Presentation of type I Chiari malformation after head trauma

An unusual case of Type I Chiari malformation that became symptomatic after closed head injury is reported. The patient manifested transient upper extremity weakness, persistent lower cranial nerve dysfunction, and cerebellar signs that slowly resolved. Magnetic resonance images showed tonsillar ectopia but no displacement of the brain stem or syringomyelia. Type I Chiari malformation should be included in the differential diagnosis of patients who present with upper extremity weakness, lower cranial nerve palsies, or cerebellar signs after trauma.     

Chiari type I malformation with an associated intramedullary schwannoma

A case of Chiari type I malformation associated with a cervical intramedullary schwannoma is presented. A review of the literature concerning intramedullary schwannomas revealed their most frequent location to be in the cervical region. Their optimal treatment seems to be total removal as early in the course as is feasible. Emphasis is given to the need for actual demonstration of the cystic nature of the swollen spinal cord when dealing with Chiari type I malformation.     

Chiari I malformation in parturients

STUDY OBJECTIVE: To assess complications of regional as well as general anesthesia in parturients with Chiari I malformation. DESIGN: Retrospective chart review. SETTING: Academic medical center. PATIENTS: All parturients in our institution who had the diagnosis of Chiari I malformation and delivered in our hospitals over a 50-year period. MAIN RESULTS: 12 parturients delivered 30 babies. Three deliveries were facilitated with general anesthesia. Nine deliveries were facilitated with central axis anesthesia, six with epidural anesthesia, two with a single injection of a spinal anesthetic, and one with a continuous spinal catheter. The patient who received a continuous spinal catheter developed a postdural puncture headache that resolved with an epidural blood patch. None of the patients who received general, spinal, or epidural anesthesia for their deliveries developed symptoms or had exacerbation of preexisting symptoms of Chiari I malformation. CONCLUSIONS: General anesthesia, as well as spinal and epidural anesthesia, appeared to be safe and effective in our series of vaginal or cesarean delivery patients. The small number of patients in our series does not negate the cautious recommendations of others, but suggests that general anesthesia, as well as spinal or epidural anesthesia, can be used safely and effectively in these patients.     

Cranio-cervical decompression for Chiari I malformation

Summary We report a series of 26 patients affected by a Chiari I malformation treated at our department between 1987 and 1993. All patients underwent pre- and postoperative evaluation by magnetic resonance imaging (MRI). Sequential perioperative motor evoked potential (MEP) recordings were performed in 8 patients. The preoperative symptoms can be divided into four subgroups: cephalgias (84.6%), cranial nerve deficits (69.2%), motor deficits (76.9%), sensory deficits (73%). Twenty-five out of 26 patients underwent craniovertebral decompression, 1 a transoral anterior decompression. One patient died 2 months after surgery because of progressive pulmonary failure. We registered following postoperative complications: transient hypoglossal palsy (1 case), vertigo (2 cases), meningitis (1 case), minor CSF leaks (3 cases). Cephalgias subsided in 17 and improved in 4 out of 22 patients. Cranial nerve deficits improved in 8 and were stabilized in 7 out of 18 patients. A limited recovery of trigeminal function was possibly due to nuclear lesions. Five patients whose vestibular disturbances were not relieved by surgery were put on a course of carbazepine. Vertigo resolved in one case and in two others improved. While hypesthesia improved after decompression, the other sensory deficits were stabilized in 5% of the patients. Spasticity improved in 12 out of 18 patients, but weakness only in 7 out of 17 patients. Motor disturbances ewre always detected by MEP-recording. MEP-characteristics were not specific, resembling those of patients with other intra-, extramedullary myelopathies. Functional recovery was not matched by an improvement of the MEP parameters. MEP may be used as a tool for survellance of patients whose clinical findings are not progressive and are not at first surgical candidates.     

