Imaging in Chiari I Malformation.

Chiari I Malformation represents a hindbrain anomaly best demonstrated radiographically with MRI. Brain and spine MRI provide optimal anatomic detail of cerebellar tonsillar descent below the foramen magnum and may reveal additional imaging features including ventriculomegaly (potentially leading to the diagnosis of hydrocephalus), characteristics of intracranial hypertension or hypotension, spinal cord syrinx, scoliosis, and/or tethered spinal cord. Specialized imaging sequences provide enhanced visualization of ventral and dorsal cervicomedullary cisterns and cerebrospinal fluid flow. Although these studies contribute critical information for evaluation, their impact on surgical decision-making remains uncertain. Additional radiographic measures (pBC2 and clival-axial angle) may impact surgical planning and risk assessment.