ABDOMINAL ANEURISM includes aneurism of the aorta, and of any of its branches within the abdomen.

Aneurism of the Abdominal Aorta is essentially a disease of middle age. Of fifty-nine cases collected by Dr. Crisp, thirty-three were under the age of forty. It is more common in the male than in the female sex in the proportion of about 8 : 1; and is usually traceable to strain, or to a blow upon the abdomen or back. The aneurism is most frequently located in that portion of the vessel included between the aortic opening in the diaphragm and the origin of the superior mesenteric artery. In this situation the tumour is deeply seated; liable to tension from the crura of the diaphragm; and likely to involve the great splanchnic nerves, the semilunar ganglia, and the solar plexus. Hence the occasional difficulty of diagnosis; and the frequency of boring pain in the back from erosion of the vertebræ, and of paroxisms of radiating pain in the abdominal viscera from stretching of the adjacent nerves. When situated lower down in the course of the aorta, the disease is less obscure, and the symptoms are less urgent. Aneurism of the abdominal aorta is usually of the false variety; and, as contrasted with thoracic aneurism, it is less often associated with extensive atheroma of the aorta, and with fatty or other structural disease of the heart. The symptoms referable to excentric pressure are also fewer, and, with the exception of pain, are less urgent.

SYMPTOMS AND SIGNS.--Of the symptoms, pain is the most characteristic and the most urgent; it is of two kinds, which are not, however, necessarily associated. In its usual form the pain of abdominal aneurism is essentially neuralgic; it is intermittent and paroxysmal,--radiating through the abdomen, back, pelvis, and base of the thorax, and not unfrequently into either groin or testicle. The accession is sudden, and usually attributable to some definite cause of vascular excitement. The duration extends over a period varying from one to three hours, rarely longer; and the cessation is equally abrupt, leaving the patient in a state of exhaustion, but quite free from actual suffering. The second kind of pain referred to is continuous and boring; fixed at a particular point of the vertebral column; aggravated by pressure at this point, by active movement or stamping, and by gently turning the patient half round upon his axis in the standing posture; but relieved by anti-recumbency or leaning forward. Pain so characterised is pathognomonic of erosion of the vertebræ. Pressure of an aneurism may affect the functions of several organs within the abdomen. Thus jaundice may result from pressure upon the hepatic or common biliary duct: it is, however, more frequently due to an aneurism of the hepatic or of the superior mesenteric artery. Interference with the urinary secretion, and the consequences thereof, from pressure upon the renal vessels; dysphagia from pressure upon the oesophagus; vomiting from obstruction of the pylorus; displacement of the liver forwards, or of the heart upwards--though rare symptoms--may be likewise due to the same cause. The radial pulse is not often affected. Symptoms of constitutional irritation and impaired nutrition are rarely exhibited, and appear only at the termination of protracted and painful cases, associated with great suffering and want of sleep.

The physical signs are those discoverable by palpation, percussion, and auscultation. The tumour usually projects to the left of the mesial line, and tends to descend; it is smooth and elastic; communicating to the hand alternate movements of lifting and expansion with increasing tension, and of subsidence with relaxation. The pulsation is all but invariably single, and synchronous with the radial pulse; it is limited to the tumour, and occasionally accompanied by thrill. Pressure upon the aorta below the tumour will increase the force of impulse, diminish or abolish the thrill, and arrest the collapse. In a few recorded examples the tumour was hard and uneven on the surface, and non-expansile; and in a still smaller number no pulsation was perceptible, the aperture of communication with the artery having been blocked, or the vessel compressed on the proximal side by the growth of the aneurism itself. Owing to the position of the hollow viscera in front, and the mass of lumbar muscles behind, the evidence from percusion is less conclusive in regard to abdominal than thoracic aneurism. If, however, the abdominal muscles be relaxed, and the stomach and bowels free from flatus, absolute dulness to the extent of the tumour may be detected. A sound, single or double, as distinguished from murmur, is rarely heard in front in connexion with abdominal aneurism; whereas the existence of sound without murmur, and usually double, at a point of the posterior wall of the abdomen corresponding to the tumour, is the rule, and, when detected, is of the utmost diagnostic value. Murmur in the recumbent posture is rarely absent in front; it is single, blowing, prolonged, post-systolic, and not transmitted into the vessel beyond. It may, however, be musical, or it may present both these characters, but at different points of the tumour; in one instance it was of a buzzing quality. Should the aneurism have taken an exclusively backward course, which is the exception, a single murmur, not audible in front, may be heard in the back. In a few recorded cases a double murmur has been heard over the aneurism in front. In the erect posture the murmur is usually suspended; but in a few published cases it was audible in both the erect and the recumbent posture, and in one at least in the erect posture only. These peculiarities depend upon the various conditions of the sac, its orifice, and its contents. A small aneurism engaging the posterior wall of the vessel only, and eroding the vertebræ, may be latent as to physical signs, though attended with severe fixed pain in the back.

DIAGNOSIS.--The diagnosis of abdominal aneurism has reference mainly to its physical signs. Strong pulsation of the aorta, simulating that of aneurism, may exist in connexion with hysteria, uterine or intestinal irritation, dyspepsia, or copious hæmorrhage. But in all these cases, irrespectively of the positive and specific evidence presented by each, throbbing exists throughout the aorta, and is propagated into the main arteries of the lower limbs, whereas it is localised in aneurism; and a careful exploration of the aorta, if necessary under the influence of chloroform, will show that its dimensions are at all points normal. In these cases, too, although a murmur may be produced by strong pressure with the stethoscope, it does not exist when pressure is withdrawn. A cancerous or other tumour pressing upon the aorta may likewise produce murmur, and may exhibit pulsation communicated from the aorta; but in most cases both these phenomena are promptly arrested by placing the body in the prone position; the tumour, in that position, gravitating from the vessel. The fixed local pain in the back, aggravated by pressure and motion, may be simulated by spinal rheumatism; and the paroxysmal visceral pain by biliary colic. The differential diagnosis must rest upon the specific evidence in each case, and upon the absence of the signs of aneurism.

Aneurism of the Branches of the Abdominal Aorta.--The branches most liable to aneurism are the common iliacs and their divisions; the coeliac axis and its branches; the renal and the superior mesenteric. Aneurism of the Iliac Arteries belongs to the domain of surgery, and will not be further referred to here. Aneurism of the Coeliac Axis and of its branches of division, and of the Superior Mesenteric Artery, are, in addition to the ordinary signs, equally characterized by mobility; and the first two varieties by jaundice, hæmatemesis, and melæna, from pressure. Renal aneurism may cause obstruction in the kidney or renal colic by pressure on the structures in the hilus.

DURATION AND TERMINATION.--The duration of life in cases of abdominal aneurism has, in the writer's experience, varied from fifteen days to eleven years. Death occurs usually (1) by rupture of the sac into (a) the retro-peritoneal tissue; (b) the cavity of the peritoneum; (c) the left pleura or lung; (d) the intestinal canal; (e) the inferior cava; (f) the psoas muscle; (g) the pelvis of the kidney; (h) the spinal canal; or (i) the ureter, biliary passages, or oesophagus; and in the order of relative frequency just given; or (2) by exhaustion or syncope. The duration of life after the rupture of the aneurism has ranged from a few minutes to several weeks. A consecutive false aneurism of the retro-peritoneum is specially characterised by feeble pulsation of the tumour, and diminished or arrested circulation in the femoral artery of one or both sides.

TREATMENT.--The Curative treatment of abdominal aneurism may be considered under three heads--Mechanical, Postural and Dietetic, and Medicinal. Mechanical treatment consists in pressure applied to the aorta on the proximal side of the sac, or simultaneously on its proximal and distal sides, by means of tourniquets, so as completely to stop the circulation. The bowels should be first well moved and freed from flatus; and during the continuance of pressure the patient should be kept under the influence of chloroform or ether. Five cases, if not more, in which a cure was affected by these means have been reported. The object sought to be attained being that of effecting rapid coagulation in the sac, the period during which pressure needs to be continued in these cases varies from three quarters of an hour to ten hours and a half. Where space for the application of proximal pressure does not exist, distal pressure alone may be tried. Under all circumstances, pressure must be used with circumspection, as inflammation of the peritoneum or of the bowels may result from it.

Billingham introduced the plan of treatment by posture and restricted diet. Under this plan perfect repose of mind and body is, as far as practicable to be maintained; the bowels being kept moderately free, and the dietary restricted to 10 oz. of solids and 6 oz. of liquids daily. According to the method of Mr. Tufnell, which is based upon the same principle, but is more rigid, the patient is strictly confined to the horizontal posture for a period varying from eight to thirteen weeks, as determined by the effect upon the aneurism, movement in bed being affected with caution; whilst, by a special arrangement, the bowels and the bladder may be evacuated without disturbance of the body. For breakfast, 2 oz. of white bread and butter, with 2 oz. of cocoa or milk, are allowed; for dinner, 3 oz. of meat, with 3 oz. of potatoes or bread, and 4 oz. of water or claret; and for supper, 2 oz. of bread and butter, and 2 oz. of milk or tea. The total amount in the twenty-four hours would be, solids 10 oz., liquid 8 oz. This system might be in some degree relaxed if the patient prove restive. Mild laxatives and opiates as required are the only medicines used. Ten cases of the successful treatment of aortic aneurism by this method have been reported by Mr. Tufnell. Abdominal aneurism was solidified in two instances, after treatment extending over thirty-seven and twenty-one days respectively.

Of the various medicinal agents used with a view to favouring or affecting a deposit of laminated fibrin in the sac, acetate of lead, iodide of potassium, aconite, and ergotin (hypodermically), alone claim attention. Iodide of potassium may be given with advantage in doses of 10 to 20 grs. thrice daily, with a view to reducing vascular tension, and thereby relieving pain and promoting deposition in the sac, whilst perfect rest in the recumbent posture and a restricted dietary are observed. The latter are, however, the more important factors in the treatment. Dr. G. W. Balfour has reported several cases successfully treated by means of iodide of potassium; and recently an example of a similar kind has been published by Dr. Dyce Duckworth. Dr. Grimshaw has lately had an example of cure mainly through the use of aconite. At the same time the allowance of liquids must be reduced to the lowest possible standard, whilst excretion is promoted. Alcoholic stimulants may be given in small quantity and at long intervals, if the pulse exhibit debility and the patient complain of a sensation of sinking; otherwise they should be prohibited.

The Palliative treatment as applied to Abdominal Aneurism will be found described in the article AORTA, Disease of (Aneurism). The application of a few leeches, followed by a warm poultice, is very efficacious in relieving pain. The hypodermic use of morphia is still more rapidly effective.

--Thomas Hayden.