The trigeminal nociceptive-pain pathway in pediatric mTBI: peripheral and central contributions to photophobia

Concussion, also referred to as mild traumatic brain injury (mTBI), is a neurological disorder that causes disability in children and predisposes them to challenges later in life, including significant physical, cognitive, and psychological disability. The trigeminal nerve extends from the central nervous system to innervate the greater portion of face and eye, and may offer insight into head trauma pathophysiology. In particular, painful sensitivity to light (photophobia), corneal nerve pathology, and atypical functional activity within the brain have all been reported in preliminary work evaluating persons with mTBI and trigeminal nerve pathology. Our overall hypothesis is that the trigeminal nerve is sensitive to mTBI and accounts for pain-related symptomatology. To test this hypothesis, in aim 1, we will define trigeminal nerve pathology in persons with mTBI using quantitative sensory testing (QST), in vivo corneal nerve microscopy (IVCM), and diffusion tensor imaging (DTI). In aim 2, we will define central nervous system changes to light-induced pathways with mTBI-related photophobia using fMRI and DTI. This study is likely to yield (1) a diagnostic marker that is sensitive to mTBI, (2) evince a neurological source of mTBI-related pain symptoms. Data generated from this investigation can be used to improve the diagnosis, treatment and monitoring of patients suffering from head trauma and provide an objective marker to base clinical decision making.