Unilateral occipital hyperhidrosis following Chiari I decompression: case report and a review of the literature

Introduction Paroxysmal unilateral cephalic hyperhidrosis is a rare disorder of the autonomic nervous system.Case report We report an adult male who developed this disorder almost 20 years after posterior fossa decompression for Chiari I malformation with syringomyelia as a child. Further, the patient presented with spastic diplegia. To date, this patient has refused further operative intervention. The medical literature is reviewed regarding this unusual phenomenon.Conclusion To our knowledge, hyperhidrosis of the occiput has not been previously reported in a patient with Chiari I malformation with an associated syringomyelia.     

Morphometric analysis of the craniocervical juncture in children with Chiari I malformation and concomitant syringobulbia

Introduction  Although very uncommon, Chiari I malformation (CIM) with syringomyelia may be associated with concomitant syringobulbia. We hypothesized that the anatomy of the craniocervical region may be different in CIM patients with syringomyelia who develop syringobulbia in conjunction with their syringomyelia compared to other patients with CIM with and without syringomyelia. The present study was conducted in order to prove or disprove such a theory. Materials and methods  A group of 189 children with operated CIM were reviewed for the presence of syringobulbia, and this cohort then underwent morphometric analyses of their craniocervical juncture. These measurements were then compared to both our prior patient findings and historic controls. Results  The current study did not identify any morphometrical peculiarities for patients with CIM and syringobulbia compared to other CIM patients with and without isolated syringomyelia. Conclusions  Based on our study, the mechanism behind such cerebrospinal fluid distention into the brain stem remains elusive with no single morphometrical difference in patients with CIM and syringobulbia compared to other patients with CIM. Perhaps, future testing aimed at identifying pressure gradients across the foramen magnum in patients with and without syringobulbia and concomitant CIM may be useful.     

Scoliosis in a child with Chiari I malformation and the absence of syringomyelia: case report and a review of the literature

Background Scoliosis is a common finding in children with Chiari I malformation and syringomyelia. The development of scoliosis associated with a Chiari malformation typically has been ascribed to the presence of syringomyelia. Decompression of the hindbrain hernia will often alleviate the syringomyelia and, in many cases, stabilize or reverse the scoliosis.Case report We report a child with Chiari I malformation and scoliosis who presented with Valsalva-induced headache/neck pain. MRI revealed no syringomyelia or hydrocephalus. Radiographs revealed that her scoliotic curvature was approximately 13° and was a single levoscoliotic curve. This patient underwent a posterior fossa decompression with duraplasty for her Valsalva-induced pain. Postoperatively, she had resolution of her pain and there has been no progression of her scoliosis at 3 years follow-up.Prognosis Intriguingly, and scattered throughout the medical literature, many have noted cases of scoliosis in patients with only a Chiari I malformation and no syringomyelia. Moreover, experimental studies have induced scoliosis in animals after compression of the dorsal columns. After a review of the medical literature regarding a potential cause and effect of herniated hindbrain-induced scoliosis in the absence of syringomyelia, this association although rare, does seem plausible.     

Spontaneous resolution of isolated Chiari I malformation

Introduction Spontaneous resolution of Chiari I abnormality is very rare. In most patients, the radiological abnormality either stays unchanged with time or deriorates.Case report We present a male patient who was diagnosed at the age of 18 months as having radiological evidence of Chiari I malformation without syringomyelia, which had resolved 5 years later on a subsequent MR scan. At the time of initial diagnosis, he had been experiencing recurrent jerking movements of his body and was a sufferer of chronic renal failure.Discussion The symptoms were thought to be unrelated to the hindbrain hernia. Such spontaneous resolution of an isolated Chiari I malformation has only been described once more before, although resolution of hindbrain hernia associated with syringomyelia has been described before in several cases, albeit at single figures. The mechanism for such a natural evolution is not clear.Conclusion This patient demonstrates that surgical treatment should not be considered hastily in patients with radiological evidence of Chiari I in the absence of convincing associated clinical symptoms.     

