PLEURISY, or inflammation of the investing membrane of the lung, is one of the most serious diseases of the chest. It is very often, but by no means invariably, associated with inflammation of the substance of the lung, commonly known as mien omit, (q.v.). Pleurisy without pneumonia is much more common than pneumonia without pleurisy. When both are present, but pneumonia preponderates, the correct term for the' affection is plot rn-pueumonia, although it is frequently spoken of simply as pneumonia. probably in consequence of the remedies being applied mainly to it, as the more important of the two elements in the compound malady.
The pleura being a serous membrane, its inflammation is attended with the same course of events as have been already described in our remarks on the two allied diseases, pericarditis and peritonitis. The inflammation is of the adhesive kind, and is accom panied by pain, and by the effusion of serum, of fibrinous exudation (the raagulable lymph of the older writers), or of pus, into the pleural cavity. In consequence of the anatomical relations of the pleura—one part of the membrane (the parietal) lining the firm walls of the chest, while the other part (the visceral) envelops the soft and compres-' sible lung; and these opposed surfaces being freely movable on One another—it follows that very different effects may be produced by its inflammation. For example, the visceral layer may be glued to the parietal layer, so as to prevent all gliding movement between them, and to obliterate the pleural cavity (similarly to what often happens in pericarditis, q.v.); or the two surfaces which are naturally in contact, may be abnormally separated by an infusion of scrum between them; or from a combination of these results. the opposite surfaces of the pleurre may be abnormally united. at some points, and abnormally separated at others.
The general symptoms of pleurisy are rigors, pain in the side, fever, difficulty and rapii;ity of breathing. cough, and an impossibility of assuming certain positions: and of these the most marked is the pain or stitch in the side, the point de ci;M of the French writers. From the prominence of this pain, which occupies a single spot, and is of sharp. stabbing character, the Latin writers term pleurisy morbvs /Week This spot is usually about the center of the mamma of the affected side, or just below it; but the pain should be usually restricted to that one small spot, when the inflamma tion pervades a considerable extent of surface, is a question that has never received any satisfactory answer. The pain is. however, occasionally felt it, other parts—as in the
shoulders, in the hollow of the armpit, beneath the collar-bone, along the breast-bone, etc. Cruveilhier observes that the pain sometimes affects the loins, tied simulates lum bago; while Andra' and Dr. Watson have directed attention to the fact that the pain often affects the hypoehondrimn, and may be readily mistaken for a symplon of peri tonitis, or Of occurring on the right side) of hepatitis. The pain is increased by ilercutii sion. by pressure between the ribs, 1). p inspiration, by cough, etc.; and the patient Ilhe is often observed to suppress it natural to cough, or never to draw more than a short and imperfect inspiration The cough is not invariably present, although it is an ordi nary symptom. It is small, suppressed as far as possible by the patient, and is either dry, or accompanied by the expectoration of slight catarrh. If much frothy mucus is brought up, it is a sign that bronchitis (q.v.) is also present, and the appearance of rust colored sputa indicates the co existence of pneumonia. Although the ahove-named symptoms, especially when most of them occur together, afford almost certain evidence of the existence of pleurisy. yet to the physician the physical signs are still more valu able, especially those furnish ed.by percussion and auscultation.
Pleurisy far more commonly arises from exposure to cold than from any other cause, especially if a poisoned condition of the blood, predisposing to inflammation of the serous membrane, is present; but it may be occasioned by mechanical violence (as by a penetrat ing wound of the thorax by the splintered ends of a broken rib, etc.), or by the acci dental extension of disease from adjacent parts. The disease may terminate in resolu tion and complete recovery; or in adhesion, which often only causes slight embarrass ment of preathing: or it may end with such a retraction of one side of the chest as to ren der the corresponding lung almost or totally useless: or it may cause death either directly by actual suffocation, if the effusion is very copious, and is not removed by tapping; or indirectly, by exhaustion. It is seldom, however, that simple pleurisy proves fatal.