744 



HERNIA. 



gerous, because the existence of strangulation 

 with all its fearful sequelae may be proved, in 

 situations and under circumstances where the 

 influence of spasm or of muscular action is ob- 

 viously impossible. Thus intestines have been 

 found strangulated within the cavity of the ab- 

 domen itself, as when a fold of intestine has 

 passed through an accidental opening in the 

 mesentery or the omentum, or when artificial 

 bands or nooses have been formed by lymph, 

 the products of former inflammation. Scarpa 

 relates a very interesting case in which he 

 found that the appendix vermiformis surrounded 

 in the manner of a ring and strangulated a long 

 loop of the ileum just before its insertion into 

 the colon. 



If it be conceded that the natural openings 

 at which abdominal herniae occur are composed 

 either of tendon or of tendon and of bone, and 

 therefore are not subject to accidental variations 

 of size from irregular muscular action, it would 

 seem on a prim a facie view that wherever any 

 substance had passed out it ought to be able 

 to return, provided an equal degree of force is 

 employed with that which originally caused 

 the displacement. And this actually does take 

 place, for the hernia returns spontaneously or 

 is easily reduced as long as the original propor- 

 tion between the size of the protruded part and 

 that of the aperture remains unaltered. Again, 

 as long as this relation is maintained, the cir- 

 culation through and from the protruded viscus 

 will continue equable and healthy, but an in- 

 testine from its structure and its functions is 

 extremely liable to a change of size, and when 

 that happens, the proportion no longer exists, 

 and the hernia begins to become incarcerated. 

 If not relieved, the protruded viscus continues 

 to swell, and is thus made to form an acute 

 angle at the spot where it escaped, which 

 tightens the ring of intestine immediately at 

 the neck of the sac : the return of the venous 

 blood is thus prevented; the swelling then 

 increases until not even gas can pass through, 

 and then strangulation is complete. In this 

 way a number of circumstances connected with 

 hernia can be explained. If the ring is small, 

 a very trifling change of size in the protruded 

 part will be sufficient to cause strangulation : 

 hence crural hernia is more liable than inguinal, 

 and very recent ruptures in which the ring is of 

 its natural size than those of long standing, in 

 which that aperture is probably enlarged. 

 Persons who are formed with large rings, and 

 thus possess an hereditary disposition to hernia, 

 are less liable to strangulation : this may ex- 

 plain Pott's remark that " if the hernia be of 

 the intestinal kind merely, and the portion of 

 the gut be small, the risk is the greater, stran- 

 gulation being more likely to happen in this 

 case ;" for assuredly if the ring is so small as to 

 ]>ermit only the escape of a knuckle of intestine, 

 a very trifling change in the latter will be suffi- 

 cient to establish a disproportion between 

 them. Again, if a hernia has come down, and 

 been reduced, and kept up until the neck of 

 the sac has been diminished in size, and if 

 afterwards a protrusion takes place, a very 

 trifling alteration in this latter will render it 



incapable of return, and explain why such her- 

 niae are so frequently strangulated at the neck 

 of the sac. Hence it appears that a straitness 

 or tightness at one of the rings may be a predis- 

 posing cause of strangulation, that is, may be 

 a reason why one hernia should become sooner 

 strangulated than another, but the immediate 

 or efficient cause is a change in the condition 

 of the viscus itself. Thus when a loop of in- 

 testine is gangrened, and its contents have 

 escaped totally or partially into the sac, the 

 hernia often returns spontaneously, the parts in 

 the immediate neighbourhood of the ring re- 

 maining unaltered. Also if such a hernia is 

 the subject of operation, there is no necessity 

 for dilating the seat of the stricture : indeed 

 Louis forbids the practice lest some essential 

 point of adhesion should be destroyed. " Di- 

 latation," says he, " is only recommended in 

 order to facilitate the reduction of the strictured 

 parts. In the gangrened intestine there is no 

 reduction to make, and there is no longer 

 strangulation, the opening in the intestines 

 having removed the disproportion that had 

 existed between the diameter of the ring and 

 the volume which the parts had acquired; and 

 the free passage of the excrement which the 

 sphacelus has permitted removes every symptom 

 that depends on the strangulation."* In like 

 manner may be understood why omental her- 

 niae are less liable to become strangulated, be- 

 cause this structure is not subject to any sud- 

 den change of shape or increase of volume : 

 when it does occur, the progress of the disease 

 is more slow, and the symptoms are said to be 

 less severe. 



The division of herniae into the incarcerated 

 and strangulated, or into the acute and chronic 

 forms of strangulation, however practically 

 valuable if it inculcates a different mode of 

 treatment for these affections, is yet pathologi- 

 cally incorrect if it supposes any analogy be- 

 tween them and the acute and chronic species 

 of inflammation. An incarcerated hernia is 

 not strangulated ; it is really in a condition re- 

 sembling irreducibility. I have before stated 

 that in large and old hernias the neck of the sac 

 generally becomes enlarged, and of course such 

 a change of dimensions in the protruded viscera 

 as is necessary to cause their strangulation will 

 be proportionally less likely to occur. But 

 hard and unwholesome and indigestible sub- 

 stances may gain admission into some of them 

 and lodge there, for it must be recollected that 

 the process of digestion cannot be very favora- 

 bly carried on in intestines thus protruded, 

 placed in positions that will render it necessary 

 that their contents must ascend against the in- 

 fluence of their own gravity, and deprived of 

 the salutary pressure exercised by the walls of 

 the abdomen on the viscera within it. If such 

 a lodgment is formed, it will be the cause of 

 future accumulation, and may occasion a deter- 

 mination of blood to the part or even inflam- 

 mation within it, thus gradually increasing its 

 volume and leading it to a state that must end 

 in strangulation. Undoubtedly, if the dura- 



* Mem. de 1'Acad. Roy. de Chir. torn. viii. p. 45. 



