Homosynaptic facilitation occurs when synapses normally involved in pain pathways undergo changes involving receptors on the post-synaptic membrane as well as the molecular pathways activated upon synaptic transmission. Lower pain thresholds of CTTH result from this homosynaptic facilitation. In contrast, heterosynaptic facilitation occurs when synapses not normally involved in pain pathways become involved. Once this occurs innocuous signals are interpreted as painful signals. Allodynia and hyperalgesia of CTTH represent this heterosynaptic facilitation clinically. Stress
In the literature, stress is mentioned as a factor and may be implicated via the adrenal axis. This ultimately results in downstream activation of NMDA receptor activation, NFκB activation, and upregulation of iNOS with subsequent production of NO leading to pain as described above. Diagnosis
With TTH, the physical exam is expected to be normal with perhaps the exception of either pericranial tenderness upon palpation of the cranial muscles, or presence of either photophobia or phonophobia. Classification
The International Headache Societys most current classification system for headache disorders is the International Classification of Headache Disorders 3rd edition (ICHD-3) as of 2018. This classification system separates tension-type headache (TTH) into two main groups: episodic (ETTH) and chronic (CTTH). CTTH is defined as fifteen days or more per month with headache for greater than three months, or one-hundred eighty days or more, with headache per year. ETTH is less than fifteen days per month with headache or less than one-hundred eighty days with headache per year. However, ETTH is further sub-divided into frequent and infrequent TTH.
Frequent TTH is defined as ten or more episodes of headache over the course of one to fourteen days per month for greater than three months, or at least twelve days per year, but less than one-hundred eighty days per year. Infrequent TTH is defined as ten or more episodes of headache for less than one day per month or less than twelve days per year. Furthermore, all sub-classes of TTH can be classified as having presence or absence of pericranial tenderness, which is tenderness of the muscles of the head. Probable TTH is utilized for patients with some characteristics, but not all characteristics of a given sub-type of TTH. Differential diagnosis
Extensive testing is not needed as TTH is diagnosed by history and physical. However, if symptoms indicative of a more serious diagnosis are present, a contrast enhanced MRI may be utilized. Furthermore, giant cell arteritis should be considered in those 50 years of age and beyond. Screening for giant cell arteritis involves the blood tests of erythrocyte sedimentation rate (ESR) and c-reactive protein. Migraine
Oromandibular dysfunction
Sinus disease
Eye disease
Cervical spine disease
Infection in immunocompromised
Intracranial mass
Idiopathic intracranial hypertension
Medication overuse headache
Secondary headache (headache due to other disorder)
Giant cell arteritis ( ≥50 years of age)
Dermatochalasis

Prevention
Lifestyle
Good posture might prevent headaches if there is neck pain.Drinking alcohol can make headaches more likely or severe.Drinking water and avoiding dehydration helps in preventing tension headache.People who have jaw clenching might develop headaches, and getting treatment from a dentist might prevent those headaches.Using stress management and relaxing often makes headaches less likely.Biofeedback techniques may also help.