(Mr. J. W. Dowden’s case.)]

The treatment is conducted on the same lines as for naevus.  When electrolysis is employed, it should be directed towards the afferent vessels; and if it fails to arrest the flow through these, it is useless to persist with it.  In some cases ligation of the afferent vessels has been successful.

#Arterial Angioma# or #Cirsoid Aneurysm#.—­This is composed of the enlarged branches of an arterial trunk.  It originates in the smaller branches of an artery—­usually the temporal—­and may spread to the main trunk, and may even involve branches of other trunks with which the affected artery anastomoses.

The condition is probably congenital in origin, though its appearance is frequently preceded by an injury.  It almost invariably occurs in the scalp, and is usually met with in adolescent young adults.

The affected vessels slowly increase in size, and become tortuous, with narrowings and dilatations here and there.  Grooves and gutters are frequently found in the bone underlying the dilated vessels.

There is a constant loud bruit in the tumour, which greatly troubles the patient and may interfere with sleep.  There is no tendency either to natural cure or to rupture, but severe and even fatal haemorrhage may follow a wound of the dilated vessels.

[Illustration:  FIG. 70.—­Cirsoid Aneurysm of Orbit and Face, which developed after a blow on the Orbit with a cricket ball.

(From a photograph lent by Sir Montagu Cotterill.)]

The condition may be treated by excision or by electrolysis.  In excision the haemorrhage is controlled by an elastic tourniquet applied horizontally round the head, or by ligation of the feeding trunks.  In large tumours the bleeding is formidable.  In many cases electrolysis is to be preferred, and is performed in the same way as for naevus.  The positive pole is placed in the centre of the tumour, while the negative is introduced into the main affluents one after another.

ANEURYSM

An aneurysm is a sac communicating with an artery, and containing fluid or coagulated blood.

Two types are met with—­the pathological and the traumatic.  It is convenient to describe in this section also certain conditions in which there is an abnormal communication between an artery and a vein—­arterio-venous aneurysm.

PATHOLOGICAL ANEURYSM

In this class are included such dilatations as result from weakening of the arterial coats, combined, in most cases, with a loss of elasticity in the walls and increase in the arterial tension due to arterio-sclerosis.  In some cases the vessel wall is softened by arteritis—­especially the embolic form—­so that it yields before the pressure of the blood.