Case number PHEH2011US010746 is a spontaneous report initially received from a healthcare professional on 25 Nov 2011 with a follow-up received from the physician on 28 Dec 2011 with another follow-up received from the physician on 20 Jan 2012 and 24 Jan 2012: This report refers to an adult male patient. Family history was negative for neurologic disease. He had a 40-pack-year history of cigarette abuse. He did not drink alcohol. His other medical history included diabetes mellitus and lipidemia. However he did not have any history of GBS or other neurological disease. He was vaccinated with FLUVIRIN (batch number: 111822P1) intramuscularly on 21 Dec 2010. Around three hours after vaccination he developed left arm and hand weakness. He reported that four and a half hours after vaccination his left hand became severely weak, with numbness of the last two fingers of the left hand. About a week later. he developed tingling in the right fingers as well as in the soles of the feet. There was no pain in the left deltoid after the flu shot. He had no numbness or weakness in the face. He felt that the weakness continued to progress in the left and right arms. He had a left ulnar nerve transposition, but this did not help his symptoms. He had not noticed weakness in the feet or ankles. In addition on 14 Sep 2011 he had a possible TIA (transient ischemic attack), where he had severe dysarthria and perioral paresthesia lasting for one or two minutes. Magnetic resonance imaging (MRI) done, showed a DWI lesion in the left frontal periventricular white matter, plus chronic scattered ischemic changes. There were no other significant medical problems. He took no medications and there were no medical allergies. The patient was sent to two neurologists. Initially it was diagnosed as "Lar neuropathy" by the hand surgeon. The onset of the reaction was acute and progressive over months. No respiratory muscles and muscles innervated by a cranial nerve were involved. His physical examination revealed no distress and supple neck without carotid bruit. There was no cardiac murmur or arrhythmia. Visual fields were full and extraocular movements were normal. Facial sensation and strength were normal, hearing was intact and bulbar function was normal. In the left arm there were multiple weak muscles (5 was normal): triceps 4, wrist extensors 4+, wrist flexors 4+, finger extensors 4+, dorsal interossei 3, palmar interossei 2 and abductor pollicis brevis 4. There was obvious atrophy of all left intrinsic hand muscles, including thenar muscle and the left forearm. In the right arm, there was isolated weakness of the triceps. The right quadriceps was possibly slightly weak at 4+/5. Sensation was impaired to pinprick in the right fifth finger and left fourth and fifth fingers and the distal medial forearm, and in a stocking distribution in the feet up to the below knees. Deep tendon reflexes test was done which revealed his right/left biceps as 1/trace, brachioradialis as 2/1, triceps as 2/2, knees as 2/2 and ankles as 1/1. Plantar responses were flexor. Impression that was left of the reflex study was a probable neuralgic amyotrophy with slight involvement of right arm and probably sensory involvement of lumbo sacral plexuses. This was likely an idiosyncratic reaction to vaccination which could not have been prevented. Nerve conduction studies for sensory nerves and motor nerves, and an electromyography done on 30 Sep 2011 revealed the following results: in the left arm sensory response was absent in the ulnar nerve and attenuated in the medial antebrachial cutaneous nerve, with marked attenuation of ulnar motor responses and absent ulnar F-wave. There was active denervation in muscles innervated by radial, median and ulnar nerves, but preferable to lower nerve roots and in a patch fashion. In the right arm there was slowing of the ulnar nerve across the elbow, with attenuation of the ulnar sensory response. These were slight prior denervation followed by reinnervation in the triceps but no active denervation. In the right leg sensory responses were absent and peroneal motor response was much attenuated. There was no denervation. The impression made from the results of EMG was patchy lower brachial plexus lesion on the left, mild ulnar neuropathy at the right elbow which was described as incidental, evidence of mild past denervation of the right triceps, large fiber polyneuropathy of the legs. In this clinical situation the findings could be consistent with chronic neuralgic amyotrophy with mild involvement of lumbosacral plexus and right lower brachial plexus. Treatment which was approved by the hand surgeon was given to the patient. Final outcome was reported as progressive weakness for the patient. The reporter assessed these events as serious (disability and medically significant). Follow-up received from a physician on 28 Dec 2011: Updated medical history, laboratory values, and route of vaccination, events, seriousness criteria and outcome. Combined follow-up received from the physician on 20 Jan 2012 and 24 Jan 2012: Updated medical history of the patient, events and tests done with their dates.