Syringomyelia is the presence of longitudinally disposed cavities in the grey matter of the spinal cord. It is thus not a disease but a condition almost always associated with other lesions. If hydrocephalus, posterior fossa arachnoid pouches or spina biflda are present in a patient with syringomyelia they indicate a disturbance of cerebrospinal fluid (CSF) physiology. Sometimes the associated lesions are clearly causing the syringomyelia, such as intrinsic spinal cord or posterior fossa tumours. In these cases the prognosis is that of the tumour.

Syringomyelia is a surgical disorder, the outcome is thus related to the appropriateness of the surgery and the skill and experience of the surgeon. The following notes follow the author's classification of syringomyelia (Williams 1991).

Hindbrain-related syringomyelia

Chiari malformation, tonsillar prolapse and cerebellar ectopia are all terms which can be replaced by ‘hindbrain herniation’. This is the commonest associated lesion and the clinical picture is often dominated by the effects of the hindbrain hernia rather than the associated syringomyelia. The commonest form of syringobulbia is bulbar symptomatology related to hindbrain herniation (Morgan & Williams 1992; Williams 1993). If left alone the progression of syringobulbia is commonly fatal within 20 years or so. The pessimism of earlier authors was because it was quickly fatal cases which came to post mortem examination (Tomesco-Sisesti 1924; Schliep 1968) and thereby to a diagnosis. Such patients dominate the essentially pathological descriptions prior to the surgical era of syringomyelia management which commenced after the work of Gardner (Gardner 1973; Gardner et al. 1977).