History,anatomic forms,and pathogenesis of Chiari I malformations

Introduction Chiari I malformations constitute a group of entities of congenital or acquired etiology that have in common descent of the cerebellar tonsils into the cervical spinal canal. In recent years, since the advent of magnetic resonance imaging, an increasing number of asymptomatic, doubtfully symptomatic, and minimally symptomatic patients with Chiari I malformations have been diagnosed. This has resulted in controversy about the multiple therapeutic strategies indicated for these problems.Object With the intention of updating the knowledge that we currently have on the Chiari I malformation and the related syringomyelia we review the literature and discuss the historical background, pathogenesis, anatomic forms, clinical presentation, and diagnostic procedures of these abnormalities.     

International survey on the management of Chiari I malformation and syringomyelia

Introduction The availability of magnetic resonance imaging (MRI) has resulted in an increasing number of asymptomatic, minimally symptomatic, and doubtfully symptomatic patients being diagnosed with a Chiari I malformation with or without syringomyelia. In an attempt to clarify how neurosurgeons manage these clinical problems, an international survey on the Chiari I malformation and related syringomyelia was undertaken.Method A questionnaire on the expected natural course of the disease and on aspects of the surgical technique for a number of hypothetical cases relating to Chiari I malformation with and without syringomyelia was used to survey Pediatric Neurosurgeons worldwide.Results Of 246 questionnaires distributed, 76 (30.8%) were completed and returned. There was a consensus that no operation should be carried out in asymptomatic patients with a Chiari I malformation, unless there is associated syringomyelia. There was a consensus that decompression of the Chiari malformation should be performed in patients with scoliosis when syringomyelia is present, and the majority decompressed the Chiari malformation in scoliotic patients even in the absence of syringomyelia. Suboccipital decompression was the standard surgical procedure for Chiari I malformations. The majority of respondents favored routine dural opening at surgery and closure with a pericranial or synthetic patch graft. In the case of a persistent or progressive syrinx after suboccipital decompression, the majority recommended shunting of the syrinx to the subarachnoid space or to the pleural cavity.Conclusion There continues to be much variation in the management of the Chiari I malformation.     

Chiari malformation, cervical disc prolapse and syringomyelia--always think twice

We present the case of a 36-year-old man with neck pain and parasthesia of both upper limbs. Magnetic resonance imaging demonstrated a cervical disc protrusion with spinal cord compression, a Chiari I malformation and cervical syringomyelia. On clinical grounds it was suspected that the cervical stenosis was the symptomatic pathology and an anterior cervical decompression was performed, followed by arthroplasty. Post-operative imaging demonstrated adequate canal decompression, preserved cervical mobility and near-complete resolution of the syrinx. Syringomyelia has a multitude of causes and synchronous pathology can occur. Cervical spondylosis is infrequently associated with syringomyelia. Chiari I malformations are increasingly incidentally detected and asymptomatic. This first report of arthroplasty for cervical spondylosis associated with syringomyelia adds to the growing body of experience with this new technology.     

与Chiari畸形或脊髓损伤无关的脊髓空洞症的外科治疗（英文）

PURPOSE Syringomyelia is a misleading disease since the problem always lies elsewhere.Arachnoiditis,because it is radiographically difficult to discern,is an especially insidious cause.To better guide selection from among surgical treatment options for syringomyelia,we reviewed our case series of patients without Chiari malformation or spinal injury.METHODS Excluding syringomyelia due to Chiari malformation,spinal cord injury,and tumors,32 patients(mean age 44 years)were operated on between 1995 and 2013and followed up for a mean of 53.8 months.Presumed causes at diagnosis,clinical and radiological findings,type of operation,clinical and radiological outcome were reviewed.RESULTS Duration of clinical history varied widely(range 6-164 months).Clinical assessment was based on the McC ormick classification(15 independent,17 dependent).Causes included birth trauma,pyogenic meningitis,tuberculous meningitis,postoperative scarring,dysraphism,and basilar impression.Treatment was local decompression with arachnoid lysis and shunts.Hindbrain-related syringomyelia was differentiated from non hindbrain-related syringomyelia.Hindbrain arachnoiditis was significantly associated with radiological findings at the foramen magnum(P=0.01)and craniocervical decompression(P0.03),with good clinical and radiological outcome at 6 months and later follow-up controls(P=0.02),whereas uneven results were observed in cases of non-hindbrain arachnoiditis.CONCLUSIONS To remove the cause of syringomyelia,surgical planning will rely on thorough clinical history and accurate imaging to determine the site of cerebrospinal fluid obstruction.Craniocervical decompression to dissect basal arachnoiditis in the posterior fossa can be recommended in hindbrain syringomyelia.Treatment of non-hindbrain arachnoiditis is more controversial,probably owing to uncertainties about the extent of adhesions.     

