Preserved motor evoked potentials fail to predict functional outcome in quadriplegia because of bilateral lesions of the supplementary motor areas - A brief report

We present a patient with a lesion of the mesial frontal cortex, including the supplementary motor areas bilaterally who on clinical examination revea led no spontaneous movements, although neurophysiological examination indic ated integrity of the corticospinal tract to thenar and tibialis anterior m uscles bilaterally. The patient was alert, speech was hesitant, and he was able to move his hands only on command. The role of the supplementary motor areas in planning, setting, and execution of skillful voluntary movements has been previously established by direct cortical electrical stimulation a nd studies of regional cerebral blood flow The findings in our patient supp ort the role of the supplementary motor areas in initiating movements. The presence of motor evoked potentials after acute insults to the brain is con sidered to be associated with a good functional outcome. This is in contras t to our patient who did not show improvement in motor performance, despite preserved motor evoked potentials. Hence, in the case of bilateral lesions to the supplementary motor areas sparing the corticospinal tract, the pres ence of motor evoked potentials may not predict functional recovery.