ABBR: BESS A modification of the Romberg test that assesses a patient’s ability to maintain postural stability following traumatic brain injury. The test is performed in two stages. The first is performed on a solid surface; the second is performed on a soft surface such as thick foam. Points are deducted for “errors” (loss of balance or sway) during testing. Preinjury test results are compared to postinjury test results to determine the magnitude of impairment following injury.