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Biomedical subjects

A Pakalnis

Publications and source records attributed to A Pakalnis.

44 records · Page 3Linked to original sources
PubMed1987

Sleep and waking disturbances in epilepsy.

We compared sleep parameters during three-hour postprandial nap recordings in 10 normal controls and 28 seizure patients. Patients had significantly less sleep, longer sleep latency, more wakefulness, less drowsiness and lighter nonREM sleep, and lower sleep efficiency than controls. Generalized seizure patients had longer sleep latency, more arousals, and more (but very little) stage III sleep. Those with partial seizures had more stage II sleep and greater sleep efficiency. Patients on polypharmacy and phenobarbital therapy slept more, phenytoin patients had very short sleep latency but more wakefulness and less sleep efficiency; those taking clonazepam were also awake more and had lower sleep efficiency, while arousals during sleep were more frequent in patients on valproate and carbamazepine. The findings suggest that disturbed sleep, possibly related to aberrant arousal occasioned by generalized epilepsy or epileptogenic foci, is common in seizure patients, and may be related to interictal behavioral and cognitive symptoms. Polypharmacy may have an additive effect on sleep to prolong and disrupt it, while sedative anti-epileptic drugs may increase sleep and other anti-epileptic medications may have alerting effects or interfere with falling asleep. Generalized and partial seizure patients may have sleep disturbances of a different character, possibly reflecting generally altered cerebral excitability by afferent stimuli in the former situation, and the more localized effects of limbic or cortical hyperactivity in the latter.

Adolescent↗
PubMed1987

Spindle coma in viral encephalitis.

Our patient's EEG evolved from the spindle coma pattern to normality in parallel with his clinical improvement. This clinical and EEG evolution has been described previously, and emphasizes the heterogeneity of the spindle pattern. The initial focal asymmetry implied focal cerebral abnormality, and was one of the clinical findings favoring HSV encephalitis in the absence of radiologic or pathologic support. The ability of partially-damaged cerebral cortex to express spindle activity is well-described with various cerebral lesions, as is the spindle coma pattern after intoxication. We are not aware of a previous report with HSV or other encephalitis, but an infectious etiology could be suspected in two patients of Hansotia et al. and is conceivable in the three comatose patients of Britt in whom no diagnosis could be established. In such cases, the pathophysiology of the spindle coma pattern is likely to involve an aberrant cortical response to normal reticular formation input and thalamic spindle pacemakers.

Adolescent↗
PubMedDate not supplied

WAIS-R factor structure in epileptic patients.

The Wechsler Adult Intelligence Scale--Revised (WAIS-R), the newest version of the Wechsler Scales, has had several factor analytic studies, but none have been done in a sample of seizure-disorder patients. The factor structure of the WAIS-R was examined in this study in a sample of 107 patients with various seizure disorders. The results of this study revealed the 3-factor solution, as has been reported in many previous studies. The most notable difference was the relatively greater prominence of the Freedom from Distractibility factor. These results are consistent with studies of the factor structure of previous editions of the Wechsler Scales in samples of epileptic patients. The relative prominence of the Distractibility factor could suggest that attentional factors are a more important influence on performance than in other patient groups. Further studies are needed to clarify the effect of various seizure-related variables on patterns of intelligence.

Adolescent↗
PubMedDate not supplied

Central conduction time in progressive supranuclear palsy.

Progressive nuclear palsy (PSP) is a parkinson-like extrapyramidal disorder with pathological evidence of brain stem demyelination. We studied brain stem auditory (BAEP) and somatosensory (SSEP) evoked potentials in 8 patients with progressive supra-nuclear palsy to look for evidence of such central demyelination. We found minor alterations in BAEPs and frequently abnormal SSEPs, suggestive of brain stem white matter involvement in this disorder. Evoked potentials may assist in the differentiation of PSP from other parkinsonian conditions.

Aged↗
PubMedDate not supplied

Visual and auditory evoked potentials in migraine.

We recorded visual (VEP) and brainstem auditory (BAEP) evoked potentials in 50 patients with clinically diagnosed common migraine attended by visual obscuration or sensory symptoms but no neurologic deficit. VEPs were recorded from Oz, 01, and 02 referenced to Fz, with replication of 200 repetitions of 1.88 per second checkerboard stimuli subtending a 56 minute retinal arc. Analysis time was 250 ms., and filter band pass was 1-250 Hz. BAEPs utilized rarefaction stimulation at 70 dB SL, with 150-3,000 Hz filter band pass and 10 ms. analysis time. Two thousand averages were recorded and replicated from Cz-A1 and Cz-A2. VEP N1, P1 and N2 latencies were longer in migraine patients than in controls, and VEP amplitudes were minimally greater. No significant differences were found between patients and controls, however. BAEP I-V and III-V interpeak latencies were significantly prolonged in migraine patients, and the degree of prolongation was greater on the left. Neither VEPs nor BAEPs exceeded clinical norms in migraine patients. VEPs and BAEPs are likely to add little to the clinical assessment of headache patients. BAEP differences may indicate dysfunction of brainstem centers, possibly related to endorphin or serotonin neurotransmission, and possibly related to the pathogenesis of migraine. The left sided asymmetry has been described previously and is of uncertain significance, but may also support a central mechanism for migraine.

Adolescent↗
PubMedDate not supplied

Effect of anti-epileptic drug monotherapy and polypharmacy on visual and auditory evoked potentials.

Previous reports have suggested that some anticonvulsants may prolong somatosensory and auditory evoked potential latencies. We compared pattern-reversal visual and brainstem auditory evoked potentials in normal controls, patients on monotherapy, and patients taking polypharmacy. Visual evoked potential amplitudes were less in seizure patients, and P1 latencies were longer in epileptics on polypharmacy than controls. Absolute latencies of brainstem auditory evoked potentials were longer in polypharmacy patients than in controls or monotherapy patients. I-III, III-V, and I-V interpeak latencies were greater in polypharmacy patients than in those on monotherapy or controls. These findings suggest that anticonvulsants may affect conduction along visual and auditory pathways, and that antiepileptic drug polypharmacy and monotherapy may differ in their effects.

Adolescent↗