ABSTRACT
Objective To investigate the efficacy of combined monitoring of motor evoked potentials with transcranial electrical stimulation (TES-MEP),somatosensory evoked potentials (SEP) and spontaneous electromyo-graphy (s-EMG) in tuberculosis surgery involving the thoracic,lumbar and sacral vertebrae.Methods Twenty-seven patients with tuberculosis of the thoracic vertebrae (T2-L2) received intra-operative SEP and TES-MEP monito-ring.Combined SEP,TES-MEP and spontaneous EMG monitoring were employed in 11 patients with tuberculosis of the lumbar or/and sacral vertebrae (L3-S1).SEP and TES-MEP were used to precisely observe the status of the sen-sory and motor pathways; s-EMG responses were used to more accurately localize nerve root irritation.ResuIts (1) SEP monitoring was successful in all of the operations.TES-MEPs were successfully monitored in 35 of them (92.1％).Combined motor and sensory monitoring was successfully achieved in 35 cases (92.1％).Abnormal SEPs were observed in 3 cases (7.9％),while abnormal MEPs were observed in 11 cases (28.9％).Abnormality in both the SEP and TES-MEP occurred in 2 cases (5.3％).There were 9 cases (23.7％) where the SEPs were nor-mal and the TES-MEPs were abnormal.In only 1 case (2.6％) was the SEP normal and the MEP abnormal.The false negative rate was 0％ with combined SEP and TES-MEP monitoring,while the false positive rate was 5.3％.There were 2 cases complicated by post-operative neurological deficits.(2) Spontaneous EMG monitoring can accu-rately determine the functioning of lumbar nerve roots during lumbar or lumbosacral tuberculosis surgery.Among 5 cases where EMG responses were observed,4 cases occurred during the spinal canal and nerve root decompression,1 case occurred in the orthopedic reset phase.Conclusions (1) During tuberculosis surgery involving thoracic,lumbar or sacral vertebrae,combined monitoring of SEPs and TES-MEPs can reflect the physiological and pathological condition of the spinal cord after ruling out interfering factors.This can improve monitoring and help assure the safety of lumbar surgery.(2) Intra-operative s-EMG monitoring can accurately reveal nerve root function in real time,help-ing to avert nerve root injury in lumbar and lumbosacral tuberculosis surgery.
ABSTRACT
Objective To compare the stability effect of the fixation segment using the new test system based robotics to simulate the complex human movement at natural state about the three-level fixa-tion by using four, five or six pedicle screws in treatment of thoracolumbar burst fractures. Methods Six human cadaveric spines were dissected from T_(11)-L_3. The inferior half part of L_1 vertebral bodies and L_1-L_2 dises were resected to mimie an unstable L_1 burst fracture with loss of anterior column support. Specimens were tested in accordance with the following order:intact, 4,5 and 6 pedicle screws fixation at the three-level fixation. The range of motion (ROM) of the fixation segment (T_(11)-L_3) was measured with the six-freedom degree robotics system controlled by mixed force and displacement during flexion, exten-sion, lateral bending and axial torsion, when the stiffness was calculated. One-way statistieal analysis was used for analyzing the collected data. Results With increased number of screws, the ROM of the fixa-tion segment (T_(11)-L_3) was gradually decreased and the stiffness gradually increased. The ROM under ax-ial rotation of six and five screws group became smaller than four screws group (P < 0.05). The stiffness under axial rotation of six screws group was higher than four screws group (P < 0.05). There was no sta-tistical difference between five screws group and four screws group in regard of the stiffness in axial rota-tion (P > 0.05). There were no significant differences in ROM and stiffness under six different loading directions between six screws group and five screws group (P > 0.05). No statistical difference was observed for three fixation modes in aspects of ROMs and stiffness under flexion-extension or lateral ben-ding (P > 0.05). Conclusions Three-level fixation of burst fractures with five or six screws offers im-proved biomechanical stability compared with traditional four screws fixation. But the difference is insig-nificant between six and five screws fixations.