|Classification and external resources|
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 the population has chronic tension-type headaches.
Tension-type headaches can be episodic or chronic. Episodic tension-type headaches are defined as tension-type headaches occurring fewer 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, months or even years, though a typical tension headache lasts 4–6 hours.
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.
Various precipitating factors may cause TTH in susceptible individuals. One half of patients with TTH identify stress or hunger as a precipitating factor .
Until recently it was believed that tension headaches were caused by muscle tension around the head and neck. 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, many researchers now question this idea, and recent research has shown that tension headache patients do not have increased muscle tension.
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 neurotransmitters 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.
Episodic tension-type headaches generally respond well to over-the-counter analgesics such as ibuprofen, acetaminophen, and aspirin. Analgesic/sedative combinations are widely used (eg, analgesic/antihistamine combinations like Syndol, Mersyndol and Percogesic, analgesiv/barbiturate combinations such as Fiorinal )Other medications for chronic tension-type headaches include amitriptyline mirtazapine, and sodium valproate (as prophylaxis). Biofeedback techniques may also help.
Botulinum toxin is a treatment trialled by some people with tension-type headache, though results are varied. There are some reports of Botulinum toxin having the opposite effect, increasing tension.
People with tension-type headache often use manual therapy, such as spinal manipulation, soft tissue therapy, and myofascial trigger point treatment. A 2006 systematic review found no rigorous evidence supporting manual therapies for tension headache. A 2005 structured review found that the evidence was weak for effectiveness of chiropractic manipulation for tension headache, and that it was probably more effective for tension headache than for migraine. A 2004 Cochrane review found that spinal manipulation may be effective for migraine and tension headache, and that spinal manipulation and neck exercises may be effective for cervicogenic headache. Two other systematic reviews published between 2000 and May 2005 did not find conclusive evidence in favor of spinal manipulation.
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 through 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.