Object: A subset of patients with Chiari malformation Type I (CM-I) presented with acute onset of a neurological deficit. In this study the authors summarize their experience with these patients' clinical presentation, imaging results, timing of surgery, and outcome following decompression.
Methods: The authors reviewed clinical records, imaging studies, and operative notes from all patients undergoing posterior fossa decompression for CM-I at St. Louis Children's Hospital from 1990 to 2008. Of the 189 patients who underwent surgery, 6 were identified with the acute onset of a neurological deficit at presentation.
Results: All 6 children (age range 3-14 years, 3 boys and 3 girls) had either syringomyelia (5 patients) or T2 signal changes in the spinal cord (1 patient) and CM-I on initial MR imaging. Three patients presented after minor trauma (1 with paraparesis, 2 with sensory deficits). Three patients presented without a clear history of trauma (1 with abrupt onset of spontaneous dysphagia and ataxia, 2 with sensory deficits). Decompression was performed at a mean 7.7 ± 4.9 days after symptom onset (7.0 ± 1.6 days after neurosurgical evaluation). In 1 patient, symptoms had resolved by the time of surgery; in the remainder of the patients, clear improvements were noted within 2 weeks of surgery, with complete resolution of symptoms by 12 months postoperatively. Follow-up MR images were obtained in 4 patients, demonstrating improvement in the extent of the syrinx in each patient.
Conclusions: Children with CM-I and syringomyelia can develop acute spinal cord or bulbar deficits with relatively minor head or neck injuries. The prognosis for symptomatic improvement in the observed deficit is good, with each patient in our series showing resolution of deficits over time. However, based on this relatively limited experience, the authors suggest that patients who present with an acute neurological deficit and are found to have CM-I be managed with early posterior fossa decompression. Patients with CM-I and syringomyelia may be at higher risk of acute neurological deficit than those without a syrinx.