title: Is thyrotoxic periodic paralysis a disease caused by muscle membrane dysfunction?
abstract: BACKGROUND
  Thyrotoxic periodic paralysis (TPP) is characterized by recurrent episodes of reversible paralysis with hyperthyroidism. It is clinically similar to hypokalemic periodic paralysis (HOPP), which features significant ion-channel dysfunction and reduced muscle fiber conduction velocity (MFCV). However, the muscle membrane function in TPP is not known.
  
  
  METHODS
  For 13 patients with TPP and 15 age-matched controls, clinical assessment and serial neurophysiological testing, including nerve conduction, prolonged exercise (PE) testing, and MFCV. were performed.
  
  
  RESULTS
  MFCV values were elevated up to 1 year from the paralytic attack in TPP patients. In the group with a positive PE test, MFCV values were higher. There was no significant relationship between MFCV values and either hypokalemia or hyperthyroidism.
  
  
  CONCLUSIONS
  Although clinical manifestations in TPP are similar to those observed in HOPP, TPP appears to feature an alternate pathogenic mechanism. Specifically, MFCV values increased rather than decreased. Further studies are needed to support these findings. Muscle Nerve, 2016 Muscle Nerve 56: 780-786, 2017.
authors.affiliation: Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 166 Gumi-Ro, Bundang-Gu, Seongnam-Si, Geonggi-Do, Seoul, Republic of Korea.
authors.forename: Yoo-Ri
authors.initials: YR
authors.lastname: Son
authors.affiliation: Department of Neurology, Dongguk University Ilsan Hospital, Goyangsi, Gyeonggido, Republic of Korea.
authors.forename: Nam-Hee
authors.initials: NH
authors.lastname: Kim
authors.affiliation: Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 166 Gumi-Ro, Bundang-Gu, Seongnam-Si, Geonggi-Do, Seoul, Republic of Korea.
authors.forename: Dong-Gun
authors.initials: DG
authors.lastname: Kim
authors.affiliation: Department of Neurology, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 166 Gumi-Ro, Bundang-Gu, Seongnam-Si, Geonggi-Do, Seoul, Republic of Korea.
authors.forename: Kyung-Seok
authors.initials: KS
authors.lastname: Park
mesh_terms: D000328:Adult; D006801:Humans; D006980:Hyperthyroidism / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D010245:Paralyses, Familial Periodic / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology*; D055815:Young Adult
keywords: electromyography; hypokalemic periodic paralysis; muscle fiber conduction velocity; prolonged exercise test; thyrotoxic periodic paralysis