This medically confirmed literature report (initial receipt 27-May-2014) concerns a 26-year-old male patient. On an unspecified date, the patient received influenza virus vaccine (manufacturer and batch number not reported) which was administered in the lateral brachium, just distal to the deltoid, in the left arm. On an unspecified date, 12 to 16 hours after vaccination, the patient developed wrist drop and inability to extend his left thumb or digits, in the vaccinated arm and was referred to specialty office. The patient denied experiencing radicular pain or paresthesias during inoculation but admitted to having localized pain that involved the upper arm and shoulder lasting 2 to 3 days. His motor palsy began as clumsiness while typing on a keyboard and progressed to a complete wrist drop with lack of digital extension over 3 to 4 hours. The patient denied having a history of traumatic injury to the left upper extremity, recent febrile illness, night sweats, chills, or any dermatologic rash. The review of his systems were negative with the exception of the described motor deficits. He also underwent extensive workup and clinical examination by other specialist. Six weeks after injury, he underwent sensory and motor nerve conduction studies were performed on the left median, radial, and ulnar nerves as well as the right radial nerve. Results were consistent with an isolated motor palsy of the left radial nerve. Needle electromyogram demonstrated complete denervation of all radial nerve-innervated muscles distal to the triceps with positive sharp waves and no voluntary motor unit potentials. All other motor groups tested were normal. His documented physical examination 6 weeks after injury recorded severe (0/5) weakness in the left radial nerve-innervated muscles with the exception of the triceps. His physical examination was otherwise normal, with preserved sensation to light touch and two-point discrimination throughout the left upper extremity. The patient was evaluated five months after the injury. There was some improvement in motor function. Physical examination at that time revealed active wrist extension but no active thumb extension or digital extension of the metacarpophalangeal joints. Sensation remained intact throughout the left upper extremity. Tinel sign was negative at the brachial plexus, radial tunnel, pronator, and dorsal radial sensory nerve. Reflexes were 2/2 throughout, and cervical spine screening was negative. The brachioradialis demonstrated 4/5 muscle strength 5 months after injury. The patient was managed with physical therapy and splinting. The patient gradually recovered motor function over the next 3 months in a pattern characteristic of proximal to-distal reinnervation. The first muscle to regain function was the brachioradialis and the last muscles were the thumb extensors and extensor indicis proprius. At follow-up 8 months post injury the patient had recovered 5/5 strength in the wrist extensors and 4/5 strength in the finger extensors. Final follow-up was conducted 14 months after the injury. Both current and retrospective QuickDASH surveys were performed at that time. The patient's score improved from 64 at the time of the initial palsy to 14 at 14 months post injury. The Work and Sports/Performing Arts modules of the QuickDASH were also completed and showed improvement from 56 to 19 and 56 to 31, respectively (scores reported on a 0- to 100-scale with higher score reflecting greater disability). The patient cited having difficulty with power grip when playing golf or racquet sports as the most currently limiting sequelae of the palsy. The outcome was recovered with sequelae. Reporter's comments: This case presented features of both Parsonage-Turner Syndrome and direct nerve injury. Also, it was reported that intramuscular injection carries a small but serious risk of nerve injury.