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Biomedical subjects

D S Dinner

Publications and source records attributed to D S Dinner.

At least 91 records · Page 5Linked to original sources
PubMed1985

Pattern evoked potentials (PEPs) in Parkinson's disease.

Controversy exists in the literature concerning whether Parkinson's disease (PD) results in prolongation of pattern evoked potential (PEP) responses. PEPs were obtained in 20 patients with PD. The latencies of the first major positive potential (P2) in response to independent left and right eye stimulation were evaluated. There was no statistically significant difference (group or individual) when patients with PD were compared with age-corrected controls. There was no difference in results in comparing patients with mild, moderate, and severe PD. These results contradict previous reports of markedly abnormal PEPs.

Aged↗
PubMed1985

Preservation of voluntary saccades after intracarotid injection of barbiturate.

We studied voluntary saccades in 44 patients undergoing Wada testing before surgery for intractable epilepsy. After intracarotid injection of barbiturate, and while they were hemiplegic, patients could still make voluntary saccades toward or away from the side of injection. Sustained ipsiversive deviation of gaze was not noted. Saccades made away from the side of injection were slower than ipsilateral saccades in only 3 of 10 tests. These data support the hypothesis of parallel, independent pathways from the frontal eye fields and from the superior colliculi to the brainstem reticular nuclei that generate saccades.

Amobarbital↗
PubMed1984

Obstructive sleep apnea in association with posterior fossa neurologic disease.

Sleep apnea in association with neurologic disease is uncommon, and its documentation with nocturnal polysomnography (PSG) is rare. Two patients with posterior fossa neurologic disease had obstructive and central sleep apnea on PSG. The first was a 40-year-old woman who experienced a respiratory arrest ten days after neurosurgical decompression of a cervical syrinx associated with syringobulbia. Nocturnal PSG demonstrated obstructive sleep apnea. Tracheostomy was performed and a second nocturnal PSG showed no sleep apnea. The second patient was a 76-year-old woman with daytime hypersomnolence, nocturnal choking spells, progressive spastic paraparesis, and left-sided cerebellar tremor. Neurologic evaluation led to the diagnosis of olivopontocerebellar degeneration. Nocturnal PSG showed multiple episodes of central and obstructive apnea. These cases support the hypothesis that central and obstructive sleep apnea can originate from a central mechanism.

Adult↗
PubMed1984

Far-field auditory evoked potentials in near-miss sudden infant death syndrome.

Auditory evoked potentials (AEPs) were determined in 16 patients with near-miss sudden infant death syndrome. The AEPs were normal in all patients except one with prolonged 1 to V interpeak latency (bilaterally) and another with an asymmetry of interear 1 to V interpeak latency difference. These results indicate that AEPs do not permit detection of infants at high risk for crib death.

Brain↗
PubMed1984

Subcortical and cortical somatosensory potentials evoked by posterior tibial nerve stimulation: normative values.

Cortical somatosensory evoked potentials to posterior tibial nerve stimulation were obtained in 29 normal controls varying in age and body height. In obtaining these potentials we varied recording derivations and frequency settings. Our recordings demonstrated the following points: N20 (dorsal cord potential) and the early cortical components (P2, N2) were the only potentials that were consistently recorded. All other subcortical components (N18, N24, P27, N30) were of relatively low amplitude and not infrequently absent even in normals. All absolute latencies other than N2 were correlated with body height. However, interpeak latency differences were independent of body height. Below the age of 20, subcortical but not cortical peak latencies correlated with age, but this appeared to be due to changes in body height in this age group. Absolute amplitudes and amplitude ratios (left/right and uni/bilateral) showed marked interindividual variability and have very limited value in defining abnormality. The use of restricted filter windows facilitated the selective recording of postsynaptic potentials (30-250 Hz) and action potentials (150-1500 Hz).

Adolescent↗
PubMed1984

Effect of stimulus intensity on subcortical and cortical somatosensory evoked potentials by posterior tibial nerve stimulation.

The effects of stimulus intensity on subcortical and cortical somatosensory evoked potentials (SEPs) to posterior tibial nerve (PTN) stimulation were studied in 16 normal controls. Stimulus intensity was evaluated as a function of sensory threshold (S). Motor threshold (M) varied between 1 S and 2 S. The amplitude of N18 (afferent volley immediately before it enters the spinal canal) increased approximately linearly up to at least 4.5 S. N20 (dorsal cord potential) also demonstrated a linear increase up to at least 4 S but the rate of increase was significantly smaller. All central components (subcortical brain-stem components P27 and N30, and cortical components N1 and P2) showed an even smaller rate of increase which was non-linear and reached a plateau at 3 S. The relatively higher rate of increase of N18 as compared with N20 was most probably due to the recording of sensory impulses plus antidromic impulses in motor fibers. The smaller rate of increase and early saturation of all the central components compared with N20 suggests that of all the afferent fibers generating N20 only the low threshold fibers participate in the generation of more central components. Stimulus intensities of 3 S are recommended for clinical studies of the central SEPs to PTN stimulation.

