Neuroinflammation is a player in coma, but in which role?

This scientific commentary refers to ‘Neuroimmune activation is associated with neurological outcome in anoxic and traumatic coma’ by Sarton et al. (https://doi.org/10.1093/brain/awae045).

Default mode network overshadow executive control network in coma emergence and awakening prediction of patients with sTBI

OBJECTIVE

We aimed to explore the pathogenesis of traumatic coma related to functional connectivity (FC) within the default mode network (DMN), within the executive control network (ECN) and between the DMN and ECN and to investigate its capacity for predicting awakening.

METHODS

We carried out resting-state functional magnetic resonance imaging (fMRI) examinations on 28 traumatic coma patients and 28 age-matched healthy controls. DMN and ECN nodes were split into regions of interest (ROIs), and node-to-node FC analysis was conducted on individual participants. To identify coma pathogenesis, we compared the pairwise FC differences between coma patients and healthy controls. Meanwhile, we divided the traumatic coma patients into different subgroups based on their clinical outcome scores at 6 months postinjury. Considering the awakening prediction, we calculated the area under the curve (AUC) to evaluate the predictive ability of changed FC pairs.

RESULTS

We found a massive pairwise FC alteration in the patients with traumatic coma compared to the healthy controls [45% (33/74) pairwise FC located in the DMN, 27% (20/74) pairwise FC located in the ECN, and 28% (21/74) pairwise FC located between the DMN and ECN]. Moreover, in the awake and coma groups, there were 67% (12/18) pairwise FC alterations located in the DMN and 33% (6/18) pairwise FC alterations located between the DMN and ECN. We also indicated that pairwise FC that showed a predictive value of 6-month awakening was mainly located in the DMN rather than in the ECN. Specifically, decreased FC between the right superior frontal gyrus and right parahippocampal gyrus (in the DMN) showed the highest predictive ability (AUC = 0.827).

CONCLUSION

In the acute phase of severe traumatic brain injury (sTBI), the DMN plays a more prominent role than the ECN and the DMN-ECN interaction in the emergence of traumatic coma and the prediction of 6-month awakening.

Recommendations for grading of concussion in athletes

Mild sports-related concussions, in which there is no loss of consciousness, account for >75% of all sports-related brain injury. Universal agreement on concussion definition and severity grading does not exist. Grading systems represent expertise of clinicians and researchers yet scientific evidence is lacking. Most used loss of consciousness and post-traumatic amnesia as markers for grading concussion. Although in severe head injury these parameters may have been proven important for prognosis, no study has done the same for sport-related concussion. Post-concussion symptoms are often the main features to help in the diagnosis of concussion in sport. Neuropsychological testing is meant to help physicians and health professionals to have objective indices of some of the neurocognitive symptoms. It is the challenge of physicians, therapists and coaches involved in the care of athletes to know the symptoms of concussion, recognise them when they occur and apply basic neuropsychological testing to help detect this injury. It is, therefore, recommended to be familiar with one grading system and use it consistently, even though it may not be scientifically validated. Then good clinical judgement and the ability to recognise post-concussion signs and symptoms will assure that an athlete never returns to play while symptomatic.

[Extended indications for decompression of the optic nerve: a differentiating analysis of restriction of the visual function, also in comatose patients]

BACKGROUND

The care of indirect traumatic optic neuropathy is still treated differently. Special diagnostic and therapeutic difficulties exist in comatose patients without definable visual acuity and in patients with complex failure of the visual field with central visual acuity still receiving sufficiently.

METHOD

The total collective of optic nerve decompressions within the period between January 1992 and August 2000 was comprised of 66 patients. 18 of these 66 patients (average age: 40.5 years) were comatose and required critical care. 3 of the 48 consciousness-clear patients showed post-traumatically different defects of the visual field with a visual acuity of 0.3, 0.4 and 1.0. The indication for surgical decompression in both groups was based on the ophthalmological findings and the CT-finding of traumatization of the optic nerve, or the orbit apex respectively.

RESULTS

During the subsequent postoperative examinations (on average 12.3 months postoperatively) five patients within the group of the unconscious patients showed a normal visual acuity (0.9-1.0), 3 patients a visual acuity of 0.7, 0.4 and 0.3 and one a visual acuity of 0.1. Six patients remained amaurotic. Three patients died from the general consequences of injury. Improvement of visual field and correction of stereoscopic function occurred in all patients, operated on primarily because of the described visual defects.

CONCLUSIONS

Due to these results the indication for the decompression of the optic nerve should find special consideration in comatose patients and in cases of severe restriction of the visual field.

MRI analysis of brain atrophy after severe closed-head injury: relation to clinical status

The purpose of this study was to determine the clinical correlates of supratentorial ventricular dilations and of corpus callosal atrophy at the subacute stage after a severe closed-head injury (CHI). Thirty-three CHI patients underwent MRI 2 months or more after injury. Morphometric measures were compared to clinical data (coma score, coma duration and Glasgow Outcome Scale). There were numerous significant correlations between clinical data and mid-third ventricle and frontal horns measurements. Fewer significant correlations were found with the lateral ventricle bodies and the corpus callosal body. There was no significant correlation with the posterior part of the corpus callosum and of the ventricles. Corpus callosum atrophy correlated significantly with anterior and deep ventricular dilatation. In conclusion, the best indicator of clinical status was ventriculomegaly, and particularly third ventricle enlargement, which probably reflects the extent of both anterior and deep white matter lesions.