Clinical Diagnosis of a Superior Glenoid Labrum Cyst with Suprascapular Nerve Entrapment (GLEN Lesion)

A ganglion cyst arising from the superior labrum with entrapment of the inferior branch of the suprascapular nerve (GLEN lesion) is a rare cause of shoulder pain and weakness. The aim of this study was to determine which clinical findings might predict a GLEN lesion. Twenty-seven clinical signs were assessed on five patients with an MRI-confirmed GLEN lesion and 29 age-matched patients who presented with shoulder pain and no GLEN lesion. The clinical assessment included power for internal rotation, external rotation, supraspinatus and lift-off using a hand-held dynamometer. The most predictive tests for the diagnosis of a GLEN lesion were a reduction of 33% or more of external rotation power compared with internal rotation power, or a reduction of 33% or more of external rotation power compared with supraspinatus power as assessed by handheld dynamometry. These tests had a likelihood ratio of 100 and 25 respectively for diagnosing a GLEN lesion.