Hyperemia following traumatic brain injury: relationship to intracranial hypertension and outcome

The role of posttraumatic hyperemia in the development of raised intracranial pressure (ICP) has important pathophysiological and therapeutic implications. To determine the relationship between hyperemia (cerebral blood flow (CBF) > 55 ml/100 g/minute), intracranial hypertension (ICP > 20 mm Hg), and neurological outcome, 193 simultaneous measurements of ICP and CBF (xenon-133 method) were obtained in 59 patients with moderate and severe head injury. Hyperemia was associated with an increased incidence of simultaneous intracranial hypertension compared to nonhyperemic CBF measurements (32.2% vs. 21.6%, respectively; p < 0.059). However, in 78% of blood flow studies in which ICP was greater than 20 mm Hg, CBF was less than or equal to 55 ml/100 g/minute. At least one episode of hyperemia was documented in 34% of patients, all of whom had a Glasgow Coma Scale (GCS) score of 9 or below. In 12 individuals with hyperemia without simultaneous intracranial hypertension, ICP was greater than 20 mm Hg for an average of 11 +/- 16 hours and favorable outcomes were seen in 75% of patients. In contrast, in eight individuals with hyperemia and at least one episode of hyperemia-associated intracranial hypertension, ICP was greater than 20 mm ...Continue Reading