ABSTRACT
Background: Persistent post-traumatic symptoms (PPS) after traumatic brain injury (TBI) can lead to significant chronic functional impairment. Pseudocontinuous arterial spin labeling (pCASL) has been used in multiple studies to explore changes in cerebral blood flow (CBF) that may result in acute and chronic TBI, and is a promising neuroimaging modality for assessing response to therapies. Methods: Twenty-four subjects with chronic mild-moderate TBI (mmTBI) were enrolled in a pilot study of 10 days of computerized executive function training combined with active or sham anodal transcranial direct current stimulation (tDCS) for treatment of cognitive PPS. Behavioral surveys, neuropsychological testing, and magnetic resonance imaging (MRI) with pCASL sequences to assess global and regional CBF were obtained before and after the training protocol. Results: Robust improvements in depression, anxiety, complex attention, and executive function were seen in both active and sham groups between the baseline and post-treatment visits. Global CBF decreased over time, with differences in regional CBF noted in the right inferior frontal gyrus (IFG). Active stimulation was associated with static or increased CBF in the right IFG, whereas sham was associated with reduced CBF. Neuropsychological performance and behavioral symptoms were not associated with changes in CBF. Discussion: The current study suggests a complex picture between mmTBI, cerebral perfusion, and recovery. Changes in CBF may result from physiologic effect of the intervention, compensatory neural mechanisms, or confounding factors. Limitations include a small sample size and heterogenous injury sample, but these findings suggest promising directions for future studies of cognitive training paradigms in mmTBI.
ABSTRACT
A 0.5 kg, 5-yr-old male bearded dragon (Pogona vitticeps) presented with a 2-mo history of lethargy, anorexia, and impaired locomotion. Upon physical examination, bradyarrhythmia (heart rate: 20 beats/min) and balance disorders were noted. Electrocardiography revealed a first-degree atrioventricular block (P-R interval: 360 ms). On echocardiography, all cardiac chambers were slightly above normal ranges. Complete blood count, blood biochemistry, and T4 were unremarkable except for mildly elevated aspartate aminotransferase. Adenovirus testing was negative by polymerase chain reaction. Following euthanasia, necropsy revealed marked thickening of the arterial trunks and histopathology confirmed multifocal atherosclerosis of efferent heart vessels, arteriosclerosis of cerebral arterioles, and multifocal spongiosis of brain tissue, more pronounced in the optic chiasma. Owing to its severity, atherosclerosis may have contributed to chronic arterial hypertension with damages to the heart, brain vessels, and brain tissue-optic chiasma.
