Elevated ICP and Hydrocephalus

Elevated Intracranial Pressure and Hydrocephalus

Background

  • Communicating hydrocephalus: can be 2/2 subarachnoid granule scarring after subarachnoid hemorrhage or meningitis, ependymoma producing excess CSF, venous sinus thrombosis
  • Non-communicating hydrocephalus (i.e. obstructive) - usually due to a mass lesion such as a tumor, abscess, or hematoma in the midline ventricular structures
  • Eventually, elevated intracranial pressures will cause herniation of brain

 

Presentation

  •  Headache, blurred vision, visual field reduction, enlarged blind spot, may pass out, develop nausea or vomiting followed by coma
  • Sixth nerve palsies are common with elevated ICP
  • Compressive 3rd nerve palsies are classically associated with uncal herniation

 

Evaluation

  • Need a good visual exam: look for restricted visual fields, enlarged blind spot, papilledema (may not be present if very rapid ICP increase, even with vision loss), and 6th nerve palsies
  • Stat head CT to look for obstructions, mass lesions
  • Venous imaging is also usually necessary: CTV or MRV to look for venous sinus thrombosis
    • Venous sinus thrombosis needs AC, even if there is some degree of hemorrhagic infarction
  • Obstructive lesions require NSGY eval for either removal of the lesion or a ventricular drain
  • If no obstructive lesion, then LP will be needed for opening pressure
  • If workup is normal, except for elevated opening pressure, it is IIH

 

Management

  • Idiopathic intracranial hypertension (IIH) is treated with diamox and/or topiramate
    • Patients with IIH will need ophthalmology evaluation emergently, if there is severe disc edema then nerve sheath fenestrations or urgent VPS placement may be needed.
    • If there is clinical concern for herniation:
      • Mannitol – 50 grams IV, can be given peripherally. Has risks of renal injury
      • Hypertonic saline – 3%, 7% or 23% saline can be given, needs central access
      • Maintain head of bed at least 30° and loosen neck obstructions (c-collars) as able
      • NSGY consult for shunt consideration
    • Hyperventilation is controversial but can be done with goal PaCO2 30-34 mm Hg or ETCO2 20-30 mmHg
      • If lower, there is concern for cerebral ischemia
      • After 4-6 hrs, compensatory pH changes in the blood prevent vasoconstrictive affects