Acute Onset Flaccid Quadriparesis With Hyperkalemia: An Unusual Presentation of Thyrotoxic Myopathy

Background: Thyrotoxic myopathy typically presents as chronic myopathy with proximal muscle involvement. Occasionally it can present as hypokalemic periodic paralysis. Acute thyrotoxic myopathy is rare, it presents acutely with flaccid quadriparesis or bulbar palsy, sometimes merging with thyrotoxic storm. Presentation of Acute thyrotoxic myopathy with flaccid quadriparesis in association with hyperkalemia is a very rare phenomenon and has not been reported previously, hence we wish to report this case. Case Presentation: A 35-year-old male presented with complaints of low back pain followed by acute onset quadriparesis. Patient had complaints of restlessness, increased sweating and significant weight loss for past 3-4 months. He had generalized hypotonia, areflexia and diminished power of grade 2/5 in upper limbs and 1/5 in lower limbs, both proximally and distally. Patient looked agitated and stare look was present, no other signs of ophthalmology were present. Goitre was absent. Thyroid function test revealed thyrotoxicosis with TSH <0.01mIU/l, free T4- 3.04 ng/dl and free T3- 7.27 pg/ml. 99mTc-pertechnate thyroid scan was suggestive of diffuse toxic goitre. Clinical presentation along with increased titres of TSH receptor antibody of 7.78 IU/l, confirmed diagnosis of Graves' Disease. Hyperkalemia along with Hyperuricemia was found with increased CPK levels suggestive of muscle injury. Urine for myoglobulin was negative. Acetylcholine receptor antibodies were negative. His EMG and NCV study of all four limbs were within normal limit. Burch-Wartofsky score was 25, suggestive of impending thyroid storm. Patient was started on antithyroid drugs, beta blocker and i.v. glucocorticoids along with anti-hyperkalemic and other supportive treatment. Patient improved significantly after treatment regaining full muscle power. Conclusion: Thyrotoxic myopathy should be considered during evaluation in patients having thyrotoxic symptoms presenting with acute flaccid quadriparesis.