title: Median and ulnar nerve compression at the wrist caused by anomalous muscles.
abstract: Compression of the median and ulnar nerves at the wrist is frequently encountered. Carpal tunnel syndrome usually occurs without any obvious extrinsic cause; several cases have however been reported caused by anomalous or hypertrophic muscles. A survey of the literature shows that compression neuropathy of the median nerve has been reported in relation with anomalies affecting three muscles: the first (or second) lumbrical, the palmaris longus and its anatomic variants and the superficial flexor of the index finger. In the ulnar tunnel the situation is thoroughly different: so-called idiopathic ulnar tunnel syndrome is rare and an extrinsic compressing structure can usually be disclosed. Anomalous muscles belong to the palmaris longus/abductor digiti minimi group; the flexor carpi ulnaris is sometimes involved. One can suspect the presence of such an anomalous muscle when the compression syndrome concerns a patient who is not within the "usual" age group with symptoms initiated or aggravated by physical exercise.
authors.affiliation: Hand Unit, Orthopaedic Department, U.Z. Pellenberg, Weligerveld 1, 3212 Lubbeek, Belgium. luc.desmet@uz.kuleuven.ac.be
authors.forename: L
authors.initials: L
authors.lastname: De Smet
mesh_terms: D006225:Hand / Q000033:anatomy & histology; D006801:Humans; D008475:Median Nerve / Q000473:pathology*; D018482:Muscle, Skeletal / Q000002:abnormalities*; D009408:Nerve Compression Syndromes / Q000209:etiology*; D014459:Ulnar Nerve / Q000473:pathology*