Syringomyelia: How MRI Aids Diagnosis and Management

Summary

MRI is an invaluable tool in the diagnosis and assessment of treatment of syringomyelia. It also confirms the theory of the pathogenesis of the disease and suggests why some operations on the condition fail.

A series of patients with Chiari I, with and without syringomyelia, have been studied with MRI both prior to surgery and following treatment. In four cases, with Chiari I alone and minor symptoms only, management has been conservative. No progression of symptoms or signs have been seen, MRI allowing syringomyelia to be excluded, both at diagnosis or development during follow-up. Patients with Chiari I, six with and one without syringomyelia, were split into two groups; those with symptoms and signs of cervico medullary compression (CMC) and those with pure cord amyotrophy with upper limb weakness and numbness of typical “cape type”. In three CMC patients, foramen magnum decompression (FMD) with fascia lata grafting and high syringotomy, and in two FMD without syringotomy, were carried out. The procedure improved pain, CMC symptomatology and clinical signs, but had only minor effects on amyotrophic symptoms. Some improvement was seen after surgery in distention of the syrinx on MRI studies, but there was no progression in the syrinx cavities. In two patients with pure amyotrophic the syrinx cavities. In two patients with pure amyotrophic symptoms, primary syringoperitoneal shunting (SPS) was carried out, and a further two patients with primary FMD subsequently went on to SPS for amyotrophic symptoms and signs. A Spetzler type system was used in the high thoracic region in all four cases. Brief symptomatic clinical improvement resulted from SPS in three of the four cases but this was not sustained and in one, symptoms developed in the segment above which remains distended on MRI.

MRI shows that below the shunt tubing in the cord, the cavity collapses, but above the shunt, the cavity remains distended. It not only supercedes CT myelography by being non-invasive and having superior imaging, but also demonstrates loculi and segmental decompression caused by surgery. Possible mechanisms are discussed.