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Biomedical subjects

A Sances

Publications and source records attributed to A Sances.

At least 73 records · Page 4Linked to original sources
PubMed1978

Early somatosensory evoked potentials.

The early somatosensory evoked potential secondary to median nerve stimulation in the human had an onset latency of 9--12 msec when recorded from scalp electrodes at vertex-to-mastoid, vertex-to-inion or at the base of the skull. Similar latencies were observed from responses recorded over the cervical dorsal columns during neurologic surgery. A latency difference of 1.5 msec was observed between the early response and the responses recorded from the junction of medial lemniscus and nucleus ventralis posterior lateralis of the thalamus during human stereotaxic surgery. Cervical cord transections and transection at the midpontine levels of the monkey showed that the evoked potential was due to generators between these levels. Depth recording of the monkey indicate that the early evoked potential originates in the region of dorsal column nuclei, while the later components are secondary to generators in cerebral cortex.

Animals↗
PubMed1978

Spinal evoked potentials in the primate: neural substrate.

Summated responses evoked by peripheral nerve stimulation were recorded from electrodes located in the epidural and subdural spaces anterior and posterior to the monkey spinal cord. Segmental microsurgical resection of the dorsal columns both at the thoracic and cervical levels resulted in total obliteration of the response recorded rostral to these lesions. Isolated segmental dorsal column preservation did not significantly alter response latency or wave form recorded at the rostral electrodes. Bilateral cervical dorsolateral column resection also resulted in no discernible alterations of these responses. These data indicate that spinal evoked potentials recorded from levels rostral to their root entry zones arise almost exclusively from the dorsal columns.

Animals↗
PubMed1977

The effect of cerebellar stimulation on focal seizure activity and spasticity in monkeys.

Experiments were carried out in awake, unmedicated monkeys to determine the effect of application of current to the cerebellar hemispheres on electrically induced focal motor seizures and surgically induced spasticity. Application of current at various frequencies and pulse amplitudes did not significantly alter focal motor seizures but did significantly reduce spasticity. Analysis of evoked potential recordings carried out during various experimental procedures suggests that application of current to the cerebellar hemispheres may reduce cortical neuronal responsiveness.

Animals↗
PubMed1976

Quantification of computer analyzed serial EEGs from stroke patients.

While considerable studies have been conducted by others in automation of the EEG, this method does appear to hold promise for quantitative evaluation and automation of the EEG in the CVA patients or those with similar neurologic deficits. Patients were followed up to 1 year post-ictus. The computerized evaluation of serial records in the CVA patients showed trends which were similar to the percent disability of the patients who were graded neurologically. The patients included in the study were those with middle cerebral artery, carotid and vertebro-basilar defects. A substantial increase in the low frequency activity with a concomitant decrease in high frequency activity was observed in the CVA patients. The results observed in these patient examples demonstrate the utility and efficacy of one method of automated analysis of serial EEGs. The parameters defined by this study have proven to be consistent and effective measures. Since these parameters are objective, they are not affected by patient histories and hence, can be utilized to track the ongoing EEG activity and the accompanying clinical state regardless of the disease entity or the course of therapy pursued. The addition of automated objective quantitative measures to EEG analysis provides a dimension not currently available to the clinician.

Aged↗
PubMed1976

Lateral extracavitary approach to traumatic lesions of the thoracic and lumbar spine.

The lateral extracavitary approach to the spine was used for resection of displaced bpne and disc located anterior to the dura in 62 patients with traumatic lesions of the thoracic and lumbar spine. Fifty-two patients had closed vertebral fractures and 10 had gunshot wounds. The spinal cord was involved in 44 patients, and the cauda equina in 18. A spinal subarachnoid block was demonstrated in 17 of 57 preoperative gas myelograms. Evoked potential recordings, although related to preception of joint rotation, tended to reflect the overall neurological condition and had some prognostic value. Significant improvement followed surgery in 46 patients with incomplete neurological lesions, and one was transiently worse. Before operation 18 patients were able to walk; nine with assistance and nine without. After operation 47 patients were able to walk; 12 with assistance and 35 without. Adequate bladder function was present in 17 patients before surgery, and in 44 after surgery. A laminectomy had been done previously in 16 patients, 11 of whom improved significantly after anterior resection. Spine fusions were required in 26 patients, five of whom had a prior laminectomy. The major factor in the pathogenesis of the incomplete neurological deficit appeared to be distortion of the cord and roots by displaced bone and disc. Consequently, the primary object of treatment was the restoration and maintenance of normal anatomical relationships between the spinal cord or cauda equina and the spinal canal.

Adult↗
PubMed1976

The effect of T-myelotomy on spasticity.

Dorsal myelotomy with lateral extension (T-myelotomy) provided excellent relief from spasticity in the lower limbs in 12 patients. Averaged evoked potential recordings helped delineate the limits of the myelotomy and were useful for evaluation of injury to the dorsal columns. While preservation of any residual motor function is unlikely following T-myelotomy, the risk of permanent loss of preserved sensory, bladder or sexual functions is not great.

Adult↗
PubMed1975

Clinical applications and theoretical analysis of NMR blood flowmeter.

Nuclear magnetic resonance principles have been applied to measure biological blood flow. The method is non-intrusive and can be used to measure peripheral blood flow or blood flow from various organs. The mechanisms of NMR are described and studies of blood flow in limbs and the head are discussed.

Animals↗
PubMed1975

A comparison between anterior and posterior spinal implant systems.

In four patients with intractable pain from metastatic cancer, application of current through electrodes placed on the anterior surface of the cord produced analgesia and pain relief below the level of implant without the development of paresthesias. Application of current through electrodes placed on the dorsal columns in these patients also relieved pain, but to a lesser degree and with the development of associated paresthesias. In one patient, application of current from anterior electrodes to posterior electrodes produced a zone of dissociated sensory loss. While it is simpler to implant electrodes over the dorsal columns, the anterior location may be superior when currents are to be applied for the pain relief in the lower lumbar and sacral dermatomes.

Animals↗