Neurologic Emergencies

Elevated Intracranial Pressure (ICP) and Hydrocephalus

Madelaine Behrens

Background 

  • Communicating/non-obstructive hydrocephalus
    • 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 can cause brain herniation

Presentation 

  • Headache (can be positional), blurred vision, visual field reduction, enlarged blind spot, nausea, vomiting, encephalopathy, coma
  • Sixth nerve palsies are common (inability for eye to abduct)
  • 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)
  • 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 sodium goal 150-155 for duration of hypertonic goal.
    • 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
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