Few of us spared the experience of head pain and it is the warning red signal indicating that something is wrong in the body. It is the physiological mechanism that triggers the Nociceptors (Pain sensors) of the forehead and face. Head pain is usually a benign symptom but occasionally it indicates some serious illness in the head or brain.
Nociceptors and Pain
Nociceptors are the pain sensors typically nerve endings present on the skin and underlying tissues. Pain usually occurs by the stimulation of Nociceptors in response to tissue injury, visceral stretching and a number of other factors. In such a situation, the pain is a physiological response mediated by the nervous system. The perception of pain will be detected by the pain centre of the brain and we feel the sense of pain.
Types of Head Pains
Head pain can be of different types. Broadly this can be divided into Simple head pain and Migraine head pain. Migraine is the most common type of head pain caused by a number of factors including stress. It is affecting approximately 15% women and 6% men of different ages. Migraine symptom includes severe head ache attacks regardless of cause, throbbing, nausea, vomiting, scalp tenderness etc. Many factors like some Food, Beverages, lack of Sleep, Glare, Stress, Odour etc can induce migraine. Migraine can be classified into different types but the broad classification is Common Migraine and Classical migraine.
This form of migraine is common and in common migraine there no focal neurological disturbance precedes the attack of head pain. This is a form of Vascular head ache without Aura. The most common symptoms are moderate to severe pain on the fore head especially on one side or both sides, Nausea, Vomiting, Photophobia ( aversion towards light), Phonophobia ( Aversion towards sound), multiple attacks lasting few hours to days etc.
Classical migraine is characterized by premonitory senses, Motor and Visual symptoms etc. The most important feature of classical migraine is the visual aura that appears in the visual field before the migraine attack. Scotoma or hallucination appears in about one third of patients and the scotoma usually appears in the central portion of the visual filed. The visual disturbance develops as a small Para central Scotoma which slowly expands into a “C” shape. This is followed by the appearance of luminous angles at the enlarging outer edge of scotoma. The scotoma then becomes colored as the scintillating scotoma expands and moves toward the periphery of the involved half portion of the visual field. After 20 to 25 minutes, the scotoma disappears through the periphery of the visual field. This phenomenon is considered as Pathognomonic and has never been described any association with the cerebral problem. The Scotoma is generally referred to as ‘Fortification Spectrum’ since the flickering ‘C’ shaped scotoma resembles the fortified town with bastions around it.
What triggers Migraine?
There are some known and unknown reasons for migraine. Many factors can induce migraine in a genetically migraine prone individuals. Some of the known factors triggering migraine are :
1. Beverages – Alcohol, Red wine, Beer etc.
2. Food – Chocolate, Cheese, Monosodium glutamate, Preservatives, Flavor agents, Nitrite containing foods etc.
3. Hunger – Irregular feeding habits, missing meals etc.
4. Sleep pattern – Irregular sleep patterns like lack of sleep or excessive sleep.
5. Organic Odours – Smell of Perfumes, chemicals, paints etc.
6. Stress – Acute changes in Stress level
7. Environmental factors – Weather changes, High altitude, Atmospheric pressure changes, Bright or Flashing light, Glare etc.
Theories of Migraine
Various suggestions and theories have been proposed to explain the reasons of migraine attacks. Some common concepts are:
1. Trigemino Vascular system
This theory focused on the activation of cells present in the Trigeminal nucleus of Medulla which is the pain processing centre for face and fore head. The stimulation of Trigeminal nucleus releases Vasoactive neuro peptides like Substance P and Calcitonin Gene-related peptides. These Neuropeptides are produced in the vascular terminations of the Trigeminal nerve. These Neuropeptides cause inflammation which activates the Nociceptive afferents arising from the wall of the blood vessels. This causes pain in the head. This concept provides a potential mechanism causing tissue swelling on the fore head and tenderness of blood vessels followed by the migraine attack.
2. Neuronal Theory of Migraine
This theory mainly focuses on the appearance of Scotoma. The slowly enlarging Fortification spectra (Migraine Aura) is the result of a slow spreading depression in the blood vessel. The spreading depression slowly moves 2 to 3 mm / minute. This causes potassium liberation of cortical activities precedes by a wave front of increased metabolic activities.
3. Role of Dopamine, Serotonin and Prostaglandins
Pharmacological studies have shown that brain neurotransmitters like Serotonin (5 Hypoxy tryptamine – 5 HT), Dopamine, tissue substance Prostaglandins etc are involved in migraine attacks. Drugs that antagonize the peripheral action of Serotonin are effective to prevent migraine attacks. Research data support the role of Dopamine in some kinds of Migraine. Most of the symptoms of migraine are induced by Dopaminergic stimulation. Drugs inhibiting the Prostaglandins synthesis also proved the effect of prostaglandins in migraine attacks.
4. Stimulation of Sympathetic Nervous system
Changes in the SNS cause migraine attacks. Factors that stimulate the SNS can trigger the migraine attacks in head pain prone individuals. These factors include Stress, environmental changes, sleep pattern, hormonal variations, hypoglycemia and the agents that cause the release of Secondary Catecholamines. Dopamine antagonists, Prostaglandin synthesis inhibitors etc are effective in migraine attack. These drugs block the Negative feed back inhibition or Nor epinephrine release caused by the Dopamine or Prostaglandins.
5. Empty Neuron theory
This theory is based on fact that migraine may relate to genetically based changes in the ability to maintain the concentration of neurotransmitters in the Post ganglionic sympathetic nerve endings.
How to escape?
Head ache is common in most of the people due to stressful life. Head pain and Migraine can be managed to a certain level through Non pharmacological approaches or changing the life style. Persons susceptible to Migraine do not encounter more stress than other people. Over responsiveness to stress appears to be the important issue. We cannot eliminate the stress of this fast every day life. Reducing the stress by various methods can eliminate the chance of migraine attacks to a certain extent. Techniques like Yoga, Meditation, Relaxation methods, Hypnosis, Conditioning techniques like Biofeedback etc will give good results. Avoidance of Migraine triggering factors (as mentioned above) is also very important. When these methods fail, it is necessary to go into the Pharmacological methods to abort the migraine attacks.