If you've heard of this form of migraine before, you've probably heard or seen the terms basilar artery migraine (BAM) or basilar-type migraine (BTM). Under the International Headache Society's _ International Classification of Headache Disorders, 3rd Edition_, the new designation for this form of migraine is migraine with brainstem aura (MBSA). It has also been called Bickerstaff syndrome, brainstem migraine, and vertebrobasilar migraine. The term basilar-type migraine was actually a bit misleading as it implied that the migraine attack was vascular in origin. It was actually termed basilar because it was first believed to be a result of spasm of the basilar artery and the subsequent ischemia. The basilar artery is part of the posterior cerebral circulation, and is formed where the two vertebral arteries join together at the base of the skull.
Since the time when the term basilar came into use, however, it has been shown that migraine is a genetic neurological disease, and MBSA, as other types of migraine are neural in origin. As with all migraine, there can be a vascular component once the migraine begins, but the origin is neurological. Early literature on the subject suggested that MBSA was most common in adolescent females. However, continued research and statistical analysis has shown MBSA to affect all age groups and both male and female. MBSA does exhibit the same female predominance seen overall in migraine; three times as many female sufferers as male.
Migraine with brainstem aura has aura symptoms originating from the brainstem, but with no motor weakness. Prior to the new knowledge that has led to this form of migraine not being called "basilar artery" or "basilar-type" migraine, migraine-specific medications such as the triptans and ergotamines were contraindicated for this form of migraine. Given that it's no longer thought that the basilar artery is involved, we're not sure if this contraindication continues to make sense. Of the preventive medications, it's recommended that beta blockers be avoided in cases of MBSA. Because of the medication contraindications, I highly recommend that migraineurs who experience MBSA wear some kind of medical identification at all times.
It's important to understand the symptoms of migraine with brainstem aura and the symptoms that are required for that diagnosis. To that end, here's the International Headache Society's diagnostic criteria for migraine with brainstem aura:
1.2.2 Migraine with brainstem aura
Previously used terms: Basilar artery migraine; basilar migraine; basilar-type migraine.
Migraine with aura symptoms clearly originating from the brainstem, but no motor weakness.
- At least two attacks fulfilling criteria B-D
- Aura consisting of visual, sensory and/or speech/ language symptoms, each fully reversible, but no motor1 or retinal symptoms
- At least two of the following brainstem symptoms:
- decreased level of consciousness
- At least two of the following four characteristics:
- at least one aura symptom spreads gradually over 5 minutes or more, and/or two or more symptoms occur in succession
- each individual aura symptom lasts 5-60 minutes2
- at least one aura symptom is unilateral3
- the aura is accompanied, or followed within 60 minutes, by headache
- Not better accounted for by another ICHD-3 diagnosis, and transient ischaemic attack has been excluded.
- When motor symptoms are present, code as 1.2.3 Hemiplegic migraine.
- When for example three symptoms occur during an aura, the acceptable maximal duration is 3 60 minutes.
- Aphasia is always regarded as a unilateral symptom; dysarthria may or may not be.
Originally the terms basilar artery migraine or basilar migraine were used but, as involvement of the basilar artery is unlikely, the term migraine with brainstem aura is preferred.
There are typical aura symptoms in addition to the brainstem symptoms during most attacks. Many patients who have attacks with brainstem aura also report other attacks with typical aura and should be coded for both 1.2.1 Migraine with typical aura and 1.2.2 Migraine with brainstem aura.
Many of the symptoms listed under criterion C may occur with anxiety and hyperventilation, and therefore are subject to misinterpretation.
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 migraine with brainstem aura 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 MBSA 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 MBSA 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 MBSA 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, MBSA can be disabling. Because of the neurological symptoms that can occur during the 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.
Migraine with brainstem aura is one of the more frightening types of migraine, but the symptoms are usually more frightening than harmful. However, as with other forms of migraine, if the pain or other symptoms are extreme or different from the usual pattern, it is best to seek medical care. Once diagnosed with MBSA, 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 MBSA, and that no other condition is present. While MBSA isn't cause to panic, it is more than reason to be sensible and take good care of yourself.
Saper, Joel R., M.D.; Silberstein, Stephen, M.D.; Gordon, C. David, M.D.; Hamel, Robert L., P.A.-C; Swidan, Sahar, Pharm.D. "Handbook of Headache Management." Baltimore, Maryland: Lippincott Williams & Wilkins, 1999.
Tepper, Stewart J., M.D. Understanding Migraine and Other Headaches. University of Mississippi Press, 2004.
Young, William B. and Silberstein, Stephen D. Migraine and Other Headaches. St. Paul, Minnesota: AAN Press, 2004.
Evans, Randolph W.; Matthew Ninan T. "Handbook of Headache." Philadelphia: Lippincott Williams & Wilkins. 2000.
Headache Classification Committee of the International Headache Society. “The International Classification of Headache Disorders, 3rd edition (beta version).” Cephalalgia. July 2013 vol. 33 no. 9 629-808 10.1177/0333102413485658
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