Ronald Emerson | Weill Cornell Medicine (original) (raw)

Papers by Ronald Emerson

Electroencephalography and Clinical Neurophysiology, 1997

Neurology, Jan 9, 2015

To determine whether resection of areas with evidence of intense, synchronized neural firing duri... more To determine whether resection of areas with evidence of intense, synchronized neural firing during seizures is an accurate indicator of postoperative outcome. Channels meeting phase-locked high gamma (PLHG) criteria were identified retrospectively from intracranial EEG recordings (102 seizures, 46 implantations, 45 patients). Extent of removal of both the seizure onset zone (SOZ) and PLHG was correlated with seizure outcome, classified as good (Engel class I or II, n = 32) or poor (Engel class III or IV, n = 13). Patients with good outcomes had significantly greater proportions of both SOZ and the first 4 (early) PLHG sites resected. Improved outcome classification was noted with early PLHG, as measured by the area under the receiver operating characteristic curves (PLHG 0.79, SOZ 0.68) and by odds ratios for resections including at least 75% of sites identified by each measure (PLHG 9.7 [95% CI: 2.3-41.5], SOZ 5.3 [95% CI: 1.2-23.3]). Among patients with resection of at least 75% ...

Journal of mathematical neuroscience, 2015

Measurements of neuronal signals during human seizure activity and evoked epileptic activity in e... more Measurements of neuronal signals during human seizure activity and evoked epileptic activity in experimental models suggest that, in these pathological states, the individual nerve cells experience an activity driven depolarization block, i.e. they saturate. We examined the effect of such a saturation in the Wilson-Cowan formalism by adapting the nonlinear activation function; we substituted the commonly applied sigmoid for a Gaussian function. We discuss experimental recordings during a seizure that support this substitution. Next we perform a bifurcation analysis on the Wilson-Cowan model with a Gaussian activation function. The main effect is an additional stable equilibrium with high excitatory and low inhibitory activity. Analysis of coupled local networks then shows that such high activity can stay localized or spread. Specifically, in a spatial continuum we show a wavefront with inhibition leading followed by excitatory activity. We relate our model simulations to observation...

Clinical Neurophysiology, 2003

Objective: To examine the effects of volume conduction of current on measurements of spatial corr... more Objective: To examine the effects of volume conduction of current on measurements of spatial correlation in the high-density electroencephalogram (EEG) at extremes of human development: infancy and adulthood.Methods: To calculate theoretical spatial correlation of EEG from volume conduction of uncorrelated cortical sources and compare theory with observations of intra/interhemispheric coherence.Results: Result verified prediction of reduced spatial correlation in infants due

Current Neurology and Neuroscience Reports, 2006

Although the ability of magnetoencephalography (MEG) to detect epileptiform discharges noninvasiv... more Although the ability of magnetoencephalography (MEG) to detect epileptiform discharges noninvasively has long been known, only recently has it become a common tool in clinical settings. Whether MEG or electroencephalography (EEG) is superior has been controversial; MEG has a theoretic edge over EEG for precise localization, but EEG has many practical advantages. Experience has shown that they often provide different

Neurosurgery, 2009

Detailed investigations of cortical physiology require the ability to record brain electrical act... more Detailed investigations of cortical physiology require the ability to record brain electrical activity at a submillimeter scale. Standard intracranial electrodes result in significant averaging of potentials generated by large numbers of neurons. In contrast, microelectrode arrays allow for recording of local field potentials and single-unit activity. We describe our initial surgical experience with the NeuroPort microelectrode array (Cyberkinetics Neurotechnology Systems, Inc., Salt Lake City, UT) in a series of patients undergoing subdural electrode implantation for epilepsy monitoring. Seven patients were implanted with and underwent semichronic recording from the NeuroPort array during standard subdural electrode monitoring for epilepsy. The electrode was placed according to company specifications in putative noneloquent epileptogenic cortex. After the monitoring period, microelectrode arrays were removed during explantation of subdural electrodes and resection of epileptogenic tissue. Successful implantation of the microelectrode array was achieved in all patients, with minor operative difficulties. Robust and durable local field potentials and single-unit recordings were obtained from all implanted individuals. Implantation times ranged from 3 to 28 days; histological analysis of implanted tissue demonstrated no significant tissue injury or inflammatory response. There were no neurological complications or infections associated with electrode implantation or prolonged monitoring. Two patients developed postresection issues with wound healing at the site of scalp egress, with 1 requiring operative wound revision. Our experience demonstrates that semichronic microelectroencephalographic recording can be safely and effectively achieved using the NeuroPort microarray. Although significant tissue injury, infection, or cerebrospinal fluid leak was not encountered, the large profile of the connection pedestal resulted in suboptimal wound closure and healing in several patients. We predict that this problem will be easily addressed in second-generation devices.

