fMRI Study: Concussions Disrupt Connections in Thalamus

Patients with mild traumatic brain injury (MTBI) exhibit abnormal functional connectivity in the thalamus, a relay station for transmitting information throughout the brain, according to a new fMRI study published online in the journal Radiology. The findings could have implications for treatment strategies.

Yulin Ge, MD, of the Department of Radiology at NYU Langone Medical Center, and colleagues used resting state functional magnetic resonance imaging (RS-fMRI) to study the brain activity of 24 patients with MTBI and 17 healthy control patients. A normal pattern of thalamic resting state networks (RSNs) with relatively symmetric and restrictive connectivity was demonstrated in the healthy control group. In the patients with MTBI, subtle injury to the thalamus apparently disrupted this pattern, with significantly increased thalamic RSNs and decreased symmetry. The findings correlated with clinical symptoms and diminished neurocognitive functions in the patients with MTBI, the authors said.

Because the causes of post-concussive syndrome are poorly understood, there is currently no treatment. But the authors said the results of this study have implications for a new therapeutic strategy based on sound understanding of the underlying mechanisms of thalamocortical disruption and post-concussive syndrome.

Thalamic functional networks have multiple functions, including sensory information process and relay, consciousness, cognition, and sleep and wakefulness regulation, the authors said. Their disruption of thalamic RSNs may result in a burning or aching sensation, mood swings and sleep disorders, and can contribute to certain psychotic, affective, obsessive-compulsive, anxiety and impulse control disorders. These symptoms are commonly seen in MTBI patients with post-concussive syndrome, they said.

According to the CDC, 1.5 million people sustain traumatic brain injuries in the United States each year. MTBI, or concussion, accounts for at least 75 percent of these injuries. Typically in patients with MTBI, there are no structural abnormalities visible on the brain, so researchers have begun using specialized imaging exams to detect abnormalities in how the brain functions.

“These findings hold promise for better elucidating the underlying cause of a variety of post-traumatic symptoms that are difficult to spot and characterize using conventional imaging methods,” Ge said.