CASEThis 18-month-old boy, previously healthy, except for recurrent bouts of otitis media, suddenly, one afternoon, started to stagger and weave while walking. Very quickly, this became worse and he then developed a left facial droop with some drooling. In addition, the mother noticed that he could not focus on her with his eyes and then she became quite concerned. All of this happened within a few hours.She took the infant to her local emergency room where the patient was evaluated. At that institution, a CT study of the brain without contrast was interpreted as being normal. The white blood cell count was 12,400 with 43% neutrophils, 45% lymphocytes, 1% monocytes, and 1% eosinophils. A urinalysis was negative and an attempted spinal tap revealed a bloody tap. Thereafter, the patient was referred to our emergency room (ER). In our ER, the previously noted neurologic deficits were substantiated and no new ones were detected. The patient did indeed stumble while walking, and for certain, had a left facial droop. At the same time, the patient was relatively coherent and would respond to commands, questions, and so forth. Repeat laboratory investigation substantiated the results from the incoming hospital.Prior to this episode, and as previously noted, the patient was healthy except for repeated bouts of otitis media. However, the patient fell at dayschool the day before and hit his right cheek. The patient also had another fall at home on a carpeted floor. None of these episodes were reflective of major trauma, and thus could be dismissed as significant factors.On arrival to our ER, the patient's heart rate was 135 per minute and regular, the blood pressure 110/62, the temperature 36.58C, and the respiratory rate was 38 and regular. Physical examination was normal except for those findings referable to the central nervous system. These findings were exactly the same as those elicited in the patient's home emergency room.A repeat spinal tap revealed a glucose level of 65 mg%, a total protein level of 61 mg%, a white blood cell count of 165 with a differential of 8% segmented neutrophils, 29% lymphocytes, 6 atypical lymphocytes, and 56% monocytes. Various clinical consultations were obtained, blood was sent off for evaluation for any abnormal aminoacidurias or other metabolic abnormalities, and an MR study of the brain was obtained (Fig. 1). What do you think the diagnosis might be in this patient?
Radiology in the ED