Posterior fossa dimension and volume estimates in pediatric patients with Chiari I malformations

Introduction Chiari I malformations (CMI) involve pathological hindbrain abnormalities reported to be correlated with a hypoplastic posterior fossa. CMI was traditionally characterized by the downward herniation of the cerebellar tonsils with a descent of 5 mm or more below the foramen magnum. The fullness of the cisterna magna and CSF flow at the level of the cervicomedullary junction have been shown to be more useful in selecting symptomatic patients for surgical decompression. The present study calculates posterior fossa dimension and volume estimates in pediatric patients using magnetic resonance imaging. The combination of neuroradiological and clinical findings is used to re-examine the criteria used for diagnosis and treatment of pediatric CMI patients. Materials and methods A retrospective chart review was conducted on patients who were admitted to the Division of Neurosurgery of the Children’s hospital of Eastern Ontario between 1990 and 2007. Clinical and radiological assessments were performed on all patients. Posterior fossa volumes (PFV) and intracranial volumes (ICV) were measured from sagittal head magnetic resonance imaging scans using the Cavalieri method. Results Sixty-one CMI patients were identified. There were 32 male and 29 female patients with a mean age of 10 years (range: 8 weeks–18 years). Thirty-four (55%) of these patients were symptomatic with scoliosis (38%), suboccipital headaches (29%), and motor/sensory deficits (26%) being the most prominent symptoms. The mean PFV/ICV ratio for all the CMI patients (0.110) was found to be statistically smaller than that of the control patients (0.127, p = 0.022). Mean PFV/ICV ratios for asymptomatic and symptomatic CMI patients were found to be similar for children aged 0–9 years (p = 0.783) but different for children aged 10–18 years (p = 0.018). Discussion Mean PFV values were found to be smaller in pediatric CMI patients than control patients; this complements earlier studies in adults and supports the present theory concerning the pathophysiological mechanism of CMI. Subtle morphometric differences among asymptomatic and symptomatic patients aged 0–9 years stress the importance of monitoring asymptomatic patients for the onset of symptoms in their adult years. Symptom development in CMI is likely multifactorial and is much more extensive than the degree of cerebellar tonsillar herniation.     

Evolution of tonsillar ectopia associated with frontal encephalocoele

Introduction  Chiari I malformation has been traditionally considered a congenital malformation. However, there is growing clinical evidence suggesting that it is an acquired phenomenon as also exemplified by this case. Case  Fetal magnetic resonance imaging (MRI) at 28th week gestation revealed a frontonasal encephalocoele with no hindbrain abnormalities. Post-natal MRI of brain and cervical spine of the 7-week-old infant showed the presence of tonsillar ectopia in the absence of hydrocephalus. The normally developed cerebellar tonsil has herniated through the foramen magnum during the third trimester and neonatal period. Discussion  We hypothesise that the presence of the encephalocoele resulted in dampening expansile forces, produced by the growing brain as well as the cerebrospinal fluid pulsation required to stimulate of the skull growth. As a result, cranial growth is diminished producing a small posterior fossa. The subsequent growth spurt of the cerebellum at the end of the third trimester and during the neonatal period has resulted in cerebellar tonsillar ectopia consequent upon the state of cephalocranial disproportion.     

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

Objective In face of continuing controversy to the optimal treatment of Chiari type I malformation, the authors analyzed three different surgical strategies. Materials and methods Sixty patients (30 boys and 30 girls, mean age 8.2 years) presented with clinical Chiari malformation. Additional syringomyelia was present in 24 children, whereas cine flow studies showed no flow in the craniocervical junction in 48 children. All patients underwent a limited occipital craniectomy; a duraplasty was performed in 21 cases; and additional tonsillar reduction was performed in 19 cases. Clinical improvement was seen in 24 patients who underwent posterior decompression with or without duraplasty. In the tonsillar group, clinical improvement was evident in 18 patients. Conclusions Duraplasty and tonsillar reduction were equally effective but significantly better than bone decompression alone. Among patients with syringomyelia, tonsillar reduction was associated with a significantly better outcome. Postoperative flow studies improved in 39 patients but did not correlate to the clinical outcome.     

