Physiotherapy Strategies in Hypokalemic Periodic Paralysis: A Case Report

The rare neuromuscular disease known as hypokalemic periodic paralysis (hypoKPP), which results in severe muscle weakness in the extremities, is brought on by abnormalities in potassