RAISED INTRACRANIAL PRESSURE

    DEFINITION

    Raised intracranial pressure is defined as an intracranial pressure
    greater than 20 cm of cerebrospinal fluid. This may form part of the
    syndrome known as Benign Intracranial Hypertension or be due to
    cerebral oedema.

    TOXIC CAUSES

     Benign Intracranial Hypertension 
    Ampicillin
    Lead (especially in children)
    Lithium
    Metronidazole
    Nalidixic Acid
    Nitrofurantoin
    Oral contraceptives 
    Tetracycline.
    Vitamin A

     Cerebral oedema 
    Most often secondary to cerebral hypoxia.  

    Other toxic causes include:
         Cellular hypoxic damage (carbon monoxide, hydrogen sulfide)
         Ethylene glycol
         Insulin
         Glutethimide
         Methanol
         Oral hypoglycaemic agents.
         Valproic acid

    NON-TOXIC CAUSES

     Benign Intracranial Hypertension 
    Hypovitaminosis A
    Idiopathic
    Dural sinus thrombosis

     Cerebral oedema 
    Central nervous system infection
    Cerebrovascular accidents
    Head trauma
    Space-occupying lesions  

    CLINICAL FEATURES

    Altered mental state, headache, nausea, vomiting, diplopia, blurred
    vision (papilloedema), blindness.  In cerebral oedema, a progression
    of these features is seen, including loss of consciousness, systolic
    hypertension, bradycardia, convulsions and, in severe cases, cerebral
    herniation.  

    RELEVANT INVESTIGATIONS

    Analytical toxicology, especially blood lead concentration. 
    Acid-base status.
    Liver function tests, including prothrombin time.
    CT scan head.

    TREATMENT

     Furosemide 40 mg intravenously and/or  mannitol 0.5 to 1 g/kg
    intravenously may be used to lower raised intracranial pressure.  

    In those who require intubation, adequate ventilation and, in some
    cases, hyperventilation.  

    CLINICAL COURSE AND MONITORING

    Vital signs
    Fluid and electrolyte balance
    Neurological status
    Intracranial pressure monitoring, where appropriate.
    Repeat CT scan of head, where appropriate.

    LONG-TERM COMPLICATIONS

    Benign intracranial hypertension may sometimes be accompanied by
    long-term visual impairment.  
    In patients with cerebral oedema, the long-term outlook is that of the
    underlying condition.

    AUTHOR(S)/REVIEWERS

    Authors:       Drs Sonia Gonzàlez and Luis C. Heuh, CIAT, Montevideo,
                   Uruguay.

    Peer Review:   Cardiff  9/96:  L. Lubomirov, T. Meredith, A. Nantel,
                   H. Persson, K. Venter.