Archives of Neurology, 2008

To determine the prevalence, predictors, and clinical significance of electrographic seizures (ES... more To determine the prevalence, predictors, and clinical significance of electrographic seizures (ESz) and other continuous electroencephalographic monitoring findings in critically ill patients with central nervous system infections.

Journal of child neurology, 2008

In this study, we examine the long-term clinical outcome of children with symptomatic infantile s... more In this study, we examine the long-term clinical outcome of children with symptomatic infantile spasm. The children between 2 and 18 years of age diagnosed with symptomatic infantile spasms were reviewed. Sixty-eight children (age range, 2-13 years; mean, 4.5 years) met the inclusion criteria. Children who underwent epilepsy surgery were excluded. Age of onset for infantile spasms ranged from 1 to 24 months (mean, 7.1 months). Developmental delay was noted in all; there was seizure freedom in 14 children (20.5%). Infantile spasms were reported as the only seizure type in 10 (14.5%) children older than age 2 years. During the follow-up; symptomatic generalized epilepsy was diagnosed in 23 children (34%) and focal epilepsy in 21 (31%). The long-term outcome of these children remains unchanged in the majority of the children with symptomatic infantile spasms. We could not establish any risk factor that might be related to favorable or adverse outcome.

Frontiers in human neuroscience, 2013

It has been well established in animal models that electrical fields generated during inter-ictal... more It has been well established in animal models that electrical fields generated during inter-ictal and ictal discharges are strong enough in intensity to influence action potential firing threshold and synchronization. We discuss recently published data from microelectrode array recordings of human neocortical seizures and speculate about the possible role of field effects in neuronal synchronization. We have identified two distinct seizure territories that cannot be easily distinguished by traditional EEG analysis. The ictal core exhibits synchronized neuronal burst firing, while the surrounding ictal penumbra exhibits asynchronous and relatively sparse neuronal activity. In the ictal core large amplitude rhythmic ictal discharges produce large electric fields that correspond with highly synchronous neuronal firing. In the penumbra rhythmic ictal discharges are smaller in amplitude, but large enough to influence spike timing, yet neuronal synchrony is not observed. These in homine o...

Frontiers in Human Neuroscience, 2008

Journal of Clinical Monitoring and Computing, 2015

Frontiers in Human Neuroscience - FRONT HUM NEUROSCI, 2008

Neurosurgery, 2002

Although in-hospital seizures have been reported for 3 to 24% of patients with aneurysmal subarac... more Although in-hospital seizures have been reported for 3 to 24% of patients with aneurysmal subarachnoid hemorrhage (SAH), nonconvulsive status epilepticus (NCSE) has not been previously described. We sought to determine the frequency and clinical features of NCSE among comatose patients with SAH. Between November 1997 and February 2000, we performed continuous electroencephalographic (cEEG) monitoring for at least 24 hours for all patients with aneurysmal SAH who were treated in our neurological intensive care unit and exhibited unexplained coma or neurological deterioration. NCSE was diagnosed when cEEG monitoring demonstrated continuous or repetitive electrographic seizures exceeding 1 hour in duration. Refractory NCSE was treated aggressively with intravenous anticonvulsant administration and continuous-infusion midazolam therapy. Of 233 patients with SAH who survived the first 48 hours of hospitalization, 101 were stuporous or comatose at some point during their hospitalization. Twenty-six of those patients underwent cEEG monitoring, and eight were diagnosed as having NCSE, an average of 18 days (range, 5-38 d) after SAH. All eight patients were receiving prophylactic anticonvulsant therapy. Four patients were persistently comatose and four demonstrated deterioration to stupor or coma; only one exhibited overt tonicoclonic activity. A worst Hunt and Hess grade of IV or V, older age, ventricular drainage, and cerebral edema on computed tomographic scans were identified as risk factors for NCSE (all P < 0.01). NCSE was successfully terminated for five patients (63%), but only one experienced clinical improvement, which was transient; all eight patients eventually died after a period of prolonged coma. cEEG monitoring detected NCSE for 8% of patients with SAH and otherwise unexplained coma or neurological deterioration. The seizures were highly refractory to therapy, and the prognosis for these patients was extremely poor. Routine postoperative cEEG monitoring of patients with SAH who are at high risk for NCSE, allowing earlier diagnosis and treatment, offers the best chance of improving the outcomes for patients with this disorder.

