Biomedical subjects

G L Krauss

Publications and source records attributed to G L Krauss.

10 recordsLinked to original sources

PubMed1992

Anterior "cheek" electrodes are comparable to sphenoidal electrodes for the identification of ictal activity.

Sphenoidal electrodes are used to localize epileptiform activity originating in the temporal lobe during complex partial seizures. Sphenoidal electrodes, however, are semi-invasive and uncomfortable to the patient. We compared skin electrodes placed on the cheek ("cheek electrodes") with sphenoidal electrodes for the detection of the side and site of complex partial seizure onset. In a masked, randomized comparison of single ictal recordings in 22 patients, there were no significant differences between sphenoidal and cheek electrode montages in detecting the side or site of ictal onset (P < 0.01). Signal/noise ratios for interictal spikes were a mean 16.5% greater at sphenoidal sites compared to cheek sites (paired t test, t = 2.4, P < 0.05). This difference, however, did not influence the detection of rhythmical ictal activity in cheek and sphenoidal montages in our study, nor the assignment of side, site or time of seizure onset by unbiased readers. Recordings from cheek electrodes are comparable to those from sphenoidal electrodes and are useful for localizing ictal activity.

Cheek↗

PubMed1992

Simple partial seizures: clinicofunctional correlation--a case report.

A 12-year-old girl developed simple partial motor and sensory seizures due to a right perirolandic astrocytoma. Subdural EEG recording and functional stimulation disclosed close correlation between EEG-clinical manifestations of focal seizures and functional responses to cortical stimulation. This case supports the idea that responses in the perirolandic area to endogenous epileptogenic activity and to cortical stimulation reflect common underlying physiologic mechanisms.

Brain↗

PubMed1992

Motor and sensory cortex in humans: topography studied with chronic subdural stimulation.

Classic neurosurgical teaching holds that once the Rolandic fissure (Rf) has been located, there are distinct differentiated primary motor and sensory functional units confined within a narrow cortical strip: Brodmann's Areas 4 and 6 for primary motor units in front of the Rf and 3, 1, and 2 for sensory units behind the Rf. To test this assumption, we examined in detail the records of cortical mapping done by electrical stimulation of the cerebral cortex via implanted subdural electrode grids in 35 patients with seizure disorders. Of 1381 stimulations of the electrode sites, 346 (25.1%) produced primary motor or motor-arrest and sensory responses in contralateral body parts: 56.8% were primary motor responses; 16.2% were motor-arrest; 22.5% were sensory; and the remaining 4.5% were mixed motor and sensory responses. Two-thirds (65.9%) of the primary motor responses were located within 10 mm of the Rf, and the remaining one-third (34.1%) were more than 10 mm anterior to the Rf or were posterior to the Rf. Furthermore, in the patient group with brain lesions, fewer than one-third (28.1%) of the responses were within the 10-mm narrow anterior strip. Our study reconfirmed that a significant number--at least one-third--of motor responses are distributed outside the classic narrow cortical strip. In patients with brain lesions, the motor representation is further displaced outside the narrow strip. This finding indicates that primary motor cortex may extend beyond the gyrus immediately anterior to the Rf.

Adolescent↗

PubMed1991

Electroencephalogram and seizures in chronic alcoholism.

CNS complications of chronic alcoholism are frequently difficult to assess due to the variety of direct and secondary conditions which can result from alcoholic drinking and lifestyles. The influence of alcoholism and alcohol-related factors on the EEG of patients with chronic alcoholism was studied in 213 patients (15.4% of all adults who had EEGs) using visual analysis. The influence of a variety of alcohol-related factors - drinking history, clinical complications, traumatic head injuries, head CT findings and laboratory results - on the EEG and alcohol-related seizures was studied. The effect of EEG results on the decision to treat alcohol-related seizures was also assessed. 152 of the patients had seizures, mostly (90% of those with defined seizure types) generalized tonic-clonic seizures. 53% of all seizures occurred in the early withdrawal period (8 h to 7 days abstinence). A history of partial seizures was significantly associated with findings of focal EEG abnormalities, a history of head injuries and structural lesions on CT. The clinical significance of these findings was unclear, however, as the majority of patients who had focal EEG abnormalities or structural brain lesions still appeared to have generalized withdrawal seizures. The EEG and CT appeared to be complementary tests: for most patients, focal abnormalities were demonstrated on only one of the two tests. The majority of patients (56%) with normal EEGs had predominantly low voltage recordings (less than 25 muV), compared with 13.9% of 1167 patients without a history of alcoholism (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Spindle coma: observations and thoughts.

The occurrence of physiological patterns of NREM sleep ("spindle coma") is well known since the first major study of Chatrian et al who--like most of the authors of subsequent studies--placed particular emphasis on the etiological role of CNS trauma. Further work showed that nontraumatic causes may also result in spindle coma. This study is based upon 11 observations of spindle coma extracted from 861 patients with acute severe CNS conditions. The age of the patients ranged from 6 months to 46 years. Metabolic, infectious and hypoxic problems were the most common etiologies; there was no case of CNS trauma. It is assumed that spindle coma represents a combination (i.e. coexistence) of true sleep and coma, the latter accounting for the failure of arousal that is attributed to impairment of the activating ascending reticular formation (midbrain level). The presence of spindles (and also vertex waves and K complexes) indicates relative integrity of the cerebral hemispheres. Such a constellation is more likely to occur in CNS trauma but--as our nontraumatic patient population shows--may also materialize in other types of CNS pathology.

Adult↗

PubMed1990

Characterization of the basal temporal language area in patients with left temporal lobe epilepsy.

