Functional evaluation using several evoked spinal cord potentials in elderly patients with cervical spondylotic myelopathy

BACKGROUND ： The recordings of evoked spinal cord potentials following epidural spinal cord stimulation are thought to be generated by volleys traversing the dorsal column pathway, and it may not directly reflect conduction defects in corticospinat tracts of cervical spinal cord. To our knowledge there has been few report using several evoked spinal cord potentials in function evaluation of the cervical spinal cord in eldedy patients with cervical spondylotic myelopathy （CSM）. OBJECTIVE： To investigate the function states of the cervical spinal cord in elderly patients with CSM and explore its pathophysictogic mechanism. DESIGN： Case observation SETTING ： Department of Orthopedics for the aged, Shenzhen Pingle Hospital of Orthopedics. Department of Orthopedic Surgery, Yamaguchi University School of Medicine. PARTICIPANTS ： A total of 23 eldedy patients with CSM who received treatment in the Department of Orthopedic Surgery, Yamaguchi University School of Medicine of Japan from January 2003 to February 2004 were enrolled in this study. Inclusive criteria： ① Multiple intervertebral levels of cervical spinal cord compression confirmed by MRI, e.g. 3 or more than 3 levels of compressin. ② Age ≥ 70 years old. ③ Numbness and sensory disturbance in the upper limbs and showed hyperreflexia in the lower limbs. Exclusive criteria： Patients with abnormal motor and sensory nerve conduction velocities in both upper and lower limbs were excluded. METHODS： Evoked spinal cord potentials （ESCPs） following transcranial electric stimulation （TCE-ESCPs）, epidural spinal cord stimulation （SpinaI-ESCPs） and median nerve stimulation （MN-ESCPs） were recorded in 23 patients from posterior epidural space intreoperatively. The abnormalities of TCE-ESCPs were defined as attenuation of amplitude of the D wave. The most cranial intervertebral level showing abnormal TCE-ESCPs with a marked reduction in size of the negative peak （reduction of over 50%） was considered as the upper level of the spinal cord lesion with respect to the corticospinal tract in white matter. The abnormalities of SpinaI-ESCPs were defined as marked reduction in the size of negative peak （reduction of over 50%）. The most caudal intervertebral level showing abnormal SpinaI-ESCPs was considered as the lower level of the spinal cord lesion with respect to the dorsal column pathway in white matter. The abnormalities of MN-ESCPs were defined as attenuation of the N13 amplitude,which was considered as the lesion level of the spinal cord with respect to the dorsal horn in gray matter. Radiological investigation： Lateral view of plain X-ray films was obtained in flexion and extension of the cervical spine. Instability of the cervical intervertebral level was determined as horizontal displacement of the vertebral body of over 3 mm. MAIN OUTCOME MEASURES ： The results of examination of TCE-ESCPs, SpinaI-ESCPs and MN-ESCPs in el- dedy patients with CSM. RESULTS： The 23 eldedy patients with CSM were participated in the result analysis. ①TCE-ESCPs： The impairment of the corticospinal tract in white matter at single intervertebral level was revealed in 18 of 23 patients by recordings of TCE-ESCPs （sensitivity 78%）. In the 18 patients, the lesion level was shown at the up- per cervical segment in 14 patients （C3-4n=10 and C4-5n=4）, and at the lower cervical segment in 4 patients （C5-6n=4）. ②Spinal-ESCPs： The impairment of the dorsal column pathway of white matter at single intervertebral level was revealed in 17 of 23 patients, by recordings of Spinal-ESCPs （sensitivity 74%）. In the 17 patients, the lesion level was presented at the upper cervical segment in 14 patients （C3-4n=10 and C4-5n=4）, and at the lower cervical segment in 3 patients （C5-6 n=3）. ③MN-ESCPs： All patients revealed abnormal MN-ESCPs at one or more intervertebral levels （sensitivity 100%）. The impairment at single intervertebral level was demonstrated in 17 patients, and the impairment at multiple intervertebral levels was shown in 4 patients （3 patients at the C3-4, C4-4, and C5-4~6, and one patient at the C4-5, C5-6, and C6-7）. ④Radiological findings： The Instability of the intervertebral level at the C3-4 or C4-5 motion segment was seen in 15 patients, with a total of 20 levels, and where 10 were at the C3-4 intervertebral level and 5 were at the C3-4, C4-5 intervertebral level. CONCLUSION ： The results suggest that in most elderly patients with CSM who have multiple intervertebral level compressions of the cervical spinal cord on MRI, white matter is impaired at the single cervical intervertebral level, and not only the dorsal column pathway, but also the corticospinal tract can be affected. Combined the findings of radiography, the excessive motion and instability of the C3-4 or C4-5 intervertebral level plays an important role in inducing the long tract lesion in elderly patients with CSM.

