#Fibrositis# or “#Muscular Rheumatism#.”—­This clinical term is applied to a group of affections of which lumbago is the best-known example.  The group includes lumbago, stiff-neck, and pleurodynia—­conditions which have this in common, that sudden and severe pain is excited by movement of the affected part.  The lesion consists in inflammatory hyperplasia of the connective tissue; the new tissue differs from normal fibrous tissue in its tendency to contract, in being swollen, painful and tender on pressure, and in the fact that it can be massaged away (Stockman).  It would appear to involve mainly the fibrous tissue of muscles, although it may extend from this to aponeuroses, ligaments, periosteum, and the sheaths of nerves.  The term fibrositis was applied to it by Gowers in 1904.

In lumbago—­lumbo-sacral fibrositis—­the pain is usually located over the sacrum, the sacro-iliac joint, or the aponeurosis of the lumbar muscles on one or both sides.  The amount of tenderness varies, and so long as the patient is still he is free from pain.  The slightest attempt to alter his position, however, is attended by pain, which may be so severe as to render him helpless for the moment.  The pain is most marked on rising from the stooping or sitting posture, and may extend down the back of the hip, especially if, as is commonly the case, lumbago and gluteal fibrosis coexist.  Once a patient has suffered from lumbago, it is liable to recur, and an attack may be determined by errors of diet, changes of weather, exposure to cold or unwonted exertion.  It is met with chiefly in male adults, and is most apt to occur in those who are gouty or are the subjects of oxaluric dyspepsia.

Gluteal fibrositis usually follows exposure to wet, and affects the gluteal muscles, particularly the medius, and their aponeurotic coverings.  When the condition has lasted for some time, indurated strands or nodules can be detected on palpating the relaxed muscles.  The patient complains of persistent aching and stiffness over the buttock, and sometimes extending down the lateral aspect of the thigh.  The pain is aggravated by such movements as bring the affected muscles into action.  It is not referred to the line of the sciatic nerve, nor is there tenderness on pressing over the nerve, or sensations of tingling or numbness in the leg or foot.

If untreated, the morbid process may implicate the sheath of the sciatic nerve and cause genuine sciatic neuralgia (Llewellyn and Jones).  A similar condition may implicate the fascia lata of the thigh, or the calf muscles and their aponeuroses—­crural fibrositis.

In painful stiff-neck, or “rheumatic torticollis,” the pain is located in one side of the neck, and is excited by some inadvertent movement.  The head is held stiffly on one side as in wry-neck, the patient contracting the sterno-mastoid.  There may be tenderness over the vertebral spines or in the lines of the cervical nerves, and the sterno-mastoid may undergo atrophy.  This affection is more often met with in children.