We evaluated 5 consecutive patients with subdural grid electrodes (including placement over the left basal temporal region) for focal resections for control of intractable epilepsy. All 5 had language dysfunction when we performed cortical stimulation over the basal temporal region (the inferior temporal gyrus, the parahippocampal gyrus) using a systematic battery of language tests. The area in which language interference could be produced began from at least 11 to 35 mm posterior to the temporal tip and ended at least 39 to 74 mm posterior to the temporal tip. The most consistently impaired language tasks were spontaneous speech and passage reading, but there was impairment of all language functions tested in some patients. Language deficits after dominant temporal lobectomy may result from resection of this area.

Adult↗

PubMed1989

The electroencephalogram and mental activation.

The mental activation (MA) is a simple test consisting of two questions and two commands given during the waking record. The responses are documented by + or - sign notations made by the technologist. In this manner, data were rapidly obtained from 1280 patients; there were 598 patients with EEG records within normal limits and 682 with various degrees of EEG abnormality. The MA serves the following purposes: a. to study the repercussions of the test on the EEG activity, b. to ascertain the optimal level of vigilance, c. to attempt a correlation of MA responses and the degree of EEG abnormality and d. to obtain brief information on the patient's mental state. The test is administered during conventional EEG recordings. It was found that alpha blocking or attenuation was the exception rather than the rule during the test. Diffuse and focal slowing also remained unchanged in the vast majority of the cases, whereas focal intermittent rhythmical delta activity (FIRDA) was blocked or reduced in most patients exhibiting this pattern. Epileptic conditions were also studied and it was found that, in a single observation, even the most difficult part of the test (item D: mental arithmetic) could be carried out during ictal-subclinical regional EEG activity.

Adult↗

PubMed1986

The use of plasma melatonin levels and light in the assessment and treatment of chronobiologic sleep and mood disorders.

Using the highly accurate and sensitive gas chromatographic-negative chemical ionization mass spectrometric assay for plasma melatonin we have measured plasma melatonin in humans as a biological marker for 24-hour (circadian) and seasonal rhythms and the effects of light on these rhythms. We propose that there are at least three critical parameters for light to be chronobiologically active in humans: intensity, wavelength and timing. With regard to timing, we have found that bright light exposure in the morning advances circadian rhythms (shifts them to an earlier time) and bright light in the evening delays them (shifts them to a later time). We have suggested that chronobiologic sleep and mood disorders be "phase typed" into either the phase advance subtype or the phase delayed subtype and that these disorders can then be treated with either evening light (for phase advanced disorders) or morning light (for phase delayed disorders). Regarding the function of melatonin in humans, we have preliminary evidence that it may participate in the regulation of the circadian rhythm of intraocular pressure.

Biological Clocks↗

PubMedDate not supplied

Parenteral magnesium sulfate fails to control electroshock and pentylenetetrazol seizures in mice.

Magnesium sulfate has been used as an anticonvulsant in the treatment of eclampsia, but efficacy of magnesium in other types of seizure disorders is poorly documented. We examined the effects of magnesium sulfate (MgSO4) on seizures produced in mice by maximal electroshock (MES) and pentylenetetrazol (PTZ), MgSO4 injection (6.7 mEq/kg i.p.) caused weakness in all animals. With suprathreshold electroshock, 10/10 controls and 11/12 treated animals had seizures with tonic hind limb extension (P = NS). Electroshock threshold was unaltered by magnesium treatment (n = 48; P = 0.47). PTZ induced clonic seizures in 12/12 controls and 5/14 treated animals (P less than 0.05). This difference was likely due to muscular weakness because frequency of EEG spikes was the same in PTZ and PTZ + MgSO4 groups. Mean serum magnesium levels were 2.3 +/- 0.3 mEq/l in animals not given MgSO4; 10.9 +/- 1.4 mEq/l and 12.8 +/- 2.2 mEq/l in treated animals with and without seizures (P = NS). We conclude that magnesium sulfate had no significant anticonvulsant activity in mouse MES and PTZ models for epilepsy. The relevance of these findings to the possible efficacy of magnesium sulfate in eclamptic seizures and other types of epilepsy remains to be determined.

Animals↗

PubMedDate not supplied

Placebo-controlled pilot study of centromedian thalamic stimulation in treatment of intractable seizures.

Stimulation of centromedian (CM) thalamic nuclei has been proposed as a treatment for seizures. We implanted programmable subcutaneous (s.c.) stimulators into CM bilaterally in 7 patients with intractable epilepsy to test feasibility and safety. Stimulation was on or off in 3-month blocks, with a 3-month washout period in a double-blind, cross-over protocol. Stimuli were delivered as 90-microseconds pulses at 65 pulses/s, 1 min of each 5 min for 2 h/day, with voltage set to half the sensory threshold. Stimulation was safe and well-tolerated, with a mean reduction of tonic-clonic seizure frequency of 30% with respect to baseline when stimulator was on versus a decrease of 8% when the stimulator was off. There was no improvement in total number of generalized seizures with stimulation, and treatment differences were not statistically significant. Stimulation at low intensity did not alter the EEG acutely, but high-intensity stimulation induced slow waves or 2-3 Hz spike-waves with ipsilateral frontal maximum. In an open-label follow-up segment with stimulator trains continuing for 24 h/day, 3 of 6 patients reported at least a 50% decrease in seizure frequency. There were no side effects. This pilot project demonstrated the feasibility of controlled study of thalamic stimulation in epilepsy, but further study will be needed to demonstrate efficacy.

Adolescent↗