Altered muscle activity during rest and during mental or physical activity is not a trait symptom of migraine—a neck muscle EMG study

DOI: https://doi.org/10.1186/s10194- 018- 0851- 5

Abstract-Summary We measured electromyography (EMG) of the neck muscles in a large cohort to identify whether neck pain and neckmuscle tension reported by migraine patients can be attributed to increased neck muscle activation during rest, mental stress or physical activity.

Surface EMG responses of the trapezius muscle were recorded during a para- digm including rest periods, mental stress and physical activity of 102 participants (31 chronic migraine, 43 episodic migraine, 28 healthy participants).

All groups showed increased trapezius activity during mental stress and physical

activity compared to rest.

There was no statistically significant difference between migraine patients and healthy controls for any of the 3 conditions except for the initial mental stress situ- ation (F (2,56.022) = 8.302, p = 0.001), where controls increased tension by only 4.75%, episodic migraineurs by 17.39% and chronic migraineurs by 28.61%.

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2 Mechanisms

Neck pain associated with migraine can therefore not be attributed to increased trapezius activity during rest, mental stress and physical activity or prolonged mus- cle activity and should not be seen as a constantly underlying trigger but rather as an accompanying symptom of migraine.

Extended: All groups showed increased bilateral trapezius muscle activity during

mental as well as physical stress (for all tasks p < 0.05).

There was no significant (point-biserial) correlation between the dominant head-

ache side and the recorded side of the neck.

This conclusion was based on the evaluation of the trapezius muscle; whether it can be generalized to all neck muscles remains to be investigated by future studies.

Background Goudswaard and colleagues [283] reported that migraine patients consistently showed higher proportional EMG levels of the corrugator muscle during periods of experimental and real-life stress but patients who developed headaches during stress had lower levels of muscle tension than participants without headaches.

The inconsistency of the existing evidence and two important additional ques- tions triggered the design of the current study: question 1 is, whether activities of remote body parts, e.g. the lower limb will result in a higher activation of neck muscles in migraine patients, and question 2 is, whether neck muscle tension is prolonged after any type of stress or physical activity.

The purpose of this study was to evaluate the level of muscle tension during vol- untary relaxation and during mental and physical tasks as well as the ability to relax after periods of mental and physical stress in patients with migraine and headache- free control participants.

Methods To test hypothesis 1 we calculated the proportion (percentage) of the difference to the previous relaxation block’s mean for each of the seven experimental conditions of the EMG signal.

We tested the main effect of mental or physical stimulation with independent, one-sample t-tests and used one-way-ANOVAs to assess significant differences between the three groups for each condition separately.

When including chronic migraine patients, a significant number of participating patients reported headache during the examination we further ran a two-sample t-test for all 7 blocks and 2 EMG channels to investigate the influence of acute head- ache on neck muscles tension.

To test hypothesis 2 we calculated the time until the mean value within the relax- ation block was reached after a mental or physical task and calculated a one-way- ANOVA between the three groups for each condition separately.

Results Forty three subjects suffered from episodic migraine (38 females; mean age 39.12 years (SD 12.2), min: 18 years, max: 60 years), i.e. had headache on fewer than 14 days per month (mean 7.3 days, SD 3.6), and 31 patients were diagnosed with

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chronic migraine (30 females; mean age 39.3 years (SD 13.8), min: 20 years, max: 68 years) with 15 or more days of headache per month (mean: 21.7 days, SD: 5.6). We could not find any significant differences between patients with and without acute headache during the examination (p > 0.05 in all two-sampled t-test) as well as between preictal patients (in a 24 h, 48 h as well as 72 h period) and patients which were free of headache since at least 4 days.

Discussion Headache status on the day of testing did not significantly influence the results, therefore neck pain or perceived muscle tension does not seem to be quantifiable with surface EMG data.

Sandrini and colleagues also applied EMG measurements as a diagnostic tool and reported significantly altered muscle activity in patients with tension-type head- ache but not in patients with migraine [284].

Our results from this study neither indicate higher levels of neck muscle tension nor increased durations of tension after stressful incidents in patients with frequent episodic or chronic migraine compared to headache-free controls.

Perceived neck muscle tension during the premonitory phase or accompanying migraine headache is therefore more likely a subjective perception not quantifiable by EMG and should be regarded as a symptom of the attack and not as a trapezius muscle dysfunction triggering an attack.

Acknowledgement A machine generated summary based on the work of Luedtke, Kerstin; Mehnert, Jan; May, Arne. 2018 in The Journal of Headache and Pain.

Fluctuations in local and widespread mechanical sensitivity throughout the migraine cycle: a prospective longitudinal study