Progress in syringomyelia.

Abstract

Syringomyelia management is showing some progressive improvements following surgical methods of investigation and treatment. Investigation of simultaneous pressure changes in the cerebrospinal fluid pathways has illustrated the importance of craniospinal pressure dissociation in impacting the cerebellar and medullary tissues in the foramen magnum in hindbrain related syringomyelia. Such pressure differences may be referred to as 'suck' and similar changes are to be found in non-hindbrain related forms of syringomyelia such as those associated with spinal arachnoiditis. When cavities have formed then impulsive movements may occur with them and enlargement of the cavities may be continued by sloshing of the fluid within them. Investigations have been improved following the widespread use of water soluble contrast media and CT scanning with reconstructions after myelography. A definite relationship between birth injury and hindbrain related syringomyelia has been established especially with cases showing arachnoiditis. The nature of the relationship to hindbrain hernia and basilar invagination remains unclear. Magnetic resonance imaging holds great promise particularly in showing hindbrain deformation in new-born babies, showing whether or not a communication commonly exists between the fourth ventricle and the cavities within the spinal cord in early childhood and also in outlining the changes in the spinal cord in the presence of acute traumatic paraplegia. Treatment still relies upon valved ventricular to extrathecal shunts for hydrocephalus, cranio-vertebral decompression to prevent suck and drainage of the syrinx in appropriate cases. Syrinx to extrathecal shunting may be preferred to shunts to the subarachnoid space. The peritoneum and the pleura are favoured sites and a valve is not necessary. The advances for the future may depend on earlier diagnosis and greater understanding of the mechanisms of pathogenesis in which MRI seems likely to play an increasingly important part.