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Biomedical subjects

A Pakalnis

Publications and source records attributed to A Pakalnis.

At least 37 records · Page 2Linked to original sources
PubMed1990

Auditory evoked potentials in vertebrobasilar transient ischemic attacks.

Brainstem auditory evoked potentials (BAEPs) are affected by stroke or migraine in the vertebrobasilar arterial system. Some studies have reported BAEP changes in vertebrobasilar transient ischemic attacks (TIAs), but others have shown no alterations. We recorded BAEPs in 35 patients with TIAs in the vertebrobasilar system who did not have a stroke, other neurologic disease or significant hearing loss. Thirty patients were recorded after resolution of symptoms, while five individuals still had some resolving signs or symptoms. TIA patients as a group had longer interpeak latencies, but I-III, III-V, and I-V latencies were not significantly longer than in controls. Wave V was significantly longer in latency and lower in amplitude in TIA patients, however. The patients whose TIAs had resolved at absolute and interpeak latencies were within normal limits, but three of five had interpeak latencies at or above three standard deviations beyond the normal mean in the still symptomatic group. One of these was later tested and found to be within normal limits. BAEPs after subsidence of symptoms may add little to the evaluation of vertebrobasilar ischemia, but further AEP analysis may show more definitive differences of diagnostic use. The occasional BAEP abnormality during the resolving transient ischemia supports the recently suggested continuum between ischemia and infarction in the vertebrobasilar territory.

Aged↗
PubMed1990

Brainstem auditory evoked responses in partial and generalized seizures.

This study presents clinical neurophysiologic evidence of altered upper brainstem function in patients with generalized epilepsy who do not otherwise differ clinically from the general population. While the differences in absolute latencies are not great enough to support the use of BAERs in routine evaluation, this data does support experimental studies implicating brainstem structures in the pathophysiology of primary generalized epilepsy. The lack of evidence of brainstem involvement in complex partial seizures may suggest a mechanism of seizure spread that is not dependent upon primary brainstem pathology, or may indicate that any brainstem abnormality in epilepsy may involve areas not mediating transmission of auditory stimuli and therefore not assessed by BAERs.

Adult↗
PubMed1990

Outpatient sleep recording during antiepileptic drug monotherapy.

The effects of sleep and sleep deprivation on epilepsy are well known, but the effects of seizures and antiepileptic drugs (AEDs) on sleep have been less well studied. We recorded nocturnal sleep in 17 patients receiving antiepileptic monotherapy with ambulatory cassette EEG devices. Twelve patients had complex partial seizures and five had tonic-clonic convulsions. Two patients' seizures were largely nocturnal, and no seizures occurred during sleep recording. Five patients each were taking phenytoin (PHT), carbamazepine (CBZ), and valproate (VPA), and two were taking clonazepam (CZP), all with therapeutic serum levels and no toxic symptoms. Total sleep time was reduced, wakefulness increased, and sleep latency prolonged in partial seizures as compared with generalized epilepsy. REM sleep was reduced and its latency decreased in partial seizure patients. Both groups had decreased slow wave sleep; that of partial seizure patients was decreased more markedly. PHT increased sleep latency and decreased sleep time, and CBZ increased awakening and diminished slow wave and REM sleep. Patients taking VPA had slight reduction in slow wave sleep; those taking CPZ had decreased sleep and REM latencies. Epilepsy may affect nocturnal sleep, and the effects of partial and generalized seizure disorders may be different. AEDs may also have differential effects on nighttime sleep. These may prove important in the long-term management of epileptic patients.

Adult↗
PubMed1990

Auditory evoked potentials in narcolepsy and sleep terrors.

