top of page

Idiopathic Intracranial Hypertension (IIH)

Frequently Asked Questions

What is Idiopathic Intracranial Hypertension (IIH)?

Idiopathic Intracranial Hypertension (IIH), also known as pseudotumor cerebri, is a perplexing neurological disorder characterized by increased intracranial pressure (ICP) in the absence of any identifiable cause.

IIH has an incidence of 0.5–2/100,000 in the general population and a greater incidence among women of child-bearing age (12–20 per 100,000), typically presenting between 25 and 36 years of age. Markey KA et. al. Lancet Neurol 15:78–91, 2016

What are the symptoms of IIH?

Patients with IIH often present with symptoms that mimic those of a brain tumor. These can include

  • Chronic headaches

  • Visual disturbances (such as transient visual obscurations and visual field defects)

  • Pulsatile tinnitus

  • Diplopia (Double vision)

  • Papilledema (Optic disc swelling)

The severity of symptoms can vary from mild to debilitating, significantly impacting the quality of life of affected individuals.

What tests do I need?

  • The diagnosis of IIH is primarily clinical, supported by specific criteria. These include:

    • Presence of symptoms consistent with increased ICP

    • Evidence of papilledema on ophthalmoscopy

    • Normal neuroimaging studies (except for findings related to elevated ICP)

    • Elevated cerebrospinal fluid (CSF) pressure measured via lumbar puncture

  • Exclusion of other secondary causes of intracranial hypertension is crucial to establish the diagnosis of idiopathic nature.

What is the cause fo IIH?

The exact pathophysiological mechanisms underlying IIH remain incompletely understood. However, several factors have been implicated in its development. These include:

  • Impaired CSF absorption

  • Abnormal cerebral venous drainage

  • Hormonal imbalances (particularly related to sex hormones)

  • Obesity, and

  • Certain medications (Antibiotics, Steroids, Vitamin A, Oral contrceptive pills)

The interplay between these factors likely contributes to the increased ICP observed in IIH.

Cerebrospinal fluid (CSF) circulation
Figure 1: Cerebrospinal fluid (CSF) [shown in blue; Normally it is colorless] is produced by Choroid plexus situated inside the ventricles in the brain. Normally in adults 0.35ml CSF per minute is produced. It circulates around the brain and spinal cord. The CSF is absorbed by arachnoid granulations that drains into the veins inside the skull.

How is IIH treated?

  • The management of IIH involves both medical and surgical approaches, with the primary goals of relieving symptoms and preserving visual function.

  • Weight loss is considered a cornerstone of therapy in obese individuals with IIH, as it often leads to a significant reduction in ICP.

  • Medications such as acetazolamide, a carbonic anhydrase inhibitor, can be prescribed to reduce CSF production and lower ICP.

  • In cases of severe or refractory IIH, surgical interventions like optic nerve sheath fenestration or cerebrospinal fluid shunting may be necessary to alleviate symptoms and prevent visual deterioration.

What is the prognosis of IIH?

  • The prognosis of IIH varies among individuals. With appropriate management, many patients experience a significant improvement in symptoms and preservation of visual function. However, the course of IIH can be unpredictable, and some individuals may experience relapses or persistent symptoms despite treatment. Potential complications of IIH include visual impairment or blindness due to optic nerve damage, venous sinus thrombosis, and rarely, herniation of the brainstem.


Dr. Lekhjung Thapa, MD, DM (Neurology)
Associate Professor of Neurology
Senior Consultant Neurologist

Dr. Lekhjung Thapa, MD, DM (Neurology)
Associate Professor of Neurology
Senior Consultant Neurologist
bottom of page