Basilar Migraine

Etiology

The exact etiology of migraine with brainstem aura is not known. Like other types of migraines, environmental factors play a role. The genetic role is suggested, but no definite linkage has been found yet. Common triggers (like in other types of migraine) include strong smells, loud noises, weather changes, excessive sleep, lack of sleep, increased stress, intense physical exertion, oral contraceptives, foods like cheese, alcohol, caffeine, and certain food preservatives like monosodium glutamate (MSG).[1][2][3][4]

Epidemiology

Actual prevalence and incidence are unknown. It is more common in females than in males. It can occur at all ages but is more common in adolescence and young adults. The age of onset is usually 7 to 20.

Pathophysiology

Basilar migraine was initially thought to have vascular pathology caused by short-term spasms of the basilar artery. However, the vascular hypothesis could not be proved, and it is now believed that like other migraine types, the basilar migraine is related to nerves.

Basilar migraine is now believed to be a type of migraine with aura. The aura is a result of cortical spreading depression, which is a self-propagating wave spreading across the cerebral cortex due to the depolarization of neurons and glia. Location of aura symptoms in a basilar migraine is brainstem or both occipital hemispheres; whereas, in migraine with typical aura, it mainly involves a unilateral hemisphere.

There is little data regarding the genetic basis of basilar migraine. Basilar type aura may be triggered by genes involved in migraine with a typical aura. Some reports suggest that the FHM gene may be involved in a basilar migraine without hemiplegia. However, no definitive genetic linkage is identified.[5][6][6]

History and Physical

Brainstem aura symptoms include vertigo, dysarthria, diplopia, tinnitus, impaired hearing, lack of coordination, confusion, and sometimes loss of consciousness. The most common symptom is vertigo. Most patients also have typical aura symptoms like photopsia, loss of vision, paresthesia, speech, and language problems like word-finding difficulty, language comprehension, and difficulty reading. Some patients may have associated anxiety and hyperventilation which can lead to misdiagnosis. All aura symptoms are completely reversible. Aura symptoms can last a few minutes to an hour followed by an occipital headache that may last hours to days. Rarely, migraine with brainstem aura occurs without a headache. Prodromal symptoms of migraine-like mood swings, irritability, tiredness, nausea, and neck pain should not be confused with aura symptoms. There are no motor or retinal symptoms in migraine with brainstem aura and symptoms like weakness, paralysis, loss of vision in one eye should prompt evaluation for an alternate diagnosis.

Symptoms can be very frightening especially when they occur the first time or until a definite diagnosis is made. Symptoms of brainstem aura can mimic some serious diseases like stroke, tumors, and infections, so it is important to seek medical attention the first time or if there is any change in symptom severity and frequency. Symptoms of migraines with brainstem aura are usually more frightening than harmful, as they are completely reversible.

Diagnosis

The International Classification of headache disorders outlined the following criteria for the diagnosis of basilar migraine.

• (A) Symptoms not attributed to another disorder
• (B) At least 2 attacks that fulfill criteria C, D, or E
• (C) Aura with more than one of the following symptoms: dysarthria, vertigo, tinnitus, hearing impairment, diplopia, ataxia, decreased level of consciousness, bilateral paresthesia, with no motor or retinal symptoms, and completely reversible symptoms
• (D) At least one of the following: At least 1 aura symptom occurring gradually over 5 minutes or more and/or 2 or more symptoms occurring in succession over 5 minutes or more, each aura symptom lasts more than 5 minutes, but less than 60 minutes, at least 1 aura symptom is unilateral
• (E) Migraine without aura begins during the aura or within 1 hour.[5][6][7][8][9]

Evaluation

Brain imaging like MRI head, MRA head, or CT angiography is usually indicated to rule out other pathologies like stroke, AV malformations, and tumors. EEG is indicated to rule out seizures especially when there is confusion and decreased the level of consciousness. Rarely, 24-hour Holter monitoring is required to rule out arrhythmias.

Treatment / Management

Treatment of acute attack is symptomatic. An acute attack of a basilar migraine is usually managed with NSAIDs and anti-emetics like prochlorperazine or metoclopramide. Aura symptoms should be used as a signal for initiating early acute treatment.

Triptans and ergotamines were excluded in the earlier trials for the treatment of a basilar migraine and have not been well studied. Recent reports have shown benefits and improvement in a headache with triptans. Many believe that these medications can be used in abortive therapy of migraine with brainstem aura like in migraine with typical aura, but traditionally triptans and ergotamines are avoided in a basilar migraine because of the risk of increasing cerebral ischemia. The safety and effectiveness of triptans and ergotamines are not confirmed yet due to a lack of data.

Principles of preventive therapy are generally the same as with other types of migraines. It is important to identify and modify the triggers if possible. Maintaining a headache diary helps to keep track of frequency, duration, and severity of symptoms and identify triggers. Modification of triggers like food, noise, stress, regular exercise, a well-balanced diet, and stress management can help prevent migraine attacks. All patients with frequent, disabling headaches should be considered for preventive therapy.

Verapamil and topiramate are the most commonly used medications for preventing migraines with brainstem aura. Propranolol has traditionally been avoided as it can affect cerebral blood flow.

Non-pharmacological therapies like relaxation, acupuncture, massage, cognitive behavior therapy, and biofeedback techniques are also helpful for prevention, like with other types of migraines.[5][6][10](B2)

Differential Diagnosis

• A basilar migraine can mimic a hemiplegic migraine and migraine with a typical aura.
• Other differentials that should be excluded before a clinician makes a definite diagnosis of a basilar migraine include Meniere disease, vestibular disease, transient ischemic attack (TIA), stroke, brainstem atrioventricular (AV) malformation, tumors, and meningitis.[7]

Prognosis

Brainstem aura migraine is often more disabling than migraine without aura and migraine with typical aura, because of increased severity and longer duration of symptoms. The frequency of brainstem aura decreases with age, and they often evolve in more typical patterns with age.

Migraines with aura have a slightly higher risk of stroke than migraine without aura; however, there is no evidence that migraine with brainstem aura has a higher risk of stroke than migraine with typical aura.

Smoking and the use of estrogen contraceptives further increase the risk of stroke, and risk factor modification should be reinforced to all patients.[1][7][8][9]

Complications

The patients can sustain falls if they suddenly lose consciousness as a part of the aura.