Hwang, Gloria, MD; Nakamura, Reina, DO; Lee, Se Won, MD

A 72-yr-old right-handed woman with syringomyelia presented with chronic instability and pain in the right shoulder. Symptom onset was gradual without preceding injury or trauma. She complained of tingling and numbness of the entire right upper limb, weakness of the right shoulder, and clumsiness and tingling of the left hand. Serial plain x-rays of the right shoulder (Fig. 1) taken for 9 yrs revealed persistent anterior glenohumeral dislocation with sclerosis, fragmentation of the glenoid, and progressive bony resorption and deformity of humeral head, consistent with neuropathic disease. Magnetic resonance imaging of the cervical spine (Fig. 2) revealed syrinx extending from C2/3 through T6/7 with inferior displacement of cerebellar tonsil, consistent with Chiari I malformation. The patient refused surgical intervention. With the help of joint protection techniques, which she was educated on, and occupational therapy, her pain decreased, and her activities of daily living improved. Differential diagnosis of chronic painful shoulder instability in this patient's age group include rotator cuff tear with/without arthropathy, chronic glenohumeral dislocation, and inflammatory/septic arthropathy. Neuropathic arthropathy of the shoulder is a rare and progressive entity causing persistent instability. Diabetes is the most common cause, followed by syphilis and syringomyelia.¹ Neuropathic arthropathies develop in 25% of patients with syringomyelia, with 80% involving the upper limb,² whereas diabetes and syphilis frequently affect the lower limb. Pain is less than expected from imaging findings, marked by bony destruction, bone resorption, and eventual deformity as illustrated in this case. Without proper management, joint deformity, ulceration, and/or superinfection, loss of function and ultimately amputation may occur. Treatment includes reducing further articular damage by prevention of repetitive trauma and protecting joints from exceeding safe limits in range of motion.³ Aspiration of a large effusion followed by stabilization may prevent further ligament laxity. Bisphosphonates can be beneficial in reducing disease activity and bone turnover. For patients who fail conservative management, with resultant limited function and persistent disabling pain, surgery for shoulder deformities, including shoulder arthrodesis, resurfacing arthroplasty, and hemiarthroplasty, can be considered.²

FIGURE 1

FIGURE 2

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