What is the workup for idiopathic (without a known cause) intracranial (within the skull) hypertension (high blood pressure)?

From the Guidelines

The workup for idiopathic intracranial hypertension (IIH) should include a comprehensive neurological examination, neuroimaging, lumbar puncture, and ophthalmologic evaluation. Begin with a detailed history focusing on symptoms like headaches, visual disturbances, and pulsatile tinnitus, followed by a thorough neurological examination. Brain MRI with and without contrast is essential to exclude secondary causes of increased intracranial pressure such as mass lesions, venous sinus thrombosis, or hydrocephalus, as recommended by the consensus guidelines on management of IIH 1. MR venography should be included to evaluate venous sinus patency. A lumbar puncture is crucial to measure opening pressure (diagnostic if >25 cmH2O in adults or >28 cmH2O in children), analyze CSF composition (typically normal in IIH), and provide temporary symptom relief. Ophthalmologic assessment should include visual acuity testing, visual field examination, and fundoscopy to document papilledema. Additional tests may include optical coherence tomography to quantify optic nerve swelling and visual field testing to assess for peripheral vision loss. Laboratory tests should evaluate for conditions that can mimic IIH, including thyroid dysfunction, anemia, and vitamin A toxicity. This comprehensive approach ensures accurate diagnosis of IIH while excluding secondary causes of increased intracranial pressure that would require different management strategies.

Some key points to consider in the workup of IIH include:

• The importance of a comprehensive neurological examination to identify any focal neurological deficits
• The use of neuroimaging, including MRI and MR venography, to exclude secondary causes of increased intracranial pressure
• The role of lumbar puncture in measuring opening pressure and analyzing CSF composition
• The need for ophthalmologic evaluation to document papilledema and assess visual function
• The consideration of laboratory tests to evaluate for conditions that can mimic IIH

It is also important to note that the diagnosis of IIH can be challenging, and a comprehensive workup is necessary to exclude other causes of increased intracranial pressure. The guidelines for the management of IIH, as outlined in the consensus statement 1, provide a framework for the diagnosis and treatment of this condition.

In terms of specific imaging recommendations, the ACR Appropriateness Criteria for imaging of suspected intracranial hypotension 1 provide guidance on the use of imaging in the diagnosis of intracranial hypotension, but are not directly applicable to the diagnosis of IIH. However, they do highlight the importance of a comprehensive imaging evaluation in the diagnosis of conditions affecting intracranial pressure.

Overall, the workup for IIH should be guided by the principles of excluding secondary causes of increased intracranial pressure, documenting papilledema and assessing visual function, and considering laboratory tests to evaluate for conditions that can mimic IIH. The most recent and highest quality study, 1, provides the best guidance on the workup and management of IIH.

From the Research

Diagnostic Criteria

The workup for idiopathic intracranial hypertension (IIH) involves several steps, including:

• Clinical presentation with symptoms such as headaches and visual changes 2, 3, 4
• Lumbar puncture with an elevated opening pressure (OP) ≥20 cm H2O 2, 5, 4
• Absence of structural lesions on neuroimaging 2, 6, 4
• Normal cerebrospinal fluid composition 6, 4

Imaging Findings

Imaging plays a crucial role in the diagnosis of IIH, with findings including:

• Partially empty sella 2
• Flattening of the posterior globe 2
• Cupping of optic disks 2
• Distension of the optic nerve sheaths 2
• Dural venous sinus stenoses 2, 3

Diagnostic Challenges

The diagnosis of IIH can be challenging, particularly in the absence of papilledema, as:

• Elevated OP is insufficient to diagnose IIH 5
• The absence of papilledema does not rule out intracranial hypertension 5
• Other conditions, such as cerebral venous sinus thrombosis, can mimic IIH 6

Treatment Options

Treatment options for IIH include:

• Medical management with acetazolamide and topiramate 3, 4
• Surgical interventions, such as optic nerve fenestration and shunting procedures 3, 4
• Endovascular treatment with dural venous sinus stent placement 3
• Weight loss, which has been shown to be beneficial in mild disease 4