Pearson's chi-square test, P = 0.047).&#x0D; Results: FMD is a safe and efficient surgical method for the Chiari malformations with or without associated syringomyelia. The subjects without associated syringomyelia benefited more from the surgery. Complications related to CSF may be reduced using additional tissue glues. Studies with greater number of cases should be conducted on the effect of degree of tonsillar herniation on surgical outcomes.

Neurological deficits are present in syndromic craniosynostosis patients with and without tonsillar herniation.

Children with syndromic craniosynostosis (sCS) have a higher incidence of cerebellar tonsillar herniation (TH) than the general population. In the general population, TH≥5mm below the foramen magnum is associated with typical neurological deficits but, in sCS, we do not know whether this degree of TH is required before such deficits occur. This prospective cohort study aimed to determine the association between findings on neurological assessment and cerebellar tonsillar position. Magnetic resonance imaging (MRI) was used to determine TH≥5mm and the presence of syringomyelia. In regard to the outcome of neurological deficits, these were categorized according to: A, cerebellar function; B, cranial nerve abnormalities; and C, sensory or motor dysfunction. Twenty of 63 patients with sCS (32% [95% confidence interval 21-45%]) had TH≥5mm and/or syringomyelia. There was no significant difference in proportion between individual forms of sCS: 16/34 Crouzon, 2/11 Muenke, 2/12 Apert, and 0/7 Saethre-Chotzen patients. Neurological deficits were prevalent (73% [95% confidence interval 60-83%]), and as frequent in patients with TH≥5mm and/or syringomyelia as those without. Surgery occurred in 3 patients overall, and only in Crouzon patients. Determining the effect of TH≥5mm on neurologic functioning in sCS patients is used to better determine when surgical intervention is warranted. However, we have found that neurological deficits are prevalent in sCS patients, irrespective of cerebellar tonsillar position, suggesting that such findings are developmental and, in part, syndrome-specific central nervous system features.

Cerebrospinal fluid area and syringogenesis in Chiari malformation type I.

Syringogenesis in Chiari malformation type I (CM-I) is thought to occur secondary to impaction of the cerebellar tonsils within the foramen magnum (FM). However, the correlation between the CSF area and syringogenesis has yet to be elucidated. The authors sought to determine whether the diminution in subarachnoid space is associated with syringogenesis. Further, the authors sought to determine if syrinx resolution was associated with the degree of expansion of subarachnoid spaces after surgery. The authors performed a retrospective review of all patients undergoing posterior fossa decompression for CM-I from 2004 to 2016 at the University of Virginia Health System. The subarachnoid spaces at the FM and at the level of the most severe stenosis were measured before and after surgery by manual delineation of the canal and neural tissue area on MRI and verified through automated CSF intensity measurements. Imaging and clinical outcomes were then compared. Of 68 patients, 26 had a syrinx at presentation. Syrinx patients had significantly less subarachnoid space at the FM (13% vs 19%, p = 0.0070) compared to those without syrinx. Following matching based on degree of tonsillar herniation and age, the subarachnoid space was significantly smaller in patients with a syrinx (12% vs 19%, p = 0.0015). Syrinx resolution was associated with an increase in patients' subarachnoid space after surgery compared with those patients without resolution (23% vs 10%, p = 0.0323). Syrinx development in CM-I patients is correlated with the degree to which the subarachnoid CSF spaces are diminished at the cranial outlet. Successful syrinx reduction is associated with the degree to which the subarachnoid spaces are increased following surgery.

Acute deterioration of adults with Chiari I malformation associated with extensive syrinx

Background: Chiari I malformation (CMI) is usually a chronic disorder, although it may also present as a life-threatening condition with need for urgent decompression. Studies of acute deterioration of CMI are scarce. The identification of preoperative radiological factors that predict acute deterioration in adult patients with CMI facilitates planning of early decompression and decreases CMI-related morbidity.Patients and methods: This is a retrospective study of all adult patients with CMI who were referred to Sahlgrenska University Hospital, Sweden and underwent occipitocervical decompression in the period 2006–2016. In total, 65 consecutive patients were included and data regarding the preoperative degree of tonsillar herniation and syrinx (size, length and degree of rostral extension) were registered. Acute deterioration and the need for urgent surgical decompression within 24 h of hospitalisation were noted.Results: Three patients presented with acute deterioration of symptoms (4.6%) and showed an increased length and size of syrinx and more rostral extension of syrinx as compared to non-acute patients with CMI.Conclusion: Our study highlights the incidence of acute deterioration of CMI and shows the importance of assessing preoperative size, length and rostral extension of CMI-associated syrinx as indicators of acute deterioration so that CMI patients can be assigned to early surgical decompression.

