Initial report was received 20 May 2008 from a health care professional. Additional information was received 22 May 2008 from the same health care provider. A two-year-old male patient, who was an identical twin born at 32 weeks gestation, had received a third dose, left thigh intramuscular injection of FLUZONE No-preservative 2007-2008, lot number UT247CA, on 13 November 2007 and four days later, on 17 November 2007, he was admitted to the hospital with an admitting diagnosis of acute loss of consciousness. According to the reporter, the patient had no concurrent illness at the time of vaccination. The patient had previously received a second dose, intramuscular right thigh injection of FLUZONE SV, lot number UT504AA, on 10 October 2007 with no reported adverse events. The patient had a history of complete heart transplant, strabismus and cortical visual impairment, gastroesophageal reflux disease, microcephalus, infectious mononucleosis, general social/family, development delay and feeding problems. The patient also had a history of infectious mononucleosis which had resolved with Valcyte therapy (dates not provided). The patient had been receiving concomitant medications which included Magnesium Sulfate 4%, Ferrous Sulfate 15mg/0.6mL, REGLAN 5 mg/Ml, POLY-VI-SOL, PROTONIX 40 mg, PROGRAF 5 MG/Ml, sirolimus 1 mg/mL and VALCYTE 450 mg/tabs. According to medical records received, the patient was admitted to the hospital's critical care unit on 17 November 2007 with an admitting diagnosis of acute loss of consciousness. According to a VAERS report filled by the reporter on 19 November 2007, the patient had been admitted on 15 November 2007 for seizures; however, this patient has a twin sibling (case 2008-01680) who had been hospitalized on 15 November 2007 with an admitting diagnosis of seizure. The following information will include information obtained from medical records received from the reporter. The patient had been seen by his neurologist for a follow-up evaluation on 22 April 2008 with a chief complaint of nonconvulsive epilepsy; global developmental delay; hypotonia; an cardiomyopathy. According to the patient's history described in the neurologists clinic notes, the patient was treated in November 2007 for nonconvulsive status epilepticus. His original EEG showed nearly continuous seizures. Follow-up EEG showed some continued electrographic seizures. The seizures in November 2007 occurred following a vaccination. It was not known whether the seizures were provoked by the vaccination. There were no associated fevers. The patient had an identical twin. Both the reporter and his twin had an unknown syndrome with dilated cardiomyopathy, hyptonia, developmental delay and seizures. They were both evaluated and multiple tests for metabolic and mitochondrial disease were negative including mitochondrial mutation and deletions, skeletal muscle biopsies, and heart muscle biopsies. The patient had two older twins siblings (age 7, male and female) and an older 8 year old sibling, all whom were normal. The patient was noted to have an allergy to aspirin and ibuprofen. The mother of the patient was concerned about the patient's overall development and was not aware that they may not eventually catch up and be normal. No diagnosis had been made despite multiple tests. Chromosomal microarray testing had not been performed. Physical examination findings by the neurologist on 22 April 2008 revealed the patient appeared healthy but hypotonic. He was unable to support his weight even in a seated position. He had significant rounding of his back with unsupported sitting. He wore glasses and had a conjugated gaze. Fixation and following were evident and occasional ocular flutter was seen. He was able to reach his hands forward towards objects. He was not able to say words, but was able to make many sounds, some which seemed to have had emotional content. He was negative for consonant production. He laughed with tickling. Cranial nerves were grossly intact with full extraocular movements, equal and reactive pupils, midline tongue and palate, and full symmetric facial movement. Motor tone was very decreased throughout in the axial and proximal planes. Reflexes were brisk, particularly in the lower extremities. He was unable to tripod sit or support his weight in vertical standing. He had increased tone in the lower extremities with vertical positioning. He remained awake and alert with no abnormal movements or staring noted during the course of the examination. Current medications receive by the patient include valproic acid 150 mg t.i.d. and KEPPRA 350 mg b.i.d. The neurologist's impression: unidentified syndrome of global developmental delay, nonconvulsive epilepsy, cardiomyopathy, and hypotonia. The mother of the patient was concerned about his overall development and long-term expectations; she had thought some day they would catch up. The neurologist did not think that was likely, and had concerns that they would not have significant verbal communication or the ability to walk. The patient's recovery status pertaining to the event of seizure and loss of consciousness was not reported. Documents held by sender: clinical records, neurology consult. The reporter for this case is the same as for case 2008-01660.