Vertebrobasilar Insufficiency Due to Distal Posterior Inferior Cerebellar Artery Compression in Chiari 1.5

Background: Chiari malformation is characterized by radiographic evidence of herniation of cerebellar tonsils below the foramen magnum and a symptom complex of headaches; breathing, swallowing, or sleep difficulties; ataxia; restless; and motor and/or sensory deficits. Case Description: We report a case of a 34-year-old woman whose imaging indicated a Chiari 1.5 with brainstem (caudal medulla) herniation and an expansive cervical syrinx. Her symptom complex showed signs both of cervical syringomyelia, as well as ones localizable to the medulla. An intradural exploration revealed the occlusion and caudal displacement of the loop of the right posterior inferior cerebellar artery, which was later confirmed via magnetic resonance angiography. Conclusions: In the setting of severe Chiari malformations, particularly the Chiari 1.5 variant, assessment of the posterior fossa vasculature may be useful in defining a subset of patients with preoperative compromise in posterior fossa blood flow and postoperative expectations. Preoperative planning and exploration of midline dorsal brain stem along with the tonsilomedullary fissure could be helpful for contribution of vascular pathology among Chiari symptoms complex in these patients.