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Elevated Intracranial Pressure (ICP) and Hydrocephalus

Madelaine Behrens

Background

  • Communicating hydrocephalus (i.e. non-obstructive)

    • Causes: subarachnoid granule scarring after subarachnoid hemorrhage or meningitis (Cryptococcal), ependymoma producing excess CSF, venous sinus thrombosis
    • Safe to perform lumbar puncture

  • Non-communicating/Obstructive Hydrocephalus

    • Causes: tumor, abscess, or hematoma in the midline ventricular structures
    • Avoid lumbar punctures due to risk of herniation

  • Eventually, elevated ICP will cause brain herniation

Presentation

  • Headache (can be positional), blurred vision, visual field reduction, enlarged blind spot, nausea, vomiting, encephalopathy, syncope, coma

  • Sixth nerve palsies are common (inability for eye to look towards ipsilateral side)

  • Third nerve palsies (blown pupil) are classically associated with uncal herniation

Evaluation

  • Visual exam: visual fields, enlarged blind spot, papilledema (may not be present if very rapid ICP increase, even with vision loss), and CN6 nerve palsies

  • STAT head CT to look for midline shift, obstructions, and mass lesions

    • Consider Neurosurgery evaluation if obstructive lesion or concern for herniation (craniectomy vs resection vs evacuation vs ventricular drain)

  • CTV or MRV w/wo to look for venous sinus thrombosis (especially in pregnant pts) o Venous sinus thrombosis needs anticoagulation, even if there is some degree of hemorrhagic infarction

  • If no obstructive lesion, obtain lumbar puncture with opening pressure (elevated OP > 20mmgHg)

    • If workup is otherwise normal, except for elevated opening pressure, this is suggestive of idiopathic intracranial hypertension

Management

  • Idiopathic intracranial hypertension

    • Acetazolamide and/or topiramate
    • Ophthalmology evaluation emergently for consideration of nerve sheath fenestrations or urgent ventriculoperitoneal shunt placement if severe disc edema

  • If there is clinical concern for herniation

    • Cushing Triad: vital sign changes in herniation, widened pulse pressure (increasing systolic, decreasing diastolic), bradycardia, and irregular respirations
    • Mannitol: 50g IV, can be given peripherally. Has risks of renal injury. Associated with initial increase in ICP, often given with furosemide to counter this.
    • Hypertonic saline: 3%, 7% or 23% saline can be given, needs central access for repeat administration but initial dose can be given via peripheral IV
    • Maintain head of bed at least 30° and loosen neck obstructions (c-collars) as able
    • Consider neurosurgery consult for shunt/external ventricular drain consideration
    • Hyperventilation can be done with goal PaCO2 30-34 mmHg or ETCO2 20-30 mmHg but is only a temporizing measure and risks rebound edema
      • After 4-6h, compensatory pH changes in the blood prevent vasoconstrictive affects