IDIOPATHIC INTRACRANIAL HYPERTENSION ABOUT THE CONDITION

Overview

Every year, approximately one to two people in 100,000 are diagnosed with idiopathic intracranial hypertension (IIH).¹ IIH is a disorder in which there is evidence of increased cerebrospinal fluid pressure in the head and spine without an obvious cause. Symptoms can include debilitating headaches and vision problems. 

IIH is sometimes referred to by an old name, “pseudotumor cerebri” (PTC). It is a disorder in which the intracranial pressure (ICP) within the skull is increased, without mass lesion or enlarged ventricles (the spaces within the brain).³ Anyone can develop IIH regardless of age, gender, weight, or ethnicity, but obesity is a major factor. For overweight/obese women of childbearing age, the incidence is 19 to 21 in 100,000 people.⁴ In the general population, it occurs in approximately one to two in 100,000 people.⁵ The incidence of IIH is increasing, most likely due to rising rates of societal obesity, greater patient and physician awareness of the disorder, and improved diagnosis.⁶

Symptoms

Many people with the condition have debilitating symptoms that bring them to their doctors, such as:

• Chronic, severe, migraine-like headaches, unrelieved by medication, which may be worse in the morning
• Dizziness
• Nausea
• Papilledema (swelling of the optic disc, where the optic nerve enters the eyeball), which may cause:
  • Blurred vision
  • Tunnel vision
  • Double vision
  • Blind spots
  • Loss of vision
• Sensitivity to light (photophobia)
• Pain behind the eyes or when moving the eyes
• Pulse-synchronous tinnitus (a swooshing sound that’s in sync with your heartbeat)
• Ringing in the ears (tinnitus)
• Hearing loss
• Shoulder, back, and/or neck pain
• Paralysis of eye muscles

It is not fully understood what causes IIH, but it is thought the symptoms are due to a reduced outflow of cerebrospinal fluid (CSF). CSF is continually produced within the brain, and there appears to be a resorption difficulty (abnormal neural hydrodynamics).⁷

Diagnosis

It’s important to keep good notes starting from the first doctor’s visit, because IIH can have a variety of symptoms, and you may see several healthcare practitioners for different symptoms. You may want to have someone accompany you to appointments to help you keep track. The people you might see for diagnosis and treatment include:

• General Practitioner (GP)
• Neurologist
• Ophthalmologist
• Neuro-Ophthalmologist
• Neurosurgeon
• Radiologist

Any increase in intracranial pressure is cause for concern, and your physician will rule out other disorders before making the diagnosis and offering treatment. Because IIH diagnosis may be difficult in some patients, a set of criteria, known as the Modified Dandy Criteria, were established to assist physicians.

One or more of the following tests are typically used to diagnose IIH and to rule out other conditions:

• A neuro-ophthalmologist will check your peripheral vision, your central vision, your ability to distinguish colours, and dilate your pupils to check for swelling of the optic nerves (papilledema).
• Even though IIH is not reliably diagnosed by using imaging, a CT or MRI scan may be done to ensure that there are no growths, enlarged ventricles, bleeding in the brain, or blood clots causing your symptoms. In some patients, special MRI studies may be used to study blood flow in brain blood vessels.
• Finally, a spinal tap will be performed, and the pressure of the cerebrospinal fluid (CSF) will be determined. If the doctor thinks the pressure is too high, they will recommend treatment options.