Evaluation of encephalitis in the toddler: what part of negative don’t you understand?

Abstract

A previously healthy 2 1 ⁄2-year-old boy was brought for treatment with a 1-day history of fever, simple partial seizures, aphasia, and emesis. One day before admission, the child awoke at 3:00 AM with a tactile elevated temperature but seemed well otherwise. Upon awakening in the morning, the boy was afebrile but had mild sinus congestion, decreased oral intake, and a single episode of emesis. His parents also noted some slurring of his speech. After a morning nap, the boy walked to his parents to show them he was having right-sided facial twitching, "frothing at the mouth," increased drooling, and aphasia.At 3:00 PM, the boy's condition was evaluated at his local emergency department, where he received intravenous (IV) fluid therapy with glucose. Blood chemistry was remarkable for a CO 2 of 19 mEq/L, glucose of 55 mg/dL, and a serum total protein of 7.8 g/dL. The complete blood count was significant for a white blood cell (WBC) count of 15.4/mm 3 with 66% neutrophils, 19% lymphocytes, and 15% monocytes. Liver enzymes were normal except for a mildly elevated serum aspartate aminotransferase of 74 IU/L. The results of urinalysis were negative. The results of nasal wash were negative for influenza A and B by enzyme immunoassay. A CT scan of the head was normal. Lumbar puncture (LP) demonstrated 20 WBC/mm 3 with 85% neutrophils, 10% lymphocytes, and 5% monocytes; red blood cell (RBC) count of 71/mm 3 , glucose level of 80 mg/dL, and protein level of 27 mg/dL. Gram stain showed rare neutrophils with no bacteria. The child was empirically given ampicillin, cefotaxime, and acyclovir for meningoencephalitis, and fosphenytoin for seizure control. Cerebral spinal fluid (CSF) was cultured for bacteria and sent for enteroviral and herpes simplex virus (HSV) polymerase chain reaction (PCR). The following morning, the child continued to have simple partial seizures and was transferred to a tertiary pediatric hospital for further evaluation by a multispecialty team.On arrival, the child had a temperature of 39.2°C, pulse of 148 beats/minute, respiratory rate of 36/minute, and blood pressure of 98/60 mm Hg. His medical history was significant only for a closed head injury 2 weeks before admission with no hospitalization or loss of consciousness. His immunizations were up to date, and his devel-