Subclinical seizures common in neonates during cardiac surgery, linked to brain injury and mortality

TORONTO – Routine EEG monitoring after surgery with cardiopulmonary bypass in neonates revealed a seizure incidence of 8% in a recent study. In most cases (85%), seizure activity was detectable only on EEG and would not have been identified or treated without EEG monitoring, reported Dr. Maryam Y. Naim, a critical care pediatrician at the Children’s Hospital of Philadelphia, during the American Association for Thoracic Surgery Annual Meeting.

Of concern, status epilepticus was noted in 62% of neonates with seizures, and mortality was higher in babies with seizures versus those without (38% vs. 3%; P less than .01).

"Postoperative seizures are associated with worse neurological outcomes," said Dr. Naim. In addition to being a biomarker of underlying brain injury, there is some evidence that the seizures themselves may cause secondary brain injury.

The American Clinical Neurophysiology Society (ACNS) recommends routine EEG monitoring following infant cardiac surgery. The CHOP group implemented this recommendation and performed a quality improvement study to determine the incidence of seizures in neonates following surgery with cardiopulmonary bypass (CBP).

A total of 161 neonates had 48-hours of EEG monitoring initiated within 6 hours of cardiac surgery with CPB. The median gestational age of the cohort was 39 weeks, 16% were premature, and 13% had identified genetic defects. The median age at the time of surgery was 5 days. Deep hypothermic circulatory arrest was used in 48% of surgeries (median time, 48 minutes), 16% had open chest with delayed sternal closure, and 9% had a cardiac arrest.

Seizures were detected in 13 (8%), with a median onset of 20 hours after return to the cardiac ICU (CICU) from surgery. Seizures were subclinical, or EEG only, in 11 patients (85%), electroclinical in the other 2 (15%), and status epilepticus was seen in 8 (62%).

When seizures occurred, the CICU team was notified by the EEG technologist, neurology consult was obtained, and the patient was treated with antiseizure medications. As well, abnormal vital signs or movements suggestive of seizure activity were noted at the bedside; although such events were recorded in 32 patients (22%), none had EEG correlates consistent with seizure activity.

"Neonates with all types of heart disease had seizures ... " reported Dr. Naim. " ... with a highest percentage occurring in those with single ventricles and arch obstruction."

Neuroimaging studies were reviewed by a neurologist to determine any association between injury and seizure location. The most commonly detected lesion was periventricular leukomalacia, and four patients had seizures arising from one of their injury sites.

Although neonates with and without seizures had similar CICU lengths of stay, mortality was higher in those with seizures (38% vs. 3%; P less than .01). No predictors of seizures were identified on multivariable analysis.

"Based on these data, we are continuing routine postoperative EEG monitoring in all neonates following surgery with cardiopulmonary bypass," said Dr. Naim.

While not discredited in any way, Dr. Naim’s data were met with a fair amount of pushback from the gathered group of pediatric cardiothoracic surgical experts. An informal poll of the audience showed that 80%-90% do not routinely monitor neonates for seizures post-CPB despite ACNS recommendations, and several of the comments questioned the technical and financial feasibility of routine EEG monitoring.

Said the invited discussant, Dr. Frank Pigula, a cardiac surgeon from Boston Children’s Hospital, "In all the groups that have studied this, in all patients who have had a seizure, there were documented brain abnormalities. So, the ways I picture these data are that a seizure is a sign of an underlying brain injury, much like a fever is a sign of an underlying infection."

"And you’ve made a good case for the routine postoperative surveillance for seizures; I’m sure everyone would agree that treating seizures is a good thing, but is there any evidence showing us that the early identification and treatment of seizures improves outcomes, either developmental delays or mortality?

In response, Dr. Naim noted that all the CHOP seizure sufferers were treated, whether they had EEG only or clinical seizures, and, at the 4-year mark, they are showing fewer neurodevelopmental issues than are previous cohorts of untreated neonates.

"I think one thing that is very concerning is emerging evidence that the seizures themselves cause secondary brain injury," she said. "So I think that the way to move forward, since our emphasis has really changed not to improving neurodevelopmental outcomes in our patients, is to monitor them postoperatively."

