Sao Paulo, Sep 24 (IANS) People suffering from chronic migraine headaches are thrice as likely to suffer from severe jawbone disorder, according to a study. The findings showed that temporomandibular disorder (TMD) -- affecting the jaw joint -- does not directly cause migraine. However, the TMD may worsen one's migraine attacks in terms of both severity and frequency, the researchers said. "Migraine is a neurological disease with multifactorial causes, whereas TMD like cervicalgia -- neck pain -- and other musculoskeletal disorders is a series of factors that intensify the sensitivity of migraine sufferers. Having TMD may worsen one's migraine attacks in terms of both severity and frequency," said lead author Lidiane Florencio, researcher at the University of Sao Paulo in Brazil. "Our study shows that patients with chronic migraine, meaning attacks occurring on more than 15 days per month, are three times as likely to report more severe symptoms of TMD than patients with episodic migraine," she added. Previous studies have indicated that migraine is somehow associated with pain in the chewing muscles. The temporomandibular joint acts like a sliding hinge connecting the jawbone to the skull, therefore, the disorder's symptoms include difficulty in chewing and joint tension. Central sensitisation may explain the association between the frequency of migraine attacks and the severity of TMD, Florencio said. "The repetition of migraine attacks may increase sensitivity to pain," she said. For the study, published in the Journal of Manipulative and Physiological Therapeutics, the team assessed women in their early to mid-30s who had either chronic migraine or episodic migraine or with no history of migraine. Signs and symptoms of TMD were observed in 54 per cent of the control participants without migraine, 80 per cent of participants with episodic migraine and 100 per cent of those with chronic migraine. While the people who suffer from migraine are predisposed to have TMD, those with TMD will not necessarily have migraine, the researchers said.