Lower Ventral Ascending Reticular Activating System Research Articles

Difference in the Ascending Reticular Activating System Injury Between Mild Traumatic Brain Injury and Cerebral Concussion.

IntroductionWe investigated differences in the ascending reticular activating system (ARAS) injuries between patients with mild traumatic brain injury (mTBI) and cerebral concussion by using diffusion tensor tractography (DTT).MethodsThirty-one patients with mTBI, 29 patients with concussion, and 30 control subjects were recruited. We used DTT to reconstruct the lower ventral and dorsal ARAS, and the upper ARAS. The fractional anisotropy (FA) value and the fiber number (FN) of the lower ventral and dorsal ARAS, and the upper ARAS were determined.ResultsSignificant differences were observed in the FA values of the lower ventral and dorsal ARAS on both sides between the mTBI and control groups and between the concussion and control groups (p < 0.05). The FN value was significantly different in the lower ventral ARAS on both sides between the concussion and control groups and between the mTBI and concussion groups (p < 0.05).ConclusionBoth the mTBI and concussion patients suffered injuries in the lower ventral and dorsal ARAS, with the concussion patients exhibiting more severe injury in the ventral ARAS than that in the mTBI patients. These results suggest that the terms mTBI and concussion should be used differentially, even though they have used interchangeably for a long time.

Relationship between consciousness and injury of ascending reticular activating system in patients with hypoxic ischaemic brain injury

Impaired consciousness is one of the main sequelae of hypoxic ischemic brain injury(HI-BI).1 The ascending reticular activating system (ARAS) comprised arousal pathways and awareness networks, which mainly originates in the...

Excessive Daytime Sleepiness and Injury of the Ascending Reticular Activating System Following Whiplash Injury.

Objectives: This study investigated injuries of the ascending reticular activating system (ARAS) following whiplash injury, in patients with excessive daytime sleepiness (EDS).Methods: Twenty-three patients with whiplash injury and 26 healthy control subjects were recruited for this study. Epworth Sleepiness Scale (ESS) was used for evaluating sleepiness. According to the ESS score, the patients were classified into two groups: subgroup A – ESS score <10, and subgroup B – ESS score ≥10. Three components of the ARAS (lower dorsal, lower ventral, and upper) were evaluated for fractional anisotropy (FA) and tract volume (TV).Results: No significant differences were observed in the FA and TV values of the lower dorsal and upper ARAS between the patient and control groups (p > 0.05). Conversely, the values of FA and TV in the lower ventral ARAS of the patient group were significantly lower than those of the control group (p < 0.05). Comparing the values of subgroups A and B, the TV value of subgroup B was significantly lower than subgroup A (p < 0.05). However, no significant differences were observed in the values of the FA and TV in the lower dorsal and upper ARAS, and the FA value in the lower ventral ARAS (p > 0.05).Conclusions: We found significant injury of the lower ventral ARAS in EDS patients with whiplash injury. These results suggest that diffusion tensor tractography (DTT) could provide useful information for detecting injuries of the ARAS following whiplash injury, in patients with EDS.

Injury of ascending reticular activating system associated with delayed post-hypoxic leukoencephalopathy: a case report

BackgroundDelayed post-hypoxic leukoencephalopathy (DPHL) is a demyelinating syndrome characterized by neurological relapse after an initial recovery from hypoxic brain injury. We describe a patient with impaired consciousness following DPHL, concurrent with injury of the ascending reticular activating system (ARAS) shown using diffusion tensor tractography (DTT).Case presentationA 50-year-old male patient was in a drowsy mental state after exposure to carbon monoxide (CO) for about ten hours. About a day after the CO exposure, his mental state recovered to an alert condition. However, his consciousness deteriorated to drowsy 24 days after the exposure and worsened to a semi-coma state at 26 days after onset. When he started rehabilitation six weeks after the CO exposure, he had impaired consciousness, with a Glasgow Coma Scale score of 8 and a Coma Recovery Scale-Revised score of 8. On 6-week DTT, decreased neural connectivity of the upper ARAS between the intralaminar thalamic nucleus and the cerebral cortex was observed in both frontal cortices, basal forebrains, basal ganglia and thalami. The lower dorsal ARAS was not reconstructed on the right side, and was thin on the left side. The lower ventral ARAS was not reconstructed on either side.ConclusionsUsing DTT, we demonstrated injury of the ARAS in a patient with impaired consciousness following DPHL. Our result suggests that injury of the ARAS is a plausible pathogenetic mechanism of impaired consciousness in patients with DPHL.