Early to recognize and Early to recover: A case series on Thyrotoxic periodic paralysis

Thyrotoxic periodic paralysis (TPP) is a rare disease of muscle, presenting with sudden onset weakness of muscles with or without features of hyperthyroidism. The disease most commonly occurs in the Asian population representing about 1.9% of thyrotoxic patients. It involves a predominantly male population with no family history, with or without hypokalemia. Pathophysiology is still not clearly understood. We are describing, a case series of two different patients of TPP presented to our emergency department (ED). One patient presented with classical episodic weakness of both lower limbs specifically during the night times with spontaneous reversal of weakness early in the morning. Another patient presented with complete weakness of both lower limbs for the past 1 day. Both of them had a history of weight loss and intermittent palpitations. They were promptly diagnosed in the ED and successfully treated. We recommend evaluating thyroid function status in the emergency room with the aforementioned clinical features, as early recognition and correction of thyrotoxic state are the definitive treatment helping in a complete reversal of weakness. Potassium supplements, beta-blockers, and antithyroid medications are used in treating acute attacks and preventing recurrence

Debilidad muscular con hipokalemia e hipertiroidismo en un adolescente con síndrome de Down / Muscle weakness with hypokalemia and hyperthyroidism in an adolescent with Down syndrome

La hipokalemia aguda es una causa poco frecuente de debilidad muscular. La parálisis periódica tirotóxica es una complicación infrecuente de la tirotoxicosis, en sus diferentes etiologías, en la cual se produce hipokalemia por un flujo masivo de potasio al compartimiento intracelular, que provoca parálisis muscular, que afecta, principalmente, la musculatura proximal de los miembros inferiores. Es importante reconocer esta entidad para instaurar un tratamiento adecuado que incluya el rápido suplemento de potasio y el uso de beta-bloqueantes no selectivos. El tratamiento del hipertiroidismo subyacente y el retorno al estado eutiroideo es imprescindible para la resolución de los episodios de parálisis periódica tirotóxica. Aquí se presenta a un paciente de 13 años de edad con síndrome de Down que consultó por debilidad muscular de los miembros inferiores y trastorno de la marcha, asociada a hipokalemia aguda, en el que se realizó el diagnóstico de hipertiroidismo por enfermedad de Graves.

Acute hypokalemic paralysis is a rare cause of acute weakness. Thyrotoxic periodic paralysis (TPP) is an unusual complication of hyperthyroidism. It is characterized by sudden onset of hypokalemia condition resulting from a shift of potassium into cells and paralysis that primarily affects the lower extremities. Failure to recognize TPP may lead to improper management. Treatment of TPP includes replacing potassium rapidly, using nonselective beta-blockers and correcting the underlying hyperthyroidism as soon as possible. TPP is curable once euthyroid state is achieved. We describe a 13-year-old male with Down syndrome who presented with acute onset of lower extremity weakness secondary to acute hypokalemia and was found to have new onset Graves' disease.

A family with Andersen-Tawil syndrome induced by a new mutation Q164R in the KCNJ2 gene and previous literature review / 中华神经科杂志