Dr. Naim reported having no financial disclosures. Dr. Pigula, the invited discussant, also reported no financial disclosures.

TORONTO – Routine EEG monitoring after surgery with cardiopulmonary bypass in neonates revealed a seizure incidence of 8% in a recent study. In most cases (85%), seizure activity was detectable only on EEG and would not have been identified or treated without EEG monitoring, reported Dr. Maryam Y. Naim, a critical care pediatrician at the Children’s Hospital of Philadelphia, during the American Association for Thoracic Surgery Annual Meeting.

Of concern, status epilepticus was noted in 62% of neonates with seizures, and mortality was higher in babies with seizures versus those without (38% vs. 3%; P less than .01).

"Postoperative seizures are associated with worse neurological outcomes," said Dr. Naim. In addition to being a biomarker of underlying brain injury, there is some evidence that the seizures themselves may cause secondary brain injury.

The American Clinical Neurophysiology Society (ACNS) recommends routine EEG monitoring following infant cardiac surgery. The CHOP group implemented this recommendation and performed a quality improvement study to determine the incidence of seizures in neonates following surgery with cardiopulmonary bypass (CBP).

A total of 161 neonates had 48-hours of EEG monitoring initiated within 6 hours of cardiac surgery with CPB. The median gestational age of the cohort was 39 weeks, 16% were premature, and 13% had identified genetic defects. The median age at the time of surgery was 5 days. Deep hypothermic circulatory arrest was used in 48% of surgeries (median time, 48 minutes), 16% had open chest with delayed sternal closure, and 9% had a cardiac arrest.

Seizures were detected in 13 (8%), with a median onset of 20 hours after return to the cardiac ICU (CICU) from surgery. Seizures were subclinical, or EEG only, in 11 patients (85%), electroclinical in the other 2 (15%), and status epilepticus was seen in 8 (62%).

When seizures occurred, the CICU team was notified by the EEG technologist, neurology consult was obtained, and the patient was treated with antiseizure medications. As well, abnormal vital signs or movements suggestive of seizure activity were noted at the bedside; although such events were recorded in 32 patients (22%), none had EEG correlates consistent with seizure activity.

"Neonates with all types of heart disease had seizures ... " reported Dr. Naim. " ... with a highest percentage occurring in those with single ventricles and arch obstruction."

Neuroimaging studies were reviewed by a neurologist to determine any association between injury and seizure location. The most commonly detected lesion was periventricular leukomalacia, and four patients had seizures arising from one of their injury sites.

Although neonates with and without seizures had similar CICU lengths of stay, mortality was higher in those with seizures (38% vs. 3%; P less than .01). No predictors of seizures were identified on multivariable analysis.

"Based on these data, we are continuing routine postoperative EEG monitoring in all neonates following surgery with cardiopulmonary bypass," said Dr. Naim.

While not discredited in any way, Dr. Naim’s data were met with a fair amount of pushback from the gathered group of pediatric cardiothoracic surgical experts. An informal poll of the audience showed that 80%-90% do not routinely monitor neonates for seizures post-CPB despite ACNS recommendations, and several of the comments questioned the technical and financial feasibility of routine EEG monitoring.

Said the invited discussant, Dr. Frank Pigula, a cardiac surgeon from Boston Children’s Hospital, "In all the groups that have studied this, in all patients who have had a seizure, there were documented brain abnormalities. So, the ways I picture these data are that a seizure is a sign of an underlying brain injury, much like a fever is a sign of an underlying infection."

"And you’ve made a good case for the routine postoperative surveillance for seizures; I’m sure everyone would agree that treating seizures is a good thing, but is there any evidence showing us that the early identification and treatment of seizures improves outcomes, either developmental delays or mortality?

In response, Dr. Naim noted that all the CHOP seizure sufferers were treated, whether they had EEG only or clinical seizures, and, at the 4-year mark, they are showing fewer neurodevelopmental issues than are previous cohorts of untreated neonates.

"I think one thing that is very concerning is emerging evidence that the seizures themselves cause secondary brain injury," she said. "So I think that the way to move forward, since our emphasis has really changed not to improving neurodevelopmental outcomes in our patients, is to monitor them postoperatively."

Dr. Naim reported having no financial disclosures. Dr. Pigula, the invited discussant, also reported no financial disclosures.

