Idiopathic intracranial hypertension (IIH)


Idiopathic intracranial hypertension (IIH), or pseudotumor cerebri, formerly called benign intracranial hypertension, is a condition with raised intracranial pressure (ICP) in the absence of identifiable cause.

  • Primarily affects young obese women in the childbearing years

History:

Quincke in 1897 reported the first cases of IIH shortly after he introduced the lumbar puncture into medicine. It was named pseudotumor cerebri in 1904 but was not well delineated clinically until the 1940’s when cerebral angiography was added to pneumoencephalography to identify cases of cerebral mass lesions. Foley coined the term benign intracranial hypertension in 1955 but reports from the 1980’s demonstrated a high incidence of visual loss and the term “benign” is no longer appropriate.


Presentation

Headache (M/C symptom):

Severe daily pulsatile headaches

Pulse synchronous tinnitus

Pulsatile tinnitus

Visual symptoms:

  • Transient visual obscurations (monocular/binocular transient blurred vision lasting < 30s)
  • Diplopia (due to CN VI paresis)
  • Papilledema and associated loss of sensory visual function
Percentage of patients and their presenting symptoms in Idiopathic Intracranial Hypertension
Percentage of patients and their presenting symptoms in Idiopathic Intracranial Hypertension, | Modified from Wall and colleagues: Wall M., Kupersmith M., Kieburtz K., Corbett J., Feldon S., Friedman D., et al. (2014a) The idiopathic intracranial hypertension treatment trial: clinical profile at baseline. JAMA Neurol 71: 693–701

Diagnosis

Modified Dandy diagnostic criteria for IIH:

  • Symptoms and signs of increased ICP
  • No localizing neurologic signs, except for unilateral/bilateral CN VI nerve palsies
  • Increased CSF opening pressure, but normal CSF composition
  • No evidence of hydrocephalus, mass, structural, or vascular lesion on imaging
  • No other cause of increased ICP identified
A flow diagram of investigation of papilloedema
A flow diagram of investigation of papilloedema. | BMI, body mass index; IIH, idiopathic intracranial hypertension. | Mollan, S. P., Davies, B., Silver, N. C., Shaw, S., Mallucci, C. L., Wakerley, B. R., Krishnan, A., Chavda, S. V., Ramalingam, S., Edwards, J., Hemmings, K., Williamson, M., Burdon, M. A., Hassan-Smith, G., Digre, K., Liu, G. T., Jensen, R. H., & Sinclair, A. J. (2018). Idiopathic intracranial hypertension: consensus guidelines on management. Journal of neurology, neurosurgery, and psychiatry, 89(10), 1088–1100. https://doi.org/10.1136/jnnp-2017-317440

Ophthalmoscopic examination:

  • Papilledema (optic disc edema) due to increased intracranial pressure (CARDINAL SIGN)
  • Ocular motility disturbances:
    • Horizontal diplopia (33% cases)
    • CN VI palsies (10-20% cases)
  • Visual acuity (decreased only in severe/long-standing cases)
  • Perimetry: Visual field loss (almost all cases)

MRI:

MRI findings in IIH.
Showing MRI findings in IIH. (a) Showing Distension of Optic Nerve Sheath (T2 Weighted; axial view); (b) Showing Distension of Optic Nerve Sheath (T2 Weighted; coronal view); (c) Showing Tortuosity of Optic Nerve (Blue Arrow) and Scleral Indentation (Green Arrow) | Takkar, A., & Lal, V. (2020). Idiopathic Intracranial Hypertension: The Monster Within. Annals of Indian Academy of Neurology, 23(2), 159–166. https://doi.org/10.4103/aian.AIAN_190_19

Lumbar puncture:

  • ↑ CSF opening pressure
  • Normal CSF characteristics

Management

Management flow chart of diagnosed IIH
Management flow chart of diagnosed IIH. | BMI, body mass index; CSF, cerebrospinal fluid; IIH, idiopathic intracranial hypertension. | Mollan, S. P., Davies, B., Silver, N. C., Shaw, S., Mallucci, C. L., Wakerley, B. R., Krishnan, A., Chavda, S. V., Ramalingam, S., Edwards, J., Hemmings, K., Williamson, M., Burdon, M. A., Hassan-Smith, G., Digre, K., Liu, G. T., Jensen, R. H., & Sinclair, A. J. (2018). Idiopathic intracranial hypertension: consensus guidelines on management. Journal of neurology, neurosurgery, and psychiatry, 89(10), 1088–1100. https://doi.org/10.1136/jnnp-2017-317440

Weight reduction

M/imp step

Carbonic anhydrase inhibitors:

Decrease CSF production and thereby decrease ICP, leading to improved symptoms and signs of IIH
  • Acetazolamide
  • Topiramate

Loop-diuretic: Furosemide

Lower intracranial pressure

Surgical management:

When other treatments have failed to prevent progressive vision loss or when the disease onset is fulminant
  • CSF diversion (e.g., ventriculo-peritoneal and lumbo-peritoneal shunting)
  • Optic nerve sheath fenestration (ONSF)

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