PubMed Health⌕ Search

Biomedical subjects

Peter W Kaplan

Publications and source records attributed to Peter W Kaplan.

At least 19 recordsLinked to original sources
PubMed2006

Clinical neurophysiologic monitoring and brain injury from cardiac arrest.

Electrophysiologic testing continues to play an important role in injury stratification and prognostication in patients who are comatose after cardiac arrest. As discussed previously, however, the adage about treating whole patients, not just the numbers, is relevant in this situation. EEG and SSEP can offer high specificity for discerning poor prognosis as long as they are applied to appropriate patient populations. As discussed previously, EEG and SSEP patterns change during the first hours to days after cardiac arrest and negative prognostic information should not be based solely on studies performed during the first 24 hours. Both electrophysiologic techniques also are susceptible to artifacts that may worsen the electrical patterns artificially and suggest a falsely poor prognosis. EEG is suppressed by anesthetic agents and hypothermia, both of which may produce ECS and burst suppression. Patients who experience respiratory arrest from a toxic ingestion of narcotics or barbiturates, in particular, may present with high-grade EEG patterns initially. Many patients also receive anesthetic medications at the time of tracheal intubation, which may linger beyond their normal half-life in patients who have hepatic or renal insufficiency or concurrent use of interacting medications. SSEP is much less susceptible to sedative anesthetic agents, but hypothermia is demonstrated to prolong evoked potential latencies. As therapeutic hypothermia becomes more common after cardiac arrest, the effect of temperature on electrophysiologic testing needs to be taken into account. The publications discussed previously also emphasize the need to adjust the prognostic value of electro-physiologic tests to the pretest probability of meaningful neurologic recovery in individual patients. Clearly, grade I EEG patterns and normal N20 potentials indicate a much better prognosis in patients who have a short du-ration of cardiac arrest, short duration of coma after resuscitation, and when the studies are performed within the first few days. In patients who remain in coma days after resuscitation and lack appropriate brainstem reflexes, however, even the most normal appearing electrophysiologic patterns do little to change the overall prognosis. Aside from prognostication, electrophysiologic testing holds great promise in defining the basic anatomy and physiology of coma emergence after cardiac arrest. In addition, quantitative EEG and automated evoked potentials have the potential to render these tools less subjective and arcane and more applicable for monitoring patients in the period during and immediately after resuscitation. Quantitative EEG also has great potential asa tool to define the time window for neuroprotective intervention and the means to track the response to such therapies in real time.

Brain↗
PubMed2006

Electrophysiological prognostication and brain injury from cardiac arrest.

Anoxic coma after cardiorespiratory arrest warrants precocious investigation to establish probable outcome. Electroencephalogram (EEG) may uncover subclinical seizures; EEG grades have provided accurate prognosis of poor and favorable outcomes, but are weakest in those patients in between. Somatosensory evoked potentials now have proven benefit in accurately establishing a poor outcome (death or persistent vegetative state) when cortical responses (N20) are absent. These studies are particularly helpful when clinical examination of coma, early on, might yield uncertain prognosis (i.e., when brain stem reflexes are present). Combining clinical examination with electrophysiology has increasingly yielded multimodality approaches to early prognostication of coma after cardiorespiratory arrest, with more recent studies using event-related and middle-latency potentials showing promise for distinguishing good outcome (to consciousness), from awake but vegetative states. Further studies are warranted for this multimodality approach which, hopefully, may yield more widespread practical use of these testing modalities.

Brain↗
PubMed2006

Evaluation of a novel EEG preamplifier.

SUMMARY: The authors performed initial clinical testing of a novel EEG transduction module (ETM), designed to record EEG signals from electrodes with high and unbalanced contact impedances. Twenty patients underwent two consecutive EEG studies. In the first, "experimental" study, electrodes were applied to an unprepared scalp, and the ETM performed initial signal transduction and pre-amplification. The second, "routine" EEG was acquired in the standard manner, with electrode contact impedances of 5 k Omega or less. Power spectral analysis was performed on all electrode signals from three experimental studies, and all studies were interpreted by three board-certified electro-encephalographers. Individual electrode impedances in the experimental studies ranged from 10 to 560 k Omega (mean 129 k Omega). Power spectra on 54 of 57 electrode signals analyzed were free of 60-Hz noise. The majority of experimental studies were technically adequate, and technical limitations were unrelated to the ETM. Interrater reliability of preparation-free and standard EEG interpretation was high. The ETM device is an effective "preparation-free" technology in the setting of a clinical EEG laboratory. It provided easily interpretable EEG signals free of 60-Hz noise, recorded from electrodes with high and unbalanced impedances placed on completely unprepared scalp with minimal electrode paste.

