Visualization of chronic neck--shoulder pain: Impaired microcirculation in the upper trapezius muscle in chronic cervico-brachial pain

This study pertains to the 71 patients who had received a diagnosisof cervico-brachial pain syndrome after thorough clinical examinationof a total series of 300 patients, who had been referred tothe National Insurance Hospital in Tranås because of chronicneck pain that interfered with their ability to work. Changesin trapezius muscle blood flow and EMG were examined and relatedto the anamnesis and physical findings. The microcirculationin the upper part of the right and left trapezius muscles wasexamined simultaneously by using optical laser-Doppler single-fibresafter insertion into the muscle directly via the skin. Continuousrecordings were made during stepwise increased static contractiondetermined electro-myographically. Signal processing was performedon-line by computer. MRT of the cervical spine was performedin 12 patients. None showed nerve root affliction. Ten showeda bulging intervertebral disc and two, a narrowed nerve hole(lateral stenosis). The muscle blood flow (LDF) was significantlylower in the most painful side compared with the opposite sidein the group of 41 patients with predominantly unilateral pain(21 women and 20 men). A lowered blood flow was also found whenthe 21 females in this group was compared with a normal controlgroup of 20 healthy women. The patients had lower rms-EMG andEMG mean power frequency (MPF) in the painful side comparedwith the opposite side. A further lowering of the MPF was observedwith induced fatigue. It was concluded that the chronic neckpain in cervico-brachial syndrome can become visualized by thefinding of lowered blood flow of the trapezius muscle whichseems to be an expression of the chronic neck pain.