Idiopathic intracranial hypertension

Background

  • Also known as pseudotumor cerebri/benign intracranial hypertension (BIH)
  • Cause is idiopathic, but believed be due to impaired CSF absorption at arachnoid villi
  • Associated with obesity, weight gain, pregnancy, cyclosporine, OCPs, vitamin A >100,000 U/day, tetracycline, amiodarone, sulfa antibiotics, lithium, thyroid disorders, and historically nalidixic acid (rarely used). Systemic steroid intake and withdrawal may also be causative.

Clinical Features

  • Tends to occur in young, obese women
  • Headache
    • Tend to be worse at night or first thing in the morning
    • Frequently starts as dull occipital pain, may become diffuse and throbbing
    • Typically worse with maneuvers to increase ICP
  • Nausea and Vomiting
  • Vision blurring
  • Papilledema
  • Irregular menses or amenorrhea
  • Neuro exam often normal
    • May have cranial nerve palsies if severe, most often abducens nerve palsy

Differential Diagnosis

Headache

Common

Killers

Maimers

Others

Aseptic Meningitis

Evaluation

  • Ocular exam including pupillary examination, ocular motility, assessment for dyschromatopsia (color plates). Also obtain systemic vitals such as blood pressure and temperature
  • CT (negative or slit-like ventricles).
  • Typically, MRI and MR venogram of the orbit and brain to rule out secondary causes of intracranial pressure such as cerebral venous sinus thrombosis. If normal, the patient may need LP to determine opening pressure and r/o other causes of optic nerve edema.
  • Consider ocular ultrasound (simple, non-invasive) to assess optic nerve diameter[1]
  • LP (Opening pressure >25 cm H2O)
    • CSF lab studies by lumbar puncture are negative
    • No special CSF studies need to be sent, unless differential includes etiologies for infection, hemorrhage, etc
    • Recognize that in rare cases, LP's can cause reactive meningeal enhancement (which is why some practitioners delay LP until after MRI). This practice might not be supported in cases where LP is necessary[2]
  • Outpatient visual field testing is the most important method for following these patients (Humphrey VF's)

Management

  • Treatment may be indicated in the following situations: severe/intractable headache, evidence of progressive decrease in visual acuity or visual field loss. Some ophthalmologists suggest treating all patients with papilledema.
  • Weight loss
  • Acetazolamide 250mg QID (or 500mg BID) initially building up to 500-1000mg QID if tolerated. Use with caution in sulfa-allergic patients. (decreases CSF production)
  • Discontinue any causative medications
  • Short course of systemic steroids, especially if any plans for surgical intervention
  • Repeat LPs (decrease CSF pressure) - large volume LPs on the order of 30-40 cc of CSF
  • Furosemide 20mg PO BID, give potassium supp as needed
  • If above treatments are unsuccessful, surgical treatments may be considered.
    • CSF Shunt (ventriculoperitoneal or lumboperitoneal) is often effective if vision is threatened
    • Optic nerve sheath fenestration

Disposition

  • Admit for:
    • Severe pain
    • Focal findings
    • Vision changes
  • Otherwise, discharge with ophtho follow up for formal visual field monitoring

See Also

References

  1. Bekerman I, Sigal T, Kimiagar I, Almer ZE, Vaiman M. Diagnostic value of the optic nerve sheath diameter in pseudotumor cerebri. J Clin Neurosci. 2016;30:106-109. doi:10.1016/j.jocn.2016.01.018
  2. Wesley SF, Garcia-Santibanez R, Liang J, Pyburn D. Incidence of meningeal enhancement on brain MRI secondary to lumbar puncture. Neurol Clin Pract. 2016;6(4):315-320. doi:10.1212/CPJ.0000000000000262
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