Posterior circulation stroke secondary to atlantoaxial instability-induced vertebral artery dissection and pseudoaneurysm in a paediatric patient.

A boy in his early teens presented with transient visual disturbances and headache. Brain imaging revealed bilateral occipital infarctions, while vascular studies demonstrated bilateral V3 vertebral artery wall abnormalities with pseudoaneurysm formation associated with C1-C2 rotatory subluxation. Initial conservative management, including resting and a rigid cervical brace, failed to prevent vascular progression. The patient underwent posterior C1-C2 fixation to address the underlying mechanical cause. Follow-up CT angiography 1 year after surgery demonstrated complete resolution of the pseudoaneurysm and near-normalisation of both vertebral artery walls. At 18 months of follow-up, he remained asymptomatic, with no recurrent ischaemic events and no progression of the pre-existing visual deficit. This case highlights the importance of considering dynamic atlantoaxial instability in children with posterior circulation strokes and supports surgical stabilisation as definitive etiological treatment in selected cases.