Effects of growth hormone therapy in pediatric patients with growth hormone deficiency and Chiari I malformation: a retrospective study

The safety and efficacy of growth hormone replacement therapy (GHRT) on pediatric patients with growth hormone deficiency (GHD) and Chiari I malformation (CIM) are not well investigated within the current body of literature. With no clear indication of the effects of GHRT on CIM disease progression, we sought to determine the effect of GHRT on tonsillar herniation and progression of CIM symptomatology. From a previously established database of 465 patients with radiologically confirmed CIM defined as > 5mm of tonsillar descent on head magnetic resonance imaging (MRI), we identified 20 patients who also had GHD. Using the imaging analysis software package, ANALYZE, the degree of change in tonsillar herniation was documented between initial and final MRI measurements. The radiologic and clinical changes over time were examined via a proportional odds model, Student's t test, Mann-Whitney test, or a mixed model corresponding to the outcomes measured either on an ordinal scale or on a quantitative scale. Incidence of GHD in our CIM population was 4.3%. There was no significant effect of GHRT on the degree of tonsillar herniation in patients with GHD and CIM. No patient became symptomatic, developed syringomyelia, or required surgical intervention for CIM. Based on our findings with a larger sample size, along with recent reports, the incidence of patients with CIM and GHD we reported (0.86-5%) is likely more indicative of the actual incidence of GHD and CIM than the prior findings within the literature (9.1-20%). We also suggest that GHRT does not significantly affect CIM morphology or symptomatology. Therefore, neurosurgeons should have no hesitation clearing these patients for GHRT.

Magnetic Resonance Imaging of Chiari Malformation Type I in Adult Patients with Dysphagia.

Objective To explore the magnetic resonance imaging (MRI) characteristics of Chiari malformation type I (CMI) in patients with dysphagia. Methods Adult patients diagnosed with CMI were retrospectively and consecutively reviewed from January 2013 to December 2016. Symptoms and medical characteristics were recorded. According to the clinical manifestations, we divided the patients into two groups. The first group had 21 patients with symptoms of dysphagia and the second group had 71 patients with nondysphagia symptoms. Various length or angle measurements of the posterior cranial fossa (PCF), syringomyelia, and degree of cerebellar tonsillar herniation were investigated using magnetic resonance imaging (MRI). Univariate, correlation, and multivariate logistic regression analyses were used to compare and analyze the data of the two groups. Results The mean length of the clivus, height of PCF, and slope inclination angle of clivus significantly decreased in the dysphagia group compared to the nondysphagia group. The mean cranial spinal angle (CSA) and degree of cerebellar tonsillar herniation were significantly larger in the dysphagia group. There were no correlations between the age, sex, disease duration, and the length of cerebellar tonsillar herniation or CSA. There was a positive correlation between dysphagia level and CSA (r=-0.50; p=0.021). Among CSA, age, sex, the degree of tonsillar herniation, syringomyelia, and disease duration, CSA was the individual sign that correlated significantly with dysphagia (OR: 1.447; 95% CI: 1.182-1.698; P<0.001). Interactions between CSA and the degree of cerebellar tonsillar herniation, syringomyelia, and dysphagia existed (OR: 1.104; 95% CI: 1.042-1.170; P=0.001 and OR: 1.081; 95% CI: 1.023-1.142; P=0.006, respectively). Conclusions The CMI patients with dysphagia were more likely to have a large CSA on MRI compared with CMI patients without dysphagia. An increased probability with syringomyelia or length of cerebellar tonsillar herniation can enhance the contribution of CSA to dysphagia in patients with CMI.

Clinicoradiological study of adult Chiari malformation type 1 patients with emphasis on cerebrospinal fluid peak flow velocity at foramen magnum level.