Treatment and management of the Chiari II malformation: an evidence-based review of the literature

Objective Multiple surgical strategies exist for the management of the symptomatic Chiari II malformation. To date, no comprehensive analysis of this medical literature in an attempt to seek out standards or guidelines has been performed, thus serving as the impetus for this present review.Methods A computerized search of the database of the National Library of Medicine was performed on the English-language medical literature between 1966 and 2003. Terms searched for included hindbrain hernia, Chiari II, Arnold-Chiari, surgery, decompression, syringomyelia, and CSF shunts. All literature found was reviewed with associated references from these sources. Each piece of literature reviewed was scrutinized and guidelines developed utilizing the methodology used by the Guidelines for the Management of Acute Cervical Spine and Spinal Cord Injuries.Results All data reviewed were deemed to be Class III in nature. No standards or guidelines could be established from the available literature. There is significant debate and variable results in the current neurosurgical literature regarding the evaluation of shunt function vs. Chiari II decompression in patients with symptomatic hindbrain herniation.Conclusions Multi-institutional prospective randomized trials are needed before any conclusions can be drawn regarding symptomatic Chiari II and its treatment paradigm. Until this time, clinical practice will be based on individual surgeons experience, training, and personal beliefs.This review was solicited and presented as part of the evidence-based practice at the Spina Bifida: Developing a Research Based Agenda National Conference, held 9–10 May 2003 in Washington DC and sponsored by the Centers for Disease Control and Prevention, National Institutes of Health, Agency for Healthcare Research and Quality, Interagency Committee on Disability Research (US Department of Education), and the Spina Bifida Association of America/Spina Bifida Foundation     

Chiari I malformation and intra-cranial hypertension:a case-based review

OBJECTIVE: To present clinical and morphological findings before and after surgery in a child with Chairi I malformation (CMI) and intra-cranial hypertension (IH). The literature is reviewed and pathophysiologic factors are discussed. CLINICAL PRESENTATION: A 13-year-old obese boy with a 3-week history of headaches, neck pain, torticollis and progressive visual deterioration was admitted. Bi-lateral chronic papilloedema and decrease in visual acuity were found in the presence of a previously diagnosed CMI. INTERVENTION AND FOLLOW-UP: Intra-cranial pressure monitoring demonstrating increased pressure levels was followed by a sub-occipital decompression, C1 laminectomy and duroplasty. Post-operatively, the boy improved markedly, the 6 months follow-up opthalmological examination demonstrated resolution of papilloedema, but consecutive bi-lateral optic nerve atrophy. CONCLUSION: IH with progressive visual deterioration represents one of the varying clinical presentations of CMI and may be classified as a secondary form of idiopathic IH. Neuro-ophthalmological examination in all patients with CMI is recommended to identify the real incidence of this presentation. Altered CSF dynamics, venous hypertension and obesity as co-factors may be causative pathophysiologic factors.     

神经内镜下寰枕部减压手术治疗Chiari畸形

目的 探讨神经内镜下寰枕减压手术治疗Chiari畸形的手术方法和临床疗效.方法 对23例经MRI确诊为Chiari畸形但不伴有寰枢锥脱位和齿突凹陷的患者在神经内镜下进行了寰枕减压手术,并进行疗效观察.结果 23例术后随访0.5-3.0年,原有症状均有不同程度改善,感觉障碍程度减轻,肢体肌力有所增强.无手术后并发症.术前合并脊髓空洞症的16例患者中,术后7例空洞消失,8例范围缩小,1例范围无明显变化.结论 神经内镜下寰枕减压手术治疗Chiari畸形方法可行,手术安全、有效、创伤小、疗效满意.

