Romberg's test

Romberg's test is a neurological test that is used to assess the dorsal columns of the spinal cord, which are essential for joint position sense (proprioception) and vibration sense.
A positive Romberg test suggests that ataxia is sensory in nature, i.e. depending on loss of proprioception. A negative Romberg test suggests that ataxia is cerebellar in nature, i.e. depending on localised cerebellar dysfunction instead.
It is sometimes used as an indicator for possible alcohol or drug impaired driving and neurological decompression sickness When used to test impaired driving, the test is performed with the subject estimating 30 seconds in their head. This is used to gauge the subject's internal clock and can be an indicator of stimulant or depressant use.