Objective To discuss clinical characteristics of a family with Andersen-Tawil syndrome, test and analyze the mutation of their pathogenic gene, and to discover the dependency of genotype and phenotype by searching every reported Andersen-Tawil syndrome patient in all accessible literature worldwide.Methods In December 2nd,2016,two patients in the Department of Neurology,the First Hospital of Shanxi Medical University, received medical history data collection and relevant examinations.PCR and DNA sequencing were applied to detect ion channel diseases related genes such as SCN4A, CACNA1S, KCNJ2, KCNE3, KCNE4, KCNJ18, KCNJ5.Random selection of 200 healthy volunteers from Shanxi Medical University served as normal controls.Andersen-Tawil syndrome cases,which are accorded with statistical criteria in published literature, were collected.Their genotype and phenotype were analyzed and summarized.Results Clinical manifestation of the pre-confirmed patient and his father was accorded with diagnostic criteria of Andersen-Tawil syndrome.Prominent characteristics included ventricular arrhythmia, periodic paralysis, and dysmorphic features.The two patients had renal tubular acidosis.One of these two patients also had increased level of renin-angiotensin-aldosterone.New mutation Q164R in the KCNJ2 gene was found in these two patients.There was no report in any literature or any database that we could find about this gene mutation at present.The mutation was not found among other healthy family members and 200 healthy controls.In this study,we referenced 55 samples of Andersen-Tawil syndrome in 12 articles,in which 54 samples are KCNJ2 gene mutation,one is KCNJ5 gene mutation.We concluded a negative correlation between the onset age of periodic paralysis and the onset age of cardiac symptoms after a statistical analysis of these 54 patients with KCNJ2 gene mutation(rs=-0.698 1,P=0.005 5).The incidence of cardiac symptoms in patients of Andersen-Tawil syndrome with periodic paralysis was reduced(33.33%(14/42)vs 9/11, χ2=6.485,P=0.011).Men(96.00%(24/25))were found more likely to have periodic paralysis than women(65.52%(19/29); χ2=7.691,P=0.006).Women (64.29%(18/28))were found more likely to have cardiac symptoms than men(20.00%(5/25); χ2=10.545,P=0.001).Conclusions New mutation Q164R in the KCNJ2 gene is the cause of Andersen-Tawil syndrome,which could cause renal tubular acidosis.We speculate that the gene may play a role in the way of potassium regulating aldosterone.For women with the KCNJ2 gene mutation and the late-onset of periodic paralysis,it is important to take drug or manual intervention as early as possible to prevent the occurrence of cardiogenic adverse events.

Clinical phenotypes and pathological features in myopathies with tubular aggregates / 中华神经科杂志

Objective To summarize clinical phenotypes and pathological characteristics in myopathies with tubular aggregates (TAs).Methods We reviewed 5 697 patients who performed muscle biopsies in our department between January 2001 and July 2015.We collected the cases with TAs and made classification based on their clinical diagnoses and pathological changes.Results Fifty-seven patients (1.00％) showed TAs in muscle specimens,including 50 (87.72％) males and 7 (12.28％) females.According to clinical,neurophysiological,pathological and genetic analysis,the diagnoses included 23 (40.35％) cases of periodic paralysis,7 (12.28％) cases of chronic alcohol intoxication,6 (10.53％) cases of congenital myasthenic syndrome,5 (8.77％) cases of exercise-induced cramps,3 (5.26％) cases of necrotizing myopathy,1 (1.75％) case of stromal interaction molecule 1-associated myopathy,limbgirdle muscular dystrophy 2E,myotonic dystrophy,myotonia congenita,paramyotonia congenitia,hypothyroid myopathy respectively.Other cases of unknown cause included unclassified distal myopathy,external ophthalmoplegia,white matter lesions,mental retardation,stroke,early onset weakness,pulmonary arterial hypertension.Besides TAs,pathological changes also included necrosis of muscle fibers (3 cases,5.26％),neurogenic changes (3 cases,5.26％) and muscular dystrophic changes (1 case,1.75％).Conclusions Our results indicated that TAs are usually found in males and could present in many types of hereditary or acquired neuromuscular disease as independent or accompanying changes.Periodic paralysis,chronic alcohol intoxication and congenital myasthenic syndrome are 3 major diseases causing myopathies with TAs.