TORONTO – Routine EEG monitoring after surgery with cardiopulmonary bypass in neonates revealed a seizure incidence of 8% in a recent study. In most cases (85%), seizure activity was detectable only on EEG and would not have been identified or treated without EEG monitoring, reported Dr. Maryam Y. Naim, a critical care pediatrician at the Children’s Hospital of Philadelphia, during the American Association for Thoracic Surgery Annual Meeting.

Of concern, status epilepticus was noted in 62% of neonates with seizures, and mortality was higher in babies with seizures versus those without (38% vs. 3%; P less than .01).

"Postoperative seizures are associated with worse neurological outcomes," said Dr. Naim. In addition to being a biomarker of underlying brain injury, there is some evidence that the seizures themselves may cause secondary brain injury.

The American Clinical Neurophysiology Society (ACNS) recommends routine EEG monitoring following infant cardiac surgery. The CHOP group implemented this recommendation and performed a quality improvement study to determine the incidence of seizures in neonates following surgery with cardiopulmonary bypass (CBP).

A total of 161 neonates had 48-hours of EEG monitoring initiated within 6 hours of cardiac surgery with CPB. The median gestational age of the cohort was 39 weeks, 16% were premature, and 13% had identified genetic defects. The median age at the time of surgery was 5 days. Deep hypothermic circulatory arrest was used in 48% of surgeries (median time, 48 minutes), 16% had open chest with delayed sternal closure, and 9% had a cardiac arrest.

Seizures were detected in 13 (8%), with a median onset of 20 hours after return to the cardiac ICU (CICU) from surgery. Seizures were subclinical, or EEG only, in 11 patients (85%), electroclinical in the other 2 (15%), and status epilepticus was seen in 8 (62%).

When seizures occurred, the CICU team was notified by the EEG technologist, neurology consult was obtained, and the patient was treated with antiseizure medications. As well, abnormal vital signs or movements suggestive of seizure activity were noted at the bedside; although such events were recorded in 32 patients (22%), none had EEG correlates consistent with seizure activity.

"Neonates with all types of heart disease had seizures ... " reported Dr. Naim. " ... with a highest percentage occurring in those with single ventricles and arch obstruction."

Neuroimaging studies were reviewed by a neurologist to determine any association between injury and seizure location. The most commonly detected lesion was periventricular leukomalacia, and four patients had seizures arising from one of their injury sites.

Although neonates with and without seizures had similar CICU lengths of stay, mortality was higher in those with seizures (38% vs. 3%; P less than .01). No predictors of seizures were identified on multivariable analysis.

"Based on these data, we are continuing routine postoperative EEG monitoring in all neonates following surgery with cardiopulmonary bypass," said Dr. Naim.

While not discredited in any way, Dr. Naim’s data were met with a fair amount of pushback from the gathered group of pediatric cardiothoracic surgical experts. An informal poll of the audience showed that 80%-90% do not routinely monitor neonates for seizures post-CPB despite ACNS recommendations, and several of the comments questioned the technical and financial feasibility of routine EEG monitoring.

Said the invited discussant, Dr. Frank Pigula, a cardiac surgeon from Boston Children’s Hospital, "In all the groups that have studied this, in all patients who have had a seizure, there were documented brain abnormalities. So, the ways I picture these data are that a seizure is a sign of an underlying brain injury, much like a fever is a sign of an underlying infection."

"And you’ve made a good case for the routine postoperative surveillance for seizures; I’m sure everyone would agree that treating seizures is a good thing, but is there any evidence showing us that the early identification and treatment of seizures improves outcomes, either developmental delays or mortality?

In response, Dr. Naim noted that all the CHOP seizure sufferers were treated, whether they had EEG only or clinical seizures, and, at the 4-year mark, they are showing fewer neurodevelopmental issues than are previous cohorts of untreated neonates.

"I think one thing that is very concerning is emerging evidence that the seizures themselves cause secondary brain injury," she said. "So I think that the way to move forward, since our emphasis has really changed not to improving neurodevelopmental outcomes in our patients, is to monitor them postoperatively."

Dr. Naim reported having no financial disclosures. Dr. Pigula, the invited discussant, also reported no financial disclosures.