1.2.6 Basilar-type migraine

G43.103

Migraine with aura symptoms clearly originating from the brainstem and/or from both hemispheres simultaneously affected, but no motor weakness.

Basilar migraine

Basilar artery migraine

Bickerstaff migraine

Basilar-type migraine (1.2.6) is a new term, replacing basilar migraine (4). The change is intended to remove the implication that the basilar artery (or its territory) is involved (5). The distinguishing feature of basilar-type migraine is a symptom profile that suggests posterior fossa involvement.

Basilar-type migraine was first brought to attention by Bickerstaff (6), after seeing a teenager whose aura symptoms were long lasting, bilateral, and very prominent. Shortly after, the same clinician saw an elderly man, with aura symptoms that rapidly progressed into coma and death. Autopsy showed thrombosis in the basilar artery. After collecting data on 34 patients, Bickerstaff postulated that “some prodromal symptoms … are not in the territory of the internal carotid, but of the basilar artery. The premonitory symptoms are different and reflect brainstem dysfunction. Symptoms consist of bilateral loss or disturbance of vision, ataxia, dysarthria, vertigo, tinnitus, and bilateral peripheral dysesthesias, followed by occipital headache. The syndrome is commonest in adolescent girls” (6,7).

Studies on the pathophysiology of basilar migraine are scarce. For years this headache was thought to originate from a transient disturbance in the vertebrobasilar circulation (6, 7, 8). Almost two decades ago, neurophysiology studies using electroencephalogram suggested the neurophysiologic basis of basilar-type migraine, by detecting a typical photoconvulsive response (9). Other studies focused on the vascular mechanism of basilar-type migraine. La Spina et al., in 1996 (10), documented a basilar-type migraine attack using transcranial Doppler (TCD), electroencephalography (EEG), and single-photon emission computed tomography (SPECT). In the aura phase, the patient had bilateral blindness and ataxia. Doppler ultrasound revealed reduced mean flow velocity of the posterior cerebral arteries, EEG showed posterior slow activity, and SPECT documented hypoperfusion in the right parietal and occipital regions. During the headache phase with normal neurologic examination, TCD showed an increase in the mean flow velocity of both posterior cerebral arteries and the EEG revealed increased in occipital slow activity. When headache subsided, EEG slow activity resolved and the TCD findings were normal.

Current migraine theories consider migraine as a state of neuronal hyperexcitability, and that neuronal events mediate both the aura and headache phases of migraine (11, 12, 13), although studies specifically investigating basilar-type migraine are still lacking. These findings support transient focal reduction of cerebral blood flow during the aura phase. It remains to be determined if the vascular changes are the cause or, as in other forms of migraine with aura, the consequence of neuronal dysfunction. To date, mutations in CACNA1A, encoding a neuronal calcium channel subunit, and ATP1A2, encoding a catalytic subunit of a sodium-potassium-ATPase, have not been found in subjects with basilar-type migraine (14).

In classifying basilar-type migraine, the following criteria are required (1):

A. At least two attacks fulfilling criteria B through E.

B. Fully reversible visual and/or sensory and/or speech aura but no motor weakness.

C. Two or more fully reversible aura symptoms of the following types:

1. Dysarthria

2. Vertigo

3. Tinnitus

4. Decreased hearing

5. Double vision

6. Ataxia

7. Decreased level of consciousness

8. Simultaneous bilateral visual symptoms in both the temporal and nasal field of both eyes

9. Simultaneous bilateral paresthesias

D. Headache that meets criteria B through D for migraine without aura (1.1) begins during the aura or follows aura within 60 minutes

E. Not attributed to another disorder

It is important to note that if distinct motor weakness is present, the diagnosis should be hemiplegic migraine even when “basilar symptoms” are present (hemiplegic migraine sufferers have basilar-type symptoms in 60% of cases) (15).

Basilar-type migraine affects all age groups with the usual female predominance, but is most common among teenage girls (16,17). A distinguishing feature of basilar-type migraine is the bilateral nature and posterior fossa origin of many of the associated symptoms (16), differentiating it from typical migraine. Visual aura, if present, is usually followed by one of the distinguishing symptoms of this disorder. A hemianopic field disturbance can rapidly expand to involve both visual fields, leading at times to temporary blindness that may precede other symptoms (17). Alterations in consciousness may be present, especially in younger subjects (18). Basilar-type migraine with prominent alteration of consciousness is often called confusional migraine, a term not adopted by the second edition of the International Classification of Headache Disorders (1).

Occipital headache appears more frequent in basilar-type migraine than in typical migraine with aura (19). Headache is most frequently throbbing. In one case series, nausea was present in most patients (83%). Two studies showed that alteration of consciousness (45% and 75%), vertigo (41%, 63%), bilateral visual disturbances (48%, 86%), bilateral sensory changes (14%, 61%), and ataxia (17%, 63%) are common symptoms in basilar-type migraine (16,19).