The neurological symptoms of patients with vitamin B12 (cobalamin) deficiency usually follow a chronic course, but a more or less acute spinal cross-section syndrome does occur. The most common early complaint is that of tingling sensations in the hands and feet. A spastic paraparesis develops along with ataxia, which is due to impairment of postural sense. The upper limbs are usually affected later than the lower limbs. If the peripheral neuropathy is severe, there may be a loss of reflexes, but plantar reflexes usually remain extensor. Visual disturbances are caused by optic atrophy. The final state of complete paraplegia with total anesthesia is seldom seen.