The aim of this study was to determine the peak cerebrospinal fluid (CSF) flow velocity at the foramen magnum level in adult patients with Chiari type 1 malformation (CM1) and to determine the changes in velocity after posterior fossa decompression. An attempt was also made to determine whether or not CSF flow velocity can be a significant predictor in patients who need surgical intervention. A prospective longitudinal study was conducted in 32 symptomatic patients of CM1 treated with craniocervical decompression. Only adult patients with age ≥18 years and tonsillar herniation ≥5 mm were included in this study. Clinical and radiological assessment of patients with reference to their CSF flow characteristics was done both preoperatively and after suboccipital decompression. Out of the 32 patients, 30 patients underwent a suboccipital decompression and two patients were treated with a venriculoperitoneal shunt procedure due to gross hydrocephalus. The preoperative mean tonsillar herniation was 10.4 ± 4.64 mm that reduced to 7.35 ± 3.10 mm in the follow up period. Postoperatively, there was also a substantial decrease in the peak CSF velocity at the foramen magnum along with reduction in the extent and size of the syrinx. These changes in CSF velocity correlated with a more normal appearing foramen magnum and an improvement in symptoms. Although the selection criteria for surgery are based mainly on the degree of tonsillar ectopia and presenting symptoms, the degree of CSF flow obstruction rather than the degree of tonsillar herniation can better select patients who are most responsive to surgery. An improved CSF velocity profile following surgery in such patients is a useful guide to anticipate a symptomatic improvement.

Anatomical features of the cervical spinal canal in Chiari I deformity with presyrinx: A case-control study.

Purpose The relationship between syringomyelia and presyrinx, characterized by edema in the spinal cord, has not been firmly established. Patients with syringomyelia have abnormal spinal canal tapering that alters cerebrospinal fluid flow dynamics, but taper ratios in presyrinx have never been reported. We tested the hypothesis that presyrinx patients have abnormal spinal canal tapering. Materials and methods At six medical institutions, investigators searched the PACS system for patients with Chiari I and spinal cord edema unassociated with tumor, trauma, or other evident cause. In each case taper ratios were calculated for C1 to C4 and C4 to C7. In two age- and gender-matched control groups, Chiari I patients with no syringomyelia and patients with normal MR scans, the same measurements were made. Differences between groups were tested for statistical significance with t tests. Results The study enrolled 21 presyrinx patients and equal numbers of matched Chiari I and normal controls. C4 to C7 taper ratios were positive and steeper in presyrinx patients than in the normal controls ( p = 0.04). The upper cervical spine, C1 to C4, tapered negatively in cases and controls without significant differences between the groups. The difference in degree of tonsillar herniation was statistically significant between presyrinx patients and Chiari I controls ( p = 0.01). Conclusions Presyrinx patients have greater than normal positive tapering in the lower cervical spine and greater degree of tonsillar herniation than the controls.

No significant difference between chiari malformation type 1.5 and type I

ObjectiveChiari malformation Type 1.5 (CM 1.5) was defined as the association of Chiari malformation Type I (CM I) and brainstem herniation. The objective was to demonstrate the difference of clinical features and surgical outcomes between CM 1.5 and CM I. Patients and methodsAll CM 1.5 and CM I adult patients who underwent posterior fossa decompression with duraplasty at our institution between 2006 and 2010 were retrospectively reviewed. Clinical characteristics, imaging features, and long-term outcomes were compared between CM 1.5 and CM I patients. ResultsA total of 142 adult patients were enrolled, including 27 CM 1.5 and 115 CM I patients. The average follow-up period was 102 months. Age at diagnosis was significantly younger in CM 1.5 group than CM I group (p=0.039). And the degree of tonsillar herniation was significantly more severe in CM 1.5 group than CM I group (p<0.001). There was no significant difference in other clinical and imaging characteristics. Moreover, improvement of symptoms was observed in 21 CM 1.5 patients (77.8%) and 94 CM I patients (81.7%), and no significant difference was detected (p=0.637). There was no significant difference in the resolution of syringomyelia between CM 1.5 (72.7%) and CM I (76.5%) patients, either (p=0. 710). ConclusionsAlthough CM 1.5 patients presented with brainstem herniation and more severe tonsillar herniation, other clinical and imaging features and surgical outcomes were similar with CM I patients. We think CM 1.5 is just a subtype of CM I, rather than a unique type of Chiari malformations.

Are evoked potentials clinically useful in the study of patients with Chiari malformation Type 1?

