Donald J. Dalessio

Pattern‐Shift Visual Evoked Responses and EEG in Migraine

SYNOPSIS

SOME REFLECTIONS ON THE ETIOLOGIC ROLE OF DEPRESSION IN HEAD PAIN

THE PHYSICIAN confronted by the patient who complains of chronic face pain or headache not infrequently finds himself in a diagnostic and therapeutic morass. Headache is considered the commonest complaint for which a patient seeks medical aid; though, in truth, the manner in which that oft-quoted statement was obtained has so far eluded this writer. Suffice it to say that headache is an extremely common affliction, and that all physicians who deal with patients are familiar with it. Yet the genesis of an individuals head pain may be most elusive. The reasons for this are multiple. The brain is encased in the cranium and, therefore, relatively impervious to study except by the most indirect and gross methods. Sensation cannot be measured, and many patients describe their complaints poorly. Though headache is common, it is relatively rare to find a single specific illness producing it, even though both the physician and the patient may have convinced themselves that they have, in fact, discovered the etiology in a particular case. Furthermore, headache may be the most benign of symptoms or it may be the only expression of the most malignant of diseases. Some clinical categories of headache are precise and well-defined, but others are not. The patient with a brain tumor may describe his head pain in desultory terms. Patients with migraine may experience agonizing discomfort, yet migraine is usually (but not always) a benign disease.

REM SLEEP, DEPRESSION, AND NOCTURNAL MIGRAINE

REM sleep is characterized by rapid eye movements and hence the name. REM periods occur approximately every ninety minutes during sleep and in young adults occupy about twenty percent of a nights sleep. REM periods last typically twenty minutes but may become longer as dawn approaches. Considerably more REM sleep occurs in children and especially in newborns, and progressively less REM occurs in the aged.

Carbon Monoxide (CO) and Headache

But elevated serum levels of CO occur most commonly in those who smoke cigarettes, a fact of some significance about which little is heard. CO is measured as carboxyhemoglobin, a laboratory procedure which can be done simply and rapidly, and which is within the capability of most hospital chemistry services. In a heavily industrialized area, one can expect to find carboxyhemoglobin levels of 0.5% to 5% in non-smokers. (About 0.5% carboxyhemoglobin is produced through endogenous metabolism in all of us). Heavy smokers, those who use more than one pack of cigarettes per day, frequently have levels of 10% carboxyhemoglobin or even higher at times. This degree of chronic hypoxia may play a role in the tendency for heavy smokers to manifest elevated hemoglobin and white cell counts.

Use of Platelet Antagonists in the Treatment of Migraine

If one accepts that vasoactive materials are important in vascular permeability which characterizes migraine, then the role of platelets is critical to the cascade schema of sterile inflammation which accompanies the migraine attack. Studies at the Scripps Clinic have clarified the roles of vasoactive amines in inflammation, using an animal model of immune complex arteritis.1 Briefly, immune complexes can be made to deposit in blood vessels of rabbits by simultaneous infusion of agents which increase vascular permeability or which liberate vasoactive amines from their storage sites. Conversely, antagonists of vasoactive amines given prior to the appearance of circulating immune complexes are generally effective in limiting the deposition of immune complexes. The prophylaxis of migraine has come to depend on precisely those drugs employed in reducing vascular injury in immune complex disease in the experimental model.2 These include methysergide, combinations of antihistamines, cyproheptadine, and corticosteroids. In addition, platelet depletion, which reduces the amounts of vasoactive amines in storage sites, is also effective. These data suggest that vascular permeability related to injury of any type, including neurogenic injury, may be evoked by the release of vasoactive substances from their reservoirs in the circulation, particularly from platelets.

METHOD OF ACTION OF ASPIRIN

It is difficult to name a medication more useful than aspirin. It is not only an analgesic, but also an antipyretic and a potent anti-inflammatory agent. Given its relatively simple chemical structure one might assume that the methods by which it produces its effects would have been worked out long ago. Such is not the case, and it is only in recent years that the means by which aspirin functions have come under scrutiny.

VASOMOTOR CHANGES DURING MIGRAINE

It has been assumed in the past that the initial preheadache experiences of migraine which include visual phenomena, paresthesias and defects in motility, aphasia and related problems, are associated with ischemia within the system supplied by the internal carotid artery, and that the second phase of the migraine attack characterized by a pounding headache is associated with vasodilatation, especially in the external carotid system. It has been well-demonstrated that extracranial vasodilatation and increase in arterial pulse pressure are associated with migraine, and that production of vasoconstriction using drugs of the Ergot variety usually leads to relief of symptoms. Until recently, however, it has not been possible to provide quantitative measurements of pathological changes within the internal carotid system during the prodromal phase of migraine.

CENTRAL MECHANISMS IN HEADACHE.

RECENT studies with the lysergic acid derivative, methysergide, are of interest with respect to the reactivity and tone of the cerebral blood vessels.1,2,3 Methysergide (1-methyl-d-lysergic acid butanolamide) differs from the hallucinogenic agent lysergic acid diethylamide only in that it contains a butanolamide rather than a diethylamide side chain. It is intimately related to the naturally occurring ergot alkaloids, especially ergonovine and its derivatives.