Age: 1.3
Sex: F
Vaccine: FLUX, FLUX
Symptoms: Simplex virus test positive, Unresponsive to stimuli, Venogram normal
Clinical narrative: This case was reported in a literature article and described the occurrence of herpes simplex encephalitis in a 16-month-old female subject who was vaccinated with Influenza vaccine (manufacturer unspecified). The subject is reported to have been healthy before the event. Her father denied home medications or ingestions, and her immunisations were up to date. She had not had any episode of vomiting, diarrhoea, rashes, head trauma or other injuries recently. No further information regarding the subject's medical, family history or concurrent medication has been provided. On an unspecified date, the subject received 1st dose of Influenza vaccine (administration site and route unknown, batch number not provided). At an unspecified time after vaccination with Influenza vaccine, the subject experienced rhinorrhea, cough, decreased activity, mouth ulcer associated with decreased oral intake and fever for 2 days. On clinical examination in triage, her temperature was 39.8 deg. C, pulse 164 bpm, respiratory rate 20 bpm and oxygen saturation 98%. She appeared tired and irritable but was consolable. She was given ibuprofen (10 mg/kg/dose). The subject became unresponsive as she was being placed in an examination room, with rightward eye deviation, drooling and symmetric tonic-clonic seizure activity. The seizure continued for more than 10 minutes despite diazepam per rectum (0.1 mg/kg/dose) and concluded after intravenous midazolam was given (0.1 mg/kg/dose). She was also given acetaminophen (15 mg/kg/dose PR). A 20-minute post-ictal period was followed by a second 10-minute seizure, which required IV midazolam (0.1mg/kg/dose) and a load of IV fosphenytoin (20 mg/kg/dose). However the subject's neurologic status failed to improve to baseline after the seizure so she was intubated and transferred to a Paediatric Intensive Care Unit with a Glasgow Coma Scale score of 7. The subject was hospitalised for 9 days. A head computerized tomography was positive for areas of hyperattenuation that were likely to be representing blood but nonspecific; so additional studies were performed. A magnetic resonance imaging showed restricted diffusivity within the bilateral posterior frontal and anterior parietal lobes, consistent with viral encephalitides with tropism for these regions of the brain. The basal ganglia were not affected which decreased the likelihood of a toxic/metabolic insult. Additionally, a vascular aetiology was less likely due to the symmetry and normal appearance of the vessels in the magnetic resonance angiography/venography. The cerebrospinal fluid obtained in a lumbar puncture showed 25 white blood cells and 32700 red blood cells per high-powered field. CSF was subsequently positive for Herpes Simplex Virus polymerase chain reaction with later serologic confirmation for HSV-1. Based on these findings, herpes simplex encephalitis was diagnosed. Initial treatment consisted of IV ceftriaxone (100 mg/kg/dose), vancomycin (15 mg/kg/dose) and acyclovir (20 mg/kg/dose); but the antibiotics were discontinued later and the subject completed a 21-day course of IV acyclovir (20 mg/kg/dose, 3 times a day). As the seizures recurred and proved difficult to treat; she was discharged to a chronic care facility after a 9-day hospital stay with significant neurologic impairment but she was continuing to make slow progress in physical and occupational therapy at the time of writing the article. The author's conclusion stated that complex febrile seizure comprises a heterogeneous group of processes, and 1 set of guidelines may not be applicable to all subjects. For subjects with 2 self limited febrile seizures in 24 hours but a return to normal neurologic status, it may be appropriate to avoid any additional workup, treating these children similarly to those with simple febrile seizure. A more aggressive approach is warranted for children with other forms of CFS, including those with status epilepticus, altered mental status, focal seizures, or focal neurologic symptoms. Additionally, abnormal physical examination findings including nuchal rigidity and a bulging fontanel, increase the risk of a more serious condition. For these children, a lumbar puncture, other laboratory tests, and imaging may be necessary in the acute visit. EEG is not usually recommended in the acute setting because there may be false positives. Children with more than 1 feature of CFS (eg, prolonged and focal), abnormal neurodevelopment, and a family history of epilepsy are indicated for follow-up with a neurologist and an outpatient EEG because there is a fivefold increase in subsequent unprovoked seizures in these children. In the subject described here, a workup including lumbar puncture and imaging was necessary because she had many worrisome features, including status epilepticus, focal seizures, a change in mental status, and an abnormal neurologic examination. A high index of suspicion for HSE should be maintained in subjects with CFS and altered mental status or abnormal imaging consistent with hemorrhagic necrosis to ensure quick initiation of adequate and appropriate treatment.