summary Neuropathic (charcot) shoulder is a chronic and progressive joint disease most commonly caused by syringomyelia leading to the destruction of the shoulder joint and surrounding structures. Diagnosis is made with radiographs of the shoulder and supplemented with cervical spine MRI to assess for a syrinx. Treatment should be individualized based on degree of functional limitation and underlying neurological condition. Neurosurgical decompression is indicated in the presence of a syrinx. Epidemiology Incidence very rare around 70 total cases reported in literature 25% of individuals with syrinxes develop neuropathic arthropathy, with 80% of cases occurring in upper extremity Demographics mean age at diagnosis is ~50 2:1 male:female ratio Anatomic location shoulder (this topic) elbow foot & ankle Etiology Pathophysiology syrinx formation syrinx formation (fluid-filled cavity) in spinal cord causes damage to the decussating fibers of the lateral spinothalamic tract leading to loss of pain and temperature sensation loss of pain/temperature leads to dissociative anesthesia in which proprioception and motor function are preserved but pain and temperature are not as syrinx enlarges, damage to dorsal column and anterior horn of spinal cord lead to areflexia, loss of motor strength and muscle atrophy. joint destruction neurotrauma loss of peripheral sensation and proprioception leads to repetitive microtrauma to the joint poor fine motor control generates unnatural pressure on certain joints leading to additional microtrauma neurovascular neuropathic patients have dysregulated reflexes and desensitized joints that receive significantly greater blood flow the resulting hyperemia leads to increased osteoclastic resorption of bone Genetics molecular biology RANK/RANKL/OPG triad pathway is thought to be involved Associated conditions shoulder syringomyelia most common etiology of neuropathic arthropathy of the upper extremity 25% of Charcot joints are a result of syringomyelia monoarticular (shoulder > elbow) cervical syringomyelia is the cause of 75% cases of charcot shoulder Hansen's disease (leprosy) second most common cause of upper extremity neuropathic arthropathy neurosyphilis (tabes dorsalis) usually affects the knee can be polyarticular diabetes most common cause of foot and ankle neuropathic joints Arnold-Chiari malformation most common cause of syringomyelia multiple sclerosis end-stage renal disease adhesive arachnoiditis and TB arachnoiditis meningomyelocele chronic alcoholism Presentation History 30% of patients report trauma to the shoulder as the inciting event Symptoms swollen shoulder 50% are painless loss of function joint instability Physical exam inspection swollen, warm, erythematous joint can mimic an infection motion loss of motion is most common finding (90%) crepitus joint laxity with mechanically instability neurovascular decreased upper extermity muscle strength sensory and temperature changes along patient's back and arms in cape-like distribution asymmetric reflexes areflexia common in late-stage disease Imaging Radiographs recommended views standard views of affected joint AP and scapular Y of the shoulder findings gold-standard in diagnosis of Charcot shoulder early changes degenerative changes may mimic osteoarthritis late changes superomedial flattening of the humeral head periarticular soft-tissue calcifications glenoid sclerosis extensive bone resorption joint destruction eventual joint subluxation and dislocation CT scan indications if significant concern osteomyelitis/chronic infection findings helpful in evaluating for intraosseous gas, cortical destruction, and sequestra MRI indications MRI of cervical spine to rule out syrinx when neuropathic shoulder arthropathy is present findings syrinx has signal intensity equal to or higher than CSF on T1-weighted images Bone scan technetium bone scan findings may be positive (hot) for neuropathic joints and osteomyelitis indium WBC scan findings will be negative (cold) for neuropathic joints and positive (hot) for osteomyelitis useful to differentiate from osteomyelitis Studies Labs ESR and WBC can be elevated making it difficult to differentiate from osteomyelitis Histology synovial hypertrophy detritic synovitis (cartilage and bone distributed in synovium) Differential Osteomyelitis/septic joint difficult to distinguish from osteomyelitis based on radiographs and physical exam common findings in both conditions swelling, warmth elevated WBC and ESR technetium bone scan is "hot" unique to Charcot joint disease indium leukocyte scan will be "cold" (negative) will be "hot" (positive) for osteomyelitis Synovial chondromatosis Soft tissue sarcoma Tumeral calcinosis Winchester syndrome Gorham's disease Milwaukee shoulder syndrome Treatment Nonoperative rest, NSAIDs, protected immobilization with a sling, restriction of activity and treatment of underlying disease indications first line treatment for neuropathic shoulder joint outcomes 50% of patients reported improvement after non-operative management intra-articular corticosteroid injection indications severe shoulder pain outcomes some case reports have shown temporary 80% reduction in pain following glenohumeral CSI Operative neurosurgical decompression indications presence of cervical syrinx outcomes decompression of syrinx has shown to slow disease progression, maximize joint function and improve bone quality studies have shown regrowth of glenoid fossa following syrinx decompression shoulder arthrodesis indications severe charcot shoulder pain having failed conservative management outcomes previously was only operative management offered for charcot shoulder shoulder arthroplasty indications neuropathy arthropathy is listed as STRICT contraindication for majority of FDA-approved shoulder arthroplasties due to concerns of prosthetic loosening arthroplasty for this condition should be physician-directed application or off-label use newer literature states that arthroplasty is a viable option for patients with charcot shoulder who have failed conservative management and have had underlying condition treated/managed outcomes 70% patients reported improved function with off-label hemiarthroplasty or reverse TSA combined with physical therapy at 5 year followup Techniques Rest, NSAIDs, protected immobilization with a sling, restriction of activity and treatment of underlying disease technique immobilization slows the progression of ligamentous and soft-tissue laxity gentle physical therapy, passive stretching, range-of-motion exercises allow for reduction of pain and swelling Intra-articular corticosteroid injection technique glenohumeral injection is considered most effective Neurosurgical decompression technique neurosurgical management has been reported to consist of 1 or more of the following posterior fossa decompression craniotomy syringoperitoneal shunt laminectomy Shoulder arthrodesis approach S-shaped skin incision beginning over scapular spine, traversing anteriorly over acromion, and extending down the anterolateral aspect of arm technique fusion position goal is to allow patients to reach their mouths for feeding think "30°-30°-30°" 20°-30° of abduction 20°-30° of forward flexion 20°-30° of internal rotation Shoulder arthroplasty technique hemiarthroplasty, anatomic TSA, reverse TSA and shoulder resurfacing have all been previously performed off-label for treatment of charcot shoulder with encouraging results. complications progressive glenoid erosion in hemiarthroplasty cases acromial stress fractures in rTSA Complications Infection risk factors high risk with surgical intervention without management of underlying condition Upper extremity DVT risk factors any surgical intervention Acromial stress fracture risk factors reverse TSA for treatment of charcot shoulder