Nerve Lesions: Suprascapular, Axillary, Thoracic Outlet, and

S. H. Kozin: Associate Professor, Department of Orthopaedic Surgery, Temple University and Hand Surgeon, Shriners Hospitals for Children, Philadelphia, Pennsylvania.

TABLE 33-1 SEDDON’S CLASSIFICATION OF NERVE INJURY

Type	Definition	Outcome
Neuropraxia	Interruption of nerve conduction; some segmental demyelination; axon continuity intact	Reversible
Axonotmesis	Axon continuity disrupted; neural tube intact	Wallerian degeneration; incomplete recovery
Neurotmesis	Complete disruption of nerve continuity; loss of axons and neural tubes	No spontaneous recovery; surgery required

Figure 33-1 Suprascapular nerve passes below the transverse scapular ligament and around lateral margin of the scapular spine (spinoglenoid notch).

Figure 33-2 Classification of suprascapular notch morphology. In type I, the entire superior border of the scapula shows a depression (8% of specimens). In type II, there is a wide, blunted, V-shaped notch (31%). In type III, the notch is symmetrical and U-shaped (48%). In type IV, there is a very small V-shaped notch (3%). Type V is similar to type III but with partial ossification of the medial portion of the transverse scapular ligament (6%). In tye VI, the transverse scapular ligament is completely ossified, resulting in a foramen of variable size (4%). (Adapted from Rengachary SS, Burr D, Lucas S, et al. Suprascapular entrapment neuropathy: a clinical, anatomical, and comprehensive study. Part 2: anatomical study. Neurosurgery 1979;5:447.)

TABLE 33-2 CAUSE OF SUPRASCAPULAR NEUROPATHY

Repetitive microtrauma	Overhead activities (e.g., volleyball, tennis, weight lifting)
Direct trauma	Glenohumeral dislocation, scapular fracture, proximal humerus fracture, iatrogenic injury (e.g., posterior shoulder surgery, distal clavicle resection, transglenoid arthroscopic shoulder stabilization, and rotator cuff surgery)
External compression	Patient positioning during spine surgery
	Glenohumeral ganglion or cyst
Infection	Brachial neuritis (Parsonage-Turner syndrome)

Figure 33-3 Magnetic resonance imaging (MRI) of glenohumeral cyst emanating from the posterior-superior capsularlabrum junction and compressing the suprascapular nerve before innervation of the infraspinatus muscle.