Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: Excitability changes in the sciatic nerve and triceps surae muscle after spinal cord injury in mice. | Ahmed et al. Journal of Brachial Plexus and Peripheral Nerve Injury 2010 5 8 http content 5 1 8 JOURNAL OF BRACHIAL PLEXUS AND PERIPHERAL NERVE INJURY RESEARCH ARTICLE Open Access Excitability changes in the sciatic nerve and triceps surae muscle after spinal cord injury in mice Zaghloul Ahmed 1 2 Robert Freedland2 and Andrzej Wieraszko2 3 Abstract Background From the onset to the chronic phase of spinal cord injury SCI peripheral axons and muscles are subjected to abnormal states of activity. This starts with very intense spasms during the first instant of SCI through a no activity flaccidity phase to a chronic hyperactivity phase. It remains unclear how the nature of this sequence may affect the peripheral axons and muscles. Methods We set out to investigate the changes in excitability of the sciatic nerve and to characterize the properties of muscle contractility after contusive injury of the mouse thoracic spinal cord. Results The following changes were observed in animals after SCI 1 The sciatic nerve compound action potential was of higher amplitudes and lower threshold with the longer strength-duration time constant and faster conduction velocity 2 The latency of the onset of muscle contraction of the triceps surae muscle was significantly shorter in animals with SCI 3 The muscle twitches expressed slower rising and falling slopes which were accompanied by prolonged contraction duration in SCI animals compared to controls. Conclusion These findings suggest that in peripheral nerves SCI promotes hyperexcitability which might contribute to mechanisms of spastic syndrome. Background The studies of Sherrington and others showed that in chronic spinalized and decerebrated preparations reflexes were easily elicitable and responded violently to stimuli which otherwise had no effect before injury 1 2 . Hyperreflexia and spasticity which is velocity dependent increase in muscle tone 3 are considered as signs for corticoreticulospinal system lesions 4 5
