DILATATION OF THE CENTRAL CANAL OF THE SPINAL CORD. SYRINGOMYELIA.
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.