1. Department of Medical Sciences, Clinical Neurophysiology, Uppsala University, Uppsala, Sweden, Umeå University, Umeå, Sweden
2. Department of Clinical Sciences, Umeå University, Umeå, Sweden
3. Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden
4. Surgery, Department of Surgical and Perioperative Sciences, Umeå University, Umeå, Sweden