The Resolution of Syringohydromyelia Without Hindbrain Herniation After Posterior Fossa Decompression

Bermans J. Iskandar, M.D., Gary L. Hedlund, D.O., Paul A. Grabb, M.D., W. Jerry Oakes, M.D., Division of Pediatric Neurosurgery and Department of Pediatric Imaging, Children's Hospital, Birmingham, Alabama

Neurosurg Focus. 2000;8(3) 

In This Article

Abstract and Introduction

Object. To provide more information about this rare condition, the authors describe five cases of syringohydromyelia without hindbrain herniation. Preoperative magnetic resonance imaging with and without gadolinium-diethylenetriamine pentaacetic acid revealed no evidence of spinal cord tumor, arachnoiditis, or spinal dysraphism.
Methods. Craniocervical decompression was performed in all patients, after which there was resolution of the symptoms in the four symptomatic patients, and all five showed marked reduction in the size of the syrinx.
Conclusions. The authors hypothesize the rare occurrence of syringohydromyelia resulting from a Chiari-like pathophysiological condition but lacking a hindbrain hernia. Patients with this condition may benefit from craniocervical decompression.

In the 1890s, Professor Hans Chiari described four cerebellar anomalies, which were later termed the Chiari malformations.[5,6] The Chiari malformations Types I, II, and III represent different degrees of herniation of posterior fossa tissue into the cervical canal (Chiari I and II), or through an upper cervical spina bifida (Chiari III), whereas the Chiari IV anomaly consists of hypoplasia of the cerebellum. Patients with Chiari I malformations may remain asymptomatic, have mild occipital headaches, or present with symptoms and signs of brainstem, upper spinal cord, and/or cerebellar dysfunction. One of the most common as well as one of the most ominous anomalies associated with these malformations is syringohydromyelia. In this report, we present five cases of syringohydromyelia without a defined hindbrain herniation, all of which improved with posterior fossa decompression. There was clinical improvement as well as a marked reduction in the size of the syrinx in all cases. This dramatic response to decompression indicates that this entity has a Chiari-like pathophysiology. The clinical, radiographic, and surgical findings in the five patients are presented, along with a brief discussion of the possible pathogenesis of the lesion.