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Title: Thyrotoxic periodic paralysis in Singapore
Authors: Cheah, J.S. 
Issue Date: 1978
Citation: Cheah, J.S. (1978). Thyrotoxic periodic paralysis in Singapore. Annals of the Academy of Medicine Singapore 7 (2) : 102-117. ScholarBank@NUS Repository.
Abstract: During a 5-year period 26 cases of thyrotoxic periodic paralysis (TPP) were studied. All were Chinese; this contrasts with the multiracial population of Singapore and the multiracial composition of the cases of thyrotoxicosis seen during the same period. Twenty-five (96.2%) were males and only 1 case (3.8%) was female. The mean age was 30 years while the age range was 18 to 46 years. The incidence of TPP among Chinese thyrotoxics was 6.0%; 19.2% among Chinese males with thyrotoxicosis and 0.3% among Chinese females with thyrotoxicosis. None of the patients had a familial history. The patients did not belong to any distinct occupational groups. Periodic paralytic attacks occurred throughout the year. The interval between 2 paralytic episodes ranged from 1 day to 7 months. In 20 cases (76.9.%) the onset of the thyrotoxicosis antedated that of paralysis while the reverse occurred in 3 cases (11.7%) and in one patient (3.8%) the onset of paralysis and thyrotoxicosis coincided. In 10 patients (38.5%) after sitting down for 2 to 3 hours to watch a cinema or television or to play 'mahjong', paralysis of the legs occurred. The onset of spontaneous paralysis was from 8 PM to 8 AM in 23 cases (88.5%). Without treatment, a spontaneous paralytic episode lasted 7 to 22 hours (mean 25 hours). Sweating was a prominent feature in 18 patients (69.3%) During paralysis, the severity of muscular weakness varied from slight to complete; the lower limbs were involved in all cases while the upper limbs were also involved in 16 cases (61.7%). During the height of paralysis, the tendon reflexes were absent in 14 patients (53.8%) while in the other 12 patients (46.2%) the tendon reflexes remained very brisk. The state of the tendon reflexes was not related to the severity of muscular weakness or hypokalaemia. Long-Acting Thyroid Stimulator (LATS) was present in 22.2% of TPP and in 22.2% of controls. During paralysis hypokalaemia was present in 25 cases (96.2%); the mean serum potassium was 2.5 MEq/L and the range was 1.6 to 3.5 MEq/L. The severity of hypokalaemia was related to the severity of muscular weakness. In 70% of the patients the potassium content of the skeletal muscles was increased during paralysis. The serum thyroxine was unchanged during paralysis but the serum triiodothyronine was significantly elevated. Light microscopy of the skeletal muscles during paralysis showed vacuolation in only 11.8%; there was no correlation between the histological changes and the severity of muscular weakness or hypokalaemia, the duratrion of thyrotoxicosis or periodic paralysis and the number of past episodes of paralysis. The main electron microscopic changes included vesicular dilatations, glycogen granules accumulation and changes in the mitochondria. There was no correlation between the severity of the ultrastructural changes and the severity of muscular weakness or hypokalaemia.
Source Title: Annals of the Academy of Medicine Singapore
ISSN: 03044602
Appears in Collections:Staff Publications

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