Surgical management of syringomyelia: a five year experience in the era of magnetic resonance imaging.

We summarize our experience with 59 consecutive surgically managed cases of syringomyelia (SM) over a 5 year period. All cases had magnetic resonance imaging (MRI) preoperatively and postoperatively. Twenty-eight patients presented with SM and the adult Chiari (Chiari I) malformation (SM-ACM), 6 patients had post traumatic syrinxes, 14 patients had syrinxes associated with an intramedullary neoplasm, 3 patients had syringomyelia associated with spinal arachnoiditis and 8 patients had idiopathic syringomyelia. Holocord syrinxes were more often associated with SM-ACM, while focal syrinxes were associated with posttraumatic, spinal arachnoiditis and neoplastic conditions. In all cases with neoplasms the MRI revealed parenchymal intramedullary signal abnormalities in addition to the syrinx cavity. Posterior fossa decompression with obex plugging (the Gardner operation) was the procedure of choice for SM-ACM and for idiopathic holocord syringomyelia. Exploration and drainage of the syrinx with or without shunting was carried out mainly for focal syrinxes associated with trauma and neoplasm. Patients with SM-ACM responded well to posterior fossa decompression with satisfactory results in 24/28 patients. Idiopathic SM is probably a forme fruste of SM-ACM and when treated with the Gardner procedure showed good results in all 8 patients. Posttraumatic and neoplastic SM had the least predictable results with surgery. The disappearance of the syrinx on postoperative MRI correlated well with a good surgical outcome.     

Some observations on the pathogenesis of syringomyelia.

The pathogenesis of most cases of syringomyelia remains obscure although a modification of the hydrodynamic theory of Gardner allows a logical surgical approach to treatment. Data are presented confirming a high incidence of traumatic birth in patients with syringomyelia who have a Chiari malformation or basal arachnoiditis, but demonstrating no increase in traumatic birth in patients with the Chiari malformation but no syringomyelia. A traumatic birth may be the factor responsible for creating the potential for syringomyelia in those individuals with the embryological defect of the Chiari anomaly.     

Malformations of the spinal cord in 53 patients with spina bifida studied by magnetic resonance imaging

The incidence of associated malformations of the hindbrain and spinal cord in patients with spina bifida was investigated by a clinical and magnetic resonance study. The incidence of these malformations in combination with spina bifida was 49/53 (92.5%). Fiftytree children born with spina bifida aperta (40 patients) or spina bifida occulta (13 patients) formed the study group. The incidence of the various malformations were: Chiari malformations, type I, 10/53 (19%), and type II, 20/53 (38%); syringomyelia, 13/53 (24.5%); hydromyelia 4/53 (7.5%); tethered cord malformation, 35/53 (66%); diastematomyelia 2/53 (4%). Thirty-seven of the 49 patients with associated malformations had no clinical signs at the time of our study. The results point to the fact that in the pediatric age group, associated spinal defects often remain asymptomatic.     

Consensus conference on Chiari: a malformation or an anomaly? Scoliosis and others orthopaedic deformities related to Chiari 1 malformation

In this article, we analysed the orthopaedic malformation in patients affected by Chiari I malformations as well as conservative or surgical treatment. The most common deformity in these patients is scoliosis. Different studies suggest a causal relation between syringomyelia and spinal deformities that differ by the type of deformities: asymptomatic scoliosis is characterized by a higher incidence of a single curve and convexity to the left, while symptomatic scoliosis is characterized by a double thoracolumbar curve. The conservative treatment with brace in these patients is not effective and scoliosis is typically evolutive. The evidence of the international data is that in patients without myelomeningocele or congenital scoliosis, but with Arnold Chiari I malformation and syringomyelia, suboccipital craniectomy gives the best chance for syrinx reduction and scoliosis improvement, particulary in children younger than 10 years and below a Cobb angle of 30°. The orthopaedic treatment in late decompression or in progressive curve is spine arthrodesis.     

