Neurogenic thoracic outlet syndrome due to subclavius posticus muscle with dynamic brachial plexus compression: a case report.
BACKGROUND
Neurogenic thoracic outlet syndrome is an underestimated cause of brachial weakness and pain. The subclavius posticus muscle (SPM) is an aberrant muscle originating from the medial aspect of the first rib reaching to superior border of the scapula, which may cause, depending on its activation, dynamic compression of the brachial plexus.


METHODS
In the present study, we report about a 32-year-old male caucasian patient with weakness in radial deviation of his left hand. An isolated macrodactyly of his left middle finger had been operated twice. Electroneurography showed a carpal-tunnel-syndrome (CTS) on the left side. MRI of the brachial plexus revealed an additional muscle in the costoclavicular space, identified as SPM. To our knowledge, this is the second case report of a neurogenic thoracic outlet syndrome due to SPM, and the first case described with isolated macrodactyly and CTS in the same patient.


CONCLUSIONS
If complaints about hand weakness are only reported in cases of distinct hand positions, a dynamic compression of the brachial plexus by SPM may be the cause. A neurogenic thoracic outlet syndrome may facilitate the development of CTS.
Department of Neurology, University Hospital Bern, Freiburgstrasse 100, 3010, Bern, Switzerland. julia.muellner@insel.ch.
Julia
J
Muellner
Neurocenter of Southern Switzerland, Opsedale Civico, Via Tesserete 46, 6900, Lugano, Switzerland. alain.kaelin@eoc.ch.
Alain
A
Kaelin-Lang
Department of Neuroradiology, University Hospital Bern, Bern, Switzerland. oliver.pfeiffer@ksa.ch.
Oliver
O
Pfeiffer
Department of Neuroradiology, University Hospital Bern, Bern, Switzerland. Marwan.El-Koussy@insel.ch.
Marwan Mohamed
MM
El-Koussy
D000328:Adult; D001917:Brachial Plexus / Q000473:pathology*; D020516:Brachial Plexus Neuropathies / Q000175:diagnosis* / Q000473:pathology; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis; D006225:Hand / Q000503:physiopathology; D018737:Hand Strength; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology; D010146:Pain; D013901:Thoracic Outlet Syndrome / Q000175:diagnosis* / Q000503:physiopathology