Abstract：

Objective To investigate the methods and effectiveness to treat Chiari malformation with the surgical decompression of the foramen magnum under endoscope. Method 23 cases with Chiari malformation.(without atlanto- axialdislocation and basilar invagination) diagnosed by magnetic resonance imaging( MRI)were operated with the surgical decompression of the foramen magnum under the endoscope. Results 23 cases were followed- up 0. 5 -3. 0, years after operation, all the symptoms and signs were remarkably relieved after the operation. No complications was found. In 16 cases with spinal cavities,7 cases spinal cavities disappeared and scases deflated,l case no evident change. Conclusions The endoscope -assisted decompression of the foramen magnum is a safe and effective surgical method to treat Chairi malformation.     

Prevalence of Chiari I malformation and cerebellar ectopia in patients with pseudotumor cerebri

BACKGROUND: Chiari I malformation (CM) may be present pre-surgically in pseudotumor cerebri (PTC) patients. Whether inferior tonsillar displacement (ITD) is coincidental or linked to increased intracranial pressure is unclear. This study aimed to identify the prevalence of both CM and cerebellar ectopia (CE) (ITD below the foramen magnum > or = 5 mm and 2-4 mm, respectively) in PTC patients. METHODS: Retrospective review combined with prospective assessment of 68 PTC patients with available brain magnetic resonance imaging (MRI) scans and reports. Data collected included patient demographics, height, weight, co-morbid conditions, and medications. MRIs were analyzed for cerebellar tonsillar position, and results were compared with original reports. RESULTS: Of 68 PTC patients, 60 (88%) had normal position of the cerebellar tonsils and 8 (12%) had ITD by report. Of the latter group, 4 were identified as CM and 4 as CE. On review of MRIs, however, 16 patients (24%) had ITD, 7 having CM and 9 having CE. All patients with ITD were female, most were overweight or obese, and most had presumed idiopathic intracranial hypertension (IIH). CONCLUSION: ITD exists pre-surgically in a significant percentage of PTC patients. ITD is most common in obese or overweight women with presumed IIH. In fact, this subset of patients may actually represent a secondary form of PTC and may benefit from correction of ITD to restore normal intracranial pressure.     

Chiari畸形合并脊髓空洞症的外科治疗

Chiari畸形又称小脑扁桃体下疝畸形.John Cleland于1883年首次描述了脑干、小脑移位变形和延髓空洞,Chiari分别于1891年、1895年将颅-椎移行区神经轴下移的程度进行了分类,1894年德国病理学家Arnold又作了更为详尽的描述,因此,1907年Schwalb和Gredig将此命名为ArnoldChiari畸形,而Sarnat和Williams则称其为Chiari畸形或描述表达为小脑扁桃体下疝畸形[1].     

Scoliosis in children with Chiari I-related syringomyelia

Objective To study the relationship between scoliosis and Chiari I malformation, with reference to the possible role of cranio-vertebral decompression in preventing the need for scoliosis correction.Material and methods Out of a total of 36 patients with symptomatic Chiari I, who underwent primary cranio-vertebral decompression by a single paediatric neurosurgeon with an interest in Chiari malformation between 1998 and 2003, 13 had clinically detected scoliosis. Of these, ten had no other structural spine abnormality, which could influence the natural history of scoliosis and were included in this study.Results In all but one patient, syringomyelia improved significantly after cranio-vertebral decompression. Of the ten patients, eight had levoscoliosis (left convexity), all single curves, and two had curves to the right (both double curves). Six patients did not require corrective scoliosis surgery after cranio-vertebral decompression. The mean Cobb angle for those not requiring scoliosis correction was 29° in contrast to a mean of 76° for those requiring correction [p=0.001, one-way analysis of variance (ANOVA)]. The mean age of patients requiring corrective surgery was 158 months against 125 months for those not requiring correction (p=0.084, one-way ANOVA). These findings were confirmed by multivariate analysis, which also confirmed that symptom duration, syrinx length and site were not significant in predicting the need for corrective surgery following cranio-vertebral decompression.Conclusions Cranio-vertebral decompression for Chiari I may prevent the need for corrective scoliosis surgery when performed before the age of ten and below a Cobb angle of 30°.     

