Introduction: Traumatic Brain Injury (TBI) patients show dysfunctional recruitment patterns of the frontal lobes when performing cognitive tasks. Regulation of frontal lobes activity through neuromodulation could improve cognitive performance and neuropsychiatric symptoms in the setting of chronic mild (mTBI). Trigeminal nerve stimulation (TNS) is a non-invasive form of neuromodulation that has been shown to modulate several regions of the frontal and cingulate regions on PET scan.
We studied the effects of TNS on the neurocognitive symptoms of mTBI in relation to resting PET scans.
Methods: This early-phase clinical trial follows a prospective open label design. Patients suffering from chronic mild TBI are enrolled and complete baseline assessments that include a resting-state FDG-PET scan along with neuropsychological testing and psychological scales. The patients are then instructed to apply a self-adhesive electrode above the eyebrows for eight hours per day for eight weeks. The electrode connects to a pulse generator that the subject adjusts to achieve a pleasant sensation over the forehead. The PET scan and the assessments are repeated at the conclusion of the trial.
Results: For the first two subjects who have completed the protocol, their PET scans demonstrated significantly increased metabolism in Broca’s area, dorsolateral prefrontal cortex, anterior cingulate cortex and medial frontal cortex. The mean changes above pre-treatment values in each of these regions ranged from 1.7% to 4.3% of whole-brain mean metabolism, and were associated with self-reported improvement in the language and memory domains as well as substantial reduction in post-traumatic headaches. Cerebral metabolism was reduced by approximately 2% of pre-treatment values in the bilateral amygdalae, with an associated improvement in anxiety levels as reported on the Beck Anxiety Inventory.
Conclusions: TNS may prove beneficial in mTBI by normalizing recruitment patterns of the frontal and cingulate cortices. These neuromodulatory changes may improve neuropsychiatric symptoms seen in patients suffering from chronic mTBI.
Patient Care: This project can improve patient care by offering a potential novel therapeutic technique for chronic mTBI
Learning Objectives: By the end of the session the participants should be able to: 1) Discuss alteration in cerebral activation patterns seen in mild TBI, 2) Discuss the findings on FDG-PET associated with the use trigeminal nerve stimulation, 3) Discuss the potential effects of TNS for mTBI patients.