The most common causes of sensory neuronopathy are anti-Hu paraneoplastic syndrome, Sjogren syndrome, pyridoxine toxicity, and exposure to certain chemotherapeutic agents.
Anti-Yo paraneoplastic syndrome can result in gait instability as well, however, this is secondary to ataxia, due to cerebellar degeneration, rather than proprioceptive loss. Anti-Hu paraneoplastic syndrome can present with sensory neuronopathy and/or cerebellar degeneration. Anti-amphiphysin paraneoplastic syndrome will result in encephalomyelitis or stiff-person syndrome. A posterior spinal artery territory infarct will result in focal damage to the posterior columns, and in turn, can cause an isolated proprioceptive issue. However, this would be acute and not progressive.