368 THE EAR nights following operation, or if the sinus wall should appear greyish-yellow or brownish-green and slough-like at the first or subsequent operations. Before opening, the sinus plate is removed to expose the healthy sinus wall above and below the diseased area. Gauze packing is inserted between the sinus and bone in an attempt to shut off the flow of blood, and the sinus is slit open and the clot evacuated. In most cases there is free bleeding in spite of the pack, and a BIPP pack should be introduced into the lumen of the sinus to check the haemorrhage. Some surgeons like to tie off the internal jugular vein in the neck at the same operation, but if this is not done routinely it is called for if the case does not settle down after the initial surgery, or if there is evidence of blood-borne infection. Septic thrombosis occasionally follows accidental injury to the sinus during mastoid operations. Injury to the wall should be treated by the application of a postage-stamp graft of fascia from the mastoid cortex, or a piece of temporalis muscle should be cut off and applied. This usually arrests the bleeding, and very often there is no further trouble. Should rigors occur postoperatively the case is treated as a sinus thrombosis. OTITIC HYDROCEPHALUS This condition may be caused by thrombosis occurring in a dural blood sinus, and the symptoms produced are considered to be due to poor absorp- tion of the cerebrospinal fluid by the arachnoid villi secondary to a choke in one of the dural sinuses, especially the sigmoid sinus. Severe headache, which may be intermittent but very intense, is a prominent symptom and it may be accompanied by vomiting. There is a variable nystagmus, incon- stant in direction, and papilloedema is frequently present while occasionally there is involvement of the abducent nerve on the homolateral side of the ear infection. The pressure of the cerebrospinal fluid is raised to 300 mm or more, but examination shows a normal cytology. On ventriculography the ventricles show no variation in size but intraventricular pressure may be raised. Treatment is by anticoagulant therapy given in the hope of pre- venting further thrombosis, and by frequent ventricular or lumbar punctures to relieve the pressure of the cerebrospinal fluid. The therapy may require to be continued for some time as the condition tends to persist for a month or longer.