Mark Quigg

A multicenter, prospective pilot study of gamma knife radiosurgery for mesial temporal lobe epilepsy: Seizure response, adverse events, and verbal memory

The safety, efficacy, and morbidity of radiosurgery (RS) must be established before it can be offered as an alternative to open surgery for unilateral mesial temporal lobe epilepsy. We report the 3‐year outcomes of a multicenter, prospective pilot study of RS.

Consensus Statement on Continuous EEG in Critically Ill Adults and Children, Part I: Indications

Introduction: Critical Care Continuous EEG (CCEEG) is a common procedure to monitor brain function in patients with altered mental status in intensive care units. There is significant variability in patient populations undergoing CCEEG and in technical specifications for CCEEG performance. Methods: The Critical Care Continuous EEG Task Force of the American Clinical Neurophysiology Society developed expert consensus recommendations on the use of CCEEG in critically ill adults and children. Recommendations: The consensus panel recommends CCEEG for diagnosis of nonconvulsive seizures, nonconvulsive status epilepticus, and other paroxysmal events, and for assessment of the efficacy of therapy for seizures and status epilepticus. The consensus panel suggests CCEEG for identification of ischemia in patients at high risk for cerebral ischemia; for assessment of level of consciousness in patients receiving intravenous sedation or pharmacologically induced coma; and for prognostication in patients after cardiac arrest. For each indication, the consensus panel describes the patient populations for which CCEEG is indicated, evidence supporting use of CCEEG, utility of video and quantitative EEG trends, suggested timing and duration of CCEEG, and suggested frequency of review and interpretation. Conclusion: CCEEG has an important role in detection of secondary injuries such as seizures and ischemia in critically ill adults and children with altered mental status.

Circadian rhythms: interactions with seizures and epilepsy

Circadian rhythms are endogenously-mediated 24 h cycles of behavioral or physiological activity. The interactions among the mammalian circadian clock, acute seizures, and chronic epilepsy are not well-characterized. Evidence suggests that seizures are susceptible to circadian modulation, and that this modulation varies with epilepsy syndrome and location of seizure foci. The circadian timing system and secondary circadian cycles of hormone secretion, sleep and wakefulness, and recurrent environmental factors are discussed as potential systems that effect spontaneous seizure recurrence. Experimental designs should take into account time-of-day effects on seizure threshold and occurrence. Further work is required to determine what mechanisms account for daily variation in seizure susceptibility.

Volumetric Magnetic Resonance Imaging Evidence of Bilateral Hippocampal Atrophy in Mesial Temporal Lobe Epilepsy

Summary: Purpose: We measured absolute volumes and volume differences of hippocampi in patients with mesial temporal lobe epilepsy (MTLE) using volumetric magnetic resonance imaging (MRI) to determine the extent of bilateral atrophy in MTLE and to relate hippocampal volumes (HV) to outcome of temporal lobectomy.

Depression in Intractable Partial Epilepsy Varies by Laterality of Focus and Surgery

Summary:  Purpose: Depression sometimes occurs after surgical treatment for medically intractable partial epilepsy. The risk of pre‐ and postsurgical depression may vary by laterality of seizure focus. We reviewed the pre‐ and postsurgical psychological assessments and clinical courses of patients to identify those at highest risk for postsurgical mood disorders.

Effects of circadian regulation and rest-activity state on spontaneous seizures in a rat model of limbic epilepsy.

Summary: Purpose: Circadian regulation via the suprachiasmatic nuclei and rest–activity state may influence expression of limbic seizures.

Predictors of efficacy after stereotactic radiosurgery for medial temporal lobe epilepsy

Background: Stereotactic radiosurgery (RS) is a promising treatment for intractable medial temporal lobe epilepsy (MTLE). However, the basis of its efficacy is not well understood. Methods: Thirty patients with MTLE were prospectively randomized to receive 20 or 24 Gy 50% isodose RS centered at the amygdala, 2 cm of the anterior hippocampus, and the parahippocampal gyrus. Posttreatment MRI was evaluated quantitatively for abnormal T2 hyperintensity and contrast enhancement, mass effect, and qualitatively for spectroscopic and diffusion changes. MRI findings were analyzed for potential association with radiation dose and seizure remission (Engel Ib or better outcome). Results: Despite highly standardized dose targeting, RS produced variable MRI alterations. In patients with multiple serial imaging, the appearance of vasogenic edema occurred approximately 9–12 months after RS and correlated with onset of seizure remission. Diffusion and spectroscopy-detected alterations were consistent with a mechanism of temporal lobe radiation injury mediated by local vascular insult and neuronal loss. The degree of these early alterations at the peak of radiographic response was dose-dependent and predicted long-term seizure remission in the third year of follow-up. Radiographic changes were not associated with neurocognitive impairments. Conclusions: Temporal lobe stereotactic radiosurgery resulted in significant seizure reduction in a delayed fashion which appeared to be well-correlated with structural and biochemical alterations observed on neuroimaging. Early detected changes may offer prognostic information for guiding management.

