Examples of motor and sensory studies for the ulnar nerve Examples of motor and sensory studies for the ulnar nerve. In (A), the setup for measuring distal motor latency for the ulnar nerve is shown. In (B), additional proximal motor testing points are illustrated. With multiple points, the conduction velocities in the forearm, elbow, and arm segments can each be calculated. In (C), an antidromic sensory testing setup is illustrated. The stimulus is applied in a location similar to that used for the motor test. Recording electrodes around the small finger measure the SNAP as it passes antidromically through the digital nerves. D illustrates a sample ulnar nerve motor study in a case with mild slowing at the elbow. Arrows o and p indicate the onset and peak of each response. E illustrates a distal sensory antidromic study. Arrows o, p, and t indicate the onset, peak, and trough of each response. F shows the measures that would be obtained from D and E. For motor studies, the latency is based on the onset, and the amplitude is measured between the onset and peak. The segments are color coded, D for distal, F for forearm, E for elbow, and A for arm. To calculate conduction velocity for the proximal segments, the latency between responses from the two sites is divided by the distance between the sites. Normal conduction velocities should be faster than 50 m per second. Note the slowing at the elbow segment. Distal motor latency for the ulnar nerve at an 8 cm distance should be less than 4.2 msec and amplitude should exceed 2.5 mV. The values presented here should a normal distal motor result. For a sensory study at 14 cm, the latency should be less than 3.7 msec and the amplitude should exceed 15 μV. Sensory latencies are based on the time of the first peak, and the amplitude is measured from peak to trough. Again, this is a normal sensory study. The results are consistent with a mild myelin injury at the elbow. (A–C Adapted with permission from Centers for Disease Control and Prevention (CDC). Performing motor and sensory neuronal conduction studies in adult humans. NIOSH Publication No. 90-113, September 1990.) Source: Motor Neuron Disease and Neuropathies, Neurologic Rehabilitation: Neuroscience and Neuroplasticity in Physical Therapy Practice Citation: Nichols-Larsen DS, Kegelmeyer DA, Buford JA, Kloos AD, Heathcock JC, Basso D. Neurologic Rehabilitation: Neuroscience and Neuroplasticity in Physical Therapy Practice; 2016 Available at: http://accessphysiotherapy.mhmedical.com/DownloadImage.aspx?image=/data/books/1760/larsen_ch15_fig-15-01.png&sec=120049215&BookID=1760&ChapterSecID=120049201&imagename= Accessed: January 02, 2018 Copyright © 2018 McGraw-Hill Education. All rights reserved