Quantitative and qualitative analysis of ambulatory electroencephalography during mild traumatic brain injury.

OBJECTIVES To characterize the neurophysiological changes in a patient with mild traumatic brain injury (mTBI) and to compare these changes with a small cohort of patients with neurocardiogenic syncope, an analogous cause of transient neurological dysfunction. DESIGN Case report and quantitative analysis of a small electroencephalography (EEG) cohort. SETTING University-affiliated teaching hospital. PATIENTS A 64-year-old man with mTBI recorded on ambulatory EEG. The comparison group was 4 patients with spontaneous neurocardiogenic syncope during continuous video EEG recording. INTERVENTION Quantitative and qualitative analysis of EEG. MAIN OUTCOME MEASURES Changes in quantitative EEG measurements between the patient with mTBI and the comparison group. RESULTS In the patient with mTBI, there was an abrupt decrease in high-frequency (beta) power and alpha-delta ratio immediately after the injury and a corresponding increase in lower-frequency (alpha, theta, delta) power. The change in beta power resolved within 5 minutes of the injury, but the increases in low-frequency power persisted up to 20 minutes after the injury before resolving. Similar but smaller changes were seen in the patients with syncope, but these changes resolved within 5 minutes, with no intermediate or long-term changes. CONCLUSIONS The quantitative EEG changes in mTBI are initially similar to those in syncope, suggesting acute transient cortical dysfunction. However, there are longer-lasting increases in low-frequency power during mTBI, suggesting ongoing disruption of cortical-thalamic circuits.