Multiple cranial nerve motor deficits, resembling polyneuritis cranialis, in a cat with hyperthyroidism

Area of Science:

• Veterinary Neurology
• Endocrinology

Background:

• Hyperthyroidism (HT) is a common endocrine disorder in older cats.
• Neurological manifestations of feline hyperthyroidism are typically associated with central nervous system effects or secondary complications like hypertension.

Observation:

• A 14+ year old domestic shorthair cat presented with acute onset of dysphagia, dysphonia, facial and ocular motor deficits, and tongue and jaw paresis.
• Clinical findings included a thyroid nodule, hypertension, cardiac murmur, and elevated thyroid hormone levels, confirming hyperthyroidism.
• Neurological examination revealed deficits in multiple cranial nerves (V, III, IV, VI, VII, IX, X, XI, XII), resembling polyneuritis cranialis.

Findings:

• Treatment with carbimazole followed by bilateral thyroidectomy led to rapid improvement and complete resolution of neurological signs within 100 days.
• This case represents the first description of multiple cranial nerve motor deficits in a cat with hyperthyroidism.

Implications:

• The findings suggest a thyrotoxic polyneuropathy selectively affecting cranial nerve motor function in cats with hyperthyroidism.
• Hyperthyroidism should be considered in the differential diagnosis for cats presenting with cranial nerve deficits.
• Successful management of hyperthyroidism can lead to significant recovery of neurological function.