Multiple clinical and paraclinical analyses of chronic tension-type headache associated or unassociated with disorder of pericranial muscles.

Thirty-two female patients fulfilling the diagnostic criteria of chronic tension-type headache underwent multiple clinical (severity index before and after biofeedback therapy; anxiety score) and paraclinical (pericranial EMG levels and pressure-pain thresholds, temporalis exteroceptive silent period) assessments. Twenty-three patients (72%) had at least one increased EMG level and/or at least one decreased pain threshold and qualified for the subgroup" associated with disorder of pericranial muscles" (code 2.2.1). Nine patients (28%) were within the normal range for both investigations and would have been classified in the subgroup "unassociated with such disorder" (code 2.2.2). No significant differences were found between these two groups of patients for headache severity, anxiety, response to biofeedback therapy or duration of temporalis second exteroceptive silent period. The various clinical and paraclinical parameters were not significantly correlated to each other. It is therefore suggested that the subdivision of chronic tension-type headache in two subgroups based on pericranial EMG levels and/or pain sensitivity might be artificial. Since both of the latter and temporalis silent periods vary independently, they appear complementary in the study of tension-type headache patients and probably represent peripheral abnormalities, which are induced to varying intensities by a common central nervous system dysfunction.