CHANGES IN NECK ELECTROMYOGRAPHY ASSOCIATED WITH MENINGEAL NOXIOUS-STIMULATION

Objective: To determine if the activity of jaw and neck muscles in a r at model is influenced by the application of small-fiber irritant must ard oil to meningeal/dural vascular tis sues. Design: Controlled anima l experiment. Setting: University neurophysiology laboratory. Interven tions: Applications of mineral oil (vehicle control) and mustard oil t o exposed meningeal/dural vascular tissues. Main Outcome Measure: Elec tromygraphic (EMG) recordings from deep suboccipital muscles, bilatera lly, and the left trapezius and left masseter muscles. Results: Minera l oil evoked no EMG responses in any muscles. The incidences of mustar d oil-evoked EMG increases were 100%, 100%, 89% and 78% for left deep neck, right deep neck, left trapezium and left masseter muscles, respe ctively. The durations of EMG responses were (mean +/- SD) 19.2 +/- 6. 6 min, 17.3 +/- 7.5 min, 14.5 +/- 6.8 min and 12.7 +/- 8.5 min, respec tively. Conclusions: These results document that meningeal/dural vascu lar irritation leads to sustained and reversible activation of neck an d jaw muscles that may be related to the clinical occurrence of muscul ar tension and pain associated with certain types of headaches, partic ularly migraine.