Paramyotonia congenita or hyperkalemic periodic paralysis? Clinical and electrophysiological features of each entity in one family

Silva, Shari M. de; Kuncl, Ralph W.; Griffin, John W.; Cornblath, David R.; Chavoustie, Steven

doi:10.1002/mus.880130106

Cited by 46 publications

(10 citation statements)

References 24 publications

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“…By contrast, a family was reported in which individual members had clinical features of either hyperkalaemic periodic paralysis or paramyotonia congenita despite common electrophysiological features 9. An Ala1156Thr mutation was reported to be responsible for the development of hyperkalaemic periodic paralysis and paramyotonia congenita in one family 9…”

Section: Discussionmentioning

confidence: 99%

Phenotypic variation of a Thr704Met mutation in skeletal sodium channel gene in a family with paralysis periodica paramyotonica

Kim

Hahn²,

Sohn³

et al. 2001

Journal of Neurology, Neurosurgery &Amp; Psychiatry

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Objectives-Patients with paralysis periodica paramyotonica exhibit a clinical syndrome with characteristics of both hyperkalaemic periodic paralysis and paramyotonia congenita. In several types of periodic paralysis associated with hyperkalaemia, mutations in the skeletal muscle sodium channel (SCN4A) gene have been previously reported. Phenotypic variations of mutations in SCN4A, however, have not been described yet. The present study aimed to evaluate genetic variations in a family with clinical and electrophysiological characteristics of paralysis periodica paramyotonia. Methods-Seven members of a family affected with symptoms of paralysis periodica paramyotonia were studied by electrophysiological and genetic analyses. There were increased serum potassium concentrations in four members during paralytic attacks induced by hyperkalaemic periodic paralysis provocation tests. Short exercise tests before and after cold immersion were carried out in four patients to distinguish electrophysiological characteristics of hyperkalaemic periodic paralysis and paramyotonia. Sequencing analyses of SCN4A were performed on one patient and a normal control to identify polymorphisms. Restriction fragment length polymorphism (RFLP) analysis was then performed at the identified polymorphic sites. Results-Electrophysiological studies showed both exercise sensitivity and temperature sensitivity. Compound motor action potential (CMAP) amplitudes were decreased (7.3%-28.6%) after short exercise tests. The CMAP amplitudes were even more severely decreased (21.7%-56.5%) in short exercise tests after cold exposure. Three polymorphic sites, Gln371Glu, Thr704Met, and Aspl376Asn were identified in SCN4A. RFLP analyses showed that all aVected patients carried the Thr704Met mutation, whereas unaVected family members and a normal control did not. Conclusion-Phenotypic variation of the Thr704Met mutation, which was previously reported in patients with hyperkalaemic periodic paralysis, is described in a family aVected with paralysis periodica paramyotonia. (J Neurol Neurosurg Psychiatry 2001;70:618-623) Keywords: paralysis periodica paramyotonica; hyperkalaemic periodic paralysis; paramyotonia congenita; human skeletal muscle sodium channel (SCN4A) gene Patients with periodic paralysis exhibit recurrent episodes of skeletal muscle weakness followed by complete recovery.

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Section: Discussionmentioning

confidence: 99%

Phenotypic variation of a Thr704Met mutation in skeletal sodium channel gene in a family with paralysis periodica paramyotonica

Kim

Hahn²,

Sohn³

et al. 2001

Journal of Neurology, Neurosurgery &Amp; Psychiatry

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“…Variation in sensitivity could be explained by an incorrect diagnosis of periodic paralysis, by the influence of treatment, by the fluctuating nature of the disease with periodic improvements in muscle excitability, or by variations in the application of the method. Although exercise testing has been reported in several studies, [5][6][7][8][9] the factors affecting the responses were not specifically evaluated. The sensitivity of exercise tests for detecting asymptomatic carriers is also unknown.…”

Section: Discussionmentioning

confidence: 99%

The exercise test as a monitor of disease status in hypokalaemic periodic paralysis

Tengan

Antunes²,

Gabbai³

et al. 2004

Journal of Neurology, Neurosurgery & Psychiatry

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Objective: To evaluate exercise test responses in hypokalaemic periodic paralysis (HPP), to determine its value as a diagnostic tool and the factors that could affect the responses. Methods: 22 subjects were studied from two families with HPP caused by R528H mutation, four patients with thyrotoxic periodic paralysis, 15 normal controls, and four controls with hyperthyroidism. All family members were submitted to clinical evaluation, electrophysiological exercise testing, and DNA analysis. Patients with thyrotoxic periodic paralysis had exercise tests before and after treatment of their hyperthyroidism. Results: Abnormal responses to the exercise tests were obtained only in subjects with recent attacks of weakness. They were not correlated with genotype, as asymptomatic carriers were unaffected. Patients with thyrotoxic periodic paralysis showed pronounced impairment while they were hyperthyroid, but improved when they were euthyroid. One patient with HPP and chronic KCl use had an increase in amplitude potentials over ,20 minutes, possibly related to alteration of potassium homeostasis. Conclusions:The exercise test is a useful diagnostic test for periodic paralysis, but in the absence of recent weakness negative results must be viewed with caution. It has advantages over the DNA test in being a non-invasive functional test that can provide insights into abnormalities of muscle excitability.

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“…Studies of more families from different ethnic backgrounds might help to establish a correlation between genotype and phenotype, Once the precise alteration in the channel is identified, patch-clamp studies might improve our understanding of how this affects channel gating in both normal and diseased muscle, and available drugs such as mexiletine, potassium-sparing agents, carbonic anhydrase inhibitors, etc. might then be more specifically used [14,30] according to the channel involved and the degree of channel gating involvement [27].…”

Section: Discussionmentioning

confidence: 99%

“…Most PC patients demonstrate some degree of myotonic worsening with K + loading. However, in some cases the attacks of weakness are associated with normo-or hypokalemia [21], even though there are patients with the features of both HYPP and PC [24,27]. Electrophysiological investigations of HYPP and PC muscle in vitro have revealed an alteration in muscle membrane sodium conductance [26,15], suggesting that sodium channels are involved in the pathogenesis of periodic paralysis [ 16,12].…”

Section: Received 15 March 1994 -Accepted 11 July 1994mentioning

confidence: 99%

Mutation in the S4 segment of the adult skeletal sodium channel gene in an Italian Paramyotonia Congenita (PC) family

et al. 1994

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Paramyotonia congenita or hyperkalemic periodic paralysis? Clinical and electrophysiological features of each entity in one family

Cited by 46 publications

References 24 publications

Phenotypic variation of a Thr704Met mutation in skeletal sodium channel gene in a family with paralysis periodica paramyotonica

Phenotypic variation of a Thr704Met mutation in skeletal sodium channel gene in a family with paralysis periodica paramyotonica

The exercise test as a monitor of disease status in hypokalaemic periodic paralysis

Mutation in the S4 segment of the adult skeletal sodium channel gene in an Italian Paramyotonia Congenita (PC) family

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