Tension headache

Overview
Tension headaches, which were renamed tension-type headaches by the International Headache Society in 1988, are the most common type of primary headaches. The pain can radiate from the neck, back, eyes, or other muscle groups in the body. Tension-type headaches account for nearly 90% of all headaches. Approximately 3% of population suffers from chronic-tension type headache.

Frequency and duration
Tension-type headaches can be episodic or chronic. Episodic tension-type headaches are defined as tension-type headaches occurring less than 15 days a month, whereas chronic tension headaches occur 15 days or more a month for at least 6 months. Tension-type headaches can last from minutes to days or even months, though a typical tension headache lasts 4-6 hours.

Pain and possible symptoms
Tension-type headache pain is often described as a constant pressure, as if the head were being squeezed in a vise. The pain is frequently bilateral which means it is present on both sides of the head at once. Tension-type headache pain is typically mild to moderate, but may be severe. In contrast to migraine, the pain does not increase during exercise.

Cause and pathophysiology
Various precipitating factors may cause TTH in susceptible individuals. One half of patients with TTH identify stress or hunger as a precipitating factor;
 * Stress - Usually occurs in the afternoon after long stressful work hours
 * Sleep deprivation
 * Uncomfortable stressful position and/or bad posture
 * Irregular meal time (hunger)
 * Eyestrain

The exact cause of tension-type headaches is still unknown. It is suggested that abnormalities in the peripheral and central nervous systems may be involved in the pathophysiology of TTH. It has long been believed that they are caused by muscle tension around the head and neck and the restriction of blood flow to those areas as a result, the cause of which is often the presence of an unresolved subconscious emotional conflict and anxiety. One of the theories says that the main cause for tension type headaches and migraine is teeth clenching which causes a chronic contraction of the temporalis muscle. Although muscle tension may be involved, scientists now believe there is not one single cause for this type of headache. Another theory is that the pain may be caused by a malfunctioning pain filter which is located in the brain stem. The view is that the brain misinterprets information, for example from the temporal muscle or other muscles, and interprets this signal as pain. One of the main molecules which is probably involved is serotonin. Evidence for this theory comes from the fact that chronic tension-type headaches may be successfully treated with certain antidepressants such as amitriptyline. However, the analgesic effect of amitriptyline in chronic tension-type headache is not solely due to serotonin reuptake inhibition, and likely other mechanisms are involved. Recent studies of nitric oxide (NO) mechanisms suggest that NO may play a key role in the pathophysiology of CTTH. . The sensitization of pain pathways may be caused by or associated with activation of nitric oxide synthase (NOS) and the generation of NO. Patients with chronic tension-type headache have increased muscle and skin pain sensitivity, demonstrated by low mechanical, thermal and electrical pain thresholds. Hyperexcitability of central nociceptive neurons (in trigeminal spinal nucleus, thalamus, and cerebral cortex) is believed to be involved in the pathophysiology of chronic tension-type headache. Recent evidence for generalized increased pain sensitivity or hyperalgesia in CTTH strongly suggests that pain processing in the central nervous system is abnormal in this primary headache disorder. Moreover, a dysfunction in pain inhibitory systems may also play a role in the pathophysiology of chronic tension-type headache.

Treatment
Episodic tension-type headaches generally respond well to over-the-counter analgesics, such as paracetamol, ibuprofen or aspirin. The effect of the analgesic is boosted if either caffeine (such as a cup of coffee) or a dose of the sedative antihistamine diphenhydramine (Benadryl, 25mg) is taken at the same time. However, these medications should be avoided in cases of chronic tension-type headache, due to the risk of medication overuse headaches.

Chronic tension-type headaches are more difficult to treat. Some therapies that are suggested for chronic tension-type headaches include:


 * Pharmacological therapy:
 * Amitriptyline
 * Mirtazapine


 * Non-pharmacological therapy:
 * Cranial chiropractic
 * Exercise such as swimming two to three times a week
 * Acupuncture
 * Biofeedback
 * Massage
 * Heat pillow
 * Relaxation techniques like:
 * Jacobson's Progressive Muscle Relaxation
 * Autogenic training

Tension headaches are exacerbated by states or activities that induce muscle tension, such as stress. Avoiding such states can lessen the frequency of tension headaches. Tension headaches can also be provoked by other conditions, such as an upper respiratory infection. Often the best treatment for a mild tension headache that does not impair a person's ability to function is simple endurance. Many tension headache sufferers receive relief from sleep. However, it is always best to see your physician for a full work-up of the headaches.
 * Avoiding triggers

Prognosis
Tension headaches that do not occur as a symptom of another condition may be painful, but are not harmful. It is usually possible to receive relief from treatment. Tension headaches that occur as a symptom of another condition are usually relieved when the underlying condition is treated. Frequent use of pain medications in patients with tension-type headache may lead to the development of medication overuse headache or rebound headache.