ISOLATED FACIAL NERVE PALSY: A RARE NEUROLOGICAL MANIFESTATION OF SEVERE HYPOTHYROIDISM

Case Presentation: A 59-year-old female with a history of hyperlipidemia and hypothyroidism presented to the emergency department with a right-sided facial droop. Physical examination revealed a right-sided facial droop, inability to close the right eye, and impaired eyebrow raise. Signs of myxedema coma were not present. Initial non-contrast CT of the head showed no evidence of hemorrhage, and subsequent MRI of the brain was negative for acute ischemia. Laboratory evaluation demonstrated severe hypothyroidism, with a TSH of 270 µIU/mL, undetectable free T4 (< 0.10 ng/dL), and low T3 (0.39 ng/dL). The patient received three days of IV levothyroxine prior to the resumption of oral levothyroxine with mild improvement in symptoms, particularly ability to close the right eye. The presentation suggests cranial nerve VII palsy (Bell’s palsy) likely related to severe hypothyroidism due to nonadherence to thyroid hormone replacement therapy.

Discussion: Hypothyroidism is known to be associated with neurologic manifestations, though typical symptoms include lethargy, mood changes, or nerve entrapment. Most cases of Bell’s palsy are idiopathic, with a smaller portion viral or autoimmune in etiology. This case describes an instance where cranial nerve VII palsy was the presenting complaint in a patient with severe hypothyroidism. This highlights a rare association between two common concerns and demonstrates the need for clinicians to remain vigilant to the possibility of hypothyroidism underlying cranial nerve palsies.

Conclusions: Severe hypothyroidism, resulting from two to three months of medication nonadherence, was identified as the primary etiology of this patient’s facial nerve palsy. The patient quickly experienced mild improvement with resumption of thyroid replacement therapy. In future practice, the addition of thyroid function testing to the evaluation of cranial nerve VII palsy may be warranted in certain cases. Identification of hypothyroidism may provide an opportunity for efficient symptom relief for some patients.