Isolated teres minor atrophy: manifestation of quadrilateral space syndrome or traction injury to the axillary nerve?

This article prospectively determines through magnetic resonance imaging (MRI) the incidence of isolated teres minor atrophy and its gender and age distribution, and documents associated findings related to the rotator cuff, labroligamentous complex, and quadrilateral space. Two hundred seventeen consecutive shoulder MRI examinations performed over a 3-month period were prospectively reviewed and evaluated for isolated teres minor atrophy. Twelve (5.5%) patients had non-compressive isolated teres minor atrophy. Ninety-two percent (n=11) of these patients had rotator cuff or labroligamentous complex tears. No patients had an associated mass within the quadrilateral space. The average patient age was 60 years and 11 of the 12 patients were male. Isolated teres minor atrophy on MRI is most commonly seen in older patients who do not fit the expected clinical presentation of quadrilateral space syndrome. The anatomical relationship of the teres minor nerve to the joint capsule and the frequency of associated shoulder injuries in these patients raises the possibility of an association between humeral decentering and teres minor atrophy. Quadrilateral space syndrome would appear to be a very rare cause of isolated teres minor atrophy.