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Biomedical subjects

H Lueders

Publications and source records attributed to H Lueders.

31 records · Page 2Linked to original sources
PubMed1981

Early somatosensory potentials evoked by median nerve stimulation: intraoperative monitoring.

We identified the sites of origin of the somatosensory evoked potentials to median nerve stimulation by recording directly from the cervical cord in the course of intraoperative monitoring. The N9 potential occurred before any potentials recorded from the cord or dorsal roots. Potentials with latencies corresponding to N11 were recorded at the median nerve root entry zone of the lower cervical cord. High-amplitude potentials were recorded at the level of the foramen magnum, with latencies approximating or following P13, suggesting that this potential is generated at the cervicomedullary junction.

Electric Stimulation↗
PubMed1981

The independence of closely spaced discrete experimental spike foci.

Stable spike foci generated by weak penicillin solutions had a minimal area of distribution of 12.5 mm2. Two foci separated by 4 mm on the same gyrus were consistently dependent and simultaneous. An area of "positive surround" between the two spikes did not prevent dependency. This contradicts the hypothesis that "positive surround" prevents spreading of epileptiform discharges. Spike foci separated by 6 mm were almost always independent. Bursts of afterdischarges remained independent if the primary spikes were independent. Postafterdischarge suppression and spreading depression of Leao affected independent spike focus selectively. These experiments suggest that cross-talking between cortical columns is limited to column 1 to 2 mm apart.

Animals↗
PubMed1981

Aphasic status epilepticus: a case report.

Complex partial status epilepticus with aphasia as the sole manifestation has been reported only twice before. We studied a 60-year-old diabetic who was aphasic for 12 days. The diagnosis of aphasic status was supported by electroencephalographic seizure patterns in the left hemisphere.

Aphasia↗
PubMed1981

Quantitative evaluation of anticonvulsant effects on penicillin-induced spike foci in cats.

We evaluated the effects of phenytoin, carbamazepine, phenobarbital, sodium valproate, and ethosuximide on penicillin-induced spike foci. Phenytoin, carbamazepine, and phenobarbital at blood levels within or slightly above the human therapeutic range in humans increased spike frequency, decreased spike duration, and abolished after discharges. Ethosuximide and sodium valproate had no statistically significant effect even at blood levels considered toxic in humans. The experimental spike focus and the method of analysis appear useful for: (1) detection of new potentially anticonvulsant drugs, (2) classifying new potentially anticonvulsant drugs according to the type of clinical seizure for which benefit is most likely, and (3) comparing different anticonvulsant drugs.

Animals↗
PubMed1981

Hyperventilation and 6-hour EEG recording in evaluation of absence seizures.

Seven patients with poorly controlled absence seizures were evaluated clinically and electroencephalographically (EEG) in control and placebo periods and then evaluated after 10 weeks on valproic acid. For analysis of epileptiform activity, 5 minutes of controlled hyperventilation recording was more reliable than 6-hour recording as a predictor of clinical seizure frequency. This apparently paradoxic result can be explained by considering that the number of epileptiform discharges in the EEG is affected by many variables (such as level of consciousness, anxiety, diurnal seizure variation, or blood glucose level) that are difficult to control for prolonged periods.

Electroencephalography↗
PubMed1981

Simple technique for monitoring intraoperative spinal cord function.

Interference with normal spinal cord functioning is an important, although uncommon, complication of spinal surgery. Spinal evoked potentials have been advocated as a means of monitoring spinal cord transmission during operative procedures. We have developed a simple technique using electrodes inserted into the interspinal ligaments for monitoring purposes. This has produced stable and reproducible recordings with obvious clinical benefit in the first 50 cases in which it has been used.

Evoked Potentials, Somatosensory↗
PubMed1980

Quantitative studies of spike foci induced by minimal concentrations of penicillin.