Clinical Diversity of SCN4A-Mutation-Associated Skeletal Muscle Sodium Channelopathy

BACKGROUND AND PURPOSE: Mutations of the skeletal muscle sodium channel gene SCN4A, which is located on chromosome 17q23-25, are associated with various neuromuscular disorders that are labeled collectively as skeletal muscle sodium channelopathy. These disorders include hyperkalemic periodic paralysis (HYPP), hypokalemic periodic paralysis, paramyotonia congenita (PMC), potassium-aggravated myotonia, and congenital myasthenic syndrome. This study analyzed the clinical and mutational spectra of skeletal muscle sodium channelopathy in Korean subjects. METHODS: Six unrelated Korean patients with periodic paralysis or nondystrophic myotonia associated with SCN4A mutations were included in the study. For the mutational analysis of SCN4A, we performed a full sequence analysis of the gene using the patients' DNA. We also analyzed the patients' clinical history, physical findings, laboratory tests, and responses to treatment. RESULTS: We identified four different mutations (one of which was novel) in all of the patients examined. The novel heterozygous missense mutation, p.R225W, was found in one patient with mild nonpainful myotonia. Our patients exhibited various clinical phenotypes: pure myotonia in four, and PMC in one, and HYPP in one. The four patients with pure myotonia were initially diagnosed as having myotonia congenita (MC), but a previous analysis revealed no CLCN1 mutation. CONCLUSIONS: Clinical differentiating between sodium-channel myotonia (SCM) and MC is not easy, and it is suggested that a mutational analysis of both SCN4A and CLCN1 is essential for the differential diagnosis of SCM and MC.

A paralysis periodica paramyotonia congenital pedigree: clinic and molecular genetic studies / 中华神经科杂志

Objective To report clinical symptoms of a Chinese pedigree of familial paramyotonia congenital (PMC) with progressive myopathy (PM), and investigate the mutations of hot spots in the adult skeletal muscle sodium channel α-subunit (SCN4A). Methods The medical history and clinical phenotype of the patients from this large family with PMC were collected. Insertional and spontaneous activity were recorded by routine electromyograph (EMG), and the exercise test (ET) and cool water test were also performed on some patients during episodes. The mutations of SCN4A were screened by PCR-SSCP and DNA sequencing in affected and unaffected members. Results The family is a four-generation kindred with 15 members affected by severe, homogeneous paralysis periodiea paramyotoniea pheuotype. The onset was early, and almost all patients developed severe progressive myopathy by middle age. Routine EMG shows myotonia discharge in all affected subjects. The compound remarkably motor action potential (CMAP) decreased more than 40% after ET with greater decreases in cool water test than in ET. The mutation screening study revealed a missense mutation (Met1592Val) in SCN4A in patients. Conclusions Autosomal dominant inheritance pattern with complete penetrance was observed in this family. The phenotype is in accord with that reported in other ethnic populations with more severe symptoms. The ET and cool water tests may be used as an easy and reliable diagnostic method. Our research supports that periodic paralysis and paramyotonia can be caused by the same mutation in SCN4A. Mutation Met1592Val is a hotspot for mutation screening in patients with PMC accompanied by PM in the Chinese population.

Clinical features of hypokalemic periodic paralysis / 北京大学学报(医学版)

Objective: To explore the clinical features of hypokalemic periodic paralysis, and compare clinical features of primary group with those of thyrotoxicosis secondary group. Methods: Clinical data of 44 patients with hypokalemic periodic paralysis in Peking University First Hospital from 1996 December to 2008 December were retrospectively analyzed. Results: There were 22 patients in primary group, and 22 in thyrotoxicosis group. Identical clinical features of both the groups; (1 ) It had a predilection in young men. (2)Main symptoms were limb movement disorder and fatigue, and paralysis recurrent attacked in most patients. (3) 40. 9% to 68. 2% patients had obvious incentives, and the common ones were a heavy meal, sweet drinks, or strenuous'exercise. (4) Serum potassium levels of the two groups were obviously lower than the normal range. (5) In 20% patients of primary group and 25% patients of thyrotoxicosis secondary group, CK levels were higher than normal, while LDH and HBDH levels were normal.(6) The doses of potassium replishment were not correlated to serum potassium levels at the onset. Different clinical features of the two groups; (1) Patients of thyrotoxicosis group had hypermetabolism symptoms and thyroid dysfunction. Patients of primary group had no hypermetabolism symptoms, and all of them were euthyroid. (2) Serum potassium levels of thyrotoxicosis secondary group were lower than those of primary group significantly [(2.25±.67) vs (2.78±.49) mmol/L, P=0;007]. (3) Hyperkalemia is easier than primary group to rebound in thyrotoxicosis secondary group, after replenishment of potassium. Conclusion: Hypokalemic periodic paralysis has its clinical features, and patients with early diagnosis and replenishment of potassium in time have good prognosis. The doses of potassium replenishment are not determined by serum potassium levels at the onset. Hyperkalemia is easier to rebound in thyrotoxicosis secondary group after replenishment of potassium, serum potassium levels should be monitored closely, and hyperthyrosis radically cured.

