Cerebellar tonsillar contusion in traumatic brain injury: an atypical presentation of previously undiagnosed Chiari I malformation.

Chiari I malformation is often seen in children and may be asymptomatic. Acute neurological injury following trauma in children with Chiari I malformation has been reported in literature. Traumatic contusion involving the cerebellar tonsils is rarely described in children and usually occurs in patients with Chiari I malformation/cerebellar tonsillar ectopia. It is unknown if activity restriction should be advised in children with asymptomatic Chiari I malformation given the potential for this injury. We describe a case of cerebellar tonsillar contusion in a child with concomitant skull vault fracture and review the literature for similar cases. We also propose a plausible mechanism to explain tonsillar contusion in patients with Chiari I malformation.