Motor unit number estimation may be a useful method to evaluate motor function recovery after spinal cord transection in rats.
METHODS
Experimental rat study.


OBJECTIVE
To investigate changes in motor unit number estimation (MUNE) value of the medial gastrocnemius (MG) muscle after thoracic spinal cord transection in rats and to correlate the MUNE with hindlimb motor function recovery.


METHODS
China Rehabilitation Research Center, Beijing, China.


METHODS
Twelve rats were subjected to spinal cord transection or sham surgery and then evaluated by MUNE and the Basso, Beattie and Bresnahan (BBB) behavioral scale 56 days after the surgery.


RESULTS
The MUNE values of the MG muscle were significantly decreased from baseline at 14-49 days after surgery. However, they returned to near pre-injury levels after 56 days. Rats recovered progressively from the severely impaired hindlimb motor function induced by spinal cord injury, as indicated by a gradual increase in BBB score during days 3-49 after surgery. However, this behavioral recovery was only partial and reached a plateau on day 49. Finally, there was a U-shape-like correlation between changes in MUNE values and BBB scores after thoracic spinal cord transection.


CONCLUSIONS
Time-dependent changes in the functional motor unit number may occur in spinal segments caudal to the transection level, and MUNE could be a useful method to evaluate motor function recovery.
Xiong
G-X
GX
Department of Rehabilitation, School of Public Health and Family Medicine, Capital Medical University, Beijing, China. roustar@sina.com
Guan
Y
Y
Hong
Y
Y
Zhang
J-W
JW
Guan
H
H
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D004185:Disability Evaluation; D004195:Disease Models, Animal; D004558:Electric Stimulation; D005260:Female; D006614:Hindlimb / Q000294:innervation / Q000503:physiopathology; D009046:Motor Neurons / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009416:Nerve Regeneration / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology; D009469:Neuromuscular Junction / Q000503:physiopathology*; D020335:Paraparesis / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D011237:Predictive Value of Tests; D011379:Prognosis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000502:physiology*; D013116:Spinal Cord / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000175:diagnosis* / Q000503:physiopathology*; D015599:Trauma Severity Indices