For a large number of neuromas no cause can be assigned, and we must at present consider them as originating spontaneously.
SYMPTOMS.—The position and connections of neuromas being so different, sometimes simply in contact with the nerve; sometimes situated in the thickness of the nerve-trunk, the fibres being pressed aside and spread out upon the surface of the tumor; sometimes involving in their tissue a part or the whole of the nerve-fibres,—we cannot but expect a very marked difference in their clinical history. Not a few cases occur in which the presence of neuromas, even in large numbers, gives rise to no symptoms during life, and their existence has been revealed only upon a post-mortem examination.
The symptom most common to neuromas, and one to be expected from their mechanical interference with the nerves, is neuralgic pain—sometimes extreme, local or shooting along the course of the nerves, stubborn, and hardly to be alleviated by remedies. It is paroxysmal, notwithstanding the unvarying character of its cause, in consonance with the tendency to periodical activity which prevails in the nervous system. Sometimes the pain is increased notably by atmospheric changes. The pain may sometimes be arrested by firm pressure upon the nerve above the seat of the tumor. In some cases pressure upon the neuroma, or even handling it, causes great pain. The intensity of the pain does not depend upon the size of the tumor, some of the smallest having earned the appropriate name of tubercula dolorosa. The continued irritation of a neuroma sometimes produces a condition of general nervous excitability, which shows itself in hysterical and even in true epileptic convulsions. Occasionally there are abnormal sensations (paræsthesiæ), formication, numbness, etc., in the distribution of the nerve affected, and when from pressure or histological changes the fibres are destroyed anæsthesia results.
The interference with the conductivity of the motor fibres, which occurs less frequently than alterations of sensation, shows itself in cramps, tumors, paresis, and paralysis, according to its degree.
Neuromas may destroy life by the continued excessive pain, which wears down the strength and depresses the vitality. Death may be caused by their peculiar situation; as, for instance, upon the cauda equina, where they produce paraplegia, paralysis of the sphincter and bladder, and trophic changes.
The DIAGNOSIS of neuromas can only be made when they are sufficiently superficial to be recognized by the touch, and along with the symptoms above detailed the tumor is situated upon the known course of a nerve, to which, moreover, its attachment allows a lateral movement.
The only TREATMENT available for neuromas is extirpation, which must be conducted with a view to sparing any fibres of the nerve not involved in the tumor. Where it is necessary to divide the nerve in the removal of the tumor, as small a portion as possible must be excised, with the hope of a regeneration and reuniting of the cut ends. The success of extirpation depends largely upon the nature of the neuroma. The true neuromas, while they often show a strong tendency to recur after removal, are benign and show no metastasis. For the false neuromas the prognosis will be in accordance with their benign or malignant character.