Spinal Cord and Root Compression

Syringomyelia :

o Sringomyelia is the acquired development of a cavity (syrinx) within the central spinal cord.

o The lower cervical segments are usually affected, but extension may occur upwards into the brain stem or downwards as far as the filum terminale.

o 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. 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