Chiari type 1 malformation and magnetic resonance imaging

The Chiari type 1 malformation is common. Unlike the Chiari type 2 and 3 malformations, it may remain latent for a long time, becoming symptomatic only in adulthood. The introduction of MRI has resulted in an increased number of diagnoses of this malformation in pediatric patients. It appears to be related to underdevelopment of the posterior cranial fossa. It must be differentiated from acquired tonsillar herniation, particularly when herniation results from intracranial hypotension; these cases are sometimes reported as acquired Chiari I malformation with spontaneous resolution. Tonsillar ectopia may cause symptoms by its direct effect on any or all of the medulla and the cerebellar and upper spinal cord. The most suggestive of the oculomotor disturbances is oscillopsia with downbeat nystagmus. Dysphonia and dysphagia are common. Potentially serious autonomic disturbances are also frequent: sleep apnea, respiratory failure, syncope and even sudden death. Another risk is syrinx formation, resulting from obstruction of CSF circulation in the cisterna magna. Syringomyelia is detected in 32 to 74% of patients with Chiari I malformation. Treatment is surgical. Posterior fossa decompression is achieved by suboccipital craniectomy combined with laminectomy of the upper cervical segments. Surgical intervention is indicated when the malformation is symptomatic and there is no doubt that it is the cause of the symptoms. When a Chiari I malformation is identified fortuitously on MRI, long-term monitoring is essential. The risk of developing symptoms increases over time. Patients should be advised not to participate in contact sports.     

The surgical treatment of Chiari I malformation

Summary A retrospective study was undertaken on 133 patients with a Chiari I malformation treated within the last 16 years at the Departments of Neurosurgery at the Nordstadt Hospital Hannover, Germany, and the University of California, Los Angeles, U.S.A. Ninety-seven patients presented with symptoms related to accompanying syringomyelia and 4 with associated syringobulbia. They underwent 149 surgical procedures and were followed for a mean of 39±52 months. A decompression at the foramen magnum was performed in 124 patients, while 22 of those with syringomyelia were treated by shunting (7 syringosubarachnoid shunts, 15 syringoperitoneal or -pleural shunts), and 3 by ventriculoperitoneal shunts for hydrocephalus.Except for ventriculoperitoneal shunting, at least a short-term decrease in size of an associated syrinx was observed for all procedures in the majority of cases. However, no long-term benefit was observed for syrinx shunting operations. The best clinical longterm results were obtained with decompression of the foramen magnum in patients with (86% free of a clinical recurrence) and without syringomyelia (77% free of a clinical recurrence). We advise against syrinx shunting, a large craniectomy, and obex plugging which are associated with higher recurrence rates. Instead, surgery should consist of a small craniectomy, opening of the dura, archnoid dissection to establish normal cerebrospinal fluid (CSF) outflow from the 4th ventricle, and a fascia lata durai graft.     

Negative pressure pulmonary edema following foramen magnum decompression for Chiari malformation type I

A 57-year-old obese female presented with vagal and hypoglossal nerve pareses, and magnetic resonance imaging revealed Chiari malformation type I. Standard surgical treatment for Chiari malformation type I was successfully performed. However, immediately after the patient was extubated, she developed signs of upper airway obstruction and chest radiography revealed pulmonary edema. Her ventilation was assisted by maintaining positive end-expiratory pressure at 8 cmH2O. Intravenous furosemide and hydrocortisone were administered. Her respiratory status improved 12 hours later, and she was extubated 3 days after the operation. Postextubational course was uneventful, and the patient was discharged 2 weeks after extubation. The initial neurological deficits had mostly disappeared by 10 months after the operation. This unusual case of negative pressure pulmonary edema indicates that obesity and lower cranial nerve paresis are further risk factors for pulmonary edema as a postextubational complication of surgical treatment.     

Asymmetric laterality of Chiari type I malformation in patients with non-syndromic single-suture craniosynostosis

Background

Chiari type I malformation is a frequent incidental finding commonly associated with craniosynostosis. However, there seems to be a paucity of literature concerning the asymmetry of tonsillar herniation in patients with non-syndromic single-suture craniosynostosis.

Methods

To study the asymmetry in this cohort, measurements of the right and left tonsils were made from sagittal images from both pre-operative and post-operative images from 11 patients with non-syndromic single-suture craniosynostosis.

Results

Pre-operatively, the mean difference between the caudal descent of all tonsils ranged from 0 to 7?mm, with a mean difference between sides of 2.45?mm. In three cases, cerebellar tonsils were symmetrically herniated. Post-operatively, the mean difference between caudal descent of all tonsils ranged from 0 to 4?mm, with a mean difference between sides of 1.45?mm. Four were symmetrically herniated. In patients with non-syndromic single-suture craniosynostosis, the tonsillar herniation is asymmetric in the majority of cases.

