CASE:

An 8-month-old female is brought into the emergency department by her mother. The infant was in her usual state of good health until three days ago, when her mother noted that she felt warm. She was less active, but eating well and had no vomiting, diarrhea, or other complaints. The following day (2 days ago), she refused to eat. She continued to have fevers and remained less active than normal. That evening she was taken to the ED and was found to have a temperature of 39.5 degrees C. She was described by her mother as being less active, not eating well, and having a decreased urine output. CBC showed a white count of 12.1 (32 Segs, 2 bands, 53 lymphs, 9 monos), hemoglobin 11.1, and hematocrit 32.8. A blood culture was obtained. A chest radiograph was felt to be normal. The infant was given antipyretics and discharged home.

The next day (yesterday), she continued to have fevers. Her temperature was 38.5 degrees C. She was less active and was not eating or drinking. She had not voided according to her mother. There was no vomiting, diarrhea, or respiratory symptoms. Her mother also noted on this morning that she had some skin lesions which resembled insect bites. They were red and raised. She was taken to see her primary care physician, who evaluated her and discharged her.

She is brought to the ED today because of increasing lethargy, very poor oral intake, no urine output for 24 hours and continued fever.

Past Medical History:

She was born via normal spontaneous vaginal delivery. Prenatal and postnatal courses were uncomplicated. She is usually on formula but has taken some solid foods. Her immunizations are up to date. She had one prior hospitalization at 4 weeks of age for fever during which time a sepsis workup was negative. Her family history is unremarkable.

Examination:

VS T 39 degrees C, P 160, R 35, BP 95/46. She is very lethargic. She is not cooing, smiling, or vocalizing. She has a weak cry and is tachypneic. She does not respond to painful stimuli. She assumes a position of comfort, in which her lower and upper extremities are flexed and her head is turned to the right. Attempts to place her head midline result in a weak cry. There is slight nuchal rigidity. She is pale with mottling of her lower extremities. There are multiple skin lesions across her face and a few on her arm. They are irregularly crusted (questionably pustular) centrally, surrounded by some erythema. She appears to have a facial droop on the right. Her anterior fontanelle is small but sunken. Her mucus membranes are sticky and she does not produce any tears when she cries. She does open her eyes, but will not follow objects and has a dysconjugate gaze. Breath sounds are bilaterally coarse. She has some upper airway rhonchi. She has no wheezes, crackles, or rales. Heart regular without murmurs. Abdomen flat and soft. Radial pulses are 2-3+ bilaterally and equal. Her hands and feet are cool.

An IV is started and IV fluid is infused. She is also given an IV dose of ceftriaxone. She begins to have extensor posturing with arching of her back. She keeps her head to the right. She also develops tonic-clonic movements of her left upper extremity, and is therefore given a IV lorazepam followed by phenytoin.

What work-up would you recommend?
Because of the infant's fever, nuchal rigidity, lethargy, and focal neurologic abnormalities, a diagnosis of meningitis and/or encephalitis is suspected. A lumbar puncture is performed which shows fluid that is questionably hazy (minimally). She is given IV acyclovir and vancomycin (ceftriaxone was given earlier). The laboratory analysis of the CSF shows 105 RBCs and 40 WBCs per cubic mm with 10% Segs, 80% lymphs, and 10% monos, glucose 75, protein 59. The Gram stain shows no organisms. These clinical and laboratory findings are most consistent with which of the following possibilities:

• Aseptic meningitis
  
  
• Bacterial meningitis
  
  
• Tuberculous meningitis
  
  
• Viral encephalitis
  
  
• Brain abscess
  
  
• Cerebrovascular accident
  
  
• Shaken infant syndrome

What is the diagnosis?