Also one of the four trigeminal autonomic cephalgias, hemicrania continua (HC) is known for being indomethacin-responsive (the other being chronic paroxysmal hemicrania). The signs and symptoms of HC are notably completely unilateral and consist of moderate to severe continuous side-lock headache without painless periods, lasting for more than three months. This prolonged headache period can fluctuate in intensity and during exacerbations must also occur with at least one sign of autonomic involvement ipsilateral to the headache such as conjunctival injection, lacrimation, nasal congestion, rhinorrhea, miosis, or ptosis. Patients with HC also commonly complain of a sharp, needle-like orbital and temporal pain. Though neuroimaging is relatively unremarkable in most cases of headache, a small study in 2004 did show that PET scans of those with HC did show activation of the ipsilateral rostral pons and contralateral posterior hypothalamus.