Persistent Ankle Pain-Running

Abstract

HISTORY: A 29 year-old female long-distance runner presented with a five-year complaint of left ankle pain after an inversion-supination injury while running. She described her ankle pain as a constant aching and throbbing which radiated proximally toward her knee and worsened with any use of her ankle, particularly running. Mild improvement was observed with rest and NSAID's but no other therapies alleviated her pain. Since her injury five years ago, she has been evaluated by five orthopedic surgeons, a rheumatologist, and a pain specialist. Her therapies have included two weeks in a solid cast, several rounds of physical therapy, six weeks of non-weightbearing, several local corticosteroid injections, two lumbar sympathetic nerve root blocks, ankle arthroscopy, a Bromstrum ankle reconstruction, NSAID's, gapapentin, and several antidepressants from various classes. She had been given a presumptive diagnosis of reflex sympathetic dystrophy. PHYSICAL EXAMINATION: Examination of her right leg did not show deficits in strength or sensation. Examination of her left leg revealed a positive Tinel's to percussion over the extensor retinaculum at the ankle. A decrease in pinprick sensation was observed over the first web space. She was tender to palpation only over the lateral malleolus. Strength throughout her leg was rated as 5/5 except toe extension which was 4/5. Her left foot was noted to be slightly darker than the right but a temperature difference was not appreciated. Normal reflexes and pulses were present bilaterally. DIFFERENTIAL DIAGNOSIS: Talar osteochondral injury Reflex sympathetic dystrophy Ankle instability Syndesmotic injury Peroneal neuropathy Osteoarthritis TESTS AND RESULTS: X-rays: normal joint spaces, age-appropriate degenerative changes Bone Scan: slightly increased uptake in the left midfoot. MRI: No signal abnormality in bone or articular cartilage. Postoperative changes along lateral malleolus. EMG/NCV: Axonapraxia of the deep peroneal nerve at the distal leg/ankle consistent with anterior tarsal syndrome. FINAL WORKING DIAGNOSIS: Entrapment of the deep peroneal nerve at the ankle. TREATMENT AND OUTCOMES. Topiramate for long-standing neuropathic pain. Surgical decompression of the deep peroneal nerve with postoperative reduction of her pain from eight to three on a visual analog scale (VAS). She returned to running five months postoperatively, but has been unable to tolerate the same distances she ran premorbidly and currently runs 5–10 kilometer races instead of marathons. Her pain has not completely resolved and her VAS score worsens from three to five when topiramate is discontinued.