The essential symptom is paroxysmal or continuous pain along the course of the nerve in the buttock, thigh, or leg.  It may be comparatively slight, or it may be so severe as to prevent sleep.  It is aggravated by movement, so that the patient walks lame or is obliged to lie up.  It is aggravated also by any movement which tends to put the nerve on the stretch, as in bending down to put on the shoes, such movements also causing tingling down the nerve, and sometimes numbness in the foot.  This may be demonstrated by flexing the thigh on the abdomen, the knee being kept extended; there is no pain if the same manoeuvre is repeated with the knee flexed.  The nerve is sensitive to pressure, the most tender points being its emergence from the greater sciatic foramen, the hollow between the trochanter and the ischial tuberosity, and where the common peroneal nerve winds round the neck of the fibula.  The muscles of the thigh are often wasted and are liable to twitch.

The clinical features vary a good deal in different cases; the affection is often obstinate, and may last for many weeks or even months.

In the sciatica that results from neuritis and perineuritis, there is marked tenderness on pressure due to the involvement of the nerve filaments in the sheath of the nerve, and there may be patches of cutaneous anaesthesia, loss of tendon reflexes, localised wasting of muscles, and vaso-motor and trophic changes.  The presence of the reaction of degeneration confirms the diagnosis of neuritis.  In long-standing cases the pain and discomfort may lead to a postural scoliosis (ischias-scoliotica).

Diagnosis.—­Pain referred along the course of the sciatic nerve on one side, or, as is sometimes the case, on both sides, is a symptom of tumours of the uterus, the rectum, or the pelvic bones.  It may result also from the pressure of an abscess or an aneurysm either inside the pelvis or in the buttock, and is sometimes associated with disease of the spinal medulla, such as tabes.  Gluteal fibrositis may be mistaken for sciatica.  It is also necessary to exclude such conditions as disease in the hip or sacro-iliac joint, especially tuberculous disease and arthritis deformans, before arriving at a diagnosis of sciatica.  A digital examination of the rectum or vagina is of great value in excluding intra-pelvic tumours.

Treatment is both general and local.  Any constitutional tendency, such as gout or rheumatism, must be counteracted, and indigestion, oxaluria, and constipation should receive appropriate treatment.  In acute cases the patient is confined to bed between blankets, the limb is wrapped in thermogene wool, and the knee is flexed over a pillow; in some cases relief is experienced from the use of a long splint, or slinging the leg in a Salter’s cradle.  A rubber hot-bottle may be applied over the seat of greatest pain.  The bowels should be well opened by castor oil or by calomel followed by a saline.  Salicylate of soda in full doses, or aspirin, usually proves effectual in relieving pain, but when this is very intense it may call for injections of heroin or morphin.  Potassium iodide is of benefit in chronic cases.