Search PubMed⌕ Search

Biomedical subjects

S J Larson

Publications and source records attributed to S J Larson.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1977

Mechanical and physiological effects of dentatotomy.

The role of the dentate ligaments in the pathogenesis of myelopathy secondary to disease conditions that alter the normal biomechanics of the spinal canal was studied in 14 dogs. The effects of posterior cord elevation on somatosensory evoked potentials (SSEP's) and tension requirements were compared before and after dentate ligaments section in acute experiments. At levels of posterior elevation usually within the confines of the canine canal, the dentate ligaments were the most significant element increasing tension requirements and SSEP alternations. Human cadaver studies also showed an approximate 50% reduction of force after dentatotomy. These findings suggests that after dentate ligaments section the applied tension is distributed over a longer segments of the cord with a reduction in tension and disruption of axonal conduction at the level at which the force was applied.

Animals↗
PubMed1977

Arachnoiditis following myelography with metrizamide in monkeys. Effect of blood in the cerebrospinal fluid.

Monkeys were injected intrathecally with blood, metrizamide (Amipaque) or a mixture of blood and metrizamide. Twelve weeks later the animals were examined for evidence of arachnoiditis. Either blood or metrizamide alone in sufficient amounts resulted in arachnoiditis. The addition of blood to metrizamide did not alter the severity or risk of arachnoiditis from experimental myelography with metrizamide.

Animals↗
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↗