A Study to Evaluate the Involvement of Parasympathetic Nervous System in Tension Type Headache

Headache is one of the most common disorders of the nervous system seen in medical practice. Tension-type headache although most prevalent is yet understudied subtype of primary headache known to cause substantial disability and diminished quality of life in patients. The neurobiology of symptoms in tension-type headache is still speculated. A few studies done earlier have suggested sympathetic autonomic dysfunction associated with etiopathogenesis of tension-type headache. Altered stress reactivity of autonomic nervous system is now known to be associated with increased risk of cardiovascular mortality.

There is a lack of data as regards involvement of parasympathetic limb of autonomic nervous system in tension type headache patients especially in the Indian population. The objective of the study is to evaluate the involvement of parasympathetic nervous system in tension type headache.

Various parasympathetic function tests were done to assess the parasympathetic activity in 50 tension-type headache patients. The evaluation was done by standard, bedside, non-invasive tests like deep breathing test, Valsalva manoeuvre and orthostatic test. The reference values of Ewing and Clark were used to interpret the results of the test.

In the present study the basal heart rate was significantly decreased in tension type headache patients as compared to healthy controls. However parasympathetic function as evaluated by the different tests was found to be normal as compared to controls.

We conclude that the decrease in resting heart rate in tension type headache patients could be suggestive of sympathetic hypo function as reported by previous studies. However parasympathetic function is unaltered in tension type headache patients.