Basilar-Type Migraine - The Basics
Important Note: Due to changes in the International Headache Society's International Classification of Headache Disorders (ICHD), this form of migraine is now called migraine with brainstem aura. This article has been replaced by Migraine with Brainstem Aura - The Basics.
A Migraine-type defined by the presence of Migraine headache with neurological symptoms which begin either in the base of the brain or from both sides of the brain at the same time; i.e. brainstem or both cerebral hemispheres.
Many compare this Migraine type more to hemiplegic Migraine (Migraine type with weakness) than to Migraine with typical aura (99% visual symptoms). Those with less understanding of this Migraine consider it as "atypical or complicated" aura.
All patients describe visual symptoms, nearly 2 of 3 sensory and least often language or aphasic aura. Vertigo is the most frequent symptom type.
In actuality, nearly all basilar-type Migraineurs suffer typical Migraine with aura as well; just more frequent sensory and speaking difficulties of longer duration and intensity.
Obtain a correct diagnosis, optimal treatment plan, and prevent as many Migraines as possible to reduce disability and improve prognosis.
Introduction If you've heard of this type of Migraine before, you've probably heard or seen the term basilar artery Migraine (BAM). Under the International Headache Society's International Classification of Headache Disorders-2004, the new designation for this type of Migraine is basilar-type Migraine (BTM). It has also been called Bickerstaff syndrome, brainstem Migraine, and vertebrobasilar Migraine. The term BAM is actually misleading as it implies that the basilar artery is the origin of the attack. It was termed basilar by Bickerstaff in 1961-62. He reported his beliefs that the events of BTM were the result of short term narrowing or spasm of the basilar artery. Reduced blood flow or "ischemia" followed and was believed to increase risk for serious events. This belief remained a concern for over 3 decades. It even resulted in the exclusion of BAM patients from clinical trials of triptans for Migraine. The absence of BAM patients in trials led the Federal Drug Administration (FDA) to contraindicate use of triptans in patients with BAM.
Migraine in now known as a common but complex genetic disorder involving environmental factors. The nerves are the cause in BTM as they are in other Migraine types. As with all Migraine, there is a blood vessel component once Migraine begins, but Migraine begins in nerves. Bickerstaff suggested that BTM was most common in adolescent females. Now BTM is known to affect all age groups. BTM does exhibit the same female predominance seen overall in Migraine; three times as many female sufferers as male.
Symptoms of BTM Basilar-type Migraine is a Migraine-type that has aura symptoms originating from the base of the brain or both sides of the brain at the same time, but with no motor weakness. These areas are named brainstem and cerebral hemispheres of the brain. In a study of familial Migraine, 95% of those meeting criteria for BTM also met criteria for Migraine with aura. In this BTM group 50% of all auras met BTM criteria. The most frequent symptom in BTM is vertigo. Among all BTM subjects 31% reported two, 45% three, 8% four, 8% five, and 8% six aura symptoms. All patients (100%) described visual aura; 40% with symptoms in both fields of vision and 60% with only one side of vision affected. Temporary blindness can be reported, which is one reason BTM can be quite scary. Symptoms involving sensation or sensory aura occur in 61% with the same involvement on both (40%) or one side (60%) as visual aura. Symptoms involving ability to form words or sentences, called aphasic aura, were present in 40%. Visual aura was the most common initial symptom in 2 of 3. Headache accompanied or followed aura in 98% and met criteria for Migraine or probable Migraine in 98%. The median length of aura of BTM in this study was 60 minutes, but with as short as 2 minutes and as long as 72 hours. The authors of this data concluded that there is insufficient evidence to distinguish basilar-type Migraine as a disease independent of Migraine with typical aura.
The Diagnosis of BTM According to the strict criteria of the International Classification of Headache Disorders (ICHD-2004) at least 2 attacks meeting the following are required:
Aura consisting of at least two of the following fully reversible symptoms, but no motor weakness:
impairments or clumsiness in the speaking of words due to diseases that affect the mouth, tongue, or throat muscles (dysarthria)
feeling of spinning (vertigo)
noise in the ears (tinnitus)
impaired hearing (hypacusia)
double vision (diplopia)
typically spots or flashes simultaneously in both temporal and nasal fields of both eyes
in-coordination of limbs or walking (ataxia)
decreased level of consciousness (state of being alert)
paresthesias (abnormal or unpleasant sensation often described as numbness or as a prickly, stinging, or burning feeling) at the same time on both sides of the face, arms or legs
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 (note this length does not hold up to patient histories)
headache meeting criteria of Migraine without aura begins during the aura or follows aura within 60 minutes
This Table of Clinical Characteristics of Basilar-type Migraine adapted from Kirchmann et al and Kaniecki simplify how your BTM diagnosis may be made compared to the strict ICHD-2004 criteria.
