Although favorable outcomes are possible among young patients with post-traumatic coma, even following prolonged coma and in the presence of radiographic evidence of brainstem injury, it is difficult to predict the prognosis of these patients, according to an editorial published in Neurology.
Post-traumatic coma is frequently associated with white matter injury, resulting in losses of network connectivity and axonal transport impairment. Technological advances, including improved magnetic resonance imaging techniques, allow for better assessment of brain lesions. Advanced imaging studies can provide evidence for microbleeds, which are considered to be a surrogate marker for diffuse axonal injury and were suggested to indicate poor prognosis in this population.
In the current issue of Neurology, Bianciardi and colleagues reported the results of their study that aimed at investigating the patterns of microbleeds associated with post-traumatic coma and exploring the association between the distribution of microbleeds and the recovery of consciousness in young patients who recovered responsiveness after being comatose for less than 10 days. .
The data suggested that multiple arousal nuclei in the brainstem and diencephalon were affected by microbleeds and that there was no singular lesion causing coma. However, brainstem microbleeds were more common in comatose (severe traumatic brain injury) compared with noncomatose (moderate traumatic brain injury) patients.
Study findings indicated that, despite acute damage to deep arousal nuclei, the patients regained consciousness and in some cases, achieved good functional recovery at 6 months.
The study had several limitations, including the inability to extrapolate the findings to older patients or those with more prolonged coma, potential selection bias, small sample size, and the limitations of susceptibility-weighted images. Study researchers noted that diffuse axonal injury can occur without microbleeds and vice versa and that additional techniques are required to determine the impact of axonal injury severity on the chances of recovery of consciousness.
“Delivering a nihilistic prognosis should therefore be avoided during the acute phase when treating young patients with coma after severe brain trauma,” concluded the study researchers.
Rabinstein AA. Good recovery is possible in young patients with post-traumatic coma and brainstem microbleeds. Neurology. Published online May 28, 2021. doi:10.1212/WNL.0000000000012197