Nonconvulsive electrographic seizures after traumatic brain injury result in a delayed, prolonged increase in intracranial pressure and metabolic crisis

Abstract

Objective: To determine whether nonconvulsive electrographic post-traumatic seizures result in increases in intracranial pressure and microdialysis lactate/pyruvate ratio.

Design: Prospective monitoring with retrospective data analysis.

Setting: Single center academic neurologic intensive care unit.

Patients: Twenty moderate to severe traumatic brain injury patients (Glasgow Coma Score 3-13).

Measurements and main results: Continuous electroencephalography and cerebral microdialysis were performed for 7 days after injury. Ten patients had seizures and were compared with a matched cohort of traumatic brain injury patients without seizures. The seizures were repetitive and constituted status epilepticus in seven of ten patients. Using a within-subject design, post-traumatic seizures resulted in episodic increases in intracranial pressure (22.4 +/- 7 vs. 12.8 +/- 4.3 mm Hg; p < .001) and an episodic increase in lactate/pyruvate ratio (49.4 +/- 16 vs. 23.8 +/- 7.6; p < .001) in the seizure group. Using a between-subjects comparison, the seizure group demonstrated a higher mean intracranial pressure (17.6 +/- 6.5 vs. 12.2 +/- 4.2 mm Hg; p < .001), a higher mean lactate/pyruvate ratio (38.6 +/- 18 vs. 27 +/- 9; p < .001) compared with nonseizure patients. The intracranial pressure and lactate/pyruvate ratio remained elevated beyond postinjury hour 100 in the seizure group but not the nonseizure group (p < .02).

Conclusion: Post-traumatic seizures result in episodic as well as long-lasting increases in intracranial pressure and microdialysis lactate/pyruvate ratio. These data suggest that post-traumatic seizures represent a therapeutic target for patients with traumatic brain injury.

Figure 1

Comparison of intracranial pressure (ICP) between groups: A, the mean ICP of all ten seizure patients by postinjury hour. B, the mean ICP of all ten patients in the comparison nonseizure group. The time course of ICP is shown. Note the higher ICP overall, and the persistence of elevated ICP beyond postinjury hr 100. The yellow bars denote the window of time during which the peak incidence of seizures occurred during the early and late phase. Of note is that the mean ICP continues to be elevated after hr 140 in the seizure group, whereas the ICP is lower in the nonseizure group.

Figure 2

Comparison of lactate/pyruvate ratio (LPR) between groups: A, the mean LPR of all ten seizure patients by postinjury hour. B, the mean LPR of all ten patients in the comparison nonseizure group. The seizure group displays higher LPR overall, and the persistence of elevated LPR beyond postinjury hr 100. The yellow bars denote the window of time during which the peak incidence of seizures occurred during the early and late phase. Of note is that the mean LPR is >40 at hr 140 in the seizure group but not in the nonseizure group.