The authors report on the case of a patient evaluated for Valsalva maneuver-induced headache, dizziness, and ataxia. Neuroimaging revealed a Chiari I malformation without syringomyelia. A history of idiopathic hypertension was noted. After posterior fossa decompression, pathologically elevated blood pressure was absent, and at 24-month follow-up evaluation the patient remained normotensive. Although seemingly rare, this case illustrates that some patients with tonsillar ectopia may exhibit elevated blood pressure. Clinicians should consider hindbrain herniation a rare cause in idiopathic hypertension.