Autonomic function in tension-type headache

The pathogenesis of tension-type headache (TTH) is poorly understood. TTH is mostly associated with the sympathetic nervous system. Reports considering autonomic nervous system functioning with regard to TTH are limited. Autonomic nervous system disorders could however play a role in the etiopathology of TTH. Compared with sympathetic nervous system functioning, techniques for evaluating parasympathetic nervous system activity are more limited. Therefore, the aim of the study was to measure heart rate recovery (HRR), an index of vagal activity, in TTH patients. Thirty-seven patients with TTH (15 with episodic and 22 with chronic TTH) and 37 control subjects underwent exercise tolerance testing according to modified Bruce protocol. Heart rate recovery (HRR) at I and 3 minutes (HRR1 and HRR3) were calculated. HRR I and 3 were found to be similar in patients and controls. However, the resting heart rate in patients with episodic TTH was found to be significantly lower than the resting heart rate in patients with chronic TTH and control subjects. These results suggest that parasympathetic nervous system function is not affected in TTH patients. However sympathetic nervous system tonus, which is evaluated by resting heart rate, is low in patients with episodic TTH, suggesting sympathetic hypofunction.