DEFINITION OF MIGRAINE
MIGRAINE is a form of recurrent paroxysmal headache often confined to one side of the head beginning in childhood to adult life.
Migraine is believed to be a disturbance of the carotid and vertebrobasilar system together with neurotransmitter system. Both intra- and extracranial vessels participate in the process.
Initially there is vasoconstriction which leads to cortical and brain stem ischaemia resulting in “aura”. This is soon followed by vasodilatation of the extracranial blood vessels which causes stretching and irritation of the nerve endings in the arterial wall which causes headache. This may be followed by muscular contraction which maintains and prolongs headache.
Before actual headache starts there is a rise of serum 5-hydroxytryptamine (serotonin) level which is a neurotransmitter. Apart from serotonin, noradrenaline, substance P are also other neurotransmitters which are involved in the process. There is release of neuropeptidase acting on the neurotransmitter of the trigeminal nerve leading to an inflammatory process. Another possible mechanism is activation of the dorsal raphe nucleus. Multiple genetic and environmental factors are related to electrical and vascular changes which either singly or in combination may be responsible for the episode.
The exact cause of migraine is unknown.
Definite precipitating factors are lacking. But sometimes anxiety, overwork, emotional upsets, menopause, hypertension, cerebral tumour premenstrual tension, head injury, spondylosis, noise, fumes, depression, lack or excess of sleep, alcohol, oral contracepives, fasting state, some foods, e.g., orange, cheese or chocolate, etc. may precipitate an attack.
Age Young adults.
Sex Common in females.
Temperament : Obsessional.
Family history is positive.
1. Prodromal symptoms: Wekness, lassitude, depression, etc. may be complained of for few days.
2. Aura The actual attack starts usually after waking from sleep. At first this aura may take the from of some visual disturbances, e.g., dazzles, scintillating scotoma, coloured lights, hemianopia, ocular pain, lacrimation and photophobia. Sometimes tingling and numbness in the face and upper extremities may be seen. This state of aura lasts for about 15 minutes to half an hour.
3. Headache : After the aura passes off, headache starts. This may be uni or bilateral or may even be generalised. Often there may be localised spot on the head from where it starts. This pain is usually very severe(splitting headache), gradually increases in intensity having a throbbing or expansile character. The side which is affected is constant in each attack. This is due to dilatation and excessive pulsation of the external carotid artery. Visual disturbances occur quite commonly, e.g., luminous visual hallucination (stars, sparks, etc.), uniformed light flashes (photopsia), geometric or zigzag paths of light field defect. Aphasia, numbness, tinglings, weakness, etc. may also be seen. At the height of headache there may be vomiting, photophobia, sweating, pallor and exhaustion. Patient prefers to lie in a dark room and refuses all foods. The superficial temporal artery is seen to throb vigorously and may be tender on palpation. The headache may last for 12-14 hours usually, but shorter or longer attacks may also occur. Facial neurological signs may also be seen which are due to constriction of branches of Internal carotid artery.
4. After attack is over sometimes there may be increased urine flow. At times patient becomes very sleepy.
TYPES OF MIGROINE
Sometimes the cerebral changes may persist for sometimes even if the headache is over.
When there is spasm of the basilar artery there may be visual disturbances, occipital headache, vertigo, ataxia, syncope, dysarthria, tinnitus, disequillibrium, perioral and distal paresthesia, confusion, semicomatose state, headache, nausea, vomiting and paresis of lower limbs.
Recurrent facial palsy is associated with migraine.
Migraine is accompanied by oculomotor palsies which may. become permanent. Sometimes ophthalmic division of Vh nerve may be involved also. This is a type of painful ophthalmoplegia and is rare.
In this condition migraine is associated with occlusion of the retinal artery or any of its branches.
Here migraine may be seen in some cases of head injury.
Migrainous neuralgia (cluster headache)
Here the attacks are very severe but short-lasting. The eyes may be red and nostrils may be blocked due to congestion, rhinorrhoea, lacrymation, red eye, Horner’s syndrome may develop. Episodes usually occur at night awakening the patient from sleep. The duration is less than 2 hours. There is no family history. Sometimes alcohol may trigger an attack
This is rare. Here the accompanying somatic or neurologic features are the sole manifestations. Headache is less prominent.
TREATMENT OF MIGRAINE
Patients should regulate their life so as to avoid both physical and mental fatigue. Precipitating factors as mentioned before should be corrected or avoided whichever is possible. Reassurance is very valuable.
This may be treated with Aspirin, Paracetamol or Codeine tablets if the attack is mild. Ergotamine tartrate is the most useful medicine and can be given orally, parenterally or even as suppository or aerosol. Dose is 1-2 mg orally to start with and is to be repeated every half an hour till a total dose of 5-10 mg is reached. In the IM route 0.5 mg may be given. By aerosol the dose is 300-400 ug. Sometimes this is combined with 100mg of Caffeine. As this drug contracts the gravid uterus it should be avoided in pregnancy. Moreover as it is a peripheral vasoconstrictor it should be avoided in peripheral obstructive vasculopathy.
Sumatriptan is a recent drug which can be given by subcutaneous or by autoinjection device. It has high affinity for serotonin receptor. It is also avoided in pregnancy. Pressure over the external carotid artery or 100% oxygen inhalation by nasal mask may be of help. Patient should take rest in a calm, quite and dark room. Zolmitriptan 2.5 mgn orally is also effective.
Prevention of Attack
Sedative like barbiturates, tranquillisers like chlordiazepoxide, antihistamines, e.g., prochlorperazine, etc. may be used.
The most effective drug is prophylactic use of dimethysergide given in a dose of 1-3 mg thrice daily. Clonidine 0.025 mg 4-6 times a day may be helpful. Propranolol may also be given in a dose of 10 mg thrice daily and gradually increasing the dose to 40 to 80 mg thrice daily. Amitriptyline (10 to 150mg), Imipramine (10 to 150 mg), Cyproheptidine (10 to 20 mg), Verapamil (80 to 160 mg) are also used with good results.