Idiopathic intracranial hypertension (IIH) is a condition in which pressure increases around the brain without an obvious tumour or other structural cause. It may cause headaches, visual problems, and a rhythmic "whooshing / ringing" sound in the ear known as pulsatile tinnitus.
Early diagnosis and treatment are important, because untreated IIH can permanently affect vision.
What is IIH?
IIH means increased pressure inside the skull with no clearly identified cause. The pressure is related to cerebrospinal fluid — the clear fluid that cushions the brain and spinal cord. This pressure can also affect the optic nerves, which carry visual information from the eyes to the brain.
Some patients develop narrowing of one or more large drainage channels of the brain, called the venous sinuses. When blood has difficulty flowing through these channels, pressure may increase further. This can create a cycle in which high pressure worsens the narrowing, and the narrowing makes pressure control more difficult.
What is Tinnitus?
Tinnitus is hearing a sound when there is no external source. In IIH the tinnitus is often pulsatile — it beats in time with the heartbeat. Patients may describe it as:
- A whooshing sound
- A pulsing or thumping noise
- Wind or rushing water in the ear
- A sound that is worse when lying down or at night
Symptoms
Possible symptoms of IIH include:
- Headache, sometimes worse in the morning or when lying down
- Pulsatile tinnitus / heartbeat-synchronous "whooshing"
- Blurred or dim vision
- Brief episodes of visual blackout (a few seconds)
- Blind spots or loss of side vision
- Double vision
- Nausea or vomiting
- Neck, shoulder, or back pain
- Sensitivity to light
- Fatigue
- Swelling of the optic nerve at the back of the eye, called papilloedema
Symptoms vary from person to person. Some patients have significant visual problems with only mild headache, while others mainly experience headache and tinnitus.
Causes & Risk Factors
The exact cause of IIH is not always known. Factors associated with a higher risk include:
- Recent weight gain or obesity.
- Being a woman of reproductive age.
- Certain medicines — such as tetracycline antibiotics, excessive vitamin A/D, or retinoids. These should not be stopped without medical advice.
- Some hormonal or medical conditions.
- Narrowing of the brain's venous sinuses.
- Previous blood-clotting problems affecting the venous sinuses.
IIH is not caused by a brain tumour, although scans are required to exclude tumours, blood clots, and other conditions that can produce similar symptoms.
When to See a Doctor
- New or persistent headaches with pulsatile tinnitus
- Blurred vision, double vision, or brief visual blackouts
- Loss of side vision or difficulty seeing at night
- A new, persistent, or worsening pulsatile sound in one ear
Seek urgent medical attention for sudden or rapidly worsening loss of vision, severe sudden headache, weakness, confusion, difficulty speaking, or loss of consciousness. Even short episodes of visual dimming should be reported — repeated pressure on the optic nerve may cause permanent visual loss.
Diagnosis
Diagnosis is usually made by a neurologist, neuro-ophthalmologist, ENT specialist, or neurointerventional team. Tests may include:
- Eye examination — an ophthalmologist examines the optic nerves for papilloedema.
- Visual-field testing — checks for loss of side vision or blind spots.
- MRI of the brain — looks for other causes of raised pressure and may show signs associated with IIH.
- MR venography or CT venography — examines the brain's venous drainage channels for narrowing or blood clots.
- Catheter venography & venous manometry — during a specialised angiographic examination, pressure is measured on both sides of a venous narrowing. This helps determine whether venous sinus stenting is appropriate; pressure measurement before stenting is strongly recommended in published selection guidance.
Treatment / Procedure
Treatment depends on the severity of symptoms, the effect on vision, and the underlying findings.
Lifestyle & Medical Treatment
- Weight management — for patients who are overweight, gradual, medically-supervised weight loss can reduce intracranial pressure and may improve IIH.
- Acetazolamide — reduces cerebrospinal-fluid production and is commonly used as an initial treatment.
- Topiramate — may help reduce pressure and can also help with headaches; not suitable for everyone.
- Other diuretics or headache medicines — used in selected patients.
- Regular eye monitoring — repeated visual-field tests and optic-nerve examinations remain important even when symptoms improve.
- Lumbar puncture — may provide short-term relief but is generally not a durable long-term treatment by itself.
Venous Sinus Stenting
A minimally-invasive procedure used in carefully selected patients who have:
- Confirmed IIH or related venous-pressure symptoms
- Documented narrowing of a venous sinus
- A significant pressure difference across the narrowed segment
- Persistent symptoms, threatened vision, or inadequate response to medicines
Other Procedures
If vision is rapidly deteriorating or medical treatment is unsuccessful, other options may include:
CSF Shunt
A tube diverts fluid from the brain or lower spine to another part of the body, usually the abdomen.
Optic Nerve Sheath Fenestration
A small opening is made around the optic nerve to reduce pressure and protect vision.
Venous Sinus Stenting
Considered when venous sinus narrowing and a significant pressure gradient are demonstrated.
Conclusion
IIH is a treatable condition, but it can threaten eyesight if it is not recognised early. Pulsatile tinnitus may be an important clue, particularly when it occurs with headaches or visual symptoms. Treatment may involve weight management, medicines, close eye monitoring and — in selected patients with proven venous sinus narrowing — venous sinus stenting.