An Overview of Paroxysmal Hemicrania

Paroxysmal hemicrania is a rare primary headache disorder that typically begins in adulthood and is more common in women than men.

This disabling disorder manifests as excruciatingly severe, one-sided headache attacks that generally last from two to 30 minutes, but may go on for up to two hours. The attacks have an abrupt beginning and end and occur anywhere from five to forty times a day.

While an upside to this headache disorder may not seem possible, there is one—paroxysmal hemicrania is treatable, with a simple daily medication.

This article explores what paroxysmal hemicrania feels like, its associated symptoms, and how headache specialists diagnose and treat it.

Symptoms

The pain of paroxysmal hemicrania is excruciatingly severe, and described with varying terms, such as "sharp", "stabbing", "throbbing", "claw-like," or "burning." The location of the pain is strictly one-sided and generally located around or behind the eye or in the temple area. Less commonly, the pain may occur in the forehead or the back of the head.

Besides head pain, there are cranial autonomic symptoms associated with this headache disorder. Autonomic symptoms result from a firing of pain-sensing nerves surrounding the brain. These nerves signal the autonomic nervous system, which controls parts of your body that you cannot consciously influence like your sweat and tear glands.

Some of these cranial autonomic symptoms include:

• Runny or stuffy nose
• Sweating or flushing of the face
• Redness or tearing of the eye
• Eyelid drooping or swelling
• Facial flushing
• Forehead or facial sweating
• Ear fullness

Other symptoms seen with paroxysmal hemicrania include agitation, restlessness, photophobia (a sensitivity to light) and nausea. Interestingly, research has found that if photophobia is present with paroxysmal hemicrania, it's more likely to be one-sided (the same side as the headache), whereas, in migraine, the photophobia most often occurs on both sides of the head.

Vomiting and phonophobia (sensitivity to sound) are not present with paroxysmal hemicrania, as they often are in migraine.

Types

There are two types of paroxysmal hemicrania, chronic and episodic.

Chronic Paroxysmal Hemicrania

The majority (around 80%) of people with paroxysmal hemicrania have the chronic form, in which no spontaneous relief from the headache attacks occurs within one year, or if relief does occur (called a remission), it is short-lived, lasting less than one month.

Episodic Hemicrania

Those who experience remissions of at least a month-long within a year of experiencing headache attacks have episodic paroxysmal hemicrania. A person with episodic paroxysmal hemicrania can eventually develop chronic paroxysmal hemicrania and vice versa, although most people have the chronic form from the start. 

Causes

The cause behind paroxysmal hemicrania is unknown but believed to be related to the trigeminal nerve, which is a cranial nerve that provides sensation to your face.

Despite the unknown "why" behind paroxysmal hemicrania, sufferers report a range of triggers, the most common ones being:

• Stress or relaxation after stress
• Exercise
• Alcohol
• Certain head or neck movements
• External pressure to the neck

Diagnosis

Paroxysmal hemicrania is a primary headache disorder, which means it occurs on its own and is not the result of another medical condition.

Due to the relative rarity of this headache disorder, and the fact that its symptoms can mimic those of other primary headache disorders, such as primary stabbing headache and cluster headache, the diagnosis of paroxysmal hemicrania requires a thorough medical history and examination by a headache specialist.

One reason is that several criteria, according to the International Classification of Headache Disorders, must be met in order to receive a diagnosis of paroxysmal hemicrania.

These criteria include:

• A person must have experienced at least twenty attacks.
• The pain must be severe, be located around or behind the eye and/or temple, and last from two to 30 minutes.
• At least one autonomic symptom (on the same side of the headache) must be present.
• Attacks must occur more than five times per day for more than half the time.
• Attacks are prevented absolutely by proper doses of Indocin (indomethacin).

Indomethacin Test

Indomethacin is a nonsteroidal anti-inflammatory (NSAID) that provides complete relief from paroxysmal hemicrania (why responsiveness to indomethacin is a criterion). The problem is that other headache disorders may also be alleviated with indomethacin, so it's not a slam dunk test, albeit a pretty convincing one if suspicion is high for paroxysmal hemicrania.

