Correlation between presence of allodynia and sleep quality in migraineurs.
Cutaneous allodynia is a frequent complaint in migraine patients, possibly induced by central sensitisation of trigeminal nucleus. The objective of this study is to investigate if sleep quality is related to the presence of migraine-associated allodynia. A total of 175 consecutive migraineurs were included, 124 with episodic and 51 with chronic forms. As control group, 73 subjects free from any kind of headache were included (HC). The presence of allodynia and sleep disturbances was assessed by a set of semi-structured questions. Chi-square test was applied to compare frequencies among groups. Sleep quality was worse among migraineurs with respect to controls for each sleep item analysed. This difference was significant for all items but one (i.e. frequency in drug use to induce sleep). The frequency of sleep disturbances was higher than in controls in both allodynic and non-allodynic migraineurs, although statistical analysis showed that all these differences were still significant in allodynic migraineurs (also in this case for all the sleep items but one, i.e. frequency in drug use to induce sleep), whilst non-allodynic migraineurs were significantly different from controls only for one item (frequency of initial insomnia). These results suggest that allodynia is strongly related to sleep quality, in a bi-directional way: sleep disturbances may favour central sensitisation, and, in turn, allodynia may impair sleep.