Hydrocephalus Types of hydrocephalus in the postoperative period include a loculated ventricle, communicating or noncommunicating A loculated (“trapped”) ventricle may cause symptoms resembling those caused by focal, expanding mass lesions A loculated ventricle occurs when the drainage pathway from one lateral ventricle into the third ventricle is blocked This blockage typically results from unilateral IVH or from a midline shift Diagnosis is confirmed with CT and must be followed by permanent drainage of the loculus The treatment of choice is emergent ventriculostomy and placement of a shunt The most common cause of communicating hydrocephalus is the blockage of absorption pathways by subarachnoid blood A CT scan shows universal dilation of all ventricles Lumbar puncture may demonstrate an elevated opening pressure Serial lumbar punctures may be performed as a temporizing measure to diagnose and treat communicating hydrocephalus If the patient’s neurologic condition improves after lumbar puncture, definitive treatment by shunting may be required Any lesion that causes an obstruction at the narrow fourth ventricular inflow or outflow track can create noncommunicating or obstructive hydrocephalus Obstructive hydrocephalus is commonly associated with lesions of the posterior fossa and is a dreaded complication of surgical procedures to this area of the brain Such lesions include cerebellar edema, infarct, or an intraventricular blood clot in the fourth ventricle Patients with a noncommunicating hydrocephalus can never be safely treated with lumbar puncture, because the pressure gradient created by this procedure places the patient at risk of tonsillar herniation and sudden death The patient may be temporarily stabilized with a ventriculostomy to provide decompression by draining CSF out of the intracranial cavity Permanent shunt placement is the definitive treatment for obstructive or noncommunicating hydrocephalus Infection Meningitis Meningitis may occur as late as weeks after surgery because of violation of mastoid air cells in the face of a CSF leak Unfortunately, after craniotomy the patient may normally exhibit all of the clinical signs of