Conclusions

Asymmetry of cerebellar tonsil herniation is a frequent finding in this cohort. The right tonsil is more inferiorly located in majority of cases, with predominance to the synostotic suture side in asymmetric craniosynostosis cases.     

Advanced Chiari malformation type I with marked spinal cord atrophy. Case report

The authors discuss the results obtained in patients who underwent foramen magnum decompression for longstanding advanced Chiari I malformation in which marked spinal cord atrophy was present. This 50-year-old woman presented with progressive quadriparesis and sensory disorders. Magnetic resonance imaging revealed the descent of cerebellar tonsils and medulla associated with remarkable C1-L2 spinal cord atrophy. After a C-1 laminectomy-based foramen magnum decompression, arachnoid dissection and duraplasty were undertaken. These procedures resulted in remarkable neurological improvement, even after 40 years of clinical progression. Spinal cord atrophy may be caused by chronic pressure of entrapped cerebrospinal fluid in the spinal canal.     

Tailored operative technique for Chiari type I malformation using intraoperative color Doppler ultrasonography

OBJECTIVE: We describe an operative technique for Chiari Type I malformation that uses color Doppler ultrasonography as a guide for performing patient-specific posterior fossa decompressions. The technique has been used since 1999 in more than 300 operations. METHODS: On the basis of real-time anatomic and physiological measurements, the following goals of surgery were monitored: 1) adequate decompression of the cervicomedullary junction; 2) creation of a retrocerebellar space of 8 to 10 cm(3) volume; and 3) establishment of optimal cerebrospinal fluid flow between the cranial and spinal compartments. RESULTS: The size of the craniectomy was tailored to conform to the area of cerebellar impaction as demarcated by compressed subarachnoid spaces. A laminectomy was not performed unless the cerebellar tonsils were herniated below C1. Before opening the dura, color Doppler ultrasonography imaging was invaluable in planning operative strategies. A simple duraplasty without additional steps was found to be appropriate treatment in occasional patients with minimal tonsillar herniation (5-8 mm). In all other cases, it was necessary to perform an internal decompression that included lysis of the arachnoid and shrinkage of the cerebellar tonsils to achieve the goals of surgery. Optimal cerebrospinal fluid flow through the foramen magnum in anesthetized, prone patients was found to have the following characteristics: a peak velocity of 3 to 5 cm/s, bidirectional movement, and a waveform exhibiting vascular and respiratory variations. The attainment of surgical goals was confirmed in most patients by postoperative neuroimaging. CONCLUSION: Color Doppler ultrasonography imaging is an important technological advance that permits the neurosurgeon to tailor the steps of Chiari surgery according to patient-specific variables. The success of this technique depends on the mastery of a new and sophisticated monitoring modality.     

Surgical technique for cranio-cervical decompression in syringomyelia associated with Chiari type I malformation

Summary Our purpose is to present our results with the surgical treatment of syringomyelia associated with Chiari type I malformation. Between October 1989 and October 1995, twenty-eight patients underwent a sub-occipital craniotomy and a C₁ laminectomy. After dura mater opening the cerebellar tonsils were mobilised. Neither catheter, nor plugging of the obex, nor tonsillar tissue removal was performed. The dura mater was enlarged by means of a wide graft to create a newcisterna magna of adequate size. Postoperative MRI scans showed an ascent of the cerebellum of 4.3±4.8 mm (measured by thefastigium to basal line), as well as of the brainstem (mean migration of the mesencephalon-pons junction of 4.3±3.3 mm). The tonsils emigrated cranially 6.5±4.8 mm. While preoperative mean syringo-cord ratio was 66.3%±13.3, post-operatively was 12.1%±12.7 (p<0.0001). A complete collapse of the syrinx was observed in 39% of the patients. Long-term improvements were obtained in 73% of the cases and 27% were unchanged. No patient got worse. We conclude that in the treatment of syringomyelia associated with Chiari I malformation an artificial cisterma magna of sufficient size must be created. This is achieved by means of an extensive sub-occipital craniotomy and C₁ laminectomy, followed by dural opening. Small bone removal with limited enlargement of theposterior fossa often results in failures of treatment and recurrences. Tonsillar removal is not necessary to obtain a good reconstruction of the cisterma magna.