Traumatic brachial plexus lesions may lead to permanent impairment of hand function despite brachial plexus surgery. In selected cases the affected forearm can be amputated and replaced by a bionic hand. It is unclear how cortical activation patterns change after the injury and after acquisition of the hand prosthesis considering the complex changes in sensory and motor feedback. The aim of the study is to measure cortical activity with fMRI during actual and imagery movements with the affected and healthy arm in a group of patients after traumatic brachial plexus injury and a group in whom this was followed by replacement with a bionic hand. In this prospective study three groups of patients will participate: 1) 3 adult patients with a traumatic brachial plexus lesion eligible for a bionic arm but prior to its acquisition, 2) 3 patients with a traumatic brachial plexus lesion who have acquired the bionic arm already, and 3) 10 healthy subjects. The investigators will measure cortical activity using fMRI BOLD tasks of closing the hand and motor imagery of this movement. Cortical activity will be compared between the three groups. Additionally, regional gray matter volume, resting-state, and DTI networks will be studied. Written informed consent will be provided prior to the investigation. The complete examination has a duration of approximately 45 minutes.

Inclusion Criteria:

• age above 18 years
• participants should understand German or English
• patients with a bionic hand are selected who are able to open and close the hand prosthesis.

Exclusion Criteria:

• the standard contraindications for MRI will be checked for according to hospital protocol (ferromagnetic devices such as clips, claustrophobia, etc.) and, if necessary, patients will be excluded from participation.

A group of 3 adult patients who acquired a bionic hand at the Medical University of Vienna after a traumatic brachial plexus lesion, and a group of 3 patients eligible for the bionic hand prior to a possible amputation will be included. The number of patients included is based on the rarity of the procedure and thus the very limited number of eligible study participants. Ten control subjects will be included for comparison.