Occupational Medicine 1998;48:189-194
© 1998 Society of Occupational Medicine
research-article |
Visualization of chronic neckshoulder pain: Impaired microcirculation in the upper trapezius muscle in chronic cervico-brachial pain
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Department of Orthopaedics, University Hospital S-501 85 Linkping, Sweden
Department of Biomedical Engineering, University Hospital S-501 85 Linköping, Sweden
This study pertains to the 71 patients who had received a diagnosis of cervico-brachial pain syndrome after thorough clinical examination of a total series of 300 patients, who had been referred to the National Insurance Hospital in Tranås because of chronic neck pain that interfered with their ability to work. Changes in trapezius muscle blood flow and EMG were examined and related to the anamnesis and physical findings. The microcirculation in the upper part of the right and left trapezius muscles was examined simultaneously by using optical laser-Doppler single-fibres after insertion into the muscle directly via the skin. Continuous recordings were made during stepwise increased static contraction determined electro-myographically. Signal processing was performed on-line by computer. MRT of the cervical spine was performed in 12 patients. None showed nerve root affliction. Ten showed a bulging intervertebral disc and two, a narrowed nerve hole (lateral stenosis). The muscle blood flow (LDF) was significantly lower in the most painful side compared with the opposite side in the group of 41 patients with predominantly unilateral pain (21 women and 20 men). A lowered blood flow was also found when the 21 females in this group was compared with a normal control group of 20 healthy women. The patients had lower rms-EMG and EMG mean power frequency (MPF) in the painful side compared with the opposite side. A further lowering of the MPF was observed with induced fatigue. It was concluded that the chronic neck pain in cervico-brachial syndrome can become visualized by the finding of lowered blood flow of the trapezius muscle which seems to be an expression of the chronic neck pain.
Keywords Chronic neck pain; electromyography; Laser Doppler flowmetry; mean power frequency; microcirculation
Received 2 July 1996
Accepted 30 October 1997
Correspondence and reprint requests to: R. Larsson, Department of Orthopaedics, University Hospital, S-501 85 Linköping, Sweden