Dysfunction of brainstem reticular activating centers has been suggested in some sleep disorders, including narcolepsy and sleep terrors. Previous studies have suggested normal brainstem auditory evoked potentials (BAEPs) in narcolepsy and enhancement of long-latency auditory event-related potentials (ERPs) in sleep deprivation and conditions of pathological somnolence. Sleep terrors have not to date been studied neurophysiologically. We recorded early latency BAEPs and long-latency auditory ERPs in 8 patients with narcolepsy and 5 individuals with sleep terrors, and compared them to 10 normal controls. Narcolepsy patients and controls did not differ significantly in absolute or interpeak latency of BAEPs. Sleep terror patients had significant prolongation relative to controls of III-V and I-V interpeak latencies. The N1, N2, and P3 AEP components were prolonged in latency in narcoleptic patients as compared to controls, while sleep terror patients did not differ from controls. No significant differences in amplitude were found. These findings suggest that a disturbance of integration of brainstem centers subserving wakefulness and sleep may play a role in the disordered arousal of sleep terrors, but suggest no specific abnormality in brainstem function in narcolepsy. The AEP changes in narcolepsy may be a manifestation of pathological sleepiness.

Adolescent↗
PubMed1990

Sleep and sleep deprived EEG in partial and generalized epilepsy.

Sleep and sleep deprivation are often used for EEG activation in epilepsy. We compared postprandial naps and day-long sleep deprived EEGs in 36 patients with generalized seizures, 57 complex partial seizure patients, and 7 individuals with mixed seizure disorders. Ten of 36 generalized seizure patients had normal sleep and sleep deprived EEGs, while both were normal in 16 of 57 partial seizure patients. Both were abnormal in 18 of 36 generalized and 22 of 57 partial epileptics. Seven generalized seizure patients had epileptiform discharges or seizures during afternoon naps but normal sleep deprived EEGs. No partial seizure patients had normal sleep deprived EEGs and abnormal nap, but 29 of 57 had abnormalities or seizures only with sleep deprivation. All 7 mixed seizure patients had abnormal sleep and sleep deprived studies, and 6 had seizures, 4 on both studies. Natural sleep may facilitate the appearance of generalized seizures or epilepti-form discharges, while sleep deprivation may accentuate the yield of EEG abnormality in partial epilepsy. Either is likely to be abnormal in patients with mixed seizures and encephalopathy. Natural sleep and sleep deprived EEGs are an appropriate combination in the evaluation of refractory seizures.

Adolescent↗
PubMed1989

Long-latency auditory event related potentials in migraine.

The pathophysiology of migraine and its associated perceptual symptoms remains controversial. We recorded long-latency auditory event related potentials (AEPs) in 30 unmedicated patients with common migraine, and compared them to 20 controls. 1,000 and 3,000 Hz tones were presented in an 80:20 ratio at 75 dB SL. 200 responses were recorded and replicated from Cz-A1 + A2, with filter band-pass of 1-100 Hz, analysis time of 1,000 ms., and interstimulus interval of 1.1 second. N100, P200, and N200 ERP components did not differ in latency or amplitude between migraine patients and controls. P300 was longer in latency among those with common migraine, and P300 amplitude was significantly reduced (P greater than 0.05). These findings suggest that migraine may have a central mechanism, and that migraineurs may have a difference in task involvement or perception which may influence their clinical course and response to therapy.

Adolescent↗
PubMed1989

Ambulatory cassette EEG in epilepsy evaluation.

The economy and effectiveness of 24-hour ambulatory cassette EEG (AEEG) are increasingly recognized. We reviewed 735 AEEGs recorded between 1983 and 1989. These findings suggest that AEEG may confirm the ictal original of attacks in patients with known epilepsy, and may improve the yield of abnormality in epileptics with normal interictal EEG. Focal slowing may be seen less well on AEEG, and the yield of AEEG is low in random sampling of patients with infrequent or nonspecific symptoms.

Ambulatory Care↗
PubMed1989

The effect of exercise on seizure frequency.

The effect of exercise on seizure frequency is uncertain. While some investigators have reported an increase in the normal background frequency of EEGs after exercise, other investigators believe that exercise increases EEG epileptiform activity in the recovery period following exercise. We asked all patients over a two month period at our outpatient Epilepsy Clinic to complete a questionnaire regarding their exercise habits. Those who were not otherwise healthy, were non-compliant with their medications, or whose blood levels were not therapeutic were eliminated from the analysis. Utilizing the complex Chi-square method, it was determined that patients who participated in some form of exercise had significantly fewer seizures than those who did not exercise (p less than 0.05). Conclusions from this brief study indicate the need for a more comprehensive trial, including EEGs, biochemical studies, and fitness evaluations, to determine the effects of an exercise program on seizure frequency.

