Applied neurophysiology
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Twelve patients with recurrent supratentorial gliomas were treated with implanted 125I seeds. The interval from initial surgery to interstitial radiation ranged from 3 months to 9 years. ⋯ CT scans performed sequentially on all patients showed progressive attenuation in areas previously enhancing, suggestive of tumor necrosis produced by the interstitial sources. The mean and median survival of these patients was 23 and 22 weeks, with the 4 most recent patients still alive.
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Applied neurophysiology · Jan 1986
Comparative StudyElectrical stimulation in multiple sclerosis. Comparison of transcutaneous electrical stimulation and epidural spinal cord stimulation.
Forty-nine multiple sclerosis patients with bladder symptoms and/or walking disability were subjected to a therapeutic trial with electrical spinal cord stimulation and transcutaneous electrical stimulation, a second aim being to compare these two treatments. A clear subjective improvement in bladder symptoms was achieved in the majority of the cases, and this was substantiated by objective parameters. In a proportion of cases a more moderate improvement seems to have been achieved in a variety of symptoms. Transcutaneous electrical stimulation seems to be a useful selection procedure for later electrical spinal cord stimulation.
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Applied neurophysiology · Jan 1986
Epidural recordings of electrical events produced in the spinal cord by segmental, ascending and descending volleys.
Epidural electrodes implanted for a percutaneous trial of therapeutic spinal cord stimulation were used to record electrical events evoked by the stimulation of peripheral nerves or of the spinal cord itself. The data collected in patients with no neurological deficit were analyzed in order (1) to check the consistency between epidural and surface recordings, (2) to get information on the genesis of such potentials, and (3) to demonstrate the feasibility of complex neurophysiological studies by means of epidural electrodes. Spinal cord potentials evoked by segmental volleys were recorded at cervical levels with the recording electrodes anterior, lateral and posterior to the spinal cord. ⋯ Our epidural recordings are similar to those obtained from the skin, but with a greater amplitude and waveform resolution. Furthermore, the use of epidural electrodes made it feasible to perform complex examinations of sensory function (i.e., the study of orthodromic and antidromic conduction along the dorsal cord and of the influence of a single dorsal cord volley on the segmental cervical potential). Finally, the genesis of the potentials recorded is discussed.
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Applied neurophysiology · Jan 1986
Use of antidromic evoked potentials in placement of dorsal cord disc electrodes.
Intraoperative recordings of somatosensory evoked potentials were made in 16 patients undergoing implantation of a dorsal cord stimulation system. Antidromic recordings, obtained by stimulating through the dorsal cord electrode placed in the epidural space and recording over peripheral nerves in the painful region of the body, and much higher signal-to-noise ratios and could be obtained with greater reliability than standard orthodromic recordings. When the placement of the electrode was adjusted to obtain evoked responses in the painful region, paresthesias referred to that region were obtained in virtually every case. Use of this procedure allows implantation and internalization of the electrodes in a single procedure under general anesthesia, and reduces the necessity of subsequent revisions.
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Applied neurophysiology · Jan 1986
Transcutaneous nerve stimulation. Frequency and waveform specificity in humans.
The effects of transcutaneous electrical nerve stimulation (TNS) of a constant alternating current administered at various frequencies and waveforms to volunteer human subjects were investigated. The TNS was found to evoke noncutaneous subjective sensations in all the subjects. Only with a sinusoid waveform of TNS were distinct frequency ranges of the stimulation associated with specific noncutaneous subjective sensations. Our findings suggest that nervous tissue is capable of discriminating the waveform parameters of an electrical stimulus.