Biomedical subjects
Publications and source records attributed to J Edmeads.
Patients "lucky" enough to have a nondisabling transient ischemic attack as a warning sign of impending stroke deserve the best possible prophylactic treatment in an attempt to avert that catastrophe. Dr Edmeads provides a step-by-step discussion of diagnostic studies and therapeutic regimens that help avoid stroke in middle-aged and older patients who are at risk.
Trained telephone interviewers contacted 1,573 adults across Canada about the nature and frequency of headaches suffered by them or by others in their households. Using a table of pain symptoms and other characteristics abstracted from the International Headache Society (IHS) classification, the headaches were assigned to migraine headache, tension-type headache or other diagnostic groups. Of the households sampled, 59% had at least one headache sufferer in residence. The proportion of headache sufferers with migraine was 14%; with tension-type, 36%; and with both, 14%. Migraine headache caused more disability than tension-type headache, with nearly 20% of migraine sufferers taking time off work and disability lasting for a mean of 1 day. It is concluded that the current prevalences of migraine and tension-type headache in Canada fall around the mean of previous studies, that the IHS criteria can form a basis for diagnostic classification and that the functional impact of migraine has been seriously underestimated in the past.
Migraine is a common condition with, usually, stereotyped symptomatology, suggesting that it is a specific disease entity (a morbus sui generis). However, occasionally a migraine sufferer will exhibit atypical manifestations of the condition; also, some specific diseases such as systemic lupus erythematosus and arteriovenous malformations, may exactly mimic the symptoms of migraine. These latter considerations raise the possibility that migraine is a syndrome rather than a disease. The recent delineation of the trigeminovascular system allows a conception of migraine as being neither disease nor syndrome, but rather a constitutional predisposition of the neurovascular system to react excessively to internal or external stimuli by a pattern of hyperactivity of the brain and of the trigeminovascular apparatus. Activation of the trigeminovascular system, whether by neural impulses from the brain or humoral factors in the circulation, results in vascular headaches, while associated activity in the brain may produce such typically migrainous symptomatology as prodrome and aura, and nonspecific symptoms such as nausea, vomiting and dizziness. In this model specific diseases may gain access to the trigeminovascular apparatus, detonating it to produce vascular headaches and neurological symptomatology which may more or less exactly mimic migraine.
Theories of migraine pathophysiology have evolved from the realms of the supernatural into the scientific arena but their further evolution seems delayed by unproductive controversy about whether or not migraine is primarily a vascular or a neurological dysfunction. This conceptual deadlock needs to be transcended by thinking beyond the neural and vascular systems, and by identifying mechanisms that could affect both to produce the characteristic clinical phenomena of migraine. One theoretical model envisages 5-hydroxytryptamine (serotonin; 5-HT) as a link between the neural and vascular systems, with global alteration of serotonergic neurotransmission affecting not only these systems, but the gastrointestinal tract as well, with incidental reverberations on platelet function. Such altered serotonergic transmission might originate from altered 5-HT receptor dynamics, a molecular change in turn produced by genetic mechanisms. Recognition of the importance of 5-HT receptor function in migraine, most notably that agonists of 5-HT1 receptors abort acute migraine and that antagonists of 5-HT2 receptors prevent migraine, may lead to significant therapeutic advances. The possibility that the "trigeminovascular system" might be the end-stage mechanism that these serotonergic changes detonate to produce the painful reverberations of migraine headache is also important. Seeking ways to muffle these reverberations, or to insulate the system itself from the action of external influences (likely through further study of peptidergic transmission and receptors) might result in more drugs that will abort or prevent migraine.
Migraine equivalents and complicated migraine are entities in which definition is difficult, presentations are pleomorphic, diagnosis is treacherous, pathophysiology is obscure, and treatment is uncertain. A useful principle is to regard them as diagnoses of exclusion that require aggressive and comprehensive investigation. Rational treatment consists of migraine prophylaxis using agents with minimal vasospastic potential and, in some cases, acetylsalicylic acid for platelet disaggregation. The prognosis for both complicated migraine and migraine equivalents is good; when patients with these diagnoses come to harm, it is often because the diagnosis is incorrect.
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Neck disorders implicated as causes of headache fall into two groups: a) those in which the cervical lesions are unequivocally demonstrable, and in which treatment of those lesions helps the headache; these are widely accepted as causes of headache, and include: congenital and acquired craniovertebral junction disorders, rheumatoid arthritis and ankylosing spondylitis of the upper cervical spine, and dissection or trauma to the carotid or vertebral arteries; b) those in which the neck disorder is either banal or not objectively demonstrable, and which seldom improve following treatment of the neck; these are not widely accepted as causes of headache; they include whiplash syndrome, segmental hypomobility-hypermobility syndrome, the posterior cervical sympathetic syndrome, cervical migraine, third occipital nerve headache, and cervicogenic headache. Features of a headache suggesting its cervical origin are: 1) abrupt onset following sudden excessive movement of the head; 2) persistent unilateral suboccipital or occipital pain; 3) consistent reproduction by neck movements and by nothing else; 4) abnormal postures of head and neck; 5) significant painful limitation of movement of upper cervical spine; 6) abnormal mobility at craniovertebral junction; 7) C2 sensory abnormalities or lower medulla or upper cervical cord signs.
Dizziness is a common but often nonspecific symptom. Through careful history taking and physical examination, primary care physicians can usually determine the type of sensation (vertigo or light-headedness) and its source. Although most causes of dizziness are benign, disorders of the central nervous system tend to be ominous and require immediate referral to a specialist.
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The first step in management of migraine is convincing the patient of the diagnosis. Once this has been accomplished, the physician needs to identify precipitating factors. Common migraine triggers include stress, menstruation, use of oral contraceptives, and certain foods. The next step is choosing appropriate therapy. Analgesics are most commonly prescribed in North America; nonsteroidal antiinflammatory drugs, ergotamine, narcotics, corticosteroids, and other drugs are also useful. Prophylactic therapy should be considered when treatment of individual attacks fails, causes adverse effects, or leads to dependence.
Headache is always a challenging diagnostic exercise but is especially so in patients who have "the worst headache ever." Such a headache should never be automatically dismissed as merely a severe but benign one. A thorough history and careful physical examination are necessary to find evidence of serious disease. If such evidence is present, immediate, aggressive, and thorough evaluation are essential to avoid severe consequences.
In most cases, patients presenting with "the worst headache ever" are found to have a benign condition, notably migraine, toxic vascular headache, or exertion-induced headache. However, ominous causes first must be excluded by appropriate investigation, such as computed tomographic or magnetic resonance imaging scans and lumbar puncture. When an ominous cause has been ruled out, appropriate therapy can be started.
In some forms of cerebrovascular disease, such as intracranial hemorrhage, headaches are well known as a prominent symptom and often are a valuable clue to diagnosis. There are difficulties, sometimes, in distinguishing between a small subarachnoid hemorrhage and a severe migraine headache, but these can be resolved using clinical observations, CT scan, and lumbar puncture. It seems less well known that headaches may accompany or precede cerebral thrombosis and embolism. When these headaches are recognized as a forerunner to stroke, they may allow an opportunity for preventive treatment.
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