Adult↗
PubMed2006

Normal adult EEG and patterns of uncertain significance.

A thorough understanding of a normal EEG is critical in defining those patterns that are abnormal. Because EEG is unique in the ability to support a clinical diagnosis of epilepsy, epileptiform patterns merit careful consideration. Certain benign patterns maybe epileptiform, yet can occur in healthy individuals without epilepsy. Understanding normal EEG and the benign variants will help to minimize over-interpretation and possibly avoid overtreatment of patients during routine clinical practice.

Brain↗
PubMed2006

The EEG of status epilepticus.

SUMMARY: Gastaut noted that there are as many forms of status epilepticus (SE) as there are seizure types. The pleomorphic EEG patterns reflect this wide variety of clinical types. The different electroclinical types of status epilepticus share EEG characteristics including rhythmic activity, epileptiform discharges, and often a waxing and waning evolution. Gray zones of interpretation exist in the form of runs of epileptiform periodic discharges, typically of lower frequency, and lesser temporal variability. In diagnosing SE, clinical correlation and response to parenteral anti-epileptic drugs (AEDs) are of particular importance. Accurate diagnosis of electroclinical SE type is essential, because it determines prognosis and dictates the intensity of therapeutic management. Some patients with benign forms of SE may benefit from nonparenteral treatment, and be followed up clinically and by spot EEGs. Conversely, intensive care unit management with anesthesia and continuous monitoring, and parenteral AEDs may be required for refractory convulsive SE.

Brain Mapping↗
PubMed2006

Lithium-induced confusional states: nonconvulsive status epilepticus or triphasic encephalopathy?

Lithium therapy can cause a confusional state by direct toxicity, precipitation of nonconvulsive status epilepticus, or by interplay with other neuroleptic medications to produce neuroleptic malignant syndrome or serotonin syndrome. These conditions resemble each other clinically, but EEG may help differentiate among them. We reviewed the EEG patterns with triphasic waves or rhythmic delta activity in lithium toxic patients and discuss clinical and EEG differentiation among syndromes. Lithium toxicity poses significant diagnostic challenges from EEG and clinical perspectives.

Adult↗
PubMed2006

EEG monitoring in the intensive care unit.

EEG recording in the intensive care setting presents a number of technical challenges. It is essential to differentiate artifact from pathophysiologic EEG changes that would suggest encephalopathy, epileptiform activity, or seizures. There are particular patterns typical of deepening encephalopathy, as well as, coma patterns that have diagnostic and prognostic significance (e.g., spindle coma, alpha coma, burst suppression activity, and triphasic waves). Epileptiform patterns, including periodic lateralized epileptiform discharges (PLEDs), bilateral independent periodic lateralized epileptiform discharges (BIPLEDs), and generalized periodic epileptiform discharges (GPEDs), present particular challenges as there is a gray-zone between interictal patterns and the evolving (usually faster) patterns of nonconvulsive seizures. Accurate use of EEG in the intensive care unit requires optimal EEG technical expertise in performing the study, and appropriate interpretation by a trained electrophysiologist.

Coma↗
PubMed2005

The clinical features, diagnosis, and prognosis of nonconvulsive status epilepticus.

Nonconvulsive status epilepticus (NCSE) is a state of ongoing seizure activity for at least 30 minutes, with cognitive or behavioral changes, but without convulsive clinical manifestations. It requires EEG for confirmation. It has been categorized into groups having focal or generalized EEG epileptic activity; and by etiology and level of consciousness (which predict outcome). Points of contention include the evolving definition of what constitutes NCSE, various reasons for a delayed, missed, or misidentified diagnosis, and the optimal management of these conditions.

Anticonvulsants↗
PubMed2005

Gaze deviation from contralateral pseudoperiodic lateralized epileptiform discharges (PLEDs).

