Treatment.—­If the tumour causes suffering it should be removed, preferably by shelling it out from the investing nerve sheath or capsule.  In the subcutaneous nodule the nerve is rarely recognisable, and is usually sacrificed.  When removal of the tumour is incomplete, a tube of radium should be inserted into the cavity, to prevent recurrence of the tumour in a malignant form.

The malignant neuroma is a sarcoma growing from the sheath of a nerve.  It has the same characters and clinical features as the innocent variety, only it grows more rapidly, and by destroying the nerve fibres causes motor symptoms—­jerkings followed by paralysis.  The sarcoma tends to spread along the lymph spaces in the long axis of the nerve, as well as to implicate the surrounding tissues, and it is liable to give rise to secondary growths.  The malignant neuroma is met with chiefly in the sciatic and other large nerves of the limbs.

The treatment is conducted on the same lines as sarcoma in other situations; the insertion of a tube of radium after removal of the tumour diminishes the tendency to recurrence; a portion of the nerve-trunk being sacrificed, means must be taken to bridge the gap.  In inoperable cases it may be possible to relieve pain by excising a portion of the nerve above the tumour, or, when this is impracticable, by resecting the posterior nerve roots and their ganglia within the vertebral canal.

The so-called amputation neuroma has already been referred to (p. 344).

Diffuse or Generalised Neuro-Fibromatosis—­Recklinghausen’s Disease.—­These terms are now used to include what were formerly known as “multiple neuromata,” as well as certain other overgrowths related to nerves.  The essential lesion is an overgrowth of the endoneural connective tissue throughout the nerves of both the cerebro-spinal and sympathetic systems.  The nerves are diffusely and unequally thickened, so that small twigs may become enlarged to the size of the median, while at irregular intervals along their course the connective-tissue overgrowth is exaggerated so as to form tumour-like swellings similar to the trunk-neuroma already described.  The tumours, which vary greatly in size and number—­as many as a thousand have been counted in one case—­are enclosed in a capsule derived from the perineurium.  The fibromatosis may also affect the cranial nerves, the ganglia on the posterior nerve roots, the nerves within the vertebral canal, and the sympathetic nerves and ganglia, as well as the continuations of the motor nerves within the muscles.  The nerve fibres, although mechanically displaced and dissociated by the overgrown endoneurium, undergo no structural change except when compressed in passing through a bony canal.