With respect to the diagnosis of pleurisy, it may be distinguished from hepatitis, says Paulus 11::gieeta, by the pain in pleurisy being pun gent, and the cough being sometimea without expectoration and some times with it, and by the pulse being hard and serrated; while in inflammation of the liver the pain is not pungent, nor is the pulse so hard, and the cough throughout is dry and without expectoration, and the face appears pale. (Compare Alex. Trail., loco cit.) It may be distinguished from inflammation of the external muscles, or 'deur°.
dynia [PLEERODYNIAL by the latter affection being (accenting to the same author) unaccompanied with cough and expectoration, nor is the pulse hard. Front pneumonia it is hard to distinguish it without calling in the aid of auscultation and percussion ; and indeed Dr.
Cullen, in his' Practice of I'llyeic; has treated of both these attixtione under one common definition. It may however be observed (with Dr. Good) that in pleurisy the face is comparatively but little flushed, and far less tumid than in pneumonia; that the pulse is harder, and that the seat of the pain is fixed, while in pneumonia it shifts not only to different parts of the same side, but often from the one side to the other. The characteristic cough of pleurisy (as distinguished from that which follows pneumonia) is a short cough, either dry from the beginning to the end, or aocompanied with a thin mucous expecto ration ; should the sputa be more abundant, or deviate from this character, we may suspect a complication either of pneumonia or bronchitis. The cough, however (adds Dr. Law), is often wanting altogether, or is so slight as to attract the attention of neither the patient nor physician. For the characteristic signs of pneumonia derived from nuscultation and percumiona the reader must see the article LUNGS, DISEASE OP TUE, while only those relating to pleurisy will be given here. Upon auscultation, the inspiration will appear feeble, distant, or inaudible, but will be restored by change of posture.
..Egophony will exist when the quantity of fluid diluted is no more than forme a thin layer between the lungs and parietes of the chest. The trait tic frotleonenl, or sound of friction, will be heard when there is partial nibuininotie exudation, with little or no effusion of serum. Upon percussion, there will be more or less of sound, with moderate resistance, decreasing from below upwards; and this dulness will be diminished or removed by change of position. It was in cases of
pleuritic effusion that Hippocrates proposed the auccussion, or shaking of tho chest, as a means of assisting the diagnosis (' 1)e )fort.; lib. i., p. 178, ed. Kuhn ; ibid., lib. ii., pp. 250, 258; Conc. l'nenot.; p. 300.; De Loc. in Horn.,' pp. 123,124) ; but it is now known that no sound can be heard unless air be present in the chest at the same time—that is, unless empyema be combined with pncumo-thorax, which is a rare occurrence.
With respect to the anatomical characters of pleurisy, they agree with what may be observed in inflammation of all serous membranes, and consist partly in morbid alterations of the pleura itself, and partly of the secreted fluid. Inflammation of the pleura, says Laennec, is always accompanied by an extravasation ou its internal surface ; the matter effused being either coagulating lymph termed a false membrane, or else aerosity, or a sero-purulent fluid. The false membrane, or exudation of lymph, is gradually changed into cellular substance, or rather into a true serous tissue, like that of the pleura. The serous effusion is absorbed, the compressed lung expands, and the false mem brane investing it and the pleura costalis become united into one substance, which afterwards becomes vascular and organised, and constitutes permanent adhesions. A severe pleurisy that has termi nated by numerous adhesions, renders the part so affected much less liable to subsequent attacks of the same disease ; and when it occurs, the inflammation and effusion do not extend to the adherent parts.
Among the occasional causes of pleurisy, enumerated by Laennec (after Celsus), are,—long exposure to cold after violent exercise; metas tasis of gout, rheumatism, and cutaneous diseases ; blows ou the chest; and fracture of the ribs. " The winter season," says dretieus, " is most liable to produce this disease, and next to it the autumn; the spring is less so, unless it chance to be a cold one, while the summer is the least so of all." In reference to the period of life, he remarks that old people are more liable to it than those who are in the prime of life, and these again than children. Among predisposing causes, Laennec mentions a slender frame, narrowness of the chest, the immoderate use of spirits, and tubercles in the lungs.