Secondary ischaemic brain damage after head injury

Therapeutic Moderate Hypothermia for Severe Traumatic Brain Injury

Use of therapeutic hypothermia to treat patients with severe traumatic brain injury was described more than 50 years ago. Unexpected improvement in some of these patients was attributed to hypothermia, but none of the early studies systematically evaluated the efficacy of hypothermia, and many patients were thought to have been harmed by the treatment, particularly when cooled below 30°C or when cooled for longer than 48 hours. Recent investigations have found that therapeutic moderate hypothermia (32–34°C) for relatively brief durations can improve histological and behavioral outcome following experimental brain injury. Cooling to this degree and duration has not been implicated as a cause for the cardiac arrhythmias, coagulation abnormalities, or infections attributed to hypothermia in the earlier studies. These laboratory investigations also defined several neurochemical mechanisms through which hypothermia may limit secondary brain injury and brain swelling. Four clinical trials of therapeutic moderate hypothermia were completed during the past three years; each detected a beneficial effect from cooling patients with severe traumatic brain injury to 32 to 34°C for up to 48 hours. In the largest of these studies, therapeutic moderate hypothermia was shown to cause a significant improvement in neurological outcomes 3, 6, and 12 months after injury for those patients with an initial Glasgow Coma Scale score of 5 to 7. The improvement in outcome for these patients was associated with a hypothermia-induced reduction of intracranial pressure and cerebrospinal fluid levels of interleukln-1β and glutamate.

Treatment of experimental brain injury with moderate hypothermia and 21-aminosteroids

Studies of experimental traumatic brain injury have found that histologic injury is significantly reduced and behavioral outcome improved in animals treated with moderate hypothermia (32-33 degrees C) or a 21-aminosteroid. Because these treatments are thought to work through different neurochemical mechanisms, their combined use might be expected to be more efficacious than either treatment alone. To test this hypothesis, we studied each treatment separately and in combination in a rodent model of controlled cortical contusion. Treatment with moderate hypothermia (32 degrees C for 4 h), a 21-aminosteroid (U-74389G, Upjohn, 10 mg/kg intravenously, repeated 3 h after the first dose), or both, was initiated 10, 25, or 40 min after injury. The brains were perfused 24 h after injury, and sagittal sections were stained for the 68-kDa "core" neurofilament subunit, a marker of axonal injury. The total number of positively stained axons in the ipsilateral internal capsule were counted under light microscopy. Compared with the control group (injury but no treatment), treatment with each therapy alone or combined, initiated 10 min after injury, caused significant reductions in the number of stained axons (21-aminosteroid alone-35% reduction; hypothermia alone-55% reduction; combination-48% reduction). The number of positively stained axons was significantly reduced in the aminosteroid and combination therapy groups at all three postinjury times (p = 0.01) and in the hypothermia groups treated at 10 or 25 min (p = 0.01) but not at 40 min after injury. We concluded that combination therapy with hypothermia and 21-aminosteroids was no more efficacious than either therapy alone, and that 21-aminosteroid therapy was more efficacious than hypothermia when treatment was initiated 40 min after injury.

Post-traumatic intraventricular haemorrhage: a reappraisal

Ten patients are described in whom intraventricular bleeding occurred after blunt head injury. A mechanism is proposed to explain this phenomenon by drawing analogies with neonatal intraventricular haemorrhage and the pathological findings in strangulation. The outcome in the patients described seems more favourable than in those hitherto reported.