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Journal of Clinical EEG & Neuroscience, July, 2007Table of Contents
Recognizing a Mothers Voice in the Persistent Vegetative StateABSTRACT We studied an 8-year-old boy after a near-drowning left him in a vegetative state (VS) for 4 years before the study. Findings fulfilled all clinical criteria for the diagnosis of VS. The purpose of this study was to investigate whether there was significant differential activation of the brain in response to hearing his mother’s voice compared with the voices of unknown women. The data were assessed using quantitative electric tomography (QEEGt), a technique that combines anatomical information of the brain by MRI with EEG patterns to estimate the sources of the EEG within the brain. We found significant differences for EEG frequencies from 14-58 Hz, with a peak at 33.2 Hz (gamma band). The 3D reconstruction showed that these statistical differences were localized in the lateral and posterior regions of the left hemisphere. No significant differences were found between unknown women vs. basal conditions. These results demonstrate recognition of the mother’s voice and indicate high-level residual linguistic processing in a patient meeting clinical criteria for VS. These findings launch new ethical and practical implications for the management of VS patients. Reduced Axon Number in Juvenile Myoclonic Epilepsy Demonstrated by Motor Unit Number Estimation AnalysisABSTRACT Some conventional and quantitative EMG studies have already demonstrated a subclinical lower motor neuron involvement in juvenile myoclonic epilepsy (JME). Our aim was to investigate this subclinical involvement by using motor unit number estimation (MUNE) analysis with modified McComas’ technique. We enrolled 75 consecutive JME patients and 26 normal controls. All subjects underwent motor and sensory nerve conduction studies, concentric needle EMG and MUNE analysis of the M. abductor pollicis brevis (APB) and M. tibialis anterior (TA). The clinical and EEG findings were evaluated to correlate with MUNE values. MUNE values of the APB (54±25) and TA (35±17) muscles were significantly lower in the JME group (p<0.001) when compared to the normal controls (109±24 and 80±26 for APB and TA muscles, respectively). Our findings show that anterior horn cells were subclinically affected in some JME patients, suggesting a shared background for both JME phenotype and grey matter disorganization in spinal cord. Transforming Electrocortical Mapping Data into Standardized Common SpaceABSTRACT Subdural grid electrodes are implanted routinely for the pre-surgical work up of epilepsy. While different approaches are available, many centers, including ours, visualize electrode locations by co-registering pre-operative 3-D MR images with post-implantation 3-D CT images. This method allows the determination of the electrode positions in relation to the individual patient’s anatomy, but does not easily allow comparison across patients. The goal of this study was to develop and validate a method for transforming electrode positions derived from 3-D CT images into standardized space. We analyzed data from twelve patients with subdurally implanted electrodes. Volumetric CT and MRI images were co-registered and then normalized into common stereotactic space. Electrode locations were verified statistically by comparing distances between the anterior commissure and a representative sampling of 8 electrode sites per patient. Results confirm the accuracy of our co-registration method for comparing electrode locations across patients. The Prognostic Significance of Interictal Epileptiform Activity in Postoperative EEGs of Patients with Mesial Temporal Lobe EpilepsyABSTRACT It has not been established whether electroencephalography (EEG) is a contributing factor in predicting the outcome of surgery for epilepsy. We conducted a prospective study on 26 patients (M/F 14/12, age: 33 ± 7.5 years, range 19-48) with mesial temporal lobe epilepsy (MTLE) who were followed for 2 years after surgery and who underwent routine EEG recordings 5.6 ± 3 months (range 3-12) postoperatively. Interictal epileptiform activity (IEA) on the EEG was compared in 17 seizure-free patients to 9 patients with recurrent seizures. The two groups were similar in gender, age, febrile convulsions, trauma, family history, seizure frequency prior to surgery, epilepsy duration and number of antiepileptic drugs. Following surgery, 17 study patients (65%) became seizure free; 9 (35%) had seizure recurrence. Postoperative EEG recordings showed IEA in 8/26 study patients (31%), 3 of whom were from the seizure-free group (3/17, 18%); 5 had seizure recurrence (5/9, 56%) (p=0.078). IEAs in postoperative EEGs were less frequently demonstrated in patients who were seizure free, but the presence of postoperative IEAs does not preclude successful surgical outcome. Gender Specific Processing of Eye Contact Within the Human Medial Temporal LobeABSTRACT Eye contact is a powerful social stimulus for human and non-human primates. However, it is unclear whether brain mechanisms that interpret eye contact are sensitive to gender. Here we show that human brain responses to eye contact are indeed gender specific. Recording event-related potentials directly from the medial temporal lobes, we found that eye contact elicited specific responses in men only when they saw female faces. Conversely, women responded specifically to eye contact only when they saw pictures of men. Thus, the human medial temporal lobes subserve specifically the processing of eye contact with persons of the opposite gender. nCPAP Treatment of Obstructive Sleep Apnea Increases Slow Wave Sleep in Prefrontal EEGABSTRACT According to standard sleep stage scoring, sleep EEG is studied from the central area of parietal lobes. However, slow wave sleep (SWS) has been found to be more powerful in frontal areas in healthy subjects. Obstructive sleep apnea syndrome (OSAS) patients often suffer from functional disturbances in prefrontal lobes. We studied the effects of nasal Continuous Positive Airway Pressure (nCPAP) treatment on sleep EEG, and especially on SWS, in left prefrontal and central locations in 12 mild to moderate OSAS patients. Sleep EEG was recorded by polysomnography before treatment and after a 3 month nCPAP treatment period. Recordings were classified into sleep stages. No difference was found in SWS by central sleep stage scoring after the nCPAP treatment period, but in the prefrontal lobe all night S3 sleep stage increased during