Spinal Cord and Root Compression

Syringomyelia : Sringomyelia is the acquired development of a cavity (syrinx) within the central spinal cord. The lower cervical segments are usually affected, but extension may occur upwards into the brain stem or downwards as far as the filum terminale. The cavitation appears to develop in association with obstruction : - Around the foramen magnum in conjunction with the chiari malformation - Secondarily to trauma or arachnoiditis

The syrinx may obliterate the central canal leaving clumps of ependymal cells in the walll In contrast HYDROMYELIA is the congenital persistence and widening of the central canal Syringomyelia should be distinguished from cystic intramedullary tumours, although both pathologies may coexist

Investigations : MRI is the investigation of choice This will demonstrate the syrinx with any assoicated Chiari malformation and exclude intramedullary tumour If MRI is unavailable – MYELOGRAPHY demonstrates widening of the spinal cord With coexisting Chiari malformations, screening in the supine position will show the cerebellar tonsils descending below the foramen magnum

Historically introduction of air into the CSF space – AIR MYELOGRAPHY- was used to ‘collapse’ the dilated segment thereby excluding an intrinsic cord tumour A CT scan, six hours after injection of intrathecal contrast, may show uptake within the syrinx, but beware of misinterpreting normal contrast uptake within spinal cord tissue Puncture of the syrinx is occasionally possible and subsequent injection of contrast shows its exact extent

Management : The natural history is variable and operative techniques only of limited benefit The approach depends on progression of symptoms and the presence or absence of an associated Chiari malformation If Chiari malformation is present- decompression by removing the posterior rim of the foramen magnum and posterior arch of the atlas and widening the dura with a patch, improves symptoms is most patients and should halt progression

This operation relieves the obstructed formaen magnum and alters the hydrodynamics of the syrinx If deteriortion continues, or if no associated Chiari malformation exists

Syringomyelia remains a difficult condition to treat Syringomyelia remains a difficult condition to treat. Drainign the syrinx into the CSF space by syringostomy may not significantly alter the haemodynamics Syringoperitoneal shunt may seem to be the most logical approach. Despite all efforts, abount one-third of patients suffer progressive deterioration