This means literally a cavity in the spinal cord but is applied to
cavities formed by dilatation of the central spinal canal, or by an
excavation in the nervous tissue immediately adjacent and usually
communicating with a dilated segment of the canal. In man it is usually
the result of an active proliferation of the epithelial cells of the
canal, blocking the same, or extending into the adjacent nervous tissue
in the form of a glioma. In different cases in dogs it occurred as the
result of pressure. It has been seen in dogs, cats and Guinea pigs, as a
casual lesion and as the result of experiment.
In a case reported by Lienaux it extended for practically the whole
length of the cord, varying in form and size at different points. In the
lumbar portion it was only slightly dilated, in the dorsal it was very
irregular with prolongations into the gray matter, toward the cervical
enlargement, its transverse section resembled an inverted V, and in the
anterior cervical part it was unevenly rounded. Notable changes were
cell proliferation and subsequent degeneration with the formation of
cavities, thickening of the neuroglia, and compression and even
obliteration of the vessels with circumscribed areas of necrosis,
terminating also in cavity formation.
_Symptoms._ These vary with the nervous structures invaded, atrophied or
destroyed. Invasion of the anterior horns of gray matter, causes
trembling and muscular wasting. The implication of the superior horns
determines more or less marked anæsthesia. Hyperæsthesia, spasms,
paresis and paraplegia are also seen but no symptom nor group of
symptoms is diagnostic of the exact lesion.
_Treatment_ is manifestly hopeless.