Assessment of post-traumatic amnesia after severe closed head injury: Retrospective or prospective?

Background-Post-traumatic amnesia is considered to be the best single indicator of the severity of closed head injury. Usually, it has been estimated retrospectively. For practical reasons this also tends to be the most common clinical method. It has been argued that prospective assessment is more accurate and reliable, but this has never been evaluated empirically in severe head injury. Methods-Post-traumatic amnesia was initially assessed prospectively and later retrospectively by a separate observer in the same patients. Results-The correlation between the two methods was high. In addition, both measures significantly correlated with other measures of severity of brain injury and with measures of outcome. Conclusion-Retrospective measurement of post-traumatic amnesia is a valid method.