Romberg sign

The Romberg test assesses the patient's ability to maintain balance using visual, vestibular, and proprioceptive inputs. The patient stands with feet together and eyes open, then closes their eyes. A positive Romberg sign occurs when the patient becomes unsteady or falls only after closing their eyes, indicating that proprioceptive input (via dorsal columns/posterior columns of the spinal cord) or vestibular input is impaired, and the patient was compensating with vision. Once vision is removed, the patient cannot maintain balance.

Clinically, Romberg sign is positive in conditions affecting the dorsal columns (proprioception/vibration sense) such as tabes dorsalis (tertiary syphilis), vitamin B12 deficiency (subacute combined degeneration), Friedreich ataxia, and peripheral sensory neuropathies (e.g., diabetic neuropathy). It can also be positive in vestibular dysfunction.

In contrast, cerebellar ataxia causes unsteadiness with eyes both open and closed (Romberg sign is negative/absent in pure cerebellar disease), since the cerebellum coordinates movement independent of visual input—cerebellar patients are already unsteady with eyes open, so closing the eyes doesn't significantly worsen their balance further (a key USMLE distinguishing point).

This is a key clinical pearl for differentiating sensory versus cerebellar ataxia and localizing lesions to the posterior columns of the spinal cord or peripheral sensory nerves versus the cerebellum.