This case was reported in a literature article and described the occurrence of central nervous system demyelination in a 50-year-old male patient who received Influenza vaccine. The patient's past medical history included smoker (1 pack per day for 3 years, successfully quitting), lipoma, hernia (repaired), appendectomy, arthroscopy and tonsillectomy. Concurrent medical conditions included alcohol use (occasionally - did not use recreational drugs), hypothyroidism, hyperlipidemia, gastroesophageal reflux disease, psoriasis, attention deficit/hyperactivity disorder, depression and penicillin allergy. Concomitant products included Levothyroxine, dexlansoprazole, clotrimazole, betamethasone, Methylphenidate and alprazolam. On an unknown date, the patient received Influenza vaccine at an unknown dose. On an unknown date, less than a day after receiving Influenza vaccine, the patient experienced central nervous system demyelination (serious criteria hospitalization and GSK medically significant), left-sided weakness (serious criteria GSK medically significant), hemiplegia (serious criteria GSK medically significant), left arm numbness, left arm paresthesia, itchy sensation in face, blurred vision in left eye, balance deficit, decreased sensation in left side, knee hyperextension, hypertonicity left side and coordination deficit. The patient was treated with methylprednisolone and prednisolone. On an unknown date, the outcome of the central nervous system demyelination, hemiplegia, left arm paresthesia, itchy sensation in face, blurred vision in left eye, balance deficit, decreased sensation in left side, knee hyperextension, hypertonicity left side and coordination deficit were unknown and the outcome of the left-sided weakness and left arm numbness were recovered/resolved. The reporter considered the central nervous system demyelination, left-sided weakness, hemiplegia, left arm numbness, left arm paresthesia, itchy sensation in face, blurred vision in left eye, balance deficit, decreased sensation in left side, knee hyperextension, hypertonicity left side and coordination deficit to be almost certainly related to Influenza vaccine. Additional information received: This case was reported in a literature article and it described the occurrence of influenza vaccine-induced central nerve system demyelisation in a 50-year-old male subject who had previously received an unspecified influenza vaccine (manufacturers unknown). The subject was a former smoker (1 pack per day for 3 years, successfully quitting in 1983), consumed alcohol occasionally but did not use recreational drugs. His medical history included removal of a right-sided supraclavicular phrenic nerve lipoma in 2007, hernia repair, appendectomy, knee arthroscopy and tonsillectomy. In addition to this, the subject had a family history of hypertension and heart disease within the maternal line of the family and a sister who suffered with anaemia. He was allergic to penicillin. Concurrent medical conditions included hypothyroidism, hyperlipidemia, gastroesophageal reflux disease, psoriasis, attention deficit hyperactivity disorder and depression. Concomitant medications for these conditions included levothyroxine, dexlansoprazole, clotrimazole/betamethasone cream, methylphenidate and alprazolam. No further information on the subject's medical history, concurrent medical conditions or concomitant medication was provided. On an unspecified date, the subject received an unspecified seasonal influenza vaccine (H1N1, H3N2, B/Yamagata and B/Victoria) (dosage, administration route and site unknown; batch number not provided). On an unspecified date, 1 day after receiving the influenza vaccine, the subject noted left arm numbness and weakness that resolved spontaneously for a few hours. However, the subject started to feel an increasing left leg weakness with full left arm paresthesia overnight and reported an "itchy" sensation over the entire left face and blurred vision in his left eye at work the following day (no discrete blurred spots were noted in the left eye and vision in the right eye remained unchanged). Upon examination at an emergency department, he was found to be afebrile and with stable vital signs. A definitive left-sided weakness was noted, with no expressive or receptive aphasia evident. Upon neurological examination, slight facial asymmetry on tests for cranial nerves 5 and 7 was revealed. The remaining cranial nerves were grossly normal. Motor testing showed arm and leg weakness at 3/5 and left-sided drift. Tone was increased on the left side, and coordination was slightly diminished on the left compared to the right with rapidly alternating movement. No tremor or ataxia was noted. Sensation to pain, temperature, and vibration was intact. Reflexes were 3+ on the left, and 2+ on the right, with down-going toes bilaterally. On presentation to the rehabilitation unit for treatment, the subject was alert and oriented to person, place, and time. He exhibited no cranial nerve abnormalities. He had significant left hemiparesis, with both upper and lower extremity strength graded as 1/5. He had mild balance deficits in the seated position and severe balance deficits in the standing position. Sensation was diminished to light touch, pain and proprioception in the left arm and leg. He required maximal physical assistance with all activities of daily living and mobility, including bed mobility, transfers, and ambulation up to 40 feet. Severe knee hyperextension during standing and walking was noticed. Additionally, significant hypertonicity and coordination deficits in the left arm and leg were demonstrated. His admission functional independence measure score was 74. This is a serious case as the subject required hospitalisation. On admission full blood count, coagulation and comprehensive metabolic panel results were within normal limits. Low-density lipoprotein and triglycerides were elevated at 106 mg/dL and 193 mg/dL, respectively. A chest X-ray performed on admission was unremarkable. Computed tomography of the head without contrast did not reveal any space-occupying lesion, intracranial haemorrhage, hydrocephalus, shifting of the ventricles, cerebral infarction or oedema. Computed tomography angiography of the head and neck was unremarkable. Bilateral carotid duplex studies revealed carotid stenosis less than 40% on the right and the left. On the second day of hospitalization, magnetic resonance imaging of the brain and full spinal cord with- and without- contrast were showed no distinct intra-axial haemorrhage, mass, mass effect, enhancing lesion or evidence of acute stroke. Scattered foci of bright T2 FLAIR signal changes were seen in the peri- and non-periventricular region, deep hemispheric centrum, peritrigonal and cortical/subcortical regions. This indicated a demyelinising disease according to the authors. Magnetic resonance imaging of the cervical spine and of the lumbar and thoracic spine were unremarkable and without evidence of herniated disc pulpous or spinal stenosis. The results of the analysis of a cerebrospinal fluid sample obtained by lumbar puncture were normal; the gram stain was negative with no growth on the culture after 7 days; cytological analysis showed no evidence of malignancy and no oligoclonal bands were identified. Cardiology tests included an electrocardiogram (normal sinus rhythm) and an echocardiogram (mild left atrial dilation and a left ventricular ejection fraction of 60%). Treatment consisted of a 5-day course of 500 mg of intravenous methylprednisolone twice a day, followed by a 12-day tapered course of 20 mg of oral prednisone once a day. Additionally, the patient was referred for comprehensive in-patient rehabilitation. At the time of reporting the outcome was unspecified. The authors commented that the subject's central nerve system demyelisation was associated with the influenza vaccine. The authors concluded that "this case report illustrated the rare clinical occurrence of a central nervous system demyelisation disorder associated with influenza vaccination. Together, clinically isolated syndrome and acute disseminated encephalomyelitis belong to a class of central nervous system demyelisation syndromes. Both clinically isolated syndrome and acute disseminated encephalomyelitis can present following recent vaccination, with the influenza vaccine having the most common association. Clinically isolated syndrome and acute disseminated encephalomyelitis have been reported with vaccines other than influenza, including rabies, diphtheria, smallpox, hepatitis B and human papillomavirus. Despite the rare occurrences of clinically isolated syndrome and acute disseminated encephalomyelitis, vaccines remain a safe and effective strategy for disease prevention and patients should not be discouraged from receiving vaccinations. Post-vaccination central nervous system demyelisation disease, while rare, remains an important clinical consideration in patients with neurologic signs and symptoms in the context of recent vaccination, but the causal mechanism has not been proven. The optimal medical management of such cases has yet to be defined".