Electrodiagnostic description of a rare variant of Berrettini anastomois: A case report

Berrettini Anastomosis is a common purely sensory anastomosis between ulnar and median nerves in palm. Here, via a communicating branch, ulnar nerve can provide sensory supply to digits 3 and 2.There have been electrodiagnostic (EDX) descriptions of the former. However, till date, to the best of our knowledge, there have been no EDX descriptions of the latter. Here, in our case report we would like to describe first instance of the same.

During an assault with a knife a 25-year-old male sustained laceration injury of right median nerve and flexor tendons which were repaired surgically. During rehabilitation, a nerve conduction study (NCS) was performed which incidentally revealed that ulnar nerve was responsible for sensory innervation of digit 2.

Until recently, it was generally believed that EDX of BA was not possible. However, recent studies on EDX features in BA, have recorded small sensory nerve action potentials (SNAP) from digit 3 on distal ulnar nerve stimulation. But there are no published reports where SNAP from digit 2 on ulnar nerve stimulation were studied, even though anatomical evidence of the same exists. In our patient, we incidentally recorded the same.

Although our patient had a complete laceration of median nerve, he did not have major sensory disturbances. NCS findings suggested sensory supply of digits 5, 4, 3 and 2 were by ulnar nerve. Without adequate knowledge of communicating branch crossovers in palm, there is a possibility that clinical findings can be misdiagnosed and NCS features can be misinterpreted. For surgeons, awareness of these communicating branches can prevent iatrogenic injuries during surgical interventions.