DESCRIPTIONA 35-year-old woman, apparently normal, who had participated in traditional Devithullal (a religious dance form involving violent head banging for hours at a time) on the evening of the following day developed vomiting, urinary incontinence, altered sensorium and quadriplegia. All blood investigations including thrombophilia workup were normal. CT scanning of the brain was normal. MRI diffusion-weighted image showed the characteristic bilateral ventral pontine hyper intensities ( figure 1A) and the apparent diffusion coeffient (ADC) map images showed bilateral ventral pontine hypointensities diagnostic of acute infarction (figure 1B). MR angiogram revealed basilar artery thrombosis ( figure 2A,B).'Head banging' denotes vigorous, rhythmical, rapid flexion and extension of the neck in time to music.1 It can cause vertebrobasilar ischaemia because the vertebral arteries are fixed in the