treatment. Furthermore, prefrontal SWS increased in the second and decreased in the fourth NREM period. There was more SWS in prefrontal areas both before and after nCPAP treatment, and SWS increased significantly more in prefrontal than central areas during treatment. Regarding only central sleep stage scoring, nCPAP treatment did not increase SWS significantly. Frontopolar recording of sleep EEG is useful in addition to central recordings in order to better evaluate the results of nCPAP treatment. QEEG Prognostic Value in Acute StrokeABSTRACT The objective of our study is to determine the predictive value of QEEG in patients suffering from an acute ischemic cerebral stroke. Twenty-eight patients were studied within the first 72 hours of clinical evolution of middle cerebral artery territory ischemic stroke. Thirty-seven QEEG recordings were obtained: 13 in the first 24 hours after cerebral stroke onset, 9 between 24-48 hours and 15 between 48-72 hours. Absolute Energies (AE) were the QEEG selected variables for statistical analysis: first, AE Z values were calculated using the Cuban QEEG norms, then the maximum and minimum AE Z values were selected within each frequency band and total power. The medians of the five neighboring Z values were also chosen. Regression models were estimated using the RANKIN scores as dependent variables and the selected QEEG variables as independent, then outcome predictions at hospital discharge and 3 months later were calculated. Percentages of concordance and errors between the estimated and real outcome scores were obtained. Alpha and theta AE were the best predictor for short-term outcome and delta AE for long-term outcome. We conclude that QEEG performed within the first 72 hours of ischemic stroke might be a powerful tool predicting short- and long-term outcome. Source Localization of Triphasic Waves: Implications for the Pathophysiological MechanismABSTRACT To investigate the current source location from the electroencephalograms (EEGs) of 12 patients who showed typical triphasic waves attributable to various causes, using the combination of a dipole source model and a distributed source model. The triphasic waves were explained by a single main dipole in 10 of the 12 patients, and 2 patients had two dipoles responsible for the triphasic waves. All the main dipoles had a radial orientation with respect to the frontal pole. The current density of the triphasic waves was distributed mainly in the bilateral medial frontal regions along the cingulate cortices. These findings suggest that current sources located in the medial frontal area are crucial for generating triphasic waves. The source localization may be useful for elucidating the pathophysiologic mechanism of generalized non-epileptic EEG activities, such as triphasic waves. Scalp-Recorded Auditory P300 Event-Related Potentials in New-Onset Untreated Temporal Lobe EpilepsyABSTRACT To investigate the current source location from the electroencephalograms (EEGs) of 12 patients who showed typical triphasic waves attributable to various causes, using the combination of a dipole source model and a distributed source model. The triphasic waves were explained by a single main dipole in 10 of the 12 patients, and 2 patients had two dipoles responsible for the triphasic waves. All the main dipoles had a radial orientation with respect to the frontal pole. The current density of the triphasic waves was distributed mainly in the bilateral medial frontal regions along the cingulate cortices. These findings suggest that current sources located in the medial frontal area are crucial for generating triphasic waves. The source localization may be useful for elucidating the pathophysiologic mechanism of generalized non-epileptic EEG activities, such as triphasic waves. Scalp-Recorded Auditory P300 Event-Related Potentials in New-Onset Untreated Temporal Lobe EpilepsyABSTRACT We studied scalp-recorded auditory event-related potentials (ERPs) of 30 untreated patients with new-onset temporal lobe epilepsy and 30 age- and sex-matched normal controls. This study was designed to eliminate the effects of intractability of seizures and chronic use of antiepileptic drugs on P300 auditory ERPs. There were no statistically significant differences in both latency and amplitude of P300 between the two groups. Similar methods were also used to analyze component latencies and amplitudes of ERPs of 9 patients who had hippocampal sclerosis with comparison to control subjects. There were no statistically significant differences between these two groups as well. Our study evidently does not support temporal lobe sources of P300 scalp-recorded auditory ERPs. We also conclude that the scalp-recorded auditory ERPs procedure is not a useful tool to evaluate temporal lobe epilepsy. Complex Partial Status Epilepticus in Paraneoplastic Limbic EncephalitisABSTRACT Paraneoplastic limbic encephalitis (PLE) results from tumor-related autoimmune mediated inflammation and degeneration of the mesial temporal structures. Cognitive and behavioral changes and seizures occur in PLE. Seizures are an uncommon presenting symptom of PLE occurring in 6 of 50 patients in one series. We present a report of complex partial status epilepticus (CPSE) as the presentation of PLE with anti-neuronal antibodies and improvement in mental status following treatment of seizures. Multimodality Imaging in a Depressed Patient With Violent Behavior and Temporal Lobe SeizuresABSTRACT Patients suffering from epilepsy commonly experience behavioral symptoms. Behavioral manifestations are especially prevalent in patients with seizures originating in the limbic system. This case report illustrates how an objective, multimodality work-up can guide the clinician in the diagnosis and the treatment of a patient with a complex presentation. After the discontinuation of some medications, the patient underwent a multimodality work-up that consisted of MRI, SPECT, and conventional and quantitative EEG (LORETA). In this case, the functional imaging studies showed a convergence of findings across the three modalities: MRI, SPECT and qEEG. Because of these findings, we supported more aggressive treatment of the seizure disorder. Ultimately this treatment resulted in resolution of the aggression and the depression. In summary, when applied routinely, a comprehensive, systematic, diagnostic approach will minimize treatment false starts and failures, may reduce costs, and also, potentially decrease the severity and the duration of symptoms. |
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