Neuroimaging and the Clinical Manifestations of Chiari Malformation Type I (CMI)

Chiari malformation type I (CMI) involves the caudal displacement of the cerebellar tonsils through the foramen magnum with resultant brainstem compression in some individuals. Due to pathophysiologic changes, secondary conditions may arise, such as syringohydromyelia (SH) and scoliosis. This disorder is unique, as the diagnosis is confirmed through radiologic findings. At times CMI is discovered incidentally on neuroimaging, but more frequently a patient will present with specific symptoms, the most common being a prototypic occipital headache. Although the true etiology of this complex condition remains speculative, the advent of neuroimaging has allowed for clarification of the enigmatic relationship between cerebrospinal fluid (CSF) dynamics, neuroanatomical compression, and clinical symptoms. Recent advancements in magnetic resonance imaging (MRI) such as diffusion tensor imaging (DTI) and CSF flow studies show promise in clarifying the underlying fluid dynamics in CMI patients and can aid in the prognosis and diagnosis of this complex disorder.