Idiopathic Intracranial Hypertension: a rapid review

Idiopathic Intracranial Hypertension

Suzie, an otherwise healthy 32-year-old female, presents to your Emergency Department complaining of her typical migraine-type headache. Slam dunk. She’ll have a normal neuro exam and then you’ll treat her headache with the usual migraine cocktail. But could it be Idiopathic Intracranial Hypertension (IIH)?

This is a guest post (hopefully the first of many) by Kristine Laing, CCPA. Kristine is Canadian Certified Physician Assistant working in emergency medicine in Toronto.  She is also a facilitator for the University of Toronto Physician Assistant Program and is part of the faculty for Dr. Arun Sayal’s incredible Casted Course. 

The papers: 

Wakerley BR, Mollan SP, Sinclair AJ. Idiopathic intracranial hypertension: Update on diagnosis and management. Clin Med (Lond). 2020 Jul;20(4):384-388. doi: 10.7861/clinmed.2020-0232. PMID: 32675143 [free full text]

Grech O, Mollan SP, Wakerley BR, Alimajstorovic Z, Lavery GG, Sinclair AJ. Emerging themes in idiopathic intracranial hypertension. J Neurol. 2020 Jul 22. doi: 10.1007/s00415-020-10090-4. Epub ahead of print. PMID: 32700012 [free full text]

Mollan SP, Davies B, Silver NC, Shaw S, Mallucci CL, Wakerley BR, Krishnan A, Chavda SV, Ramalingam S, Edwards J, Hemmings K, Williamson M, Burdon MA, Hassan-Smith G, Digre K, Liu GT, Jensen RH, Sinclair AJ. Idiopathic intracranial hypertension: consensus guidelines on management. J Neurol Neurosurg Psychiatry. 2018 Oct;89(10):1088-1100. doi: 10.1136/jnnp-2017-317440. Epub 2018 Jun 14. PMID: 29903905 [free full text]

What is Idiopathic Intracranial Hypertension (IIH)?

IIH is a condition of raised intracranial pressure with no known cause. IIH was previously known as pseudotumor cerebri or benign intracranial hypertension. If left untreated, IIH may lead to permanent vision loss and/or chronic debilitating headaches.

How common is it?

IIH has always been considered a rare condition. The incidence of IIH is increasing and it appears it is increasing as the rates of obesity grow worldwide. Epidemiology studies range from 2 – 9/100,000 depending on country and sex.

Who gets it?

It generally occurs in overweight females of reproductive age (typically between the ages of 20 to 40).  It rarely occurs in men.  Yet another one for the ladies, sigh.

How does it present?

Headache is the main symptom. Although patients occasionally present with classic symptoms of high intracranial pressure (a headache that is worse on wakening, with Valsalva, coughing, or bending over), the headache is generally nonspecific. It can be diffuse, focal, or present as a patient’s typical migraine.

Papilledema (swelling of the optic discs) is common but not universal. Some IIH patients present after papilledema is found on a routine eye checkup by their optometrist.

Other possible symptoms include vision changes such as blurry vision or transient visual loss (typically due to papilledema), horizontal diplopia caused by Abducens nerve palsy, pulsatile tinnitus, dizziness, neck or back pain, and, in the worst cases, confusion.

When do we need to think about this in the ED?

IIH is commonly missed because it is rare and the symptoms are non-specific. Given the rise in cases each year, we must consider IIH, especially when a young, overweight female patient presents with any of the above signs/symptoms. The primary driver of further investigation is going to be the identification of papilledema, as papilledema is a major sign of raised intracranial pressure.

What does papilledema look like?

Yes, the fundoscopic exam is still an important skill to have.  It gets easier with practice. (Or you might just use ultrasound to measure the optic disc.) 

On fundoscopy, papilledema will appear as blurred disc margins, lack of venous pulsations, enlarged retinal venules, and in severe cases hemorrhage overlying the optic disc. That being said, papilledema can be a difficult diagnosis to make, with many false positives, so expert consultation with an ophthalmologist is recommended before follow-up invasive testing.

How is it diagnosed?

IIH is a diagnosis of exclusion. It is crucial to rule out other serious causes of raised intracranial pressure.

