Elevated Intracranial Pressure (ICP) and Hydrocephalus¶
Background¶
-
Communicating hydrocephalus (i.e. non-obstructive)
- Causes: subarachnoid granule scarring after subarachnoid hemorrhage or meningitis, ependymoma producing excess CSF, venous sinus thrombosis
-
Non-communicating hydrocephalus (i.e. obstructive)
- Causes: tumor, abscess, or hematoma in the midline ventricular structures
-
Eventually, elevated ICP will cause brain herniation
Presentation¶
-
Headache, blurred vision, visual field reduction, enlarged blind spot, nausea, vomiting, syncope, coma
-
Sixth nerve palsies are common
-
Third nerve palsies (blown pupil) are classically associated with uncal herniation
Evaluation¶
-
Good visual exam: 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
- NSGY evaluation if obstructive lesion (removal vs ventricular drain)
-
CTV or MRV to look for venous sinus thrombosis
- Venous sinus thrombosis needs AC, even if there is some degree of hemorrhagic infarction
-
If no obstructive lesion LP with opening pressure
- If workup is otherwise normal, except for elevated opening pressure diagnosis = IIH
Management¶
-
Idiopathic intracranial hypertension (IIH)
-
Diamox and/or topiramate
-
Ophthalmology evaluation emergently for consideration of nerve sheath fenestrations or urgent VPS placement if severe disc edema
-
If there is clinical concern for herniation:
-
Mannitol: 50g 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 can be done with goal PaCO2 30-34 mm Hg or ETCO2 20-30 mmHg but is only a temporizing measure and risks rebound edema
- After 4-6 hrs, compensatory pH changes in the blood prevent vasoconstrictive affects
-