We present the case of a 42 year old woman from Papua New Guinea with Graves' Disease, who presented with sudden onset of flaccid quadriparesis, facial diplegia and hypophonia in the setting of thyroid storm. Severe hypokalaemia (2.7mmol/L) was treated initially with aggressive intravenous potassium supplement, but responded quickly to the addition of Propranolol as part of the definitive management of the thyrotoxicosis. However, despite normalization of the serum potassium, the weakness persisted to include respiratory muscles, thus leading to intubation and ventilation. In the ICU, a combination of Carbimazole, Dexamethasone , Propranolol and Lugol's Iodine led to a rapid resolution of the biochemical thyrotoxicosis (FT4 57 reduced to 16 after 3 days). The weakness was slow to improve and predominantly affected proximal muscles in the lower limbs and bulbar muscles. CK was only mildly elevated, Acetylcholine Receptor antibodies were negative. Acid fast bacilli were identified in the sputum and pleural fluid to confirm active multi-drug resistant tuberculosis as the precipitant for the thyroid storm. She is being treated with a combination of six anti-tuberculous antibiotics.
Thyrotoxic1 periodic paralysis is a rare complication of thyrotoxicosis that usually affects Asian males and is characterized by sudden onset of hypokalaemia and weakness. The weakness typically responds quickly to normalization of the serum potassium, which is achieved with beta-blockers and anti-thyroid drugs. Thyrotoxic myopathy2 typically presents as proximal weakness which slowly recovers with resolution of the thyrotoxicosis. It rarely causes flaccid quadriparesis and bulbar muscle weakness.
Our patient presents with the combination of two very rare complications of thyrotoxicosis. The sudden onset of weakness and hypokalaemia was in keeping with thyrotoxic periodic paralysis, while the slow recovery of muscle function in association with normalization of thyroid function was typical of severe thyrotoxic myopathy. This is the first time this combination has been described.