Chiari I malformation with acute neurological deficit after craniocervical trauma: Case report, imaging, and anatomic considerations

BACKGROUND: In patients with Chiari I malformation (CMI), the occurrence of acute neurologic deficit after craniocervical trauma is rare. However, the pathologic potential of exacerbating anatomic overcrowding of the posterior fossa has immense clinical consequences and prompt recognition is essential. CASE DESCRIPTION: This case study describes a 41-year-old male who sustained a single blow to the face, fell, and struck the occiput. On admission, neurological examination revealed a profound paraparesis, upper extremity diplegia, a C4 sensory level and apnea that required intubation. On arrival, computerized axial tomography of the head showed a small amount of contrecoup left frontal traumatic subarachnoid hemorrhage. Magnetic resonance imaging (MRI) performed 19 h after admission was negative except for the presence of a CMI. He acutely declined on post injury day 2, prompting emergent decompression of the posterior fossa where anatomic overcrowding was observed. At 19 weeks post injury, his motor function had significantly improved. CONCLUSION: The constellation of severe neurologic deficit in patients with CMI after relatively minor craniocervical trauma has been previously described. In our patient, neurologic deficit disproportionate to the mechanism of injury was observed and likely in part attributed to the presence of a Chiari malformation. Unfortunately, MRI has not yet been able to clearly define the underlying pathoanatomy, help understand the mechanism of injury, and delineate when operative intervention is indicated in these patients. Here, we review similar cases from the literature, examine findings on MRI, and evaluate mechanisms of injury following craniocervical trauma in patients with CMI to help clarify these questions.