Chiari 1.5 Malformation : An Advanced Form of Chiari I Malformation

The Chiari 1.5 malformation is defined as a tonsillar herniation within a Chiari I malformation with additional caudal descent of the brainstem through the foramen magnum. We describe a patient with Chiari I malformation who evolved to Chiari 1.5 malformation during longitudinal follow-up. A 15-year-old girl presented with neck pain during exercise for two years. She had been diagnosed with Chiari I malformation with mild hydrocephalus after minor cervical trauma at the age of six years. At that time, she was asymptomatic. After she complained of aggravated neck pain, neuroimaging (nine years after first imaging) revealed caudal descent of the brainstem and syringomyelia in addition to progression of tonsillar herniation. Posterior fossa decompressive surgery resulted in complete resolution of neck pain. Based on neuroimaging and operative findings, she was diagnosed as Chiari 1.5 malformation. Neuroimaging performed seven months after surgery showed an increased anterior-posterior diameter of the medulla oblongata and markedly decreased syringomyelia. This case demonstrates progressive developmental process of the Chiari 1.5 malformation as an advanced form of the Chiari I malformation.     

Pediatric Chiari I malformations: do clinical and radiologic features correlate?

BACKGROUND: Although Chiari I malformation is increasingly recognized in children, little is known about its clinical presentation in this age group. OBJECTIVE: To evaluate the relationship between clinical and MRI features of pediatric Chiari I malformations. METHODS: We performed a chart review and MRI analysis of 49 children with Chiari I malformation. The degree of tonsillar ectopia was compared with age at onset, presence of syringomyelia, and a neurologic severity score as follows: asymptomatic = 0, symptomatic with normal neurologic examination = 1, and symptomatic with abnormal examination = 2. RESULTS: Age at onset of symptoms ranged from 10 months to 14 years. Fifty-seven percent of patients were asymptomatic. Headache and neck pain were the most frequent complaints. Syringomyelia was detected in 14% of patients and skull base abnormalities in 50%. The magnitude of tonsillar ectopia (5 to 23 mm) correlated with severity score (p = 0.04) but not with other clinical measures. CONCLUSIONS: The clinical symptoms of Chiari I malformations in children are nearly identical to those seen in adults. Children with greater amounts of tonsillar ectopia on MRI are more likely to be symptomatic.     

Consensus conference on Chiari: a malformation or an anomaly? Scoliosis and others orthopaedic deformities related to Chiari 1 malformation

In this article, we analysed the orthopaedic malformation in patients affected by Chiari I malformations as well as conservative or surgical treatment. The most common deformity in these patients is scoliosis. Different studies suggest a causal relation between syringomyelia and spinal deformities that differ by the type of deformities: asymptomatic scoliosis is characterized by a higher incidence of a single curve and convexity to the left, while symptomatic scoliosis is characterized by a double thoracolumbar curve. The conservative treatment with brace in these patients is not effective and scoliosis is typically evolutive. The evidence of the international data is that in patients without myelomeningocele or congenital scoliosis, but with Arnold Chiari I malformation and syringomyelia, suboccipital craniectomy gives the best chance for syrinx reduction and scoliosis improvement, particulary in children younger than 10 years and below a Cobb angle of 30°. The orthopaedic treatment in late decompression or in progressive curve is spine arthrodesis.     

Familial Chiari type I malformation with syringomyelia in two siblings: case report and review of the literature

Objective Familial cases of Chiari malformation with syringomyelia are rare. The majority of the reported series and case reports detail sporadic cases. The authors report two siblings who presented with Chiari type I malformation and syringomyelia (CMI+S).Clinical presentation We report two sisters who each presented with scoliosis on routine school physicals. Their clinical examination was unremarkable; however, imaging studies demonstrated a Chiari malformation with syringomyelia. Both underwent cervicomedullary decompression, and follow-up imaging studies revealed resolution of the syringomyelia.Conclusion A review of the literature reveals fewer than ten previous reports of familial CMI+S in the past 30 years. Although rare, the existence of familial cases of CMI+S suggests a genetic component to the pathogenesis of this condition in at least a proportion of patients. Neurosurgeons should be aware of the familial aggregation of CMI+S.     

Chiari in the family: inheritance of the Chiari I malformation

This report presents three families with Chiari malformation type I that became symptomatic during childhood: a mother and son; a set of monozygotic twins; and two half-siblings and their two maternal cousins. These children presented with various symptoms, including headache, stiff neck, and swallowing difficulty. A review of the relevant literature is presented, with an emphasis on familial examples and proposed inheritance. Less common presentations of Chiari malformation type I are discussed, as well as the possible pathogenesis of Chiari malformation type I and associated syringomyelia.     

