Hi,
I agree with physiobob.

Neurologically, balance depends on three systems. On even ground, the relation is 80% eye sight, 10% sensory, 10% vestibular. Apparently (and I cannot find the reference for this), on uneven ground this changes to 50% eye sight, 10% sensory and 40% vestibular.

So, if Romberg is positive, either the sensory or the vestibular system is affected (or a combination :-)). You can then go to Sharpened Romberg or use other outcome measures to test sensation and vestibular functions.

However -as above- swaying in unsupported standing has not neccessarily a neurological origin.
I like the BEST Test, which differentiates between all possible systems (e.g. posture, musculoskeletal system, strength).

Regards,
Fyzzio