Kenneth L. Cummins

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A method is presented for estimating nerve fiber conduction velocity distributions from non-invasive measurements of the compound action potential at two distinct locations separated by a known distance along the nerve bundle. This method is based on a model of the compound action potential as a weighted sum of delayed single-fiber action potentials, but(More)
A method is described for estimating the distribution of nerve-fiber conduction velocities in a nerve bundle. This method is based on a detailed general model of the nerve bundle compound action potential, which is characterized as a weighted sum of delayed single-fiber action potentials. The non-iterative estimation method is applied to two examples taken(More)
Cerebral somatosensory evoked potentials (SEP's) were elicited by electrical stimulation of the median nerve in the arm (SEPA) and of the posterior tibial nerve in the leg (SEPL) in 23 patients with incomplete localized lesions (including traumatic injuries, neoplasms, vascular malformations and infarcts) of the low cervical, thoracic, or lumbar spinal(More)
The electrical stimulus pulse and the surface electrodes commonly used to study compound action potentials of peripheral nerves give rise to an artifact consisting of an initial spike and a longer lasting tail which often interferes with the recorded signal. The artifact has four sources: 1) the voltage gradient between the recording electrodes caused by(More)
The distributions of nerve fiber conduction velocities (DCVs) derived from the median nerves of 29 adult diabetic patients (mean age, 52.1 +/- 12.3 years) with mild or no symptoms or signs of polyneuropathy were compared with DCVs from 34 age-appropriate normal subjects. Ten patients (34%) had normal findings (type A DCVs). In the 19 patients (66%) with(More)
Five electrical characteristics--impedance, broadband noise generation, line interference sensitivity, signal distortion, and common-mode conversion--were measured in five electromyographic (EMG) concentric needle electrodes (CNEs) from each of six commercial manufacturers. Untreated CNEs showed considerable variation in impedance and broadband noise(More)
Nitrogen oxides (NO x =NO+NO 2) play an important role in tropospheric chemistry, in particular in catalytic ozone production. Lightning provides a natural source of nitrogen oxides, dominating the production in the tropical upper troposphere, with strong impact on tropospheric ozone and the atmosphere's oxidizing capacity. Recent estimates of lightning(More)
Intra-axonal recordings were obtained in vitro from frog sciatic nerve axons. Adjusting whole nerve stimulation current to just subthreshold for the impaled axon elicited triphasic threshold changes in that axon. Threshold changes were determined by direct intra-axonal current application. Graded subthreshold depolarizations were present in many axons(More)
A model was presented describing the nerve-bundle CAP in terms of its constituent SFAPs. The model has a general structure capable of accommodating a large variety of specific assumptions regarding the nature of the CAP. Using this model, several techniques were presented for estimating the DCV of a nerve bundle. One method, refered to as the 2CAP method,(More)
We have assessed the clinical applicability of a previously described new method for analyzing the distribution of conduction velocities (DCV) in peripheral nerve. Surface-recorded median sensorimotor compound action potentials (CAPs) were found to contain contributions from classes of fibers conducting between 25 and 80 m/sec in the elbow-to-axilla(More)