OBJECTIVE In this study, the authors describe the brainstem auditory evoked potential (BAEP) and somatosensory evoked potential (SSEP) alterations found in a large cohort of patients with Chiari malformation Type 1 (CM-1), the relationship between the BAEPs/SSEPs and the clinical findings, the abnormalities in patients with associated syringomyelia, and the clinical and neuroradiological risk factors that are associated with abnormal evoked potentials (EPs). METHODS A prospectively collected database containing 545 patients with CM-1 was queried to search for patients satisfying the following criteria: 1) an age of at least 14 years, 2) neuroradiological criteria of CM-1, 3) no prior Chiari-related surgeries, and 4) preoperative EP studies conducted at the authors' institution. The 200 patients included in this cohort were classified into CM-0, CM-1, and CM-1.5 subtypes. Linear, planimetric, and angular measurements of the posterior fossa were conducted, as well as syringomyelia measurements. Two separate multiple logistic regression models were used, one to predict the covariates associated with abnormal BAEPs, and a second model to explore the variables associated with an abnormal SSEP. In these models, the BAEPs and SSEPs were dichotomized as being normal or abnormal. RESULTS Headaches were the main symptom in 70.5% of the patients, and Valsalva-induced headaches were most frequent in patients with CM-1 and CM-1.5 compared with patients with CM-0 (p = 0.031). BAEPs were abnormal in 38.5% of patients, and abnormal SSEPs were found in 43.5% of the entire cohort. Syringomyelia was most frequent in patients with CM-0 (64.3%) and CM-1 (51.1%) compared with those with CM-1.5 (34.7%; p = 0.03). Age (OR 1.03, 95% CI 1.00-1.06), the degree of tonsillar herniation (OR 1.08, 95% CI 1.01-1.16), and lower cranial nerve dysfunction (OR 3.99, 95% CI 1.29-14.01) had a statistically significant correlation with abnormal BAEPs. Only age (OR 1.07, 95% CI 1.04-1.10) and the degree of tonsillar herniation (OR 1.11, 95% CI 1.04-1.19) had a statistically significant correlation with abnormal SSEPs. CONCLUSIONS A high percentage of patients with CM-1 exhibited EP alterations regardless of their clinical or radiological findings. These findings suggest that EPs do not add any clinically relevant information nor are they helpful in establishing which symptomatic patients with CM should undergo surgical treatment. However, BAEP and SSEP studies clearly play an important role in incidentally detected patients with CM and may help to establish objective evidence of subclinical dysfunctions. In addition, neurophysiological studies may help to define subgroups of patients who require further testing and follow-up to personalize strategies for the management of incidental and oligosymptomatic patients.

Cerebrospinal fluid disturbance in overweight women after occipitocervical decompression in Chiari malformation type I.

Cerebrospinal fluid disturbance (CSFD) is a well-known complication after occipitocervical decompression (OCD) in patients with Chiari malformation type I (CMI). There is scarce data focusing on preoperative patients' factors predisposing to development of CSF disturbance. The aim of this study is to evaluate a prognostic value of some patients' factors in the prediction of CSFD after OCD in CMI patients. We undertook a 10-year (2003-2013) retrospective study of all OCD in patients with CMI performed at Sahlgrenska IC, Sahlgrenska University Hospital, Sweden. A total of 52 consecutive patients were obtained from the operation database and we excluded one patient who was previously diagnosed with normal-pressure hydrocephalus. Data regarding preoperative age, body mass index, gender, degree of tonsillar herniation and syrinx were registered. Development of CSFD after OCD was noted. Of the 51 patients reviewed, six had CSFD after OCD and were managed using a form of CSF diversion procedure. All of the patients who developed CSFD were females. They had a mean body mass index of 32.3 compared to a mean of 24.3 in patients without CSFD (p = 0.0011). There was no difference between the two groups with regard to the other examined patient factors. CSF diversion was needed in six consecutive adult Chiari malformation type I patients who underwent occipitocervical decompression. All patients with postoperative CSFD were female and their mean BMI was significantly higher than patients without this complication.