Always 2 or more basilar-type aura symptoms
Always visual aura characterized by positive or negative features
Sometimes with sensory aura characterized by positive or negative features
Sometimes with either aphasia or dysarthria
Aura symptoms almost always develop gradually, or occur in succession, over > 5 minutes
Aura duration 5-120 minutes
Headache with Migraine features begins after onset of aura
Age of onset < 50 years
Almost always co-existing attacks of Migraine with typical aura
Correct Diagnosis Migraine experts caution that when there is motor weakness, great care be taken to arrive at the proper diagnosis. At times it can be difficult to differentiate between Migraine types. Basilar-type Migraine, hemiplegic Migraine (HM) and non-familial Migraine with unilateral (one-sided) motor symptoms (MUMS) with give-way weakness are several examples. The classification committee for the ICHD-2004 comments on similarities of HM and BTM indicating that basilar symptoms are common in HM. If motor weakness is present the current ICHD-2004 criteria require diagnosis as familial hemiplegic or sporadic (non-familial) hemiplegic Migraine. Comments are made that motor weakness can be difficult to tell apart from sensory problems. Another reason an expert Migraine and headache provider is needed in diagnosis is that many of the symptoms of BTM mimic other far more serious medical conditions. It is essential that the diagnosis be definitive and correct. This may require imaging as discussed next. If the provider making the diagnosis is hesitant about it, definitely seek a second opinion from another provider. Since features and associations of BTM are not well known to many providers, seeing a Migraine and headache specialist is advisable when possible. You may achieve best advice if this provider is certified by the United Council of Neurological Subspecialties (UCNS). Find a Healthcare Professional. It is also important to continue medical treatment as advised by your doctor and not skip follow-up appointments. Upon correct diagnosis BTM sufferers should consider having medical identification of some kind on their person as many providers will not recognize BTM. This will alert them to refresh what they know.
Tests Get a head CT scan if recent bleeding in the brain is a concern. Otherwise evaluation should be a brain MRI with and without intravenous (IV) contrast. Avoid contrast with proven allergy or kidney function less than 30 GFR (unlikely due to age, gender of most patients). In diagnosing BTM imaging helps rule out:
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.
An EEG is often performed to rule out seizure disorders which are especially a consideration with new events, confusion or change in the alert state and younger patients.
Treatment Migraine-specific medications such as the triptans and ergotamines are contraindicated for BTM. This is because they were not studied in scientific trials of Migraine. This is due to a belief at the time that artery narrowing or spasm was the cause of these symptoms. The triptans and ergotamines are known to constrict blood vessels and were believed to likely cause safety issues if used. Such beliefs however did not lead to the exclusion of Migraine with aura patients. As described above, BTM is essentially a Migraine with aura subtype. Three Migraine and headache specialists in 2001 reported on 13 patients with basilar-type Migraine, familial hemiplegic Migraine, or Migraine with prominent or prolonged aura who had received triptans. No harm was done (no adverse events) with excellent relief of headache and symptoms. They concluded that the contraindication of triptans in basilar-type Migraine should be reconsidered. They also wrote that prominent or prolonged aura may not represent a reasonable contraindication to triptan therapy. In a larger group of patients meeting criteria for BTM, no increased incidence of adverse events was reported following inadvertent or intentional triptan exposure. To avoid the historical restriction on artery narrowing drugs a combination of nonsteroidal anti-inflammatory with and an antiemetic phenothiazine is often used and can be effective. It is also reasonable to discuss your treatment needs with your provider and obtain an expert opinion if offered only a non-specific treatment. An effective treatment plan will require acute use typically early in less than 15-60 minutes and when possible at mild pain.
Of the preventive medications, there is some evidence in children for topiramate success. Many use a calcium channel blocker with benefit although this is based on experience only. Otherwise, BTM is generally managed with traditional preventatives although many recommend that beta blockers be avoided due to rare reports of complicating events.
Disability and Prognosis As with other forms of Migraine, BTM can be disabling. Because of the neurological symptom types, with vertigo the most frequent, BTM is often more debilitating than Migraine with aura due to aura intensity, number of symptoms and longer length. Perhaps fortunately, the majority of BTM patients are older children, adolescents or young adults. Basilar-type Migraine can mean special problems for people in the traditional work force or trying to care for young children. For many, however, aura in BTM commonly becomes more typical during later mid-life. While disabling, symptoms of BTM are usually more frightening than harmful. A concern or myth about stroke risk has existed for decades. There is no evidence that BTM patients have any greater stroke (cerebrovascular) risk than Migraine with typical aura. Migraine with aura does have a slightly higher stroke risk than Migraine without aura in those younger than 45, so optimal prevention and knowledge of stroke risk factors and their control is important. As a BTM patient, if others are not educated about BTM, it is particularly important that efforts be made to inform them.
Summary Basilar-type Migraine is one type of Migraine with aura; it is one of the most frightening of head pain disorders. As with other forms of Migraine, it is necessary to have an accurate diagnosis and effective treatment plan. This requires use of that treatment as early as possible when pain is mild without waiting to learn how extreme the pain will become. Severe BTM will often require seeking emergency care. Unfortunately, ED/ERs will often fail to consider BTM as your diagnosis. It may be reasonable that BTM sufferers have medical identification of some kind on their person; consider a Medical ID as important. If providers do consider it, they typically will not know how to treat it. Access to a Migraine and headache specialist is also important. Once diagnosed with BTM, it is important (as with any form of Migraine) to minimize the frequency of attacks through optimal prevention. Also contact your provider if your symptoms or Migraine pattern change. Without consulting a knowledgeable provider, 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, be sensible and take good care of yourself.