Neurology, 2007

http://www.neurology.org/cgi/content/full/69/13/1356 located on the World Wide Web at:

NeuroImage, 2007

Abnormally strong functional linkage between cortical areas has been postulated to play a role in... more Abnormally strong functional linkage between cortical areas has been postulated to play a role in the pathogenesis of partial epilepsy. We explore the possibility that such linkages may be manifest in the interictal EEG apart from epileptiform disturbances or visually evident focal abnormalities. We analyzed samples of interictal intracranial EEG (ICEEG) recorded from subdural grids in nine patients with medically intractable partial epilepsy, measuring interelectrode synchrony using the mean phase coherence algorithm. This analysis revealed areas of elevated local synchrony, or "hypersynchrony" which had persistent spatiotemporal characteristics that were unique to each patient. Measuring local synchrony in a subdural grid results in a map of the cortical surface that provides information not visually apparent on either EEG or structural imaging. We explore the relationship of hypersynchronous areas to the clinical evidence of seizure localization in each case, and speculate that local hypersynchrony may be a marker of epileptogenic cortex, and may prove to be a valuable aid to clinical ICEEG interpretation.

Neurocritical Care, 2006

Predicting outcome in patients with poor-grade subarachnoid hemorrhage (SAH) may help guide thera... more Predicting outcome in patients with poor-grade subarachnoid hemorrhage (SAH) may help guide therapy and assist in family discussions. The objective of this study was to determine if continuous electroencephalogram (cEEG) monitoring results are predictive of 3-month outcome in critically ill patients with SAH. We prospectively studied 756 patients with SAH over a 7-year period. Functional outcome was assessed at 3 months with the modified Rankin Scale (mRS). Patients that underwent cEEG monitoring were retrospectively identified and EEG findings were collected. Multivariate logistic regression analysis was performed to identify EEG findings associated with poor outcome, defined as mRS 4 to 6 (dead or moderately to severely disabled). In 116 patients with SAH, cEEG monitoring and 3-month mRS were available. Of these patients, 88% had a Hunt & Hess grade of 3 or worse on admission. After controlling for age, Hunt & Hess grade, and presence of intraventricular hemorrhage on admission CT scan, poor outcome was associated with the absence of sleep architecture (80 versus 47%; odds ratio [OR] 4.3, 95%-confidence interval [CI] 1.1-17.2) and the presence of periodic lateralized epileptiform discharges (PLEDS) (91 versus 66% OR 18.8, 95%-CI 1.6-214.6). In addition, outcome was poor in all patients with absent EEG reactivity (n = 8), generalized periodic epileptiform discharges (n = 12), or bilateral independent PLEDs (n = 5), and in 92% (11 of 12) of patients with nonconvulsive status epilepticus. cEEG monitoring provides independent prognostic information in patients with poor-grade SAH, even after controlling for clinical and radiological findings. Unfavorable findings include periodic epileptiform discharges, electrographic status epilepticus, and the absence of sleep architecture.

Journal of Clinical Neurophysiology, 2005

FIGURE 2. Evolving LRDA: Lateralized rhythmic delta activity that evolves in morphology and frequ... more FIGURE 2. Evolving LRDA: Lateralized rhythmic delta activity that evolves in morphology and frequency. It begins as low-voltage, sharply contoured 1.5-Hz delta in the left parasagittal region, evolves to 3-Hz rhythmic delta, and then slows once again. FIGURE 3. LRDA-plus: LRDA with superimposed repetitive sharp waves (several marked with asterisks). 130 FIGURE 4. GPDs: One-per-second generalized periodic discharges.

