Refusal to walk and stiff neck in toddler boy

THE CASE

You are on your pediatric neurology rotation and receive a call from the pediatric neurology attending that a 19-month-old boy will be coming to the emergency department (ED) with refusal to walk, a stiff neck, and a change in his baseline behavior. Soon after his arrival, you go to see him as you are forming a differential diagnosis in your mind, with meningitis at the top.

When you arrive, you see that the boy is very irritable and crying but consolable in his mother's lap. His head is side bent to the left, and he will only turn his head, neck, and shoulders all together to look at you.

The parents say that the boy was delivered at term, vaginally without complications, and began walking at 11 months old but did not have any issues until recently. The boy had an upper respiratory illness 3 months before this time, with fever for 5 days that reached up to 39.4° Celsius. One or 2 days after the fever started, he was noted to have a full body rash that was described as "lacey" in appearance. The rash resolved when the fever resolved. The parents note that after the febrile illness, the skin on the palms of his hands and soles of his feet began to peel. He also had red, cracked lips, which resolved on their own.

The rash reappeared 2 weeks before the boy came to the ED, but this time it was noted to be flat and was described as "hives" by his primary care physician. He was prescribed an antihistamine. He also had lab work done at that time that revealed microcytic anemia. The patient was started on an iron supplement, and his parents were advised to limit his milk intake because he was drinking more than 24 ounces of milk a day.

The boy's vital signs in the ED are: pulse, 136 beats per minute; temperature, 36.7° Celsius (tympanic); and respiratory rate, 28 breaths per minute. His weight is in the 70th percentile, and his height in the 80th percentile.

The boy is very irritable and screams as you approach him. His head continues to be side bent to the left. His pupils are equally reactive to light and accommodation. There is difficulty in palpation of the left side of his neck because of the side-bending position; however, no fluctuance, spasticity, or adenopathy is seen. Passive range of motion of the neck is full but with a good deal of resistance because the boy is obviously upset. The oropharynx is moist and clear without lesions. His chest is clear to auscultation throughout lung fields. No murmurs are appreciated on cardiac exam. His abdomen is soft, nontender, and nondistended. He has no organomegaly, and he has active bowel sounds. The extremities have brisk capillary refill.

On musculoskeletal exam, there is no swelling noted of the posterior neck, shoulders, elbows, wrists, knees, or ankles. Range of motion of the joints is difficult to measure because the boy is resistant to the exam. There is a diffuse erythematous macular rash that blanches on the anterior and posterior trunk. No petechiae and no peeling of the palms of his hands or soles of the feet are noted.