Various precipitating factors may cause TTH in susceptible individuals:
- Stress: usually occurs in the afternoon after long stressful work hours or after an exam
- Sleep deprivation
- Uncomfortable stressful position and/or bad posture
- Irregular meal time (hunger)
One half of patients with TTH identify stress or hunger as a precipitating factor.
Tension headaches may be 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.
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.
Read more about this topic: Tension Headache
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