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Level I.

BACKGROUND AND PURPOSE:Widening of the basion-dens interval is an important sign of cranioverterbral junction injury. The current literature on basion-dens interval in children is sparse and based on bony measurements with variable values. Our goal was to establish the normal values of a recently described new imaging parameter, the basion-cartilaginous dens interval in children.

A 42-year-old man living with HIV (viral load, 220 copies/mL; CD4 count, 408 cells/μL) presented with 2 days of confusion and vision changes. He also reported constant headache and dizziness but denied weakness, fevers, or chills. He was disoriented to time, had word-finding difficulties, poor concentration, and impaired short-term memory. Neurologic examination was notable for right homonymous hemianopia but no motor, sensory, or other cranial nerve abnormalities. Cerebrospinal fluid analysis showed