The onset is gradual and uniform. The pathological findings of<unk><unk>  degeneration consist of patchy losses of myelin in the dorsal and lateral columns. Patients present with weakness of the legs, arms, and trunk, and tingling and numbness that progressively worsens. Vision changes and change of mental state may also be present. Bilateral spastic paresis may develop and pressure, vibration and touch sense are diminished. A positive Babinski sign may be seen. Prolonged deficiency of vitamin B12 leads to irreversible nervous system damage. HIV-associated vacuolar myelopathy can present with a similar pattern of dorsal column and corticospinal tract demyelination. It has been thought that if someone is deficient in vitamin B12 and folic acid, the vitamin B12 deficiency must be treated first. However, the basis for this has been challenged, although due to ethical considerations it is no longer able to be tested if "neuropathy is made more severe as a result of giving folic acid to vitamin B12- deficient individuals". And that if this were the case, then the mechanism remains unclear. Administration of nitrous oxide anesthesia can precipitate<unk><unk>  degeneration in people with subclinical vitamin B12 deficiency, while chronic nitrous oxide exposure can cause it even in persons with normal B12 levels. Posterior column dysfunction decreases vibratory sensation and proprioception (joint sense). Lateral corticospinal tract dysfunction produces spasticity and dorsal spinocerebellar tract dysfunction causes ataxia.
Subacute combined degeneration of spinal cord
Vascular myelopathy
Acute flaccid myelitis
Paraneoplastic cerebellar degeneration
CMV polyradiculomyelopathy
Surfer's myelopathy
Medial medullary syndrome
Bickerstaff brainstem encephalitis