The minimal concentrations of penicillin which induce stable recurrent spikes (20,000 U/ml) and which elicit stable recurrent after-discharges (100,000 U/ml) were determined. A quantitative study of the inter-relationships, variability and changes with time of a number of spike parameters (spike latency, spike amplitude, amplitude of prepositivity, spike duration and spike frequency) was performed. The study adds new information on the pathogenesis of the experimental spike focus and serves as baseline for quantitative evaluation of the effects of anticonvulsants on the characteristics of the primary spike focus and on after-discharges.

Animals↗
PubMed1980

The effects of phenytoin on the penicillin-induced spike focus.

A quantitative evaluation of the effects of phenytoin on penicillin-induced spike foci is reported. Phenytoin at blood levels considered within therapeutic range in humans increased spike frequency, decreased spike duration and abolished after-discharges. Spiking at weak foci was completely abolished when high concentrations of phenytoin were used. It is concluded that phenytoin affects mainly the long chain pathways whether the ultimate effects of these pathways are excitatory or inhibitory.

Animals↗
PubMed1979

Effect of stimulus intensity on short latency somatosensory evoked potentials.

The peripheral and central potentials evoked by percutaneous electrical stimulation of the median nerve were investigated in a group of neurologically normal subjects. We found: (1) Motor threshold stimulation gave consistently submaximal responses and probably does not represent an optimal intensity for routine use. (2) The sum of motor plus sensory threshold gave potentials which were consistently at, or close to, maximal in amplitude. This intensity was comfortable for all subjects. (3) When stimulating at intensities above motor threshold, the increase in amplitude of peripheral potentials markedly exceeded that of the central potentials. There was evidence suggesting that amplitudes would decline at very high stimulus intensities. (4) The P13 peak latency and the P13--N9 interpeak latency declined and the N17--P13 interpeak latency increased with increasing intensities of stimulation. The N9 and N18 peak latencies remained stable.

Adult↗
PubMed1978

Complex partial status epilepticus: case report and proposal for diagnostic criteria.

A child had complex partial status epilepticus after resection of a craniopharyngioma. The status epilepticus was manifested by confusion and documented electroencephalographically by continuous focal seizure patterns in the right temporal region. Complex partial status epilepticus is an electroclinical syndrome of prolonged or repetitive complex partial seizures (with continuous interictal confusion) accompanied by electroencephalographic seizure patterns, which are either focal (usually temporal lobe) or secondarily generalized from a focal pacemaker.

Child, Preschool↗
PubMedDate not supplied

Adjunctive hyperbaric oxygen in the treatment of thermal burns. An economic analysis.

Current reimbursement for burn care underscores the importance of cost containment in the treatment of burn injuries. We evaluate the economic impact of adjunctive hyperbaric oxygen in burns of 19% to 50% total body surface area in patients admitted to our burn center from January 1982 to July 1987. Length of hospitalization, number of surgical procedures, and total cost of care, exclusive of surgical fees, were examined. Eleven patients did not receive adjunctive hyperbaric oxygen therapy, whereas 10 did. The hyperbaric oxygen-treated group had an average decrease in length of stay of 14.8 days, a reduction of surgical procedures of 39%, and an average saving per case of $31,600.

Adolescent↗
PubMedDate not supplied

A new technique for intraoperative monitoring of spinal cord function: multichannel recording of spinal cord and subcortical evoked potentials.

A new technique for intraoperative monitoring of spinal cord function is described. Evoked potentials to peripheral nerve stimulation are recorded with interspinous ligament needles from below and from two or more levels above the surgery. Simultaneously subcortical potentials are recorded with scalp electrodes from cervical-scalp derivations. Simultaneous recordings from multiple levels (below and above the surgical procedure) permit reliable differentiation between technical problems and alteration of cord function due to the surgical procedure. The interspinous ligament technique for recording of spinal potentials has significant advantages over previous monitoring techniques. One case in which monitoring during surgery detected a reversible acute spinal cord dysfunction is described.

Adolescent↗