Consensus Statement on Continuous EEG in Critically Ill Adults and Children, Part II: Personnel, Technical Specifications and Clinical Practice

Introduction: Critical Care Continuous EEG (CCEEG) is a common procedure to monitor brain function in patients with altered mental status in intensive care units. There is significant variability in patient populations undergoing CCEEG and in technical specifications for CCEEG performance. Methods: The Critical Care Continuous EEG Task Force of the American Clinical Neurophysiology Society developed expert consensus recommendations on the use of CCEEG in critically ill adults and children. Recommendations: The consensus panel describes the qualifications and responsibilities of CCEEG personnel including neurodiagnostic technologists and interpreting physicians. The panel outlines required equipment for CCEEG, including electrodes, EEG machine and amplifier specifications, equipment for polygraphic data acquisition, EEG and video review machines, central monitoring equipment, and network, remote access, and data storage equipment. The consensus panel also describes how CCEEG should be acquired, reviewed and interpreted. The panel suggests methods for patient selection and triage; initiation of CCEEG; daily maintenance of CCEEG; electrode removal and infection control; quantitative EEG techniques; EEG and behavioral monitoring by non-physician personnel; review, interpretation, and reports; and data storage protocols. Conclusion: Recommended qualifications for CCEEG personnel and CCEEG technical specifications will facilitate standardization of this emerging technology.

Current practice in administration and clinical criteria of emergent EEG

Summary Policies of administration and availability of EEG offeredduring nonbusiness hours vary widely among EEG laboratories. The authorssurveyed medical directors of accredited EEG laboratories (n = 84) todetermine the ranges of availability and clinical indications for approval ofcontinuously available emergent EEG (E-EEG). Of 46 respondents, 37 (80%)offered E-EEG. Two centers recently lost funding for E-EEG. Availability wasnot associated with the total number of EEGs performed annually. The meanestimated response time from request to expert interpretation was 3 ± 4hours (range, 1–24 hours). The five clinical indications for which mostrespondents approved E-EEGs were possible nonconvulsive status epilepticus(100%), treatment of status epilepticus (84%), cerebral death exam (81%),diagnosis of convulsive status epilepticus (79%), and diagnosis of coma orencephalopathy (70%). Respondents disagreed widely when asked which clinicalsituations merited E-EEG, with some approving all requests and others denyingall except for nonconvulsive status epilepticus. The wide range of currentpractice suggests that research focused on outcomes of aggressive, EEG-aidedpatient evaluation and treatment are needed to define better the costs andbenefits of a continuously available EEGservice.

Quantification in patient urine samples of felbamate and three metabolites: acid carbamate and two mercapturic acids.

Summary: Purpose: Previously we proposed and provided evidence for the metabolic pathway of felbamate (FBM), which leads to the reactive metabolite, 3‐carbamoyl‐2‐phenylpropionaldehyde. This aldehyde carbamate was suggested to be the reactive intermediate in the oxidation of 2‐phenyl‐1,3‐propanediol monocarbamate to the major human metabolite 3‐carbamoyl‐2‐phenylpropionic acid. In addition, the aldehyde carbamate was found to undergo spontaneous elimination to 2‐phenylpropenal, commonly known as atropaldehyde. Moreover, atropaldehyde was proposed to play a role in the development of toxicity during FBM therapy. Evidence for atropaldehyde formation in vivo was reported with the identification of modified N‐acetyl‐cysteine conjugates of atropaldehyde in both human and rat urine after FBM administration. Identification of the atropaldehyde‐derived mercapturic acids in urine after FBM administration is consistent with the hypothesis that atropaldehyde is formed in vivo and that it reacts with thiol nucleophiles. Based on the hypothesis that the potential for toxicity will correlate to the amount of atropaldehyde formed, we sought to develop an analytic method that would quantify the amount of relevant metabolites excreted in patient urine.