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What is IIH?

Idiopathic intracranial hypertension (IIH) is a disorder of elevated pressure within the brain without an identifiable cause.

Overview

The increased pressure from IIH can lead to permanent damage to the brain and eyesight if left untreated. The term idiopathic is used when there is no detectable reason for increased pressure within the brain. However, as researchers continue to investigate potential causes, the term “idiopathic” may become a term of the past.¹

IIH is most commonly seen in overweight women in their reproductive years, usually in the 3rd and 4th decades of life. In the United States, approximately 19 per 100,000 women in this group are diagnosed with IIH.² With increasing rates of obesity in the US, defined as a body mass index (BMI) of 30 or greater, the number of people affected by this syndrome is projected to increase.

The most common signs and symptoms of IIH are: headaches, dizziness, nausea, vision loss, and double vision.³ Papilledema – swelling of the optic nerve that carries visual signals from the eye to the brain – is a common finding during a visual exam in one with IIH. As swelling of the optic nerve persists, vision worsens and can progress to blindness which can be permanent.

Signs & Symptoms

Other signs and symptoms of IIH may include: radicular pain, sixth nerve palsy, and pulse synchronous tinnitus.³ Radicular pain is hypothesized to be an effect of increased cerebrospinal fluid pressure, compressing nerves in the arms and legs causing the sensation of pins and needles. Sixth nerve palsy is the weakening of the lateral rectus muscle of the eye and can lead to double vision. Pulse synchronous tinnitus is the humming, whooshing, whistling, or marching noise that can be heard in one or both ears that is in sync with their own pulse.

Diagnosis

The diagnosis of IIH requires a detailed neurological history, complete physical, a visual exam (conventionally with an ophthalmologist), lumbar puncture, and imaging studies to diagnose this condition. If signs and symptoms are related to increased pressure within the brain, a lumbar puncture yields normal cerebrospinal fluid results and elevated opening pressure, and imaging studies of the brain do not show an identifiable reason for increased intracranial pressure, then IIH is suspected.

The criteria required to diagnose IIH are:

  • Signs and symptoms of increased pressure within the brain or papilledema without an identifiable cause
  • Intracranial pressure is increased when measured in lateral decubitus position. This is obtained by performing a lumbar puncture and the opening pressure is measured at or greater than 250 mm.
  • The composition of cerebrospinal fluid is normal.
  • Other conditions associated with increased intracranial pressure are ruled-out⁴
    Diseases that are associated with increased pressure within the brain include: polycystic ovarian syndrome (PCOS), hypercoagulable state, obstructive sleep apnea, and systemic arterial hypertension.⁵﹐⁶

Medications that have shown to increase intracranial pressure are: anabolic steroids, withdrawal from chronic corticosteroids, vitamin A and retinoids, hormones, and certain antibiotics and can be a potential cause of IIH.³,⁷,⁸

There are a subset of people who do not fit the IIH criteria as stated above. These patients may not be overweight, may have normal opening pressure on lumbar puncture, and may have medical conditions that can obscure signs and symptoms that are typical of IIH but in fact have elevated intracranial pressure due to venous congestion, venous stenosis or narrowing, and venous thrombosis.¹

As women’s health has proven an essential topic of medical interest, the discoveries made will help diagnose, treat, and prevent diseases that are female-related. Current medical research is studying how genetics, hormones, medications, and venous pressure contribute to this debilitating syndrome in hopes of a curative therapy.

  1. Fargen, K. (2019). Idiopathic intracranial hypertension is not idiopathic: proposal for a new nomenclature and patient classification. Journal of NeuroInterventional Surgery. November 27, 2019;12(2). doi:10.1136/neurintsurg-2019-015498
  2. Wall M, Kupersmith MJ, Kieburtz KD, et al. The idiopathic intracranial hypertension treatment trial: clinical profile at baseline. JAMA Neurol. June 1, 2014;71(6):693-701. doi:10.1001/jamaneurol.2014.133
  3. Ball A, Clarke C. Idiopathic intracranial hypertension. The Lancet Neurology. May 2006;5(5):433-442.
  4. Friedman D, Liu G, Digre K. Revised diagnostic criteria for the pseudocerebri syndrome in adults and children. Neurology. August 21, 2013;81(13):1159-1165.
  5. Markey K, Uldall M, Botfield H, et al. Idiopathic intracranial hypertension, hormones, and 11β-hydroxysteroid dehydrogenases. Journal of pain research. April 19, 2016;9:223–232. https://doi.org/10.2147/JPR.S80824
  6. Glueck, C. J., Aregawi, D., Goldenberg, N., Golnik, K. C., Sieve, L., & Wang, P. (2005). Idiopathic intracranial hypertension, polycystic-ovary syndrome, and thrombophilia. Journal of Laboratory and Clinical Medicine, 145(2), 72–82. doi:10.1016/j.lab.2004.09.011
  7. Libien J, Kupersmith MJ, Blaner W, et al. Role of vitamin A metabolism in IIH: Results from the idiopathic intracranial hypertension treatment trial. J Neurol Sci. January 15, 2017;372:78-84. doi:10.1016/j.jns.2016.11.014
  8. Fuerst J, Wann R, Kline L. Vitamin A as a Cause of Pseudotumor Cerebri Syndrome: Not to Be Forgotten. Journal of Neuro-Ophthalmology. September 2021;41(3):403-406.

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