Paper of the week: Improving clinical outcomes following brain injury

Hartings, J. A., Bullock, M. R., Okonkwo, D. O., Murray, L. S., Murray, G. D., Fabricius, M., Maas, A. I., et al. (2011). Spreading depolarisations and outcome after traumatic brain injury: a prospective observational study. Lancet Neurology, 10(12), 1058-1064

Traumatic brain injury (TBI) is a leading cause of mortality and disability in young people in developed countries. A hallmark feature of TBI is spreading depolarization – a slowly propagating cortical wave (2-5 mm/min) that results in near complete and sustained depolarization of neurons and astrocytes in its path.

The danger with this type of neural activity is its potential for causing further injury by way of excitotoxicity. Thus, the goal of this study was to establish whether spreading depolarization was a causal factor affecting clinical outcome.

A multicenter study was completed across seven neurosurgical centers involving 109 patients with TBI (e.g., from falls, vehicle accidents, assaults). An electrode strip was placed on the surface of the cortex near the site of injury to monitor electrocorticographic activity for a maximum of 7 days post TBI. Neurological outcomes were assessed at 6 months using the Extended Glasgow Outcome Scale.

Over half (56%) of the patients exhibited spreading depolarizations. Results also showed that the occurrence of spreading depolarization was associated with an increased risk of unfavorable clinical outcome at 6 months, such as death (33% vs. 20% without spreading depolarization) and vegetative state (9% vs. 2% without spreading depolarization).

That spreading depolarization was found to be an independent risk factor for unfavorable clinical outcomes suggests a causal role in secondary brain injury. The authors conclude that monitoring spreading depolarization in future clinical trials could help establish this technique as a useful prognostic marker that may be used to guide treatment decisions.

30 December 2011