Headache is one of the most common symptoms of intracranial hypertension. Approximately 90% of people who have chronic IH, report headache, though a minority (less than 10%) have intracranial hypertension and do not experience headache.
The headache that accompanies IH is unbearably painful and, most notably, is not relieved by any migraine, conventional headache or pain medication. It has been described as the worst headache ever. In fact, many people with undiagnosed intracranial hypertension end up in the emergency room, believing that they are suffering from the worst migraine headache imaginable.
How is an IH headache different from a migraine headache?
While an IH headache may share certain characteristics with a migraine headache, such as sensitivity to light or odor, or worsening when exercising or coughing, there are additional symptoms that set it apart.
Unlike a migraine headache, an IH headache is frequently accompanied by pulse synchronous tinnitus (a whooshing noise in one or both ear(s) that occurs in sync with one’s pulse), which is the third most common reported symptom of IH. Visual symptoms are the second most common reported symptoms of IH. They include spontaneous dim-outs of vision in one or both eyes; momentary grey spots or dots perceived in one or both eyes (transitory visual obscurations or TVOs), especially with a change in position; blurred vision; and double vision (diplopia) These are all signs of intracranial hypertension headaches, rather than migraine. Additionally, they may indicate papilledema (swollen optic nerves), a diagnostic sign of intracranial hypertension.
Importantly, these visual symptoms are different from the temporary flashing or flickering objects that usually last for about 20 minutes (known as an aura) that some people see before the onset of a migraine headache, which then disappear after the headache begins.
An IH headache does not necessarily occur in one specific area. It is not unusual for some individuals with IH to experience pain behind eyes (which may be worse by eye movement), while others might find the headache occurs at the back of the head or begins on one side.
What causes the IH headache?
The actual cause of headache with intracranial hypertension is unknown. Other factors besides increased intracranial pressure may play a role including a predisposition to headache.
How long does an IH headache last?
The answer to this question depends on each individual. An actual episode of headache may last hours, days, even weeks. Many people with chronic IH live with daily headache that never truly goes away. Others may experience cycles of headache, in which their headaches may become more severe for a period of time. Some women with chronic IH report that their headaches become significantly worse during menstruation.
Each of these experiences holds important clues for researchers. Determining why an IH headache occurs is vital to understanding how to treat and prevent it.
How is an IH headache treated?
Lowering intracranial pressure is key to treating IH headaches. This is usually done by physically removing excess spinal fluid or by inhibiting spinal fluid production through the use of drugs known as carbonic anhydrase inhibitors.The most common carbonic anhydrase inhibitor is acetazolamide (Diamox), though no drug has ever been specifically developed to treat intracranial hypertension. Other drugs thought to have less potent carbonic anhydrase inhibition properties than acetazolamide include Lasix (furosemide), Topamax (topiramate), and Neptazane (methazolamide).
Lumbar punctures, or spinal taps, may temporarily ease the IH headache; however, since spinal fluid regenerates quickly (.3cc per minute), long-term use of this therapy has limited benefits. Surgery to implant a neurosurgical shunt may also be an option if drug therapy hasn’t adequately reduced intracranial pressure. But better, more effective treatments—either drug or surgical–to lower intracranial pressure are needed.