Journal of Clinical Neurophysiology, 2005

Continuous EEG monitoring in the intensive care unit (ICU) is superficially similar to that which... more Continuous EEG monitoring in the intensive care unit (ICU) is superficially similar to that which occurs in the epilepsy monitoring unit, but it also presents unique technical challenges. ICU monitoring imposes an expectation of reliability on EEG recording equipment exceeding that which may be demanded by other settings; performance requirements may also differ. Reliable network connectivity between ICUs and other hospital locations is necessary, as is provision for off-site EEG review and display. Staffing should be adequate to support continuous recording, including performing hookups at off-hours. Selection of electrode number, type, and application method requires weighting of monitoring needs, nursing concerns, and imaging requirements.

Journal of Clinical Neurophysiology, 2003

Intraoperative electrophysiologic monitoring can diminish the risk of neurologic injury by enabli... more Intraoperative electrophysiologic monitoring can diminish the risk of neurologic injury by enabling the detection of injury at a time when it can be reversed or minimized. Although it is clear that in patients with cervical spine disease monitoring during surgery reduces the incidence of neurologic injury, almost no data are available regarding its utility in patients undergoing suboccipital decompression for Chiari I malformation. Patients with Chiari I malformation have caudal displacement of the cerebellar tonsils below the skull base, thereby creating a tight foramen magnum and cervical canal. Although the majority of pediatric neurosurgeons perform a bony decompression with duraplasty for symptomatic patients, there is much controversy regarding the amount of bony decompression required for clinical improvement and whether a duraplasty is essential. The authors therefore conducted a prospective, observational study using intraoperative brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials in pediatric patients undergoing suboccipital decompressions for Chiari I malformations to determine whether there were consistent changes in intraoperative BAEPs that could help the operating surgeon decide how extensive a decompression was needed in these patients, and whether changes in BAEPs or somatosensory evoked potentials occurred during operative positioning that could be modified to reduce the risk of neurologic injury.

Electroencephalography and Clinical Neurophysiology, 1997

Neurology, Jan 9, 2015

To determine whether resection of areas with evidence of intense, synchronized neural firing duri... more To determine whether resection of areas with evidence of intense, synchronized neural firing during seizures is an accurate indicator of postoperative outcome. Channels meeting phase-locked high gamma (PLHG) criteria were identified retrospectively from intracranial EEG recordings (102 seizures, 46 implantations, 45 patients). Extent of removal of both the seizure onset zone (SOZ) and PLHG was correlated with seizure outcome, classified as good (Engel class I or II, n = 32) or poor (Engel class III or IV, n = 13). Patients with good outcomes had significantly greater proportions of both SOZ and the first 4 (early) PLHG sites resected. Improved outcome classification was noted with early PLHG, as measured by the area under the receiver operating characteristic curves (PLHG 0.79, SOZ 0.68) and by odds ratios for resections including at least 75% of sites identified by each measure (PLHG 9.7 [95% CI: 2.3-41.5], SOZ 5.3 [95% CI: 1.2-23.3]). Among patients with resection of at least 75% ...

Journal of mathematical neuroscience, 2015

Measurements of neuronal signals during human seizure activity and evoked epileptic activity in e... more Measurements of neuronal signals during human seizure activity and evoked epileptic activity in experimental models suggest that, in these pathological states, the individual nerve cells experience an activity driven depolarization block, i.e. they saturate. We examined the effect of such a saturation in the Wilson-Cowan formalism by adapting the nonlinear activation function; we substituted the commonly applied sigmoid for a Gaussian function. We discuss experimental recordings during a seizure that support this substitution. Next we perform a bifurcation analysis on the Wilson-Cowan model with a Gaussian activation function. The main effect is an additional stable equilibrium with high excitatory and low inhibitory activity. Analysis of coupled local networks then shows that such high activity can stay localized or spread. Specifically, in a spatial continuum we show a wavefront with inhibition leading followed by excitatory activity. We relate our model simulations to observation...

