Bilateral Knee Pain, Spasticity, And Gait Abnormality

HISTORY: The patient is a 63-year-old female with hypothyroidism and diabetes presenting with bilateral anterior knee pain and stiffness, left more than right, worse with weight-bearing. She reports instability in her knees with swelling, loss of balance, weakness, and numbness in her feet. She requires a cane for stability. Symptom onset coincided with diabetic gastroparesis for which she was prescribed metoclopramide; and an unintentional 25-pound weight loss. PHYSICAL EXAMINATION: The patient is in no apparent distress. Musculoskeletal: Moderate left knee effusion. No varus or valgus deformity. Bilateral tenderness along the medial joint line and medial and lateral patellar facets. Exam limited by pain and guarding. Zero degrees of extension bilaterally. While seated, flexion to 90 degrees in bilateral knees. Supine, she resists any passive or active knee flexion on the left and has significant quadriceps activation. Unable to perform special tests due to pain. Neuro: CN 2-12 grossly intact. Non-velocity dependent increased tone of lower extremities, somewhat asymmetric posturing/dystonic-appearing movement of lower extremities, shuffling gait. DIFFERENTIAL DIAGNOSIS: 1. Inflammatory arthritis 2. Patellofemoral osteoarthritis 3. Drug-induced Parkinsonism and dystonia 4. Stiff person’s syndrome TEST AND RESULTS: Left joint aspiration was negative for crystals and infection. Additional labs per request of neurologist showed elevated glutamic acid decarboxylase antibody titer at 34.4 nmol/L. Paraneoplastic panel negative. FINAL WORKING DIAGNOSIS: Stiff person’s syndrome TREATMENT AND OUTCOMES: 1. The patient received a cortisone injection into her left knee with pain relief for at least four months. 2. The patient received IVIG for treatment of stiff person’s syndrome. 3. She was started on 5 mg diazepam three times daily and 100 mg gabapentin daily with reduction in pain and spasticity though still with limited function and poor gait. 4. The patient received a Botox injection into the left hamstring for spasticity with improvement. 5. The patient saw physical therapy to improve function and gait mechanics. 6. At one year follow up, the patient was walking independently with minimal symptoms of knee osteoarthritis.