Chiari malformation type 1.5 in male monozygotic twins: Case report and literature review

Chiari malformation Type 1.5 (CM 1.5) was defined as the association of Chiari malformation Type I (CM I) and brainstem herniation. The objective was to demonstrate the difference of clinical features and surgical outcomes between CM 1.5 and CM I.All CM 1.5 and CM I adult patients who underwent posterior fossa decompression with duraplasty at our institution between 2006 and 2010 were retrospectively reviewed. Clinical characteristics, imaging features, and long-term outcomes were compared between CM 1.5 and CM I patients.A total of 142 adult patients were enrolled, including 27 CM 1.5 and 115 CM I patients. The average follow-up period was 102 months. Age at diagnosis was significantly younger in CM 1.5 group than CM I group (p = 0.039). And the degree of tonsillar herniation was significantly more severe in CM 1.5 group than CM I group (p < 0.001). There was no significant difference in other clinical and imaging characteristics. Moreover, improvement of symptoms was observed in 21 CM 1.5 patients (77.8%) and 94 CM I patients (81.7%), and no significant difference was detected (p = 0.637). There was no significant difference in the resolution of syringomyelia between CM 1.5 (72.7%) and CM I (76.5%) patients, either (p = 0. 710).Although CM 1.5 patients presented with brainstem herniation and more severe tonsillar herniation, other clinical and imaging features and surgical outcomes were similar with CM I patients. We think CM 1.5 is just a subtype of CM I, rather than a unique type of Chiari malformations.

Basilar invagination: Surgical results.

Introduction:Basilar invagination (BI) is a congenital craniocervical junction (CCJ) anomaly represented by a prolapsed spine into the skull-base that can result in severe neurological impairment.Materials and Methods:In this paper, we retrospective evaluate the surgical treatment of 26 patients surgically treated for symptomatic BI. BI was classified according to instability and neural abnormalities findings. Clinical outcome was evaluated using the Nürick grade system.Results:A total of 26 patients were included in this paper. Their age ranged from 15 to 67 years old (mean 38). Of which, 10 patients were male (38%) and 16 (62%) were female. All patients had some degree of tonsillar herniation, with 25 patients treated with foramen magnum decompression. Nine patients required a craniocervical fixation. Six patients had undergone prior surgery and required a new surgical procedure for progression of neurological symptoms associated with new compression or instability. Most of patients with neurological symptoms secondary to brainstem compression had some improvement during the follow-up. There was mortality in this series, 1 month after surgery, associated with a late removal of the tracheal cannula.Conclusions:Management of BI requires can provide improvements in neurological outcomes, but requires analysis of the neural and bony anatomy of the CCJ, as well as occult instability. The complexity and heterogeneous presentation requires attention to occult instability on examination and attention to airway problems secondary to concomitant facial malformations.

The role of nocturnal polysomnography in assessing children with Chiari type I malformation

ObjectiveTo evaluate nocturnal polysomnogram findings in children with suspected symptomatic Chiari type I malformation, correlate them with clinical and magnetic resonance imaging data and to determine if this information has value in clinical decision making process. MethodsA retrospective review identified 24 children with type I Chiari malformation, presumed symptomatic who had undergone neurological assessment, cranial magnetic resonance imaging and nocturnal polysomnography. Perimedullary subarachnoid space effacement on the magnetic resonance studies and the magnitude of cerebellar tonsillar descent in relation to the McRae line were correlated with frequency of obstructive or central sleep apnea, number of cortical arousals and evidence of impaired vocal mobility on laryngoscopy. The Wilcoxon rank sum test was applied for continuous variables and the Fisher exact test for categorical variables. ResultsThe median age of the subjects was 6 years. The findings from 16/24 subjects with perimedullary subarachnoid space effacement (effaced group) were compared with those of 8/24 in the non-effaced group. The central apnea index [1.5 (IQR 1–3.5) versus 0.5 (IQR 0–1.5)] and cortical arousal index [12 (IQR 10–19) versus 8 (IQR 6.5–9)] were significantly higher in the effaced group than in the non-effaced group (p=0.0376 and 0.0036 respectively). Greater descent of tonsils as measured by distance from the McRae line to the tonsil tip was associated with significantly higher central apnea index, total arousal index and respiratory event related arousals. Measurements of clivus-canal angle, Klauss index and pB-C2 line did not correlate with abnormalities on polysomnography. ConclusionThe central apnea and arousal indices derived from the nocturnal polysomnogram correlate well with magnetic resonance imaging findings of subarachnoid space effacement and degree of tonsillar herniation. In children with Chiari type I malformation, the nocturnal polysomnogram findings provides important information that aids in the decision making process about proceeding with surgical decompression.