Brain MRI

Besides these criteria and a careful neurological examination, which should be normal with paroxysmal hemicrania) a brain magnetic resonance imaging (MRI) is important for the initial diagnosis. With a brain MRI, abnormalities within the brain that may mimic symptoms of paroxysmal hemicrania, like a pituitary brain tumor or blood vessel problem, can be ruled out.

Treatment

The primary treatment for paroxysmal hemicrania is Indocin (indomethacin). Taking indomethacin every day means that treatment is focused on prevention, considering attacks of paroxysmal hemicrania are sometimes too short to treat right at that moment.

While a daily medication, the good news is that most people experience absolute headache cessation within one to two days of starting indomethacin. Still, paroxysmal hemicrania tends to be a lifelong condition

Dose

The usual starting dose of indomethacin is 25 mg three times a day for adults, and one to two milligrams per kilogram every day, given in two divided doses, for children fourteen years of age and younger.

Keep in mind, though, close follow-up with your headache specialist is needed, as your indomethacin dose may need to be altered based on the varying severity and frequency of attacks.

Withdrawal

While indomethacin is perhaps a medical cure for most with paroxysmal hemicrania, upon stopping the drug, headaches tend to recur, as soon as twelve hours and up to two weeks upon discontinuation. This is why it is important to take indomethacin as prescribed, and not skip or delay any doses.

When you and your headache specialist decide to stop indomethacin (more commonly with the episodic form), a gradual tapering down of the medication is important to minimize the likelihood of the headaches returning.

Side Effects

As an NSAID, there are a number of potential side effects associated with indomethacin, most commonly gastrointestinal problems, like stomach discomfort and heartburn. Other side effects include dizziness, diarrhea, constipation, feeling sleepy or tired, among others.

Bleeding, high blood pressure, kidney, and heart problems are more serious potential concerns. Moreover, some people have an allergy to NSAIDs. Signs of an allergy may include hives, itching, red, swollen, blistered, or peeling skin, wheezing, chest or throat tightness, problems breathing, or swelling of the mouth, lips, or tongue.

In addition to reviewing side effects and allergies with your healthcare provider, be sure to give your practitioner a list of all of your vitamins, supplements, and medications, both prescription and over-the-counter. This way your healthcare provider can ensure there are no unsafe interactions with indomethacin.

Other Options

For those who cannot take indomethacin (for example, if a person has a history of an NSAID allergy or a history of stomach ulcer disease), or for the rare person who does not respond to indomethacin (if this is the case, the diagnosis of paroxysmal hemicrania should be greatly questioned), other medication options include:

• Verapamil: A blood pressure medication, called a calcium channel blocker, rarely used in migraine prevention.
• Tegretol (carbamazepine): An anti-seizure medication traditionally used to treat trigeminal neuralgia.
• Topamax (topiramate): An anti-seizure medication used in migraine prevention.
• Amitriptyline (Elavil): An atypical antidepressant used in migraine prevention.

Sometimes, headaches specialist will consider aspirin or other NSAIDs (if there is no contraindication), like Aleve (naproxen), Voltaren (diclofenac), or Feldene (piroxicam).

For people who continue to experience headaches despite medication, peripheral nerve blockade (for example, greater occipital blockade or supraorbital nerve blockade) may be an option, although the scientific data backing up its benefit is scant.

Acute Therapy

For acute therapy (treating the attack right in the moment) medications used, include:

• Indomethacin (most common)
• Imitrex (sumatriptan)
• Oxygen
• Nerve blockade
• Feldene (piroxicam)
• Steroids like prednisone (least common)

A Word From Verywell

In summary, the two key features of paroxysmal hemicrania are the following:

• The headache is strictly located on one side of the head
• The headache resolves (nearly always) with indomethacin

With the rarity of paroxysmal hemicrania, though, be sure to see a headache specialist for a proper diagnosis. Other conditions, like a pituitary gland problem, which can mimic the symptoms of this unique headache disorder need to be ruled out first.