Puzzler: "Funny face" in the ED: An infant with vomiting, fever, and neurologic signs

You've been called down to the emergency department early this morning by the ED attending to see a 5-month-old girl brought in by her parents because of vomiting. The attending does not see signs of dehydration, but reports that the baby "looks funny."

At first glance, you note that this well-developed, well-nourished infant is not moving her left side as well as her right side, and has an asymmetric face. Upon questioning her parents-who speak Spanish and little English-you learn that the baby is the product of an unremarkable pregnancy and delivery and was born in the United States to immigrant parents. She has otherwise been healthy-until recently, when she was hospitalized for pneumonia, otitis media, and fever after being unresponsive to amoxicillin at home for these problems. She was discharged just 36 hours ago, on amoxicillin-clavulanate, and now she's back in the ED.

The girl's symptoms include nonbloody, nonbilious emesis in the past 24 hours, slightly diminished interest in breastfeeding, and a persistent fever (38.6° C on arrival in the ED). The parents report good urine output. The history is negative for travel; there is no family history of bleeding disorders or stroke. The attending reports no signs of upper respiratory infection or trauma, and no seizures.

You categorize the differential diagnosis of this infant with hemiparesis as vascular (stroke, bleed), infectious (meningitis, encephalitis), metabolic, and a mass causing hydrocephalus or increased intracranial pressure. You plan your workup.

An emergent computed tomographic (CT) scan of the head does not show a mass effect or a bleed; the radiologist sees what might be mild edema in the area of the right sylvian fissure. Lumbar puncture shows a white blood cell count of 47/µL in the cerebrospinal fluid (CSF), with 35% polymorphonuclear cells, 28% lymphocytes, and 37% monocytes; a red blood cell count of 1/uL; glucose, 41 mg/dL; and protein, 86 mg/dL. Gram stain is negative for organisms; tests of bacterial antigens are negative. Other admission laboratory tests, including electrolytes, cholesterol, triglycerides, prothrombin time, partial thromboplastin time, and venous blood gases, are remarkable only for a low sodium level (131 mEq/L). A complete blood count reveals a WBC count of 19.7 x 10³/uL, with 43% granulocytes, 47% lymphocytes, and 9% monocytes. A chest radiograph shows persistent right middle-lobe pneumonia.

Your principal worry is partially treated bacterial meningitis, so you start the patient on vancomycin and cefotaxime. You also start acyclovir, because of concern about herpes simplex virus meningoencephalitis. Magnetic resonance imaging (MRI) of the head is scheduled.

Later that morning, the child has a brief right-sided seizure, with decreased movement on the left side; an electroencephalogram does not show epileptiform activity, however. MRI of the head is significant for left-sided schizencephaly and left frontal-lobe atrophy, without evidence of a bleed or an infarct. You load her with phenobarbital.

Turning again to imaging for guidance After several days, the left hemiparesis has failed to improve, the girl has intermittent emesis, and fever persists while bacterial and viral cultures again return negative. Your concern continues to be partially treated meningitis, so, on hospital Day 6, the patient undergoes a repeat CT scan. This time, films of the head show new, large areas of low attenuation involving the right frontal, anterior parietal, and medial temporal lobes. There is meningeal enhancement in those areas and in the left sylvian fissure and cerebellum. She undergoes repeat MRI of the head, which shows enhancing meninges, right greater than left, especially in the sylvian cistern, basal cisterns, and enhancing nodules within the right cerebellar peduncle and bilateral cerebellar hemispheres. There is associated ventriculomegaly.