Trans-cranial Doppler in severe head injury: Evaluation of pattern of changes in cerebral blood flow velocity and its impact on outcome

Oligemia is the most common change within 6 hours of head injury. Persistence of oligemia beyond 24 hours is associated with poor outcome. Early (within 24 hours posttrauma) onset of vasospasm is associated with poor outcome; however, delayed (>24 hours after trauma) vasospasm is not associated with poor outcome.