Adult↗
PubMed1988

Effects of seizure type and waveform abnormality on memory and attention.

Deficits in memory, learning, and attention were examined in a sample of 57 patients admitted for investigation of intractable seizure disorder. The patients were grouped according to seizure type and nature of electroencephalographic abnormality. Patients with complex partial seizures were impaired in comparison with controls. Patients with spike-and-wave abnormalities were more impaired on some tests, while those with slow-wave abnormalities were impaired on other tests. These results suggest that, contrary to previous studies, patients with complex partial seizures have greater deficits than other seizure types in some areas of cognitive function.

Attention↗
PubMed1988

Evoked potentials in chronic inflammatory demyelinating polyneuropathy.

Eighteen patients with chronic inflammatory demyelinating polyneuropathy were studied with evoked potentials to assess for evidence of central nervous system demyelination. Both visual and brain-stem auditory evoked responses were obtained, and the results were compared with magnetic resonance imaging (MRI). An evoked potential was abnormal in nine of 18 patients, five of whom had central nervous system evidence of demyelination by MRI. Evoked potentials identified four patients with probable anterior optic pathway involvement that was not demonstrable by MRI. These findings continue to support that chronic inflammatory demyelinating polyneuropathy is associated with a central demyelinating disorder and more importantly emphasize the possibility of a common pathogenic mechanism in central and peripheral nerve demyelination.

Brain Stem↗
PubMed1988

Auditory event related potentials in violent and nonviolent prisoners.

The neurophysiologic substrates of violence and aggression have been extensively studied. Although the EEG is often normal in violent persons any abnormalities are generally nonspecific in nature. Evoked potentials have been infrequently used to study such behavior disorders. Long latency auditory event-related potentials (AEPs) were studied in prison inmates incarcerated for unmotivated violent crimes or violence during the commission of other crimes, and in prisoners jailed for non-violent offenses. Habitually violent inmates were compared with an equal number of non-violent prisoners and neurologically and audiologically intact controls. AEPs were recorded to an "oddball" paradigm from vertex and left and right temporal electrodes. None of the prisoners had latencies more than 3 standard deviations beyond the normal group mean. N1 and P2 components were longer in latency and lower in amplitude in prisoners than in controls, but this was not statistically significant. Violent and non-violent individuals did not differ in these measures. P3 was significantly prolonged in latency in violent inmates, but not in those who had committed a violent act. All components were longer in latency on the right in violent prisoners, while amplitudes were lower but not significantly so. This asymmetry was not present in non-violent prisoners or control subjects. Caution is needed in identifying differences between criminals and the general population, and in seeking markers of violent behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Magnetic resonance imaging and clinical correlations in multiple sclerosis.

We examined the relationship between magnetic resonance imaging (MRI) cerebral findings and clinical evaluations in 66 patients with clinically definite multiple sclerosis (MS). MRI observations included total number and location of lesions visualized, degree of periventricular involvement, degree of degeneration of the corpus callosum, and extent of generalized parenchymal atrophy. Overall physical disability was evaluated by the Kurtzke Expanded Disability Status Scale (EDSS) and individual symptoms were rated according to the Kurtzke Functional Systems (FS) scale. Our results suggest that MRI brain abnormalities are significantly related to the overall severity of disease, but MRI is not particularly useful to predict the presence or absence of individual symptoms. These findings do suggest that the MRI may provide useful information to monitor clinical progression of patients with MS, but the lesions visualized need not always be symptomatic nor are we sure that all symptomatic lesions, particularly in the spinal cord and optic nerves, will be visualized.

Adult↗
PubMed1988

EEG frequency analysis in conversion and somatoform disorder.

