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 Classification system for<unk> -type<unk> . The International<unk>  Society's most current classification system for<unk>  disorders is the International Classification of<unk>  Disorders 3rd edition (ICHD-3) as of 2018. This classification system separates<unk> -type<unk>  (TTH) into two main groups: episodic (ETTH) and chronic (CTTH). CTTH is defined as fifteen days or more per month with<unk>  for greater than three months, or one-hundred eighty days or more, with<unk>  per year. ETTH is less than fifteen days per month with<unk>  or less than one-hundred eighty days with<unk>  per year. However, ETTH is further sub-divided into frequent and infrequent TTH. Frequent TTH is defined as ten or more episodes of<unk>  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<unk>  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<unk>  * Secondary<unk> <unk>  due to other disorder) *Giant cell arteritis ( ≥50 years of age) *Dermatochalasis
Tension headache
Migraine
External compression headache
Lupus headache
Vascular headache
Cold-stimulus headache
Cluster headache
Thunderclap headache