Aneurysm near the origin has to be diagnosed from subclavian, innominate, and aortic aneurysm, and from other swellings—­solid or fluid—­met with in the neck.  It is often difficult to determine with precision the trunk from which an aneurysm at the root of the neck originates, and not infrequently more than one vessel shares in the dilatation.  A careful consideration of the position in which the swelling first appeared, of the direction in which it has progressed, of its pressure effects, and of the condition of the pulses beyond, may help in distinguishing between aortic, innominate, carotid, and subclavian aneurysms.  Skiagraphy is also of assistance in recognising the vessel involved.

Tumours of the thyreoid, enlarged lymph glands, and fatty and sarcomatous tumours can usually be distinguished from aneurysm by the history of the swelling and by physical examination.  Cystic tumours and abscesses in the neck are sometimes more difficult to differentiate on account of the apparently expansile character of the pulsation transmitted to them.  The fact that compression of the vessel does not affect the size and tension of these fluid swellings is useful in distinguishing them from aneurysm.

Treatment.—­Digital compression of the vessel against the transverse process of the sixth cervical vertebra—­the “carotid tubercle”—­has been successfully employed in the treatment of aneurysm near the bifurcation.  Proximal ligation in the case of high aneurysms, or distal ligation in those situated at the root of the neck, is more certain.  Extirpation of the sac is probably the best method of treatment, especially in those of traumatic origin.  These operations are attended with considerable risk of hemiplegia from interference with the blood supply of the brain.

The external carotid and the cervical portion of the internal carotid are seldom the primary seat of aneurysm, although they are liable to be implicated by the upward spread of an aneurysm at the bifurcation of the common trunk.  In addition to the ordinary signs of aneurysm, the clinical manifestations are chiefly referable to pressure on the pharynx and larynx, and on the hypoglossal nerve.  Aneurysm of the internal carotid is of special importance on account of the way in which it bulges into the pharynx in the region of the tonsil, in some cases closely simulating a tonsillar abscess.  Cases are on record in which such an aneurysm has been mistaken for an abscess and incised, with disastrous results.

Aneurysmal varix may occur in the neck as a result of stabs or bullet wounds.  The communication is usually between the common carotid artery and the internal jugular vein.  The resulting interference with the cerebral circulation causes headache, giddiness, and other brain symptoms, and a persistent loud murmur is usually a source of annoyance to the patient and may be sufficient indication for operative treatment.