New test may identify mild traumatic brain injury with underlying brain damage

Al Saint Jacques, MDLinx | February 20, 2017

A new test that uses peripheral vision reaction time (PVRT) could lead to earlier diagnosis and more effective treatment of mild traumatic brain injury (mTBI), often referred to as a concussion, according to Peter J. Bergold, PhD, professor of physiology and pharmacology at SUNY Downstate Medical Center and corresponding author of a study newly published online in the Journal of Neurotrauma.

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While most patients with mTBI or concussion fully recover, a significant number do not, and earlier diagnosis could lead to better management of patients at risk for developing persistent symptoms.

While most patients with mTBI or concussion fully recover, a significant number do not, and earlier diagnosis could lead to better management of patients at risk for developing persistent symptoms, explained Dr. Bergold and his co-authors.

Lingering symptoms may include loss of concentration and/or memory, confusion, anxiety, headaches, irritability, noise and light sensitivity, dizziness, and fatigue.

“Mild traumatic brain injury is currently diagnosed with subjective clinical assessments,” stated Dr. Bergold. “The potential utility of the peripheral vision reaction test is clear because it is an objective, inexpensive, and rapid test that identifies mild TBI patients who have a more severe underlying injury.”

The study was designed to determine whether PVRT in patients with mTBI correlated with white matter abnormalities in centroaxial structures and impairments in neuropsychological testing. Patients 18 to 50 years of age were included in the study if they had a post-resuscitation Glasgow Coma Scale greater than 13 and an injury mechanism compatible with mTBI. The healthy controls were either age- and gender-matched family members of the mTBI subjects or healthy volunteers.

Crossed reaction times (CRT), uncrossed reaction times (URT), and crossed–uncrossed difference (CUD) were measured in 23 patients within 24 hours after sustaining a mTBI. Researchers used a laptop computer that displayed visual stimuli predominantly to either the left or the right visual field of the retina. The CUD is a surrogate marker of the interhemispheric transfer time (ITT). Within 7 days post-injury, patients received a diffusion tensor-MRI (DTI) scan and a battery of neuropsychological tests. Nine uninjured control subjects received similar testing.

Study authors reported that CUD deficits greater than 2 standard deviations (SD) were seen in 40.9% of the patients. The CUD of injured patients correlated with mean diffusivity (MD) (P < 0.001, P = −0.811) in the posterior corpus callosum. Patients could be stratified on the basis of CUD on the Stroop 1, Controlled Oral Word Association Test (COWAT), and the obsessive-compulsive component of the Basic Symptom Inventory tests.

Study results suggested that the PVRT indirectly measures white matter integrity in the posterior corpus callosum, a brain region frequently damaged by mTBI.

Dr. Bergold’s co-authors include colleagues from the University of Texas Southwestern Medical Center; The University of Texas at Dallas; Washington University; the National Institute of Neurological Disorders and Stroke; the Uniformed Services University of the Health Sciences; and SUNY Downstate.

The research leading to the results published by the Journal of Neurotrauma was funded by an award from the United States Army Medical Research and Materiel Command, award number W81XWH1011061. Support was also received by the Center for Neuroscience and Regenerative Medicine. The United States Army Medical Research and Materiel Command had no input into the design and conduct of the study; the collection, management, analysis, or interpretation of the data; or the preparation, review, or approval of the manuscript. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding sources.

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