A sixty-two-year-old woman was admitted to our hospital with a left dropfoot and anterior pain and numbness in the left leg. There was no history of spinal disorder or diabetes mellitus. Initially, the patient had a spontaneous onset of acute posterior pain in the left leg. Her general practitioner diagnosed sciatica and prescribed bed rest. One week later, because of persistent symptoms, she received the first of a series of acupuncture treatments, and the pain decreased after several treatments. During the sixth treatment, she felt a sudden radiating pain in the anterior part of the left leg when the acupuncture needle was inserted. A burning sensation and numbness in the anterior part of the left leg occurred immediately after this treatment. When the patient was stepping out of the bathtub on the following night, she noticed a left dropfoot for the first time, and she experienced difficulty with walking. The pain, burning sensation, numbness, and weakness in the left leg persisted. After receiving additional acupuncture treatments, she consulted a neurologist, who diagnosed an L5 radiculopathy and referred her to the orthopaedic department.
On physical examination in our department, sensation was diminished on the dorsum and lateral side of the left great toe and on the dorsal aspect of the web space between the great and second toes but was otherwise normal. The strength of the tibialis anterior and extensor hallucis longus muscles was graded 1 of 5, but the strength of the peroneus longus and flexor hallucis longus muscles was graded 5 of 5. The Tinel sign was positive just posterior to the fibular head. A small brown discoloration was noted in this area, which, according to the patient, was where an acupuncture needle had been inserted. Radiographs showed a metallic needle-like object, approximately 1 cm in length, lying near the fibular head (
Fig. 1 ), and magnetic resonance imaging demonstrated metallic artifact in the same area. Examination of the lumbosacral spine revealed normal findings. Compound muscle action potentials of the peroneal nerve in the left leg showed a remarkable decrease in amplitude distal to the level of the fibular head (
Fig. 2 ).
Surgery was performed two weeks after the presumed nerve injury. A skin incision was extended from the medial side of the biceps tendon to the posterior aspect of the fibula. The peroneal nerve was identified and was traced distally. No foreign body was visible at first, but something firm could be palpated within the nerve. On reflection of the nerve, a broken needle was found just proximal to the point of division of the deep and superficial peroneal nerves (
Fig. 3 ). No scar tissue or sign of infection was identified about the nerve. The needle fragment, which was 12 mm in length and had penetrated the nerve by approximately 5 mm, was removed without difficulty. On the day after the surgery, sensation and strength remained unchanged, but the pain and numbness had disappeared. The patient was provided with a dorsiflexion assist ankle-foot orthosis. Four months after the operation, the strength of the tibialis anterior muscle was graded 4 of 5, and that of the extensor hallucis longus muscle was graded 2 of 5. The hyperesthesias remained unchanged. The gait had become normal, and use of the orthosis was discontinued. Ten months after the operation, the tibialis anterior and extensor hallucis longus muscles had improved in strength and were graded 5 of 5 and 4 of 5, respectively, but the hyperesthesias remained unchanged.