LAUSR

The differentiation between an upper motoneuron (UMN) lesion and lower motoneuron (LMN) lesion of forearm muscles in patients with tetraplegia is critical for the choice of treatment strategy. Specifically, the M. pronator teres (PT), M. flexor digitorum profundus III (FDPIII) and M. flexor pollicis longus (FPL) were studied since they represent key targets in nerve transfer surgery to restore grasp function. Forearm muscles of 24 patients with tetraplegia were tested bilaterally with electrical stimulation (ES) to determine whether UMN lesion or LMN lesion was present. For detecting and testing the nerve stimulation points, a standardised mapping was developed and clinically applied. The relation between the anatomical segmental spinal innervation and the innervation pattern tested by ES was determined. The data of 44 arms were analyzed. For PT, 19 arms showed an intact UMN, 18 arms an UMN lesion and seven arms partial denervation. For FDPIII, 3 arms demonstrated an intact UMN, 26 arms an UMN lesion, 10 arms partial denervation and 5 arms denervation. For FPL, 2 arms presented an intact UMN, 16 arms an UMN lesion, 12 arms partial denervation and 14 arms denervation. 20.1% ES tested muscles were partially denervated. In four patients only one arm could be tested because of surgery-related limitations. According to the level of lesion and the segmental spinal innervation most denervated muscles were present in the patient group C6 to C8. The ES together with the developed mapping system is reliable and can be recommended for standardized testing in surgery and rehabilitation. It offers the possibility to detect if and to what extent UMN and LMN lesions are present for the target muscles. It allows for refined preoperative diagnostics and prognostics in SCI neurotization surgery. Electrical stimulation, Tetraplegia, Motor point topography, Grip function, Nerve transfer.