Clinical Neurophysiology, 2003

Objective: To examine the effects of volume conduction of current on measurements of spatial corr... more Objective: To examine the effects of volume conduction of current on measurements of spatial correlation in the high-density electroencephalogram (EEG) at extremes of human development: infancy and adulthood.Methods: To calculate theoretical spatial correlation of EEG from volume conduction of uncorrelated cortical sources and compare theory with observations of intra/interhemispheric coherence.Results: Result verified prediction of reduced spatial correlation in infants due

Current Neurology and Neuroscience Reports, 2006

Although the ability of magnetoencephalography (MEG) to detect epileptiform discharges noninvasiv... more Although the ability of magnetoencephalography (MEG) to detect epileptiform discharges noninvasively has long been known, only recently has it become a common tool in clinical settings. Whether MEG or electroencephalography (EEG) is superior has been controversial; MEG has a theoretic edge over EEG for precise localization, but EEG has many practical advantages. Experience has shown that they often provide different

Neurosurgery, 2009

Detailed investigations of cortical physiology require the ability to record brain electrical act... more Detailed investigations of cortical physiology require the ability to record brain electrical activity at a submillimeter scale. Standard intracranial electrodes result in significant averaging of potentials generated by large numbers of neurons. In contrast, microelectrode arrays allow for recording of local field potentials and single-unit activity. We describe our initial surgical experience with the NeuroPort microelectrode array (Cyberkinetics Neurotechnology Systems, Inc., Salt Lake City, UT) in a series of patients undergoing subdural electrode implantation for epilepsy monitoring. Seven patients were implanted with and underwent semichronic recording from the NeuroPort array during standard subdural electrode monitoring for epilepsy. The electrode was placed according to company specifications in putative noneloquent epileptogenic cortex. After the monitoring period, microelectrode arrays were removed during explantation of subdural electrodes and resection of epileptogenic tissue. Successful implantation of the microelectrode array was achieved in all patients, with minor operative difficulties. Robust and durable local field potentials and single-unit recordings were obtained from all implanted individuals. Implantation times ranged from 3 to 28 days; histological analysis of implanted tissue demonstrated no significant tissue injury or inflammatory response. There were no neurological complications or infections associated with electrode implantation or prolonged monitoring. Two patients developed postresection issues with wound healing at the site of scalp egress, with 1 requiring operative wound revision. Our experience demonstrates that semichronic microelectroencephalographic recording can be safely and effectively achieved using the NeuroPort microarray. Although significant tissue injury, infection, or cerebrospinal fluid leak was not encountered, the large profile of the connection pedestal resulted in suboptimal wound closure and healing in several patients. We predict that this problem will be easily addressed in second-generation devices.

Archives of Neurology, 2008

To determine the prevalence, predictors, and clinical significance of electrographic seizures (ES... more To determine the prevalence, predictors, and clinical significance of electrographic seizures (ESz) and other continuous electroencephalographic monitoring findings in critically ill patients with central nervous system infections.

Journal of child neurology, 2008

In this study, we examine the long-term clinical outcome of children with symptomatic infantile s... more In this study, we examine the long-term clinical outcome of children with symptomatic infantile spasm. The children between 2 and 18 years of age diagnosed with symptomatic infantile spasms were reviewed. Sixty-eight children (age range, 2-13 years; mean, 4.5 years) met the inclusion criteria. Children who underwent epilepsy surgery were excluded. Age of onset for infantile spasms ranged from 1 to 24 months (mean, 7.1 months). Developmental delay was noted in all; there was seizure freedom in 14 children (20.5%). Infantile spasms were reported as the only seizure type in 10 (14.5%) children older than age 2 years. During the follow-up; symptomatic generalized epilepsy was diagnosed in 23 children (34%) and focal epilepsy in 21 (31%). The long-term outcome of these children remains unchanged in the majority of the children with symptomatic infantile spasms. We could not establish any risk factor that might be related to favorable or adverse outcome.

