INTRODUCTION Nerve anastomoses in the hand are deviations from the anatomical norm. They do not lead to illness, but still they are events related with electrodiagnostic difficulties and, due to their unexpected presentation, also with iatrogenesis in regional surgical interventions.

CASE REPORT We report the neurophysiological study conducted on a 45-year-old female who was found to have Riche-Cannieu-type motor anastomosis between the median and ulnar branches in the palm of the hand, complete innervation of the 4th finger by the ulnar nerve and complete innervation by the superficial radial of the back of the hand.

CONCLUSIONS Anatomical descriptions of abnormal innervations in the hand are frequent, especially of the sensory kind. They do not usually give rise to any problems, even when the communicating branch is injured, probably owing to the scant participation of axons that usually occurs in anastomosis. They are not difficult to recognise by means of electroneurography if we are aware of their different types and we have a good knowledge of the anatomical routes. This will enable us to develop accurate diagnostic protocols. Knowledge of these variants will prevent electrodiagnostic errors and surgical iatrogenic effects from occurring.

Introducción Las anastomosis nerviosas en la mano constituyen desviaciones de la norma anatómica. No son motivo de enfermedad, pero sí eventos relacionados con dificultades electrodiagnósticas, y por su presentación inesperada también con yatrogenia en cirugías regionales.

Caso clínico Describimos el estudio neurofisiológico de una mujer de 45 años en la que demostramos una anastomosis motora medianocubital en la palma de tipo Riche-Cannieu y dos variantes sensitivas, inervación completa del dedo IV por el cubital e inervación completa por el radial superficial del dorso de la mano.

Conclusiones Las descripciones anatómicas en la mano de inervaciones anómalas son frecuentes, en especial las sensitivas. No suelen provocar problemas, aun cuando se lesione la rama comunicante, probablemente por la habitual escasa participación de axones en la anastomosis. Saber reconocerlas mediante electroneurografía no es difícil si estamos al tanto de sus tipologías y conocemos con rigor los recorridos anatómicos; de este modo podremos desarrollar precisos protocolos diagnósticos. El conocimiento de estas variantes evitará errores electrodiagnósticos y yatrogenia quirúrgica.