Figure 1.

Zones of lost protective sensation with the different types of brachial plexus palsy. Mapping was performed following assessments using Semmes-Weinstein monofilaments. In those with a C5-C6 injury, hand sensation was totally preserved. In the C5-C7 injury group, hand sensation was decreased, but still was within the normal range. A longitudinal area of absent protective sensation was present on the lateral aspect of the forearm and arm. In the C5-C8 palsy group, there was a similar longitudinal area along the lateral side of the arm and forearm, associated with no protective sensation. The dorsal side of the hand also was now markedly affected. On the palmar aspect of the hand, sensation decreased to a variable degree. Almost half of the patients had normal sensation, and the remaining half experienced thumb anesthesia. In those with a C5-T1 lesion with post-fixation of the plexus, only a small zone was observed in which there was preserved sensation over the medial side of the forearm. Hand sensation was markedly reduced. The thumb was anesthetized, but protective sensation was demonstrated in the long fingers (inset). In the C8-T1 palsy group, a loss of protective sensation was evident on the medial side of the forearm and in the ulnar fingers. In the C7-T1 injury group, the inner aspect of the arm also was affected, together with additional involvement of the long finger.