Effect of renewed SS-cream on spinal somatosensory evokedpotential in rabbits

Aim: The effect of a renewed SS-cream (RSSC) on the treatment of premature ejaculation (PE) was evaluated and compared with the original SS-cream (OSSC). Methods: Sixty male white New Zealand rabbits, weighing 2.5kg-3.0 kg, were divided at random into 3 groups: the RSSC, OSSC and placebo groups. The spinal somatosensory evoked potential (SSEP) elicited by electric stimulation of the glans penis with disk electrode was investigated with an electrophysiograph (Poseidomn, Shanghai, China) before and 10, 30 and 60 min after drug or placebo application on the glans. The Onset and the N1 latencies and the amplitude of SSEP were recorded and analyzed. Results: There was no significant difference (P>0.05) in the mean Onset and Nl latency of SSEP among the 3 groups before drug application. Compared with the pre-application value, the mean Onset and Nl latencies in the RSSC and OSSC groups were significantly prolonged at 10, 30 and 60 min after treatment (P<0.05), while they were not significantly changed (P>0.05) in the placebo group. The mean Onset latency of RSSC at 10 and 30 min and that of OSSC at 30 min were significantly delayed (P<0.05) compared with the placebo group. The mean Nl latency of RSSC at 30 and 60 min and that of OSSC group at 30 min were also significantly delayed (P<0.05). Conclusion: RSSC delays the latencies of SSEP, suggesting a local desensitizing effect on the sensory receptor of the glans penis dorsal nerve, which provides the potential for PE treatment. The desensitizing effect of RSSC is higher than that of OSSC.

Recording of spared motor evoked potentials and its augmentation by 4-aminopyridine in chronic spinal cord-injured rats

Objective To research the direct electrophysiological evidence of discomplete spinal cord injury (SCI) and the effect of 4-aminopyridine on it.Methods Motor evoked potentials (MEPs), both spinal cord recorded MEPs (scMEPs) and extracellularly recorded MEPs (exMEPs) were recorded and characterized on a T13 epidural electrode (scMEPs) and an extracellular microelectrode (exMEPs) for 10 normal rats and 40 rats with lesions of various severity (sham, 35?g*cm force (gcf), 70?gcf, 100?gcf impact injury) at the T8-T9 cord using the Allen's drop model. The incline plane and Tarlov techniques were used to assess clinical neurological function. Results MEPs in the normal rats were elicited by applying transcortical suprathreshold stimulation consisting of 3-4 early negative peaks (N1, N2, N3 and N4) followed by several late waves. The N1 and N2 peaks were largest in the anterior and ventrolateral funiculus, respectively, which was indicative of extrapyramidal pathways. The 100?gcf impact injuries and the cord transection abolished the MEP distal to the lesion, whereas the 35?gcf injuries resulted in a latency shift and amplitude decrement of the MEP peaks. Eighteen of the 20 rats with 70?gcf injuries showed clinical paraplegia. Among them, 7 rats had neurophysiological evidence of residual conduction pathways through the lesioned cord segment, such as the presence of N1 and N2 peaks in the scMEPs or exMEPs. After 4-aminopyridine (4-AP) administrations (1?mg/kg), the amplitude of the spared exMEP increased significantly and spread more widely. Conclusions MEPs evoked by transcortical stimulation travel mostly in the extrapyramidal tract. MEP monitoring could provide an excellent method of detecting the functional integrity of the motor tracts after SCI, and could even detect spared motor fibers after discomplete SCI. Furthermore, the use of 4-AP or other K+ channel blocking agents may be a potential treatment for patients with chronic moderate to severe SCI.