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Basilar Migraine

migraineStefan was a 38 year old man who had recently been promoted in his job two months ago. He now worked long hours and felt he was coping adequately. However, in the last four weeks he had suffered episodes of severe dizziness, unsteadiness and vomiting which was followed within the hour by a severe headache at the back of the head. These symptoms then continued for 24 to 48 hours. There was no true vertigo and he did not fall to one particular side. He did not have visual symptoms, dysarthria, deafness, tinnitus, limb weakness or any abnormal sensations.

The GP took a very specific history and it was clear that these episodes began on a Friday evening, or waking Stefan overnight on Friday/Saturday, and continued until approximately Sunday. He would have to lie down in a dark room during this time. He would go to work on Monday exhausted and off colour, but without a headache or any of the other symptoms. Stefan had no medical problems and no medications. His mother had suffered from severe, recurrent headaches and he thinks migraine was mentioned as a diagnosis.

Stefan’s physical examination was quite normal when he saw the GP on a weekday. Basic blood tests (notably his C-reactive protein) were normal. He had had a normal eye review with an optometrist and an MRI that was ordered of his brain was normal. He was referred to a neurologist who confirmed the GP’s suspicion of basilar migraine. The typical features that led to this diagnosis were the classical migraine symptoms and periodicity of the headache (occurring on weekends).

Basilar migraine is a migraine variant, and there does not have to be a headache present for the diagnosis to be entertained. There have been several theories as to why there is unsteadiness and/or true vertigo in cases of basilar migraine. These include spasm of the internal auditary artery, resulting in dysequilibrium, neurotransmitter imbalance (especially serotonin), symmetric neuropeptide release and spreading neuronal depression, creating metabolites from vasospasm that then cause electrolyte changes (especially potassium and calcium) in the neurones.

The differential diagnosis is Meniere’s disease. There is one theory that basilar migraine and Meniere’s disease are part of the same illness, but basilar migraine patients have no progressive high frequency hearing loss (although they may complain temporarily of this during attacks). Basilar migraine symptoms normally last for longer, and the balance symptoms may continue mildly for up to several weeks after the headache has gone. Meniere’s disease, however, typically lasts less than 24 hours.

basilar migraine

Other differential diagnoses include a perilymphatic fistula, benign positional vertigo, recurrent vestibular neuritis, vestibular neuropathy, vertebral artery insufficiency, multiple sclerosis, central paroxysmal positional vertigo, cervicomedullary compression from abnormalities of the craniovertebral junction.

The most useful investigation is the MRI scan. Gadolinium may be required if the patient does not improve with migraine therapy, or if the diagnosis is in doubt. There are no specific tests that will confirm the diagnosis, but if hearing is affected during attacks a baseline hearing test when the patient is well is suggested. Caloric testing,  vestibular evoked myogenic potentials and  electronystagmography all have an increased likelihood of being abnormal in basilar migraine sufferers but are not usually indicated.

Prevention of the basilar migraine is important, if triggers can be identified. These triggers include stress, fatigue, hypoglycaemia, alcohol, strong smells and certain foods (aged cheeses, chocolate, MSG). Vestibular physiotherapy may help with the unsteadiness if this is lasting for some time after each attack.  Medications for migraine may help with the headache but not be very effective in the management of the dizziness and the patient should be made aware of this.

In Stefan’s case, the migraines were frequent enough to warrant prophylactic medication. He was offered the choice of verapamil, propranolol or nortriptyline. Other medications that are less commonly used include topiramate. This medication is PBS indicated for migraine if there are more than three a month for over six months in patients who cannot tolerate beta blockers and who have an intolerance or unacceptable risk of weight gain from pizotifen. Venlafaxine and valproic acid have also been used. The unsteadiness, but not the headache, may respond to lamotrigine or acetazolamide.

 

1. Benson, A.G. Migraine-associated vertigo, Medscape, 2 March 2015
http://emedicine.medscape.com/article/884136-overview#a7