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By Douglas J Gelb MD PhD

Hypothyroidism is also known as or subsumes Myxedema. -ed.

Hypothyroidism can affect the central and peripheral nervous systems at multiple levels, producing a diverse array of neurologic symptoms and signs. Clinicians should be particularly aware of the diagnostic and management issues related to myxedema coma, dementia, myopathy, and polyneuropathy. Carpal tunnel syndrome may be the most common neurologic abnormality associated with hypothyroidism. The importance of hypothyroidism as a “reversible cause of dementia” remains unclear. The diverse manifestations of Hashimoto encephalopathy–a steroid-responsive syndrome that appears to be inflammatory rather than a direct result of inadequate thyroid hormone levels–are important to recognize because the syndrome typically responds to high-dose steroid treatment.

Key Points

  • Hypothyroidism can affect practically every level of the central and peripheral nervous system.
  • Although coma due to severe hypothyroidism (myxedema coma) is rare, it should always be considered in comatose patients without a clear cause because it requires rapid and specific treatment.
  • Carpal tunnel syndrome is the most common peripheral nerve manifestation of hypothyroidism.
  • An elevated thyrotropin level is the key diagnostic finding in primary hypothyroidism, which is the most common form of hypothyroidism.