Pseudoperiodic lateralized epileptiform discharges (PLEDs) usually produce "negative" neurologic findings. This contrasts with seizures which typically induce cortical activation with "positive" clinical manifestations. Gaze preference may arise from ipsilateral frontal eye fields (FEFs) damage because of the unopposed action of an intact contralateral FEF. Epileptic nystagmus (EN) and gaze deviation (GD) can also occur with focal temporo-parieto-occipital or hemispheric seizures in awake or obtunded patients. A patient with old right frontal and parieto-temporal cerebral infarctions manifested leftward gaze preference and deviation (without nystagmus) while alert and talking. Digitized EEG demonstrated PLEDs at approximately 1 Hz over the right fronto-central region, without electrographic seizures. This report illustrates that PLEDs without seizures may excite frontal regions proximate to the FEFs to produce contraversive gaze preference in an awake patient, and discusses putative mechanisms. Gaze deviation, in this case, was the principal clinical feature of PLEDs.

Aged↗
PubMed2004

Reproductive health effects and teratogenicity of antiepileptic drugs.

Women with epilepsy are less likely to bear children than women in the general population, and although this reduced fertility can be attributed in part to effects of the disease itself, the effects of antiepileptic drugs (AEDs), including changes in reproductive endocrine function, are also a factor. Conversely, some AEDs interact with oral contraceptives and can increase the risk for contraceptive failure and unplanned pregnancy. Women with epilepsy also have elevated rates of congenital anomalies and major malformations in their offspring, for which exposure of the developing fetus to AEDs taken by the mother appears to be responsible. In utero exposure to some AEDs may also be associated with increased risk for impaired cognitive function in the growing child. Clearly, possible long-term effects on reproductive health and pregnancy outcomes require careful attention when AED therapy is being considered for a patient with childbearing potential. Moreover, because AEDs are increasingly being used in therapy for other conditions such as migraine, bipolar disorder, and pain, it is not only the treatment of women with epilepsy that will be affected by these concerns.

Abnormalities, Drug-Induced↗
PubMed2004

Updates on the treatment of epilepsy in women.

Epilepsy is a condition of the central nervous system that is characterized by recurrent seizures. The goal of management is to make patients seizure free without intolerable adverse effects from treatment. Men and women differ in their physiologic makeup and therefore have different needs that must be considered when attempting to attain this goal. There are special concerns for women of child-bearing years with regard to contraception, pregnancy, and teratogenicity that should be considered during counseling and selection of appropriate treatment. There are also emerging concerns about the interaction of antiepileptic drugs and endocrine function that can affect ovarian function, induce polycystic ovary (PCO)-like syndrome, and threaten fertility. Systemic adverse effects can have a negative impact on weight, cosmetic appearance, sexual function, and bone health. Individualized treatment coupling antiepileptic drug use and the specific phase of impact of the reproductive cycle must be considered in treatment selection. Important concerns regarding long-term therapy are being raised as there are more treatment options to consider because of the plethora of new antiepileptic drugs that are available, often with more favorable pharmacokinetics and different adverse event profiles. Also, sex hormone fluctuations during maturation may exacerbate seizures at particular points during the life cycle for women, including menarche, during menses, during pregnancy, or later in the perimenopausal years, often presenting a uniquely challenging aspect to treatment. As the number of available treatment options for epilepsy increases, the optimal goal for primary care physicians is to work as a team with obstetricians, gynecologists, and neurologists in an effort to ensure the best treatment of women with epilepsy.

Anticonvulsants↗
PubMed2004

Neurologic aspects of eclampsia.

Eclampsia continues to be a significant cause of maternal and fetal death throughout the world. Neurologists have a specific role to play in the diagnosis and management of patients who have eclampsia, especially those who have recurrent seizures, raised intracranial pressure, and coma. Postpartum patients may be admitted to a neurology service when they present to the emergency department with seizures. The cornerstone of treatment has been blood pressure control and magnesium sulfate with its antivasospastic effect. Should this fail, antiepileptic drugs of proved efficacy, such as diazepam and phenytoin, can be used. Recent studies reveal genetic and mitochondrial defects in eclampsia, but further investigation is warranted to determine the complex underlying pathophysiologic interplay and the optimum prophylactic and therapeutic management.

Brain↗