If you've heard of this form of Migraine before, you've probably heard or seen it called Basilar Artery Migraine (BAM). Under the International Headache Society's International Classification of Headache Disorders, the new designation for this form of Migraine is Basilar-Type Migraine (BTM). Early literature suggested that BTM was most common in adolescent females. Continued research and statistical analysis has shown BTM to affect all age groups and both male and female. BTM does exhibit the same female predominance seen overall in Migraine; three times as many female sufferers as male.
A Basilar-Type Migraine is a Migraine that has aura symptoms originating from the brainstem and/or affecting both hemispheres of the brain at the same time, but rarely any motor weakness. Many Migraineurs who have BTM also report Migraine with typical aura. The aura of BTM can include temporary blindness, which is one reason they can be quite terrifying. However, BTM is actually essentially Migraine with aura where the aura is localized to the brainstem. Still, because of that localization, Migraine-specific medications such as the triptans and ergotamines are contraindicated for BTM. Because of the medication contraindications, I highly recommend that Migraineurs who experience BTM wear some kind of medical identification at all times. Diagnosis of BTM requires at least two attacks meeting the following criteria:
Aura consisting of at least two of the following fully reversible symptoms, but no motor weakness:
- dysarthria (impairments or clumsiness in the speaking of words due to diseases that affect the oral, lingual, or pharyngeal muscles)
- hypacusia (impaired hearing)
- visual symptoms simultaneously in both temporal and nasal fields of both eyes
- decreased level of consciousness
- simultaneously bilateral paresthesias (abnormal or unpleasant sensation often described as numbness or as a prickly, stinging, or burning feeling)
At least one of the following:
- at least one aura symptom develops gradually over five or more minutes and/or different aura symptoms occur in succession over five or more minutes
- each aura symptom lasts five or more and 60 minutes or less
- headache meeting criteria Migraine without aura begins during the aura or follows aura within 60 minutes
BTM symptoms can mimic other, far more serious conditions. It is essential that the diagnosis be correct. A CT scan or MRI should be performed to rule out other causes for the symptoms. An EEG is often performed to rule out seizure disorders. If your doctor hesitant about the diagnosis, seek a second opinion. Since BTM is not common, seeing a Migraine specialist is advisable when possible. Continue medical treatment as advised by your doctor and don't skip follow-up appointments. Some other conditions that should be ruled out in diagnosing BTM are:
- seizure disorders
- space-occupying lesions of the brain
- brainstem Arteriovenous Malformation (AVM): a congenital defect consisting of a tangle of abnormal arteries and veins with no capillaries in between.
- vertebrobasilar disease
Basilar-Type Migraine is one of the most frightening of head pain disorders, but the symptoms are generally frightening, not harmful. Because BTM does slightly increase stroke risk, it is essential to seek emergency care if an attack becomes unusually severe. Once diagnosed, it is important to consult your doctor if your symptoms or Migraine pattern change to be sure that new symptoms or changes in pattern are attributable to BTM, and that no other condition is present. While BTM isn't cause to panic or be more fearful, it is reason to be sensible and take good care of yourself.
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