Frontiers in human neuroscience, 2013

It has been well established in animal models that electrical fields generated during inter-ictal... more It has been well established in animal models that electrical fields generated during inter-ictal and ictal discharges are strong enough in intensity to influence action potential firing threshold and synchronization. We discuss recently published data from microelectrode array recordings of human neocortical seizures and speculate about the possible role of field effects in neuronal synchronization. We have identified two distinct seizure territories that cannot be easily distinguished by traditional EEG analysis. The ictal core exhibits synchronized neuronal burst firing, while the surrounding ictal penumbra exhibits asynchronous and relatively sparse neuronal activity. In the ictal core large amplitude rhythmic ictal discharges produce large electric fields that correspond with highly synchronous neuronal firing. In the penumbra rhythmic ictal discharges are smaller in amplitude, but large enough to influence spike timing, yet neuronal synchrony is not observed. These in homine o...

Frontiers in Human Neuroscience, 2008

Journal of Clinical Monitoring and Computing, 2015

Frontiers in Human Neuroscience - FRONT HUM NEUROSCI, 2008

Neurosurgery, 2002

Although in-hospital seizures have been reported for 3 to 24% of patients with aneurysmal subarac... more Although in-hospital seizures have been reported for 3 to 24% of patients with aneurysmal subarachnoid hemorrhage (SAH), nonconvulsive status epilepticus (NCSE) has not been previously described. We sought to determine the frequency and clinical features of NCSE among comatose patients with SAH. Between November 1997 and February 2000, we performed continuous electroencephalographic (cEEG) monitoring for at least 24 hours for all patients with aneurysmal SAH who were treated in our neurological intensive care unit and exhibited unexplained coma or neurological deterioration. NCSE was diagnosed when cEEG monitoring demonstrated continuous or repetitive electrographic seizures exceeding 1 hour in duration. Refractory NCSE was treated aggressively with intravenous anticonvulsant administration and continuous-infusion midazolam therapy. Of 233 patients with SAH who survived the first 48 hours of hospitalization, 101 were stuporous or comatose at some point during their hospitalization. Twenty-six of those patients underwent cEEG monitoring, and eight were diagnosed as having NCSE, an average of 18 days (range, 5-38 d) after SAH. All eight patients were receiving prophylactic anticonvulsant therapy. Four patients were persistently comatose and four demonstrated deterioration to stupor or coma; only one exhibited overt tonicoclonic activity. A worst Hunt and Hess grade of IV or V, older age, ventricular drainage, and cerebral edema on computed tomographic scans were identified as risk factors for NCSE (all P < 0.01). NCSE was successfully terminated for five patients (63%), but only one experienced clinical improvement, which was transient; all eight patients eventually died after a period of prolonged coma. cEEG monitoring detected NCSE for 8% of patients with SAH and otherwise unexplained coma or neurological deterioration. The seizures were highly refractory to therapy, and the prognosis for these patients was extremely poor. Routine postoperative cEEG monitoring of patients with SAH who are at high risk for NCSE, allowing earlier diagnosis and treatment, offers the best chance of improving the outcomes for patients with this disorder.

Neurology, 2007

http://www.neurology.org/cgi/content/full/69/13/1356 located on the World Wide Web at:

NeuroImage, 2007

Abnormally strong functional linkage between cortical areas has been postulated to play a role in... more Abnormally strong functional linkage between cortical areas has been postulated to play a role in the pathogenesis of partial epilepsy. We explore the possibility that such linkages may be manifest in the interictal EEG apart from epileptiform disturbances or visually evident focal abnormalities. We analyzed samples of interictal intracranial EEG (ICEEG) recorded from subdural grids in nine patients with medically intractable partial epilepsy, measuring interelectrode synchrony using the mean phase coherence algorithm. This analysis revealed areas of elevated local synchrony, or "hypersynchrony" which had persistent spatiotemporal characteristics that were unique to each patient. Measuring local synchrony in a subdural grid results in a map of the cortical surface that provides information not visually apparent on either EEG or structural imaging. We explore the relationship of hypersynchronous areas to the clinical evidence of seizure localization in each case, and speculate that local hypersynchrony may be a marker of epileptogenic cortex, and may prove to be a valuable aid to clinical ICEEG interpretation.