A late complication of CSF shunting: acquired Chiari I malformation

Acquired Chiari I malformation developing after cerebrospinal fluid (CSF) shunting is an intriguing late complication of CSF shunt surgery and not only raises questions as to its pathogenesis but also poses many queries about the possible adverse effects on the subsequent child development as well as on the indications and possibilities of surgical correction. We report a series of 17 patients with the neuroradiological evidence of an "acquired" Chiari type I malformation. These patients, 3 to 24 years (mean 11.3 years), had been treated previously with an extrathecal CSF shunt. The follow-up varied from 2 to 12 years (mean, 6). Neuroradiological investigation demonstrated a small posterior cranial fossa, small ventricles, markedly reduced periencephalic subarachnoid spaces, and thickening of the skull vault and base. The degree of tonsillar herniation did not correlate with clinical manifestations. All patients with severe clinical manifestations or with progressive worsening of neuroradiological findings were considered for surgical treatment. Decompressive supratentorial craniotomy seemed to fit with the purpose of enlarging the intracranial volume without the risk of aggravating the hindbrain herniation. An immediate relief of clinical manifestations was observed in all patients. Not surgically treated patients did not show any clinical or radiological modification during all the follow-up. This study contributes to the understanding of the underlying pathogenetic mechanisms of acquired Chiari type 1 malformation in cases of long-lasting supratentorial CSF shunting and provides a base for planning the best management, whether conservative or surgical.

JULY 2004: 40-YEAR-OLD MAN WITH HEADACHES AND DYSPNEA

A 40-year-old man had a 6-week history of severe frontal headaches and dry cough. Chest x-ray showed hilar adenopathy with bilateral parenchymal infiltrates. A diagnosis of atypical pneumonia was made. Four weeks later he was admitted with persistent headache. Infectious screen was negative. Brain MR post contrast, revealed cerebellar enhancement and swelling with moderate tonsillar herniation; findings which precluded the performance of a lumbar puncture. High resolution CT thorax confirmed hilar abnormalities; shown by microscopy to represent non caseating granulomata. A presumptive diagnosis of sarcoidosis was reached. Despite an initial symptomatic improvement his headache persisted. Repeat MRI, eleven days after admission, showed reduced cerebellar enhancement and swelling with no change in the degree of tonsillar herniation. He deteriorated acutely and died two weeks after admission. Autopsy revealed cerebral oedema with tonsillar herniation secondary to cryptococcal meningitis variety neoformans. There was no evidence of neurosarcoid. Active and inactive sarcoid was identified in the lungs and hilar nodes with no evidence of systemic sarcoid. Focal evidence of cryptococcal pneumonitis was present in the lung as a necrotic focus. A strong index of clinical suspicion is necessary to diagnose the rare association of cryptococcus complicating sarcoidosis.

Herniación amigdalina en la malformación de Chiari I en la edad pediátrica: observación y evolución en el tiempo

ObjetiveTo assess possible changes in Chiari type I malformation in pediatric patients. Material and methods. A retrospective study of patients dianosed as having Chiari type I malformation, without surgical intervention, who had undergone at least one follow-up imaging study after an interval of at least one year. The diagnosis was established by sagittal magnetic resonance images showing displacement of the cerebellar tonsils of more than 5 mm through the foramen magnum. The clinical data, degree of tonsillar herniation and associated intracranial and medullary anomalies were recorded. The relationships between the degree of tonsillar herniation and the presence of associated symptoms and of medullary cavity, respectively, were analyzed using the chisquare test with Fisher's exact test and the positive likelihood ratio. ResultsEleven patients (7 boys and 4 girls) ranging in age between 4 months and 14 years (men: 6.5 years) were studied. At diagnosis, the egree of tonsillar herniation ranged between 6 mm and 20 mm. The finding was considered incidental in 9 of the 11 cases (81%); the remaining two patients presented headache and neck pain. The follow-up imaging studies were performed after an interval of 13 to 79 months. Stability of the herniation was observed in 6 patients (54%), progression in 3 (27%), a reduction in 1 (9%) and spontaneous regression in 1 (9%). Two patients presented neurofibromatosis type I accompanied by the characteristic intracranial lesions. Focal subcortical heterotopia was observed in another. Medullary cavities were found in 2 asymptomatic patients (18%). There was no significant relationship between the degree of herniation and the presence of either symptoms or medullary cavities. DiscussionIn children, Chiari type I malformation is often discovered incidentally. Associated medullary cavity is less common than in adults, suggesting that this phenomenon develops over the long term. During the course of the disease, nearly half the patients presented changes in tonsillar herniation, including an exceptional case of spontaneous regression of the malformation.