Spontaneous resolution of a Chiari malformation Type I and syrinx after supratentorial craniotomy for excision of a cavernous malformation.

The pathogenesis of Chiari malformation Type I (CM-I) and associated syringomyelia is incompletely understood. Patients often present in middle age with incidental or minimally symptomatic CM-I, whose management is controversial. One option is clinical and radiographic observation of asymptomatic and minimally symptomatic patients. The authors here present the case of a 36-year-old woman who had been monitored for 6 years for a minimally symptomatic CM-I and cervicothoracic syrinx. After 5 years of follow-up, she suffered spontaneous rupture of a cerebral cavernous malformation when she was 27 weeks pregnant. The ruptured cavernous malformation and hematoma were operatively managed via a right frontal craniotomy. Ten months after the craniotomy for resection of the ruptured cavernous malformation, follow-up MRI demonstrated resolution of the CM-I and syrinx. Few similar cases have been reported in adults. This case argues for the presence of dynamic factors in the development and maintenance of CM-I and supports the nonoperative treatment of asymptomatic and minimally symptomatic patients.