The present invention relates to a device for fixation to a head of a patient during neurological diagnosis, therapy or surgery, in particular during MRI diagnosis. The device comprises at least one fixation pin for fixation to the head, a sleeve member (5) having an internal threaded through bore to at least partly receive and hold said fixation pin, and a pin support member for supporting said fixation pin and sleeve member. The sleeve member is exchangeable and provided in at least two different lengths in order to allow adaptation of the sleeve member to the size of the head to improve the fixation of the head and avoid the fixation pin to protrude beyond the outer boundary of the pin support member. The invention also relates to a method for fixation of a head.