Chiari畸形伴脊髓空洞症的微创手术治疗

目的探讨Chiari畸形并脊髓空洞症的微创外科手术治疗方法。方法回顾性分析74例患者微创手术治疗情况。微创手术治疗74例,均行后颅窝小骨窗减压,下疝小脑扁桃体切除,松解蛛网膜下腔的粘连,开放正中孔至第四脑室及小脑延髓侧池,改善蛛网膜下腔脑脊液循环,原位缝合硬脑膜。结果术后临床症状消失和改善者68例,无变化6例。随访56例,脊髓空洞明显缩小。结论微创手术是治疗Chiari畸形并脊髓空洞症的有效方法。恢复蛛网膜下腔的脑脊液循环是治疗的关键。     

Chiari I malformation with syrinx

The Chiari I congenital malformation is characterized by caudal displacement of the cerebellar tonsils through the cervical canal. Although this malformation is often asymptomatic, coexisting syringomyelia can result in neurologic symptoms. We report a case of progressive ataxia with brainstem dysfunction in an adolescent female manifesting a severe Chiari I malformation with syrinx. Chiari decompression 4 years after initial presentation led to rapid improvement in most of her long-term symptoms. This case demonstrates the importance of consideration of Chiari I with syringomyelia in the differential diagnosis of progressive ataxia and brainstem symptoms.     

Syringomyelia in twin brothers discordant for Chiari I malformation: case report

Familial syringomyelia outside of trauma, tumor, or infection has been reported. Cases are presented that highlight the possible connection between familial syringomyelia and the Chiari 0 malformation. We report on 11-year-old twin brothers both with syringomyelia. Magnetic resonance imaging further revealed that one brother had Chiari I malformation and the other had Chiari 0 malformation. Both underwent posterior fossa decompression with radiologic improvement of their syringes. These case reports lend credence to earlier reports of improvement in syringomyelia following posterior fossa decompression in the absence of Chiari I malformation, the so-called Chiari 0 malformation. In addition, these case reports should influence the manner in which familial syringomyelia without tonsillar ectopia is defined and addressed, that is, posterior fossa decompression versus shunting of the syrinx, thereby addressing the potential cause of the syringomyelia and not only the enlarged cavity itself.     

Treatment of Syringomyelia due to Chiari Type I Malformation with Syringo-Subarachnoid-Peritoneal Shunt

Chiari type I malformation is a tonsillar herniation more than 3 mm from the level of foramen magnum, with or without concurrent syringomyelia. Different surgical treatments have been developed for syringomyelia secondary to Chiari''s malformations: craniovertebral decompression with or without plugging of the obex, syringo-subarachnoid, syringo-peritoneal, and theco-peritoneal shunt placement. Shunt placement procedures are useful for neurologically symptomatic large-sized syrinx. In this paper, authors define the first successful treatment of a patient with syringomyelia due to Chiari type I malformation using a pre-defined new technique of syringo-subarachnoid-peritoneal shunt with T-tube system.     

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.     

颅后窝重建术治疗Chiari I畸形合并脊髓空洞症

目的探讨后颅窝重建术(后颅窝减压+硬脑膜成形+小脑扁桃体切除+蛛网膜粘连分解)治疗Chiari I畸形合并脊髓空洞症的方法及疗效。方法 2002年11月至2008年1月对收治的46例Chiari I畸形合并脊髓空洞症患者行后颅窝重建术。结果后颅窝重建术症状改善率84.8%,脊髓空洞长度明显减小,KPS评分显著改善。结论后颅窝重建术是治疗Chiari I畸形合并脊髓空洞症较为合理的术式。     

Endoscopic third ventriculostomy in the management of Chiari I malformation and syringomyelia associated with hydrocephalus

BACKGROUND: Chiari malformation with syringomyelia is conventionally managed with foramen magnum decompression and duroplasty. In presence of hydrocephalus, a ventriculoperitoneal shunt insertion has been the initial preferred mode of treatment. METHODS: Two patients of Chiari I malformation with syringomyelia who had associated hydrocephalus were initially treated with endoscopic third ventriculostomy (ETV). RESULTS: At follow up, both the patients symptomatically improved. Repeat MRI studies revealed collapse of the syrinx cavity and reduction of the Chiari malformation. CONCLUSIONS: Chiari malformation and syrinx associated with hydrocephalus may be effectively managed with endoscopic third ventriculostomy.