In the recent years several clinical syndromes have been recognized that are purely sensory in character and therefore the site of lesion is seemingly restricted to nerve cell bodies in the posterior root ganglia. Collectively, these disorders are referred to as sensory neuronopathies. Although they may present as distinct clinical entities with different etiologies, the severity of the clinical manifestations and outcomes varies and may overlap with those of sensory neuropathy. This similarities are better understood in the case of toxic sensory neuropathies where a dose-dependent response has been clearly demonstrated; experimentally, low doses of pyridoxine induce sensory neuropathy whereas higher doses cause neuronopathy.