Cervicocerebral artery dissection is a major cause for stroke in young adults. While knowledge of cervical artery dissection (CeAD) has increased thanks to a number of high quality studies, knowledge on intracranial artery dissection (IAD) is limited. Due to treatment and publication bias little is known about the natural history of IAD. Overall, IAD is assumed to have a more severe course than CeAD, with a more ominous outcome in patients with subarachnoid hemorrhage (SAH). Furthermore, little information is available on the risk of recurrent IAD as well as on the risk of recurrent ischemic and haemorrhagic events in non-Asian patients. Radiological diagnosis of IAD can be challenging given the small size of intracranial arteries, and the subtle and non-specific radiological signs which tend to evolve over time. The optimal treatment of IAD is unknown. There are no randomised trials and only observational studies with relatively small sample sizes are available, thus providing a very low level of evidence. Finding the factors that are decisive for outcome and recurrence after intracranial artery dissection is key to an improved management of this potentially severe disease predominantly affecting young patients. By using standardised protocols for diagnosis, imaging and follow-up, the investigators intend to obtain large representative patient samples in order to fill the gap of evidence.