Analysis of 8 Children with Familial Periodic Paralysis and Literature Review / 实用儿科临床杂志

Objective To understand well this disease,8 children with familial periodic paralysis(FPP) were reported and the(rela)-ted literatures were reviewed.Methods The hereditary characters,clinical manifestations,auxiliary examination and managements were summarized retrospectively in 8 cases of FPP patients hospitalized from January 1996 to December 2005,and etiopathogenis and diagnosis were also analyzed.Results Six cases of FPP were diagnosed as hypokalemic periodic paralysis,and all occured as an autosomal dominant condition.During paralytic episodes,the patients showed obviously low serum potassium levels [1.9-2.8 mmol/L,(2.4?0.38) mmol/L)] and hypokalemic electrocardiogram findings,such as U-wave.The level of blood glucose was lower than normal range.Other 2 cases with normal serum potassium ion level at attack were diagnosed as normokalemic periodic paralysis with autosomal dominant pattern.One of the two cases,the level of blood glucose was lower.Thyroid functions,renal functions and electromyograms were all normal in 8 cases.Conclusions FPP is a group of relatively uncommon inherited disorders known as the skeletal muscle channelophathies.It can be diagnosed by hereditary characters,clinical manifestataions,auxiliary examinations.

Genetics of Channelopathy: Familial Periodic Paralysis

Familial periodic paralysis (FPP) is inherited as a dominant trait, and the intermittent failure to maintain the skeletal muscle resting potential is due to mutations in the genes coding for the voltage-gated ion channels. Because several variants of FPP have been delineated on the bases of clinical features, the expectation was that these variants might be due to involvement of different classes of ion channels. The reality of the situation has proven to be more complicated. Mutation-induced defects in the same channel may give rise to diverse phenotypes (phenotypic heterogeneity) and, conversely, mutation in different channel genes may produce a common phenotype (genetic heterogeneity). Regardless of which type of ion channel is defective, the final common pathway is the depolarization-induced loss of muscle excitability; gain-of-function defect in voltage-gated Na channel may cause myotonia, periodic paralysis or both, clinical features of hyperkalemic periodic paralysis and paramyotonia congenita, and loss-of-function defects in voltage-gated Na and Ca channel and K channel may be responsible for periodic paralysis, cardiac arrhythmia or both in hypokalemic periodic paralysis or Andersen's syndrome, respectively. This review focuses on the clinical features, molecular genetic defects, and pathophysiologic mechanisms that underlie FPP.

The detection of a novel mutation by screening SCN4A gene in normokalemic periodic paralysis / 中华神经科杂志

Objective To detect a novel mutation in SCN4A gene related to normokalemic periodic paralysis (normoPP) in one Chinese family.Methods Genomic DNA of two patients and their relatives in this family was extracted from peripheral blood leukocytes and amplified by polymerase chain reaction (PCR). All 24 exons of SCN4A gene were screened with denaturing high performance liquid chromatography (DHPLC) technology,and then sequence analysis of those DHPLC chromatograms showing heteroduplex were compared with the unaffected controls.Results Routine laboratory tests were carried on within normal ranges with the exception of an elevated creatine kinase (1126 U/L,normal