Motor neuron diseases*

Hereditary

Spinal muscular atrophy types 0–4

Acquired diseases that begin suddenly

Polio, infections due to coxsackievirus or other enteroviruses (rare), and West Nile virus infection

Acquired diseases that are chronic

Amyotrophic lateral sclerosis* (Lou Gehrig disease), paraneoplastic syndromes, postpolio syndrome, and progressive bulbar palsy

Nerve root disorders

Hereditary

Neurofibromas (soft, fleshy growths of nerve tissue)

Acquired

A herniated disk, infections, injuries, metastatic cancer, osteoarthritis, and rheumatoid arthritis

Plexus disorders

Acquired

Acute brachial neuritis, autoimmune disorders, damage during delivery in newborns, diabetes mellitus, a hematoma (a pocket of blood), severe injuries (such as those due to high-speed motor vehicle accidents), metastatic cancer, radiation therapy, neurofibromatosis (rare), and nerve tumors

Peripheral nerve disorders

Hereditary

Hereditary neuropathies (such as Charcot-Marie-Tooth disease)

Infectious

Hepatitis C, herpes zoster, HIV infection, Lyme disease, SARS-CoV-2 (the virus that causes COVID-19), and syphilis

In developing countries, diphtheria, leprosy, and parasite infections

Inflammatory

Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy

Ischemic (due to blockage of the blood supply)

Vasculitis (inflammation of blood vessels)

Metabolic

Amyloidosis, diabetes mellitus, vitamin B deficiencies, undernutrition due to chronic excess consumption of alcohol, and kidney failure

Pressure-related (called nerve entrapment syndromes)

Carpal tunnel syndrome, cubital tunnel syndrome (a type of ulnar nerve palsy), radial nerve palsy, peroneal nerve palsy, and tarsal tunnel syndrome

Toxins

Arsenic, lead, and mercury

Neuromuscular junction disorders

Various

Botulism in infants, Eaton-Lambert syndrome, myasthenia gravis, and dysfunction caused by exposure to certain insecticides (organophosphate insecticides) or chemical-warfare agents (such as sarin gas and Novichok, which was developed in Russia and has been used in assassination attempts) or by use of certain drugs (such as curare, which has been used to help relax muscles during surgery and to paralyze and kill when placed on the tip of poison darts)