Consequently, when the pain is occasioned by it, it is felt along the lower jaw on the one side, in the teeth and chin, and a tender point may be in front over the place of exit of the nerve. The slightest pressure of the jaw, as in chew ing, will, in some cases, produce excruciating pain. Thus this branch may be irritated by a decayed tooth, and if • the irritation be severe the whole branch may be involved, and the irrita tion may even spread backwards from it to the other branches till the whole nerve is affected.
Treatment for tic naturally consists in re moving the bad tooth, the disease of the ear, &c., if such exists. Besides the treatment men tioned for neuralgia generally, the application of aconite ointment to a small part of the sur face, the use of warm applications and of blisters, and the employment of a constant current of electricity over the affected nerve are all use ful. Very often, if a medical man be at hand to administer it, the injection under the skin of hth of a grain of morphia will relieve in a few minutes.
Sciatica is neuralgia of the sciatic nerve, which passes down the back of the thigh to the knee (p. 153). It is often very acute and persistent, resisting all remedies. Any of the causes already noted, as producing inflammation of nerves and neuralgia, may operate on the sciatic nerve and occasion sciatica. In addition, it must be noted that the sciatic nerve arises in the pelvis, and passes out of it into the thigh through an opening in the bony wall of the pelvis. In the pelvis, where it arises, it may be pressed upon or irritated, for instance by accumulations in the bowel, by abscesses or growths in its neighbourhood ; it may be in volved in inflammations occurring in its neigh bourhood; and tubercular disease of the bony notch through which it passes may extend to it. It can, therefore, be easily understood how a persistent case of sciatica may require most careful, patient, and elaborate investigation to determine its exact cause and seat of production, and how it may frequently be exceedingly difficult to get at the place where the mischief arises. While this is so, it is equally true that the most frequent cause of sciatica is a gouty or rheumatic inflammation of the sheath, which surrounds the nerve, in some part of its course.
Treatment to be satisfactory must have regard to the cause and the place where it is operating.
In the rheumatic and gouty cases full doses of some anti-rheumatic remedy like salicine, salol, aspirin, iodide of potassium, or anti-gouty remedies like lithia, carbonate of potash, thialion, piperazine, aided when necessary by morphia, will obtain relief. When the acute stage is
over, massage, electricity, and treatment at sulphur spas like Harrowgate, Strathpeffer, Aix-la-Chapelle, &c., are frequently necessary to remove thickenings and adhesions in the nerve sheath, which maintain pain and cripple the patient.
Injuries of nerves are common. A wound may completely divide a nerve ; a dislocated bone may so compress it as practically to de stroy a portion of it; and a fractured bone may seriously tear it. If a nerve has been severed, or so injured that it is destroyed as a continuous structure, then it is evident that paralysis of sensation or motion will be pro duced in the part which it supplied, according as it was a motor or sensory nerve. If, how ever, the cut ends are brought together, they will unite, and in time sensation and motion may return. The earliest such a result could be expected is from three to four weeks. On the other hand, the nerve may be so injured that it is impossible for restoration to be accom plished. In such a case the power of move• went will be lost in the muscles to which it proceeded. Further, the muscles will wash/ and decay, and may contract spasmodically, and so produce deformity. If the nerve has beau one of sensation, then degenerative changes will be set up in the region of skin which it supplied, and the skin become blistered, or ulcerated, or covered with eruptions, whila numbness will pervade the region. Severe pain and inflammation may also be produced.
The treatment of such injuries is so depen dent on their character that medical aid can hardly be dispensed with. It need only be mentioned that shampooing paralysed muscles, and the use of electricity, will delay decay and its more serious results for a considerable time, while morphia injected under the skin will re lieve pain.
Of course proper treatment of fractures and dislocations from the moment of their occurrence will do much to prevent such evils, by guarding the nerves and other structures from injury after the accident in the way described on page 79; while the accurate bringing together of the edges of a wound, and keeping them together, is as necessary for union of cut nerves as for other tissues. (See WOUNDS.)