Anatomical progression of the Chiari II malformation

To evaluate whether anatomic change of the relationship of the Chiari II malformation and the cranial base was occurring, 22 children with meningomyelocele had serial MRI scans reviewed. A ratio (B/A) was established between the distance from the foramen magnum to the caudalmost portion of herniated cerebellum (B) and the diameter of the foramen magnum (A) and this ratio was compared on serial MRI scans. Eighteen children had an increase in the B/A ratio, two children had a decrease, and two had no change. This indicates that continuous anatomic change of the Chiari II malformation and the skull base is occurring. Clinical deterioration in the older child may be explained by a combination of compressive and traction forces due to this change.     

枕大池重建术治疗Chiari畸形合并脊髓空洞

目的　介绍一种小脑扁桃体切除 枕大池成形术治疗Chiari畸形合并脊髓空洞症的手术方法。方法　枕下正中入路 ,咬开枕大孔后缘上至下项线 ,两侧至枕大孔的 4、 8点钟位置 ,约2 5cm× 4 0cm。咬除寰椎后弓 ,“T”形切开硬脑脊膜和蛛网膜。软膜下切除两侧小脑扁桃体 ,开放正中孔直至四脑室底并且打通两侧小脑延髓外侧池。取肌筋膜行硬脑脊膜连同蛛网膜的扩大修补 ,形成新的枕大池。结果　 12例中 ,男 5例 ,女 7例 ,年龄 18～ 5 1岁。MRI示脊髓空洞腔 <5节段 2例 ,5～ 8节段 8例 ,>8节段 2例。术后 3个月至 2年随访 9例 ,MRI复查见空洞腔均明显缩小 ,其中 3例空洞消失。感觉的恢复优于肌力的恢复。结论　此手术方法效果满意。其要点是 :(1)小脑扁桃体在软膜下切除并行软膜缝合。 (2 )四脑室正中孔开放并与两侧小脑延髓外侧池相通。 (3)枕大孔区蛛网膜下腔扩大修补缝合。无须行后颅窝减压术     

Posterior fossa morphometry in symptomatic pediatric and adult Chiari I malformation

The linear dimensions and volume of the posterior fossa, and the length of the supra-occiput and the clivus in children with Chiari I malformations (CMI) were studied. A statistical relationship between patient demographics, radiological features, posterior fossa and occipital bone morphometry in the study and control groups was investigated. The results of 21 pediatric patients was compared to those of a matched control group. The posterior fossa volume (PFV) of an adult CMI group was also studied. Linear measurements were used to calculate the length of the occipital bone, spherical PFV and intracranial volume (ICV) using pre-operative MRI and CT scans. A PFV to ICV ratio was obtained to standardize the comparison. The volumetric measurement in the pediatric study group was also compared to the adult CMI group.The antero-posterior dimension, width, and volume of the posterior fossa and the PFV to ICV ratio in pediatric CMI patients was significantly lower than in the control group (p < 0.05). There was no statistical difference in the length of the clivus and the supra-occiput between the two pediatric groups. The difference in the PFV to ICV ratio between pediatric and adult CMI patients was not statistically significant. Thus, the authors provide a simple, yet accurate, and reproducible method of comparison of posterior fossa volume in patients with CMI in different age groups, based on linear measurements. There is no significant difference between the length of the occipital bone at the base of the skull in pediatric CMI patients and the normal pediatric population. Development of the clivus due to late fusion of the sphenoid and occipital synchondroses in the second decade could result in manifestation of the disease in adulthood in CMI patients who were asymptomatic as children.     

Chiari malformation type I: related conditions

Chiari malformation type I (CMI) is a morphological diagnosis defined as the inferior displacement of the cerebellum through the foramen magnum. In parallel to this basic definition of CMI, there are diagnoses that co-exist with CMI in selected patients. In addition, there are specific constellations of clinical symptoms and signs reported in the literature that occur non-randomly in patients affected by CMI. There is no established system that categorizes these CMI-related conditions or even defines them as causes or consequences of CMI. Identifying the relationship between CMI and these associated disorders may allow greater understanding of CMI etiology and potentially inform CMI management.