Patients with "hysterical" neurologic symptoms have long puzzled neurologists and psychiatrists. "Hysteria" has recently been subdivided into conversion and somatoform disorder. We applied computerized EEG frequency analysis to 10 patients with diagnosed conversion disorder, 10 somatoform disorder patients, and 10 control subjects. One minute EEG samples composed of 4 sec epochs were recorded from left frontal (F7-C3), right frontal (F8-C4), left posterior (T5-01) and right posterior (T6-02) derivations. Spectral power was calculated for 4 bands (0.25-4HZ, 4.25-8Hz, 8.25-13Hz, and 13.25-30Hz), and for the full frequency range. Low (0.25-8Hz) and high (8.25-30Hz) frequency bands were compared to determine high/low power ratios on the left and right (PHLL) and (PHLR), ratios of left/right front (PLRF) and posterior (PLRP) power, mean alpha frequency deviation frontally (FLRF) and posteriorly (FLRP), and mobility of left and right frontal power (MOLF and MORF). No significant differences were found between conversion disorder patients and controls in PHLL, PHLR, PLRP, and MORF. PLRF, FLRF and MOLF differed significantly between patients and controls. Power and frequency ratios of right frontal mobilities suggested a decrease in high frequency power, reduction in mean alpha frequency, and lower predominant frequency in the right frontal area in somatoform disorder patients as compared to controls, but significance was not reached. Somatoform and conversion disorder patients differed significantly in these spectral measures. These observations suggest that the two "hysterical" disorders may have distinct pathophysiology, and may be due to eventually identifiable cerebral dysfunction in some cases.

Adult↗
PubMed1987

Forced normalization. Acute psychosis after seizure control in seven patients.

An antagonistic relationship between psychosis and seizures has been described in some patients and is sometimes termed "forced normalization." We saw seven epileptic patients without a previous psychiatric history, who developed acute psychotic states on establishment of seizure control and normalization of previously abnormal electroencephalograms with frank epileptiform activity. A possible hypothetical relationship between psychosis and epilepsy regarding the mesolimbic dopaminergic system and kindling of this system with epileptic discharge in temporal-limbic circuits could induce a florid psychotic state in some patients. This biochemical relationship to schizophrenia with heightened dopamine activity would also easily explain the amelioration of acute psychotic activity in our seven patients with neuroleptic agents and their antagonism of this increased dopaminergic outflow state.

Adult↗
PubMed1987

Magnetic resonance imaging correlates of dementia in multiple sclerosis.

Thirty-two patients with clinically definite multiple sclerosis were evaluated with neuropsychological procedures and magnetic resonance imaging (MRI). Neuropsychological evaluation included assessment of language, memory, cognition, visuospatial skills, and depression. Significant impairment in any three areas, compatible with diagnosis of a dementia syndrome, was observed in 28% of these patients, and lesser or no cognitive impairment characterized the remaining patients. Magnetic resonance imaging was used to evaluate the number and distribution of lesions as well as the presence of cerebral atrophy and atrophy of specific anatomic structures such as the corpus callosum. Results suggest that neither the number of lesions, the distribution of lesions, nor the extent of generalized cerebral atrophy was significantly greater in demented compared with non-demented patients. The primary finding was that atrophy of the corpus callosum was significantly more extensive on MRI scans in demented patients. Although the callosum itself may not be implicated directly in the pathogenesis of dementia, the presence of callosal atrophy on MRI scans should alert the physician to the possible occurrence of dementia in patients with multiple sclerosis.

Adult↗
PubMed1987

Evoked potentials and EEG in multiple sclerosis.

Thirteen patients with clinically definite multiple sclerosis (MS) were studied with electroencephalogram (EEG), magnetic resonance imaging (MRI), evoked potentials and cerebrospinal fluid (CSF) analysis. We attempted to correlate the findings with physical disability as defined by Kurtzke score and presence of dementia or seizures. More severe plaque disease on MRI and increased physical disability correlated significantly with abnormality on brain-stem auditory evoked potentials (BAEPs) while visual evoked potential (VEP) abnormality correlated only with MRI findings. No such correlation was found with the EEG. The close relationship between BAEP and MRI abnormalities probably reflects frequent involvement of brain-stem corticospinal pathways.

Adult↗