Pericranial muscle tenderness in a population based sample of chronic tension-type headache. The Akershus study of chronic headache

Abstract

Objectives: The aims of the study were to quantify the pericranial muscle tenderness in a large population based sample of persons with chronic tension-type headache (CTTH). We also wanted to compare the total tenderness score with the general population. Background: The pathofysiological mechanisms involved in CTTH are not fully understood. Muscular factors probably play a crucial role. Several studies have shown that the tenderness of pericranial myofascial tissues are increased in patients with tension-type headache. However, little is known about CTTH characteristics in the general population. Methods: This is a cross-sectional population-based study. An age- and sex-stratified sample of 30,000 persons, aged 30-44 years, residing in eastern Akershus County was in 2005 drawn from the National Personal Registry. Akershus County has both rural and urban areas, is situated in close proximity to Oslo, the capital of Norway. The study population received a posted questionnaire. Those with self-reported chronic headache (i.e. 15 days or more within the past month and/or 180 days or more within the past year) were invited to Akershus University Hospital. Two neurological residents experienced in headache diagnostics conducted all interviews and the physical and neurological examinations. All headaches were classified according to the explicit diagnostic criteria of the ICHD-II and the revised criteria for medication-overuse headache. The response rate to the questionnaire was 71%, and the rate of participation in the interview was 74%. A muscle tenderness score was used to investigate peri-cranial tissue tenderness. 8 pairs ofmuscles and tendon insertions were palpated. The 4-point (0-3) scale at each location and values from left and right sides were summed to a total score. For comparison, cross-sectional data from the Danish general population using the same instruments were used. Results: Those with CTTH had a high total pericranial tenderness compared with the general population. Headache characteristics, age of onset, co-occurrence of migraine or medication overuse had no influence on the total tenderness score. Those with unilateral CTTH had a slightly higher score on the headache side compared to the non headache side, but no significant differences were revealed. Conclusions: Persons with CTTH have an increased pericraniell muscle tenderness compared to the general population. No significant differences in tenderness score within the CTTH sample were revealed. The pathofysiological mechanisms involved in CTTH are not fully understood and further studies are needed.