Median and Ulnar Nerve Injuries in Children and Adolescents Long-term outcome and Cerebral reorganisation

A peripheral nerve injury may lead to serious disability and influence the individual ́s quality of life. It is considered that children can regain better sensory and motor function after a peripheral nerve injury, but the exact mechanism behind such superior recovery is not known. The aim of the thesis was to study the long-term clinical outcome after a peripheral nerve injury in patients injured in childhood and adolescence and to relate the clinical outcome to changes in the central and peripheral nervous systems. In addition, the consequences of the nerve injury for the patient ́s life were explored. A short-term pilot study with four patients showed remaining clinical and electrophysiological abnormalities and functional Magnetic Resonance Imaging (fMRI) showed that the cerebral activation pattern after tactile stimulation of the injured hand was different compared to the pattern of the healthy hand. In a larger study, the long-term functional outcome after nerve repair in those injured in childhood was compared to the outcome of those injured in adolescence. Patients below the age of 21 years, operated on at our hospital for a complete median or ulnar nerve injury at the level of the forearm 1970-1989, were followed up at a median of 31 years. Outcome was significantly better in those injured in childhood, i.e. below the age of 12 years, with almost full sensory and motor recovery. No significant differences in recovery were seen between patients with median and ulnar nerve injuries, or even when both nerves were injured. The median DASH scores (i.e. questionnaire; Disability Arm Shoulder and Hand) were within normal limits and cold sensitivity was not a problem in either age group. Those injured in adolescence (i.e. above the age of 12 years) had a significantly higher impact on their profession, education, and leisure activities. Electrophysiological evaluation (amplitude, conduction velocity and distal motor latency) showed pathology in all parameters and in all patients, irrespective of age at injury. This suggests that the mechanisms behind the superior clinical outcome in children are not located in the peripheral nervous system. With fMRI it was shown that patients injured in childhood had a cortical activation pattern similar to that of healthy controls and it was observed that cerebral changes in both hemispheres may explain differences in clinical outcome following a nerve injury in childhood or adolescence. Finally, fifteen patients injured in adolescence, who were interviewed to explore the experiences after a nerve injury and its consequences for daily life, described emotional reactions to trauma. Even symptoms related to post-traumatic stress disorder were mentioned and the patients described different adaptation strategies used. Educational and professional life had changed completely for some. The present thesis shows that age is an important factor that influences outcome after a peripheral nerve injury. The reason for the agerelated difference in outcome is alterations in the central nervous system. In addition, a nerve injury had a severe impact on the individuals ́ life. By further exploring the mechanisms of plasticity and by modifying the rehabilitation, we might eventually improve the outcome after a peripheral nerve injury.