The diagnostic criteria are:

  1. Papilledema*
  2. Normal neurologic exam (except maybe sixth cranial nerve palsy)
  3. Normal neuroimaging, including exclusion of cerebral venous thrombosis
  4. Normal CSF analysis
  5. Elevated lumbar puncture opening pressure (there is some debate about the exact cutoff, but generally anything over 25 cm is considered abnormal)

* Some patients will still be diagnosed with IIH if they have all of the other criteria, but not papilledema.

Elevated opening pressure on lumbar puncture may be the only sign of IIH. Therefore it is crucial to obtain an accurate reading.  LP should always be performed with the patient laying in lateral decubitus position. The needle entry point must be at the same level as the spine which is also at the same level as the patient’s head. Even a few centimeters of head tilt can falsely raise the opening pressure measurement. (Doherty 2014)

How is IIH managed?

There are three main goals of management:

  1. Treat the underlying disease
  2. Protect the vision
  3. Control/minimize headache morbidity
Weight LossThe most effective way to manage this disease
Aim for > 15% weight loss
Vision LossThreatened: Acute management is surgical either by CSF diversion (shunt) or optic nerve fenestration
Stable vision: Acetazolamide or Topiramate for medical therapy to reduce intracranial pressure (although there is not strong evidence for either medication)
HeadacheFirst line: Tylenol, non-steroidal inflammatory
Avoid opioid use
Consider occipital nerve blocks
Topiramate may be an effective choice for both headache and to reduce ICP  Monitor for medication overuse headache
Lumbar punctures relieve pressure and therefore improve headaches; however this is very temporary and not recommended on a continuous basis due to the risks associated with LPs.

What is fulminant IIH?

In less than 10% of presentations, patients present with rapidly progressive visual loss. In these patients, a rapid reduction in ICP is required to preserve vision. Get an urgent neurosurgical consultation.

Bottom line for the ER

  1. If vision is impaired, stat referral to neurosurgery
  2. Treat headache with your usual medications
  3. Urgent referral to both Ophthalmology and Neurology
  4. Rule out life-threatening causes of papilloedema / raised ICP

Other FOAMed

EM Docs EM@3AM: Idiopathic Intracranial Hypertension

EMCases POCUS Cases 3 Idiopathic Intracranial Hypertension and Ocular POCUS

PulmCrit: Algorithm for diagnosing ICP elevation with ocular sonography


You can find more rapid review topics here


References

Doherty CM, Forbes RB. Diagnostic Lumbar Puncture. Ulster Med J. 2014 May;83(2):93-102. PMID: 25075138; PMCID: PMC4113153.

Grech O, Mollan SP, Wakerley BR, Alimajstorovic Z, Lavery GG, Sinclair AJ. Emerging themes in idiopathic intracranial hypertension. J Neurol. 2020 Jul 22. doi: 10.1007/s00415-020-10090-4. Epub ahead of print. PMID: 32700012 [free full text]

Wakerley BR, Mollan SP, Sinclair AJ. Idiopathic intracranial hypertension: Update on diagnosis and management. Clin Med (Lond). 2020 Jul;20(4):384-388. doi: 10.7861/clinmed.2020-0232. PMID: 32675143 [free full text]

Mollan SP, Davies B, Silver NC, Shaw S, Mallucci CL, Wakerley BR, Krishnan A, Chavda SV, Ramalingam S, Edwards J, Hemmings K, Williamson M, Burdon MA, Hassan-Smith G, Digre K, Liu GT, Jensen RH, Sinclair AJ. Idiopathic intracranial hypertension: consensus guidelines on management. J Neurol Neurosurg Psychiatry. 2018 Oct;89(10):1088-1100. doi: 10.1136/jnnp-2017-317440. Epub 2018 Jun 14. PMID: 29903905 [free full text]

Papilledema image from Jonathan Trobe, M.D on Wikipedia Commons

Cite this article as: Kristine Laing, "Idiopathic Intracranial Hypertension: a rapid review", First10EM blog, November 16, 2020. Available at: https://first10em.com/idiopathic-intracranial-hypertension-a-rapid-review/.

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