Hand dissections were performed in 100 fresh cadaver palms to determine the frequency with which superficial palmar communication between the median and ulnar nerves occurs and to what extent it might incur iatrogenic injury during endoscopic carpal tunnel release.
Superficial palmar communication between the median and ulnar nerves was present in 81% of the dissected hands. Superficial palmar communication, also known as the Berrettini branch, has been classified into four distinct types by Ferrari and Gilbert. Thirty hands were classified as Group 1 (communication in an oblique course from the ulnar to the median nerve), 16 hands were classified as Group 2 (communication parallel to the distal margin of the transverse carpal ligament), and 35 hands were classified as Group 3 (communication in an oblique course from the ulnar nerve to the third common digital nerve, originating below the distal margin of the transverse carpal ligament). No hand fit the Group 4 classification (atypical communication).
These findings led the authors to conclude that changing the course of an incision in the distal part of the carpal ligament radially from the ulnar side a few millimeters is strongly recommended. Sensory branch iatrogenic injury can be avoided by using this technical alteration, in light of the fact that superficial palmar communication between the median and ulnar nerves may be the more likely anatomical finding.
