Đáng chú ý là các bệnh nhân được giới thiệu phần lớn là vì các khiếu nại liên tục và do đó không thể là đại diện của tất cả các bệnh nhân bị chấn thương não nhẹ. Nhóm này sau đó đã chứng minh mối tương quan giữa các đặc điểm nhất định chẳng hạn | Mild Brain Injury and the Postconcussion Syndrome 297 patterns was consistent with predictable areas of brain injury. Of note is that the patients were referred largely because of persistent complaints and thus may not be representative of all patients with a mild brain injury. This group has subsequently demonstrated correlations between certain electroencephalographic characteristics such as electroencephalographic coherence a measure of homogeneity of electrical activity across different distances and electroencephalographic amplitude within different wave frequencies . alpha beta delta and theta and the brain water proton relaxation times T2 obtained with conventional MRI Thatcher et al. 1998a 1998b . The average T2 relaxation time is in part a function of the distribution of the H1 imaging agent in intracellular water extracellular water and protein lipid membrane and this distribution can and often does change after a tissue injury. Thus changes in the T2 relaxation time can reflect past injury. Thatcher et al. 2001 compared a variety of electroencephalographic measures between groups with mild moderate and severe TBI and proposed an EEG Severity Index that showed promise in distinguishing MTBI from more severe forms. These reports suggest that quantitative electroencephalographic techniques may prove to be more valuable in the assessment of mild brain injury than standard EEGs although they remain experimental and as yet are not recommended as routine diagnostic procedures in the guidelines put forth by the American Academy of Neurology and the American Clinical Neurophysiology Society Gaetz and Bernstein 2001 . A similar picture emerges with respect to the EP and ERP literature. In their study of brainstem auditory evoked responses in 165 patients with mild brain injury GCS 13-15 LOC less than 20 minutes Schoenhuber and Gentilini 1986 showed that approximately 10 of patients had at least one prolonged interpeak latency. However these abnormalities did .