Neurocritical Care, 2006

Predicting outcome in patients with poor-grade subarachnoid hemorrhage (SAH) may help guide thera... more Predicting outcome in patients with poor-grade subarachnoid hemorrhage (SAH) may help guide therapy and assist in family discussions. The objective of this study was to determine if continuous electroencephalogram (cEEG) monitoring results are predictive of 3-month outcome in critically ill patients with SAH. We prospectively studied 756 patients with SAH over a 7-year period. Functional outcome was assessed at 3 months with the modified Rankin Scale (mRS). Patients that underwent cEEG monitoring were retrospectively identified and EEG findings were collected. Multivariate logistic regression analysis was performed to identify EEG findings associated with poor outcome, defined as mRS 4 to 6 (dead or moderately to severely disabled). In 116 patients with SAH, cEEG monitoring and 3-month mRS were available. Of these patients, 88% had a Hunt & Hess grade of 3 or worse on admission. After controlling for age, Hunt & Hess grade, and presence of intraventricular hemorrhage on admission CT scan, poor outcome was associated with the absence of sleep architecture (80 versus 47%; odds ratio [OR] 4.3, 95%-confidence interval [CI] 1.1-17.2) and the presence of periodic lateralized epileptiform discharges (PLEDS) (91 versus 66% OR 18.8, 95%-CI 1.6-214.6). In addition, outcome was poor in all patients with absent EEG reactivity (n = 8), generalized periodic epileptiform discharges (n = 12), or bilateral independent PLEDs (n = 5), and in 92% (11 of 12) of patients with nonconvulsive status epilepticus. cEEG monitoring provides independent prognostic information in patients with poor-grade SAH, even after controlling for clinical and radiological findings. Unfavorable findings include periodic epileptiform discharges, electrographic status epilepticus, and the absence of sleep architecture.

Journal of Clinical Neurophysiology, 2005

FIGURE 2. Evolving LRDA: Lateralized rhythmic delta activity that evolves in morphology and frequ... more FIGURE 2. Evolving LRDA: Lateralized rhythmic delta activity that evolves in morphology and frequency. It begins as low-voltage, sharply contoured 1.5-Hz delta in the left parasagittal region, evolves to 3-Hz rhythmic delta, and then slows once again. FIGURE 3. LRDA-plus: LRDA with superimposed repetitive sharp waves (several marked with asterisks). 130 FIGURE 4. GPDs: One-per-second generalized periodic discharges.

Journal of Clinical Neurophysiology, 2005

Continuous EEG monitoring in the intensive care unit (ICU) is superficially similar to that which... more Continuous EEG monitoring in the intensive care unit (ICU) is superficially similar to that which occurs in the epilepsy monitoring unit, but it also presents unique technical challenges. ICU monitoring imposes an expectation of reliability on EEG recording equipment exceeding that which may be demanded by other settings; performance requirements may also differ. Reliable network connectivity between ICUs and other hospital locations is necessary, as is provision for off-site EEG review and display. Staffing should be adequate to support continuous recording, including performing hookups at off-hours. Selection of electrode number, type, and application method requires weighting of monitoring needs, nursing concerns, and imaging requirements.

Journal of Clinical Neurophysiology, 2003

Intraoperative electrophysiologic monitoring can diminish the risk of neurologic injury by enabli... more Intraoperative electrophysiologic monitoring can diminish the risk of neurologic injury by enabling the detection of injury at a time when it can be reversed or minimized. Although it is clear that in patients with cervical spine disease monitoring during surgery reduces the incidence of neurologic injury, almost no data are available regarding its utility in patients undergoing suboccipital decompression for Chiari I malformation. Patients with Chiari I malformation have caudal displacement of the cerebellar tonsils below the skull base, thereby creating a tight foramen magnum and cervical canal. Although the majority of pediatric neurosurgeons perform a bony decompression with duraplasty for symptomatic patients, there is much controversy regarding the amount of bony decompression required for clinical improvement and whether a duraplasty is essential. The authors therefore conducted a prospective, observational study using intraoperative brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials in pediatric patients undergoing suboccipital decompressions for Chiari I malformations to determine whether there were consistent changes in intraoperative BAEPs that could help the operating surgeon decide how extensive a decompression was needed in these patients, and whether changes in BAEPs or somatosensory evoked potentials occurred during operative positioning that could be modified to reduce the risk of neurologic injury.