F-WAVE VELOCITY IN MOTOR NEURON DISEASE

The F-wave velocity in the central segment (axilla to spinal cord) was studied employing the collision technique described by Kimura (1974), and compared with the conduction velocity obtained with the the usual methods. In 25 normal subjects the F-wave velocity increased proceeding proximally, reaching the maximum values in the central tract (64.86 .+-. 2.23 m/s in ulnar nerve). In 11 patients affected by motor neuron disease and 11 patients affected by amyotrophic lateral sclerosis the F-wave velocity decreased significantly proceeding proximally and the minimum values were found in the central tract (52.51 .+-. 2.15 m/s in MND and 48.64 .+-. 5.60 m/s in ALS). The use of F-wave velocity is a more complete element for precise localization of the lesion in the central segment when the motoneuron is primarily involved.