Adolescent↗
PubMed1984

Recording of auditory evoked potentials in man using chronic subdural electrodes.

With the aid of chronic subdural electrodes we have been able to record from the posterior banks of the sylvian fissure, auditory evoked potentials (AEPs) that had morphologies and peak latencies compatible with the primary AEPs described by Celesia and Puletti (1969). These AEPs had amplitudes that were not only affected by the side of stimulus presentation but were maximal in an area close to the primary auditory cortex. The AEPs also displayed an extremely steep spatial gradient and were not altered by pentobarbitone sodium and nitrous oxide anaesthesia. Together, these properties suggest that these subdurally recorded potentials are near-field evoked potentials from the primary auditory cortex. The focal nature of these potentials also allows them to be used as effective electrophysiological tools for localization of the primary auditory cortex in patients.

Adolescent↗
PubMed1984

The location of speech and writing functions in the frontal language area. Results of extraoperative cortical stimulation.

In three patients stimulation of the frontal speech area resulted in one or more of the following symptoms: speech arrest, writing arrest, or impaired rapid alternating movements of the tongue, fingers or toes. Speech arrest could be altered at individual points either with or without impairment of rapid movements or writing, but writing was not impaired without concomitant difficulties with either speech or rapid finger movements. Our data suggest that the frontal speech area may function to integrate complex motor functions, some speech related and others not. We also confirm previous conclusions that Exner's writing centre is not separate from Broca's area and that the writing defect in Broca's aphasia can occur without involvement of the motor strip.

Adult↗
PubMed1984

Cortical afterdischarge and functional response thresholds: results of extraoperative testing.

We have evaluated the afterdischarge thresholds and functional response thresholds in 21 patients with chronically implanted arrays of subdural electrodes. Afterdischarge thresholds varied from 2 to greater than 15 mA over the tested cortex, by as much as 12 mA in individual patients, and by as much as 12 mA between adjacent electrodes. Thresholds for functional alteration varied from 2 to 15 mA in tested cortex, by as much as 9.5 mA in individually tested patients, and by as much as 6.5 mA between adjacent electrodes. We conclude that the optimal localization of functional cortical areas requires different stimulation intensities at different points. The use of too high an intensity would produce afterdischarges at some positions. The use of too low an intensity would falsely make others appear functionally "silent."

Adolescent↗
PubMed1984

High-dose monotherapy in treatment of intractable seizures.

We evaluated the therapeutic efficacy and toxicity of high-dose monotherapy, using carbamazepine or phenytoin, in patients with previously uncontrolled seizures. Treatment with a single drug was equal to or better than polypharmacy, but only a few patients became free of seizures. Toxicity was mild and associated with higher total plasma levels after polypharmacy. Free fractions ranged from 0.14 to 0.30 for carbamazepine and from 0.60 to 0.13 for phenytoin. Toxicity was associated with free phenytoin levels above 3 micrograms/ml; there was no clear relationship between free carbamazepine level and toxicity.

Adult↗
PubMed1984

Transient neuropsychological abnormalities (including Gerstmann's syndrome) during cortical stimulation.

A patient with intractable partial seizures was intensively studied before surgical removal of the epileptogenic focus. A subdural electrode array was surgically placed over the left temporoparietal cortex to better localize the epileptogenic focus and localize cortical function. In addition to speech and sensory findings, acalculia, agraphia, right-left confusion, and finger agnosia were transiently produced by electrical stimulation in the perisylvian area. These findings and their relationship to the controversy surrounding Gerstmann's syndrome are discussed.

Adolescent↗
PubMed1983

Origin of far-field subcortical evoked potentials to posterior tibial and median nerve stimulation. A comparative study.

Posterior tibial nerve (PTN) evoked potentials (EPs) at the lumbar-low thoracic level have waveforms similar to median nerve (MN) EPs at the cervical level. They consist of a short-duration negativity (N18 and N10, respectively), which reflects the afferent volley before it enters the spinal canal, and a longer-duration, later negativity (N20 and N12, respectively), which consists mainly of slow frequencies and most probably is a postsynaptic dorsal cord potential. At the neck-scalp derivation the MN EP consists of two near-field negativities (N10 and N12) that are recorded from the neck electrode and two far-field positivities (P11 and P13) that are recorded from the scalp electrode. The neck-scalp response to PTN stimulation consists of a near field potential N24 that is followed by a far-field potential P27.

Brain↗