Dorsal scapular nerve injury after trigger point injection into the rhomboid major muscle: A case report

Article type: Research Article

Authors: Lee, Dong Gyu | Chang, Min Cheol^*

Affiliations: Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Taegu, Korea

Correspondence: [*] Corresponding author: Min Cheol Chang, Department of Physical Medicine and Rehabilitation, College of

Abstract: BACKGROUND AND OBJECTIVE: We report the case of a patient who presented with right dorsal scapular neuropathy after a trigger point injection into the right rhomboid major muscle. Through a nerve conduction study and electromyography, we demonstrated dorsal scapular nerve injury in this patient. CASE REPORT: A 38-year-old man complained that his right shoulder functioned less optimally during push-up exercises after a trigger point injection 4 weeks prior. Physical examination revealed mildly reduced right shoulder retractor muscle strength compared with the left side. We performed a nerve conduction velocity test and electromyography 5 weeks after the injection. The compound muscle action potential of the right dorsal scapular nerve showed low amplitude (left vs. right side: 5.2 vs. 1.6 mV) and delayed latency (left vs. right side: 4.9 vs. 6.8 ms). Positive sharp wave (1+) and mildly reduced recruitment were seen on electromyography of the rhomboid major muscle. The findings of the nerve conduction velocity test and electromyography indicated partial right dorsal scapular neuropathy. The nerve injury seemed to have been caused by the needle inserted during trigger point injection. CONCLUSION: Clinicians should pay attention to the occurrence of dorsal scapular nerve injury when performing trigger point injection into the rhomboid muscle.

Keywords: Peripheral nerve injuries, myofascial pain syndromes, intramuscular injections, lidocaine, nerve conduction, electromyography

DOI: 10.3233/BMR-169740

Journal: Journal of Back and Musculoskeletal Rehabilitation, vol. 31, no. 1, pp. 211-214, 2018