#Intracranial aneurysm# involves the internal carotid and its branches, or the basilar artery, and appears to be more frequently associated with syphilis and with valvular disease of the heart than are external aneurysms.  It gives rise to symptoms similar to those of other intracranial tumours, and there is sometimes a loud murmur.  It usually proves fatal by rupture, and intracranial haemorrhage.  The treatment is to ligate the common carotid or the vertebral artery in the neck, according to the seat of the aneurysm.

#Orbital Aneurysm.#—­The term pulsating exophthalmos is employed to embrace a number of pathological conditions, including aneurysm, in which the chief symptoms are pulsation in the orbit and protrusion of the eyeball.  There may be, in addition, congestion and oedema of the eyelids, and a distinct thrill and murmur, which can be controlled by compression of the common carotid in the neck.  Varying degrees of ocular paralysis and of interference with vision may also be present.

These symptoms are due, in the majority of cases, to an aneurysmal varix of the internal carotid artery and cavernous sinus, which is often traumatic in origin, being produced either by fracture of the base of the skull or by a punctured wound of the orbit.  In other cases they are due to aneurysm of the ophthalmic artery, to thrombosis of the cavernous sinus, and, in rare instances, to cirsoid aneurysm.

If compression of the common carotid is found to arrest the pulsation, ligation of this vessel is indicated.

#Subclavian Aneurysm.#—­Subclavian aneurysm is usually met with in men who follow occupations involving constant use of the shoulder—­for example, dock-porters and coal-heavers.  It is more common on the right side.

The aneurysm usually springs from the third part of the artery, and appears as a tense, rounded, pulsatile swelling just above the clavicle and to the outer side of the sterno-mastoid muscle.  It occasionally extends towards the thorax, where it may become adherent to the pleura.  The radial pulse on the same side is small and delayed.  Congestion and oedema of the arm, with pain, numbness, and muscular weakness, may result from pressure on the veins and nerves as they pass under the clavicle; and pressure on the phrenic nerve may induce hiccough.  The aneurysm is of slow growth, and occasionally undergoes spontaneous cure.

The conditions most likely to be mistaken for it are a soft, rapidly growing sarcoma, and a normal artery raised on a cervical rib.

On account of the relations of the artery and of its branches, treatment is attended with greater difficulty and danger in subclavian than in almost any other form of external aneurysm.  The available operative measures are proximal ligation of the innominate, and distal ligation.  In some cases it has been found necessary to combine distal ligation with amputation at the shoulder-joint, to prevent the collateral circulation maintaining the flow through the aneurysm.  Matas’ operation has been successfully performed by Hogarth Pringle.