Romberg’s test or the Romberg maneuver is a test used in a neurological examination, as well as for drunken driving. The exam is based on the premise that a person requires at least two of the three following senses to maintain balance while standing: proprioception (the ability to know one’s body in space); vestibular function (the ability to know one’s head position in space); and vision (which can be used to monitor [and adjust for] changes in body position).
What is being tested in Romberg test:
With the eyes open, three sensory systems provide input to the cerebellum to maintain truncal stability. These are vision, proprioception, and vestibular sense. If there is a mild lesion in the vestibular or proprioception systems, the patient is usually able to compensate with the eyes open.
When the patient closes their eyes, however, visual input is removed and instability can be brought out. If there is a more severe proprioceptive or vestibular lesion, or if there is a midline cerebellar lesion causing truncal instability, the patient will be unable to maintain this position even with their eyes open. Note that instability can also be seen with lesions in other parts of the nervous system such as the upper or lower motor neurons or the basal ganglia, so these should be tested for separately in other parts of the exam.
See more at: http://www.medical-institution.com/romberg-test-physical-examination-video-tutorial/