Common mechanisms include the following: Ischemia (eg, brain infarction, spinal cord infarction, vasculitis) Demyelinating disorders (eg, multiple sclerosis, Guillain-Barré syndrome) Mechanical nerve compression (eg, by tumors or a herniated disk [nucleus pulposus], in carpal tunnel syndrome) Infections (eg, HIV, leprosy) Toxins or drugs (eg, heavy metals, certain chemotherapy drugs) Metabolic disorders (eg, diabetes, chronic kidney disease, thiamin deficiency, vitamin B12 deficiency) Immune-mediated disorders (eg, postinfectious inflammation, such as transverse myelitis) Degenerative disorders (eg, hereditary neuropathies) Etiology of Numbness There are many causes of numbness.