Active Muscle Trigger Points as Sign of Sensitization in Chronic Primary Headaches

Abstract

Objective: To describe the differences in the presence of trigger points [TrPs] in neck and shoulder muscles that elicit referred pain to the head between nummular headache [NH], chronic tension-type headache [CTTH], and healthy controls [HNC].

Methods: Ten NH [i.e., head pain exclusively felt in a small rounded or elliptical area of the head, not attributed to another disorder], 10 CTTH, and 10 HNC participated. The upper trapezius, sternocleidomastoid, and temporalis muscles were bilaterally examined by an assessor blinded to the subjects' condition for the presence of muscle TrPs as follows: hyperirritable spot within a taut band, local twitch response, and referred pain with palpation. TrPs were considered active if the referred pain reproduced the pattern and features of spontaneous headache attacks.

Results: The number of TrPs was significantly higher [P < 0.001] in the CTTH group [mean: 4.4, standard deviation [SD]: 1.7] as compared to both NH [mean: 0.9, SD: 0.7] and HNC groups [mean: 1.2, SD: 0.6], but not significantly different between NH and HNC [P = 0.8]. Active TrPs were only found in the CTTH group [P < 0001]. Latent TrPs were more conspicuous in both temporalis muscles within the CTTH group [P < 0.05], but not significantly different for the remaining muscles [P = 0.6]. Differences in the distribution of TrPs were significantly different between CTTH and both NH and HNC groups [P < 0.01], but not between the two last groups [P = 0.7].

Conclusions: The absence of active TrPs could be clinically useful to distinguish NH, a peripheral primary headache, from CTTH, a central primary headache.

KEYWORDS:

• Nummular headache
• chronic tension-type headache
• muscle trigger points
• referred pain
• central sensitization