How to do the test?
The test is done by requesting the patient to keep his feet firmly together, arms by the side and the eyes open at first. The balance of the patient is noted.
Now the patient is asked to close both eyes and the balance is now noted for around 1 minute. The physician should stand in front of the patient with his arms extended on either side of the patient but not touching him. This is done as the latter may fall.
1) If with the eyes open, the balance is not good then there may be a problem with the cerebellum. This condition is called as cerebellar ataxia.
2) If closing the eyes causes a much worse balance then the test is said to be positive (Romberg test positive). It indicates that the patient is excessively reliant on his vision to maintain balance. The problem may lie in the vestibular or proprioceptive systems.
The physiology behind this test is that to maintain balance we need at least 2 of the following 3 components: vision, proprioception and vestibular function.
In simple words. . .If a patient has a vestibular problem then with his eyes open he can maintain balance because his proprioception as well as vision is helping him. But now if he closes his eyes, then there is only proprioception to maintain balance and that is not sufficient. So the patient will sway and may fall.
The same is true for someone with a problem of proprioception. With his eyes open, the patient can maintain balance because he is using his normal vision and vestibular apparatus. But when he closes his eyes, he is only relying on his vestibular function now and thus he will sway and may fall.
Common causes of positive Romberg test:
1) Vitamin B12 deficiency - Subacute combined degeneration of the cord,
2) Diabetic peripheral large fibre neuropathy,
3) Friedrich's ataxia,
4) Tabes dorsalis.