Influence of osteopathic treatment on pain, blink reflex and exteroceptive suppression of the temporal muscle in patients with ‘frequent episodic tension-type headache’.

Abstract

Hoste R.¹, Van Damme G.,  Santens P.² , Van Maele G.³

Introduction Reflexes are considered to be a fundamental parameter to obtain objective information on local circuits in the central nervous system. In this pilot-study we examined the effects of osteopathy on different brainstem reflexes on one hand, and on the complaint pattern of patients with frequent episodic tension-type headaches (FETTH) on the other hand. We also investigated the correlation between both parameters.

Design Experimental pilot-study.

Methods Ten FETTH patients were selected according to criteria of the International Headache Society, using a simple timeframe design with pre- and post-measurements in one research group.
A visual analogue scale (VAS) was used to assess the amount of pain the patients experienced as a consequence of their headache and its impact on daily-, social-, personal- and professional activities. For the measurement of the brainstem reflexes we used the blink reflex and the exteroceptive suppression of the temporal muscle using an EMG (Synergy, Medelec, Oxford).
Blink reflex procedure: stimulation of the supra-orbital nerve results in a reflex contraction of the orbicular muscle, which normally consists of an ipsilateral response (R1) and a bilateral response component (R2).
Patients were asked to lie relax in a supine position on the table, with their eyes open or gently closed. Surface recording electrodes were bilaterally placed over the inferior orbicular muscles. Stimuli were applied to the supra-orbital nerve. The stimulus intensity was increased until a stable R1 response was seen, with an interval of at least 10 sec. Filter settings were between 2Hz – 2kHz.
Exteroceptive suppression procedure: the exteroceptive suppression consists of two electric silent periods (ES1 & ES2) interrupting the voluntary EMG activity in the ipsilateral and contralateral temporal muscles. Patients were in the same position as described for the blink reflex. A needle electrode was used for the temporal muscle. Single electric shocks, 0.1 ms in duration, were applied to the commissure of the lip. The stimulus intensity was increased until a stable ES1 response, with an interval of at least 30 ms, was reached. Filter settings were between 2Hz and 2 kHz.
The intervention consisted of four osteopathic treatments, according to the “black-box” method, with an interval of two weeks. A follow-up on the VAS-scales was made after one and after three months.

Results The intensity of headaches, as well as the impact of pain on daily-, social-, personal- and professional activities, was significantly (p<0.05) less after osteopathic intervention for each of the compared measuring moments. One of the sub parameters “the most worse headache” however, showed no significant change and the “headache at this moment” showed only a borderline missed significance.
Significant differences (p<0.05) were found concerning brainstem reflexes in case of stimulation on the left side in R2 latency contralateral and ES2 duration ipsilateral, and an obvious tendency in the differences of the R2 latency ipsilateral. Stimulations on the right hand side did not show any significant difference in the R2 latency measured ipsi- and contralateral. Concerning the ES2 latency, measured ipsi- and contralateral when stimulating both left and right side, no significant differences were found between both measuring moments. The ES2 duration contralateral when stimulated left and right, and on top also the ES2 duration ispilateral when stimulated right, show no significant difference.
There was no correlation found between clinical and fundamental parameters.

Conclusion We conclude that osteopathy has a significant (p<0.05) impact on the pattern of complaints of the patient who suffers from tension headaches.
The significant results of both brainstem reflexes were only found in case of stimulation of the left side. However, we can use this as a standard when talking about a modified inhibition on the brainstem level after osteopathic treatment.
In spite of lack of correlation, we can assume that there is sufficient indication to continue to investigate a potential causal relationship between clinical and fundamental parameters.

^{1 Lecturer at College Sutherland for Osteopathic Medicine (The Netherlands)
2 Department of Neurology, Univeristy Hospital, Ghent (Belgium)
3 Department Medical Informatics & Statistics, University Hospital, Ghent (Belgium)}