Can the electrically stimulated manual muscle test differentiate upper from lower motor neuron injury in persons with acute SCI?

ABSTRACT

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.

KEYWORDS:

• Spinal cord
• spontaneous activity
• SMMT
• EMG
• upper motor neuron
• lower motor neuron

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The contents of this presentation were developed under a grant from the National Institute of Disability, Independent Living and Rehabilitation Research. grant # 90SI5025.

Notes on contributors

Ashley de Padua

Ashely de Padua is currently an attending physiatrist at St. Luke's University Health Network.  She went to Temple University (Lewis Katz) School of Medicine where she completed her MD and Masters in Urban Bioethics. She completed her residency in PM&R at Thomas Jefferson University Hospital, and a fellowship in Spinal Cord Injury Medicine at Case Western Reserve University/The MetroHealth System.