Functional, electrophysiologic and morphometric evaluation of peripheral nerve regeneration after bridging a 14 mm gap in the rat sciatic nerve

032 Introduction 033 Material and Methods 033 Results 036 Discussion 042 Conclusion 045 Acknowledgements 046 References 046 4. Paper 2: Somatosensory assessments 049 Abstract 050 Introduction 051 Material and Methods 053 Results 058 Discussion 066 Conclusion 072 Acknowledgements 073 References 073050 Introduction 051 Material and Methods 053 Results 058 Discussion 066 Conclusion 072 Acknowledgements 073 References 073 Table of contents iii 5. Paper 3: Ambulatory assessments 079 Abstract 080 Introduction 081 Material and Methods 083 Results 088 Discussion 095 Conclusion 100 Acknowledgements 100 References 101 6. Paper 4: Electrophysiologic assessments 105080 Introduction 081 Material and Methods 083 Results 088 Discussion 095 Conclusion 100 Acknowledgements 100 References 101 6. Paper 4: Electrophysiologic assessments 105 Abstract 106 Introduction 107 Material and Methods 108106 Introduction 107 Material and Methods 108 Results 115 Discussion 122 Conclusion 130 Acknowledgements 130 References 131 7. Discussion 137 7.1 Choice of animal model and specifically of rat strain 137 7.1.1 Anatomical investigations (Paper 1) 137 7.1.1.1 Population examined 138 7.1.1.2 Results 138 7.1.1.3 Conclusions and practical implications 139 7.2 Choice of methods for the assessment of sciatic nerve regeneration 141 7.2.1 Methods applied in comparable studies 141 7.2.2 Cut-off time 141 7.2.3 Assessment plan 142 7.3 Additional considerations 144 7.3.1 Physiotherapy and training 144 7.3.2 Housing and voluntary physiotherapy 145 7.3.3 Surgical procedures and postoperative care 146 7.4 Conclusions drawn after applying various methods of evaluation 148 7.5 Compensation and plasticity 149 7.5.1 Sensory system 149 Table of contents iv 7.5.1.1 Comparable events described in the literature 149 7.5.1.2 Compensatory events in the periphery – collateral sprouting 150 7.5.1.3 Central plasticity 151 7.5.2 Motor system 153 7.5.2.1 Comparable events described in the literature 154 7.5.2.2 Compensatory events in the periphery – trick movements 154 7.5.2.3 Central plasticity 157 7.5.2.4 Induction of plasticity 159 7.5.2.5 The concept of enriched housing 160 7.6. Methodological problems affecting certain types of evaluation 163 7.6.1 Somatosensory evaluations 163 7.6.1.1 Implementation of somatosensory assessments 164 7.6.1.2 Results of somatosensory and supplementary assessments 164 7.6.1.3 Anatomical considerations 165 7.6.1.4 Implications for both existing and future somatosensory assessments 166 7.6.2 Analysis of footprints 167 7.6.2.1 Unpublished observations and implementations of footprint gathering 168 7.6.2.2 Results achieved in footprint analysis 169 7.6.2.3 Implications for both existing and future footprint assessments 169 7.6.3 Electrophysiologic assessments of the regenerating sciatic nerve 170 7.6.3.1 Results achieved in electrophysiologic investigations 170 7.6.3.2 Follow-up study to investigate the source of electrical activity 171 7.6.3.3 Implications for both existing and future electrophysiologic assessments 172 7.7 Never evaluate without morphometry 174 7.7.1 Groups of assessments employed in comparable studies 174 7.7.2 Mean gap length in comparable studies 175