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Objective: To determine if the motor response on the stimulated manual muscle test (SMMT) in muscles with a grade 0 motor score on the manual muscle test (MMT) can differentiate lower motor neuron (LMN) from upper motor neuron (UMN) injury based on the presence of spontaneous activity (SA) with needle EMG.
Design: Prospective Study.
Participants/methods: Twenty-one subjects with acute traumatic cervical SCI.
Methods: An upper extremity International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) evaluation was completed on all subjects. A needle EMG and an electrically stimulated manual muscle test (SMMT) were completed on all key upper extremity muscles with a MMT motor score of zero.
Results: The MMT, SMMT and Needle EMG were done on 77 muscles. The SMMT motor score was 0 on 10 muscles and >1 on 67 muscles. The needle EMG identified spontaneous activity (SA) in 55/77 muscles. Seventy percent (7/10) of the muscles with MMT and SMMT motor score of zero demonstrated SA on EMG. Seventy-two percent (48/67) of the muscles with MMT motor score = 0 and SMMT motor score ≥1 demonstrated SA on EMG.
Conclusion: In our study, 70% of the muscles with a SMMT motor response of zero and 72% of the muscles with a SMMT motor response greater than or equal to one demonstrated SA on EMG. The use of the SMMT as a clinical measure to differentiate LMN from UMN integrity may be limited when applied.
Ashley de Padua, Cassandra Renfro, Maria Grabnar, Kevin Kilgore, Anne Bryden, Mary Joan Roach, Greg Nemunaitis