Unilateral and isolated absence of opponens pollicis and adductor pollicis: Could it be Cavanagh's syndrome?

Abstract

Functions of the human hand such as grasping and releasing require synchronous action of thenar muscles and thereby require considerable mechanical complexity. Isolated absence of thenar muscles is often reported in association with syndromes such as Cavanagh's syndrome or Holt–Oram syndrome (in addition to cardiac defects). During routine anatomical dissection of an approximately 55-year-old male formalin-embalmed cadaver, we observed a unique variation in the left palm where opponens pollicis and adductor pollicis muscle were completely devoid of muscle fibers and solely constituted by fibrous tissue. We could not make out any other nervous/vascular/musculoskeletal abnormalities or signs of surgical procedures on the left superior extremity. We followed a step-wise approach rule out possible clinical syndromes and etiologies. The presumable hypothesis would be focal deficiency in the proliferation of premyogenic cells in the limb bud. This rare variation would be of paramount importance to plastic surgeons who can offer surgical correction (tendon transfers) if presented at earlier ages.