Type I Chiari malformations (CMs) is an acquired or congenital disorder characterised by the presence of the cerebellar tonsils at 5 mm or below of the spinal canal, which can result in abnormal cerebrospinal fluid flow and produce headaches, syrinx or hydrocephalus. CMs are still considered an uncommon disease with a prevalence in the USA of less than 1%.1 2 We present a 44-year-old man with no medical history who presented to the emergency department complaining of nausea, vomiting, vertigo and a 2-day history of headaches exacerbated with Valsalva manoeuvres. He was initially admitted with a working diagnosis of ischaemic stroke and underwent a CT scan of the brain, which was unremarkable. Further work-up with brain MRI disclosed incidental cerebellar herniation 6.5 mm below the foramen magnum (figure 1) and no abnormalities in spinal canal MRIs. The patient was treated symptomatically with oral acetaminophen 500 mg three times …
