Infections although more frequently in the latter. The local inflammation in the

wall of the sinus results in thrombus formation which can spread to involve the

whole lumen. In untreated or rapidly developing cases the thrombus may extend in

either direction to involve the superior petrosal sinus (rare), cavernous sinus

(rare), jugular bulb (common) or the internal jugular vein (rare). The thrombus

tends to stop where two vessels meet. If the thrombus becomes infected an

abscess can develop and this may result in pieces of infected clot breaking away

and being carried to other parts of the body.

A pyaemia therefore occurs and abscesses are set up in the lungs and other

organs. If the infection breaches the medial wall of the sinus, meningitis,

subdural abscess or brain abscess can develop.

CLINICAL FEATURES. Sinus thrombosis may run its course without symptoms,

particularly where antibiotics have been used, and be found later at a

definitive operation for the underlying chronic otitis media. The classical

presentation, now rarely seen, consists of the occurrence of chilly sensations

or rigors in which the temperature rises suddenly to 39,5 or 40oC and falls

again as rapidly, the fall being accompanied by profuse sweating. There may be

only one rigor daily, usually in the afternoon or evening, or several. There is

a concomitant rise in the pulse rate. A high evening temperature for several

days after a mastoid operation calls for exploration of the sinus. In the

Intervals between the rigors the patient is free from symptoms, although in

advanced cases there is persistent pyrexia. Headache and vomiting occasionally

occur, the tongue is dry, there may be herpes on the lips, an enlarged spleen

and a congested optic disc. Lumbar puncture, which should only be done if a

brain abscess can be excluded, may demonstrate raised cerebrospinal fluid

pressure, particularly when complete occlusion is present. In such cases the

Tobey-Ayer test is positive. This consists of compressing the jugular vein of

the normal side which causes a rise of cerebrospinal fluid pressure in the

manometer connected to the lumbar puncture needle, while compression of the vein

on the affected side produces little or no rise in pressure. Occasionally oedema

is present in the neighbourhood of the mastoid emissary vein (Griesinger's

sign).

If the thrombosis extends into the neck torticollis may develop, and there may

be tenderness over the line of the jugular vein. Occasionally a cavernous sinus

thrombosis can occur. As a result of escape of portions of the clot into the

general circulation pneumonia or lung abscess may arise. If the particles are

small, metastatic abscesses may appear in other parts of the body, especially in

the subcutaneous tissues or in the bones and joints.

DIAGNOSIS. The conditions with which sinus thrombosis is most likely to be

confused are malaria, typhoid fever, bronchopneumonia and erysipelas. The

diagnosis of sinus thrombosis is suggested by the occurrence of rigors in the

course of middle-ear suppuration; it is more difficult if the condition is

complicated by the presence of meningitis or brain abscess, both of which must

be treated first. Examination of the peripheral blood will show a

polymorphonuclear leucocytosis. In severe infections a falling haemoglobin can

occur. Blood cultures are rarely of value.

TREATMENT. Early energetic antibiotic and anticoagulant therapy often makes

operative treatment unnecessary. The same antibiotic regime as for labyrinthitis