Ulnar Neuropathy Following Implanon Removal: A Case Report

Case Diagnosis: Left ulnar neuropathy in the arm due to implantable contraceptive

Case Description or Program Description: A 21-year-old female presented with continuous pain, numbness and tingling affecting her left ring finger, small finger and medial hand three months post-removal of an Implanon contraceptive implant. She had no weakness, diminished sensation to pinprick in all digits 2-5, normal reflexes, and negative Tinel sign at the left carpal tunnel and ulnar groove. Nerve conduction studies showed a 70% decrease in sensory nerve action potential amplitude to the small finger when compared to the contralateral side but normal motor studies, including studies to the first dorsal interosseus and short segmental incremental studies. Needle electromyography of the LUE, including ulnar and C8 innervated muscles, was unremarkable. Neuromuscular ultrasound showed mild focal enlargement of the left ulnar nerve and scar tissue near the site of implantation. Symptomatic treatment was undertaken.

Setting: Outpatient electrodiagnostics laboratory

Assessment/Results: One year after Implanon removal, the patient returned with chronic LUE pain and paresthesia and was started on pregabalin 25mg twice daily. Follow-up electrodiagnostic study showed a slight improvement in ulnar sensory nerve action potential amplitude in the small finger.

Discussion (relevance): Few studies report implant-site neuropathy, with the lateral and medial antebrachial cutaneous nerves most commonly affected. Ulnar nerve injury after implant removal is rare, but factors like low body mass index, implant migration, and improper placement may contribute.

Conclusions: Ulnar neuropathy is a potential complication of implantable contraception that should be discussed with patients prior to implantation . Ultrasound-guided extraction and alternative insertion sites should be considered to avoid this complication in the future.