A systematic review found spinal manipulative therapy as effective as commonly used first-line prophylactic medications for both TTH and migraine headaches, but the Authors emphasized that their conclusions were based on only a few trials, raising the question of whether their analysis was methodologically adequate. A more recent systematic review concluded that spinal manipulation might alleviate TTH but that the small quantity of available data prevented any definitive conclusions. The combination of physical therapies with medications, can also increase the success of the treatment, particularly in case of comorbid mood disorders and unremitting headaches, as previously suggested. Although results of these and others published studies suggest positive effects, OMTh has rarely been rigorously tested for the care of patients with headache in general.