Altered neuromuscular control of a hand muscle in chronic rotator cuff tears
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Previous EMG studies have shown that chronic rotator cuff tears (RCT) may be associated with an altered activation of adjacent shoulder muscles. The effect of RCT on central neuromuscular control mechanisms of hand muscles has as yet not been studied in detail. This study investigated the cortico-motor excitability of the first dorsal interosseus muscle (FDI) in patients with RCT.
Materials and methods
The resting motor threshold (RMT) of the FDI on both sides were obtained from patients with unilateral chronic RCT and compared with healthy control subjects without any shoulder pathologies with transcranial magnetic stimulation. Analysis of variance for repeated measures was performed to detect possible differences in RMT of the FDI in patients and healthy controls.
The RMT of FDI in patients on the affected side was lower when compared to the non-affected side (p = 0.015) and to both sides in control subjects (p = 0.041, F = 4.8).
The reduced RMT of FDI in patients with unilateral RCT may be related to alterations in the sensory output from the shoulder and points toward a complete sensimotor restriction of the involved upper limb. These findings seem to be assigned to adaptive changes in the motor cortex as a consequence of chronic RCT.
KeywordsShoulder Rotator cuff tear Transcranial magnetic stimulation First dorsal interosseus muscle
This research was supported by Deutsche Arthrose Hilfe e.V.
- 3.Awiszus F (2005) Quantification of motoneurone pool responses to transcranial magnetic stimulation with surface electromyography. Biocybern Biomed Eng 25(3):3–10Google Scholar
- 6.Berth A, Pap G, Neumann W, Awiszus F (2009) Central Neuromuscular Dysfunction Of The deltoideus muscle in patients with chronic rotator cuff tears. J Orthopaed Traumatol (in press)Google Scholar
- 8.Constant CR, Murley AH (1987) A clinical method of functional assessment of the shoulder. Clin Orthop Relat Res (214):160–164Google Scholar
- 11.Ginanneschi F, Dominici F, Biasella A, Gelli F, Rossi A (2006) Changes in corticomotor excitability of forearm muscles in relation to static shoulder positions. Brain Res 1073–1074:332–338 (Epub Feb 2)Google Scholar
- 20.Norwood LA, Barrack R, Jacobson KE (1989) Clinical presentation of complete tears of the rotator cuff. J Bone Jt Surg Am 71(4):499–505Google Scholar