BTM (Basilar Type Migraine)

Basilar-Type Migraine

This form of migraine was previously known as Basilar Artery Migraine (BAM). Under the International Headache Society’s International Classification of Headache Disorders, 2nd Edition, the new designation for this form of Migraine is Basilar-Type Migraine (BTM). It has also been called Bickerstaff syndrome, brainstem Migraine, and vertebrobasilar Migraine.

The term Basilar-Type Migraine is actually a bit misleading as it implies that the Migraine attack is vascular in origin due to spasm of the basilar artery and the subsequent ischemia.

Since the time when the term Basilar came into use, however, it has been shown that Migraine is a genetic neurological disease, and BTM, as other types of Migraine are neural in origin.

As with all Migraine, there is a vascular component once the Migraine begins, but the origin is  neurological. Early literature (Bickerstaff 1962) suggested that BTM was most  common in adolescent females. However, presently it is seen 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 with no motor weakness.
The aura of BTM usually lasts less than 60 minutes, but in some cases can be more extended. 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 with the aura localized to the brainstem. Still, because of that localization, Migraine-specific medications such as the triptans and ergotamines are contraindicated for BTM. Of the preventive medications, it’s recommended that beta blockers be avoided in cases of 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)
diplopia (double vision)
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

Migraine experts caution that when there is motor weakness, great care be taken to arrive at the proper
diagnosis as there are times when it can be  difficult to differentiate between Basilar-Type Migraine and
Hemiplegic Migraine. The IHS criteria also note that if motor weakness is present, the disorder should
be coded as Familial Hemiplegic or Sporadic Hemiplegic Migraine.
Another reason great care must be taken in diagnosis is that many of the symptoms of BTM are also
stroke symptoms.
Basilar-Type Migraine presents symptoms that can mimic other, far more serious conditions. It is
essential that the diagnosis be definitive and correct. An imaging study such as a CT scan or MRI
should be performed to rule out other causes for the symptoms, and an EEG is often performed to
rule out seizure disorders. If the doctor making the diagnosis is hesitant about it, definitely seek a second
opinion from another doctor. Since BTM is not common, seeing a Migraine specialist is advisable when
possible. It is also important to continue medical treatment as advised by your doctor and not 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. The blood pressure in the veins is higher than
normal and may result in a rupture of the vein and bleeding into the brain.
vertebrobasilar disease

As with other forms of Migraine, BTM can be disabling. Because of the neurological symptoms that can
occur during Basilar-Type Migraine aura, it can present a larger hurdle than Migraine with aura because
the aura itself is debilitating and can last longer. This can mean special problems for people in the
traditional work force or trying to care for young children. If they are in an environment where others are
not educated about Migraine disease, it is particularly important that efforts be made  to educate those
around them.
Basilar-Type Migraine is one of the most frightening of head pain disorders, but the symptoms are
usually more frightening than harmful.
However, as with other forms of Migraine, if the pain is extreme, it is best to seek emergency care. BTM
does increase the risk of stroke slightly more than Migraine with aura and Migraine without aura, so
additional care should be taken. Once diagnosed with BTM, it is important (as with any form of
Migraine) to consult your doctor if your symptoms or Migraine pattern change. Without consulting a
doctor, it’s impossible 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, it is more than reason to be sensible
and take good care of yourself.

In basilar migraine and in other migraine equivalent vertigos the otological aspect is subsidiary to the
main disease. Investigation fails to reveal a primary labyrinthine disorder and treatment is the province of medical or neurological specialties.