Initial report received on 12 Aug 2010: This patient was enrolled in study V59P23 to evaluate the safety of Novartis MenACWY conjugate when administered with routine infant vaccinations to health infants. The patient received the first dose of study vaccine on 25 Aug 2009, the second dose on 26 Oct 2009, third dose on 12 Jan 2010 and fourth dose on 02 Jul 2010. On 31 Jul 2010, the patient experienced ataxia. On 06 Aug 2010, the patient was admitted to hospital for ataxia and abnormal white matter in the periventricular areas posteriorly. On 09 Aug 2010, the patient was discharged from hospital. At the time of reporting, the patient's condition was persisting. The investigator did suspect a possible relationship between ataxia and the study vaccine. In the absence of the investigators assessment of causality, the Novartis medical safety physician provisionally assessed the event abnormal white matter as suspected to be related to the study vaccine. Follow-up received on 20 Aug 2010: The initial report was received on 11 Aug 2010 (not 12 Aug 2010 as previously reported). Follow up received on 03 Sep 2010: The MRI (magnetic resonance imaging) showed non-specific ill-defined peri-ventricular white matter signal change posteriorly, which was consistent with acute disseminated encephalomyelitis (ADEM) versus leukodystrophy versus adrenoleukodystrophy. The final diagnosis for the white matter remained undetermined. Other available lab results were either negative or within normal limits. The investigator assessed the abnormal white matter as suspected to be related to the study vaccine. Follow up received on 10 Sep 2010: The investigator confirmed that the date of the varicella vaccine was 02 Jul 2010, not 07 Jul 2010. Follow up received on 30 Nov 2010: The investigator confirmed that the patient dropped out of the study due to the events. On 06 Aug 2010, the patient again experienced ataxia. The patient had a second hospital admission on 14 Oct 2010. During hospitalisation, a lumbar puncture was performed results were 'CSF showed WBC and no evidence of acute infection'. The patient was started on intravenous pulse steroids. The ataxia improved. On 15 Oct 2010, the patient underwent an MRI which showed overall; slightly improved appearance of the brain, previously noted white matter abnormally present although it appeared that myelination had progressed somewhat from the prior exam. The patient's cortisol and lysosomal enzymes were normal. On 16 Oct 2010, the patient was discharged from hospital, with plans to revaluate when the patient was 2 years of age. The patient's outcome was reported as event persisting. In the absence of the investigators assessment of causality, the Novartis medical safety physician provisionally assessed the second occurrence of ataxia as suspected to be related to the study vaccine. Follow up received on 09 Dec 2010, prior to circulation of previous follow up: The final diagnosis was confirmed as ataxia. The patient's final outcome was reported as condition improving. The investigator assessed the ataxia (onset date 31 Jul 2010) as non serious "at this time" and suspected to be related to the study vaccine. Follow up received on 18 Jan 2011: The investigator stated that based on clinical and neurological MRI findings in Aug 2010 and Oct 2010 a disorder of myelinization was found which was consistent with ADEM. Improvement was shown after pulse steroids were administered during Oct 2010 hospital admission. There were no changes in laboratory tests or technical examinations since the last report. The medical statement of the leading diagnosis was acute disseminated encephalomyelitis (ADEM). The patient's final outcome was reported as condition still present and unchanged. Follow up received on 27 Jan 2011, prior to circulation of previous follow up: The investigator suspected a relationship between the ADEM and the study vaccine. Follow up literature report received on 17 Jan 2014: The reported event of "acute disseminated encephalomyelitis" was cited in an article.