| One-Minute Clinician

Blinded by the Light: Idiopathic Intracranial Hypertension

What to know:

  • The brain and spinal cord are surrounded by dura, a membrane, and in typical adults there’s 150 mL of cerebrospinal fluid (CSF) in that region, which gets turned over 3 times a day
  • But if a patient produces too much CSF and they can’t get rid of it in a timely fashion, there will be increased pressure within that membrane that surrounds the brain

Final diagnostic criteria:

  • If a patient comes in with papilledema, pulsatile tinnitus, and transient visual obscurations, first get them an MRI and MRV
  • Then get a neuroopthalmological eval to get a look at their visual fields
  • Check for problems with perimetry; Humphrey’s visual fields
  • The last thing: a lumbar puncture. The diagnostic criteria is, basically, when you stick that needle in and get the opening pressure, if it’s above 25 to 30 cm of water, that pretty much clenches the diagnosis

Will this offer relief?

  • Actually, it will for most people, particularly if they have headache
  • If the opening pressure is 30 cm of water or above, ask the person doing the lumbar puncture to drain 20 to 30 mL of fluid
  • That will decrease the headache
  • BUT I’ve seen patients who've been hospitalized for 2.5 weeks and having LPs every other day, which is absurd; that’s not a way to treat it

Of note:

  • Carbonic anhydrase inhibitor, which is a medication like acetazolamide, will prevent overproduction of cerebrospinal fluid
  • Idiopathic intracranial hypertension doesn’t always go away. You might quell it, you might use the medication and the patient will go into remission. I’ve had patients who’ve had idiopathic intracranial hypertension on and off for 15 to 20 years

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