Migraine

Introduction
Cause and Pathogenesis
Symptoms and Signs
Investigations and Diagnosis
Treatment and Prognosis
Prevention

Migraine is a condition characterized by sudden bouts of throbbing headache often unilateral (pain localized to one side of the head). Migraine can last from a few hours to days. The pain may be accompanied by other manifestations like nausea, vomiting and visual disturbances. Each year, the number of people worldwide seeking medical treatment for recurrent headache has been on the increase. Tension headaches are very common and occur in adults of all ages and gender throughout the world. Women in their early childbearing years are the most susceptible, particularly just before or during menstrual periods. Cluster headaches are most common in men of about 30-40 years of age. The incidence of migraine is much higher in those engaged in stressful work, involving much mental activity like businessmen and scientists. It is also more common in nervous and highly emotional individuals.

Migraine headache is thought to be due to vascular disturbances. Cluster headaches are also vascular in nature. The exact cause of migraine has not been clearly defined. Vascular disturbances can also be caused by exposure to toxic chemicals like alcohol, lead, arsenic, and carbon monoxide, and are also causes of headache. The most common type of headache is tension headache, but their precise cause is not well-defined. However, most are related to muscle tension, minor trauma, increased stress or anxiety, food and environmental allergens, infection or lesions of the oral or nasal cavity, ear infections, or eyestrain.

Intracranial headaches may be caused by increased pressure inside the skull resulting from an underlying pathological process such as a brain tumor, abscess, or hematoma, meningitis, syphilis, tuberculosis, cancer, or subarachnoid hemorrhage. Also, cranial changes in the skull caused by tumors, temporal arteritis, or involvement of the sensory nerves of the scalp due to herpes zoster can cause headaches. The pain occurs when pain fibers on the cranial nerves (V, VII, IX, or X) carry the sensory stimuli to the brain tissue. The location and diffusion of the pain depends on the cause, the amount and region of tissue affected, and the cranial nerves involved. The pain can be highly localized and specific or diffused and generalized. The involvement of the deeper brain structure may cause referred pain.

The following symptoms are characteristic of Migraine headaches.
It is paroxysmal in nature (occurs in sudden bouts), the pain is throbbing, often unilateral (localised to one side of the head) and may last from a few hours to days. It has a cyclic pattern accompanied sometimes by nausea and vomiting. The patient has an aversion to light and noise. It may be preceded by an aura (shimmering visual manifestation) or prodromal behavioral alterations which can range from depression to euphoria or hunger. Cluster headaches are characterised by a deep, severe, and non-throbbing pain that often begin during sleep and involve an eye, temple, cheek, and forehead on one side. It usually lasts from 30 minutes to three hours, with several bouts of headaches occurring each day for many weeks, along with watering and redness of the eye on the affected side . Tension headaches are characterised by a bilateral, dull, non-pulsatile ache, typically bifrontal (front of the head) or nuchal-occipital (back of the head) in nature that may be transient or chronic. Traction headache has symptoms of deep, dull, constant ache that is worse in the early morning and aggravated by coughing or straining. Arteritis is characterised by a soreness of one or both temples that becomes a chronic, burning, localised pain. The artery on the affected scalp region is prominent, tender, incompressible, and non-pulsatile.

The main aim in the diagnosis of headaches is on classification of the type of pain and identifying the potential cause. A neurologic history and a clinical examination are done, with the aim of identifying the precipitating causes or underlying pathology or disease. Computed Tomography (CT-Scan) and Magnetic Resonance Imaging (MRI) are also very useful in detecting intracranial lesions like tumors. Cerebral Angiography is used to detect any vascular abnormality. Electroencephalogram (EEG) may also be done.

This consists of the treatment of any identified underlying cause or disease. The application of cold or heat compresses is done to relieve symptoms. Elimination of food or environmental allergens will help to prevent headaches caused by these factors. Counselling and psychological treatment may also be required. Stress management and biofeedback will also be helpful.

Drug therapy in Migraine

Analgesics are used to relieve the pain, ergot preparations are also effective. Sumatriptan is used for acute attacks of migraine. Betablockers may also be helpful. In cluster headaches, prophylaxis with drugs such as Valproic Acid, Verapamil, or Lithium Carbonate is more effective than the use of drugs during acute attacks. Tension headaches are controlled well by the use of analgesics.

The prevention of a migraine attack is by trying to identify any precipitating factor and avoiding the same. Avoiding alcohol, smoking and controlling hypertension is also essential. The use of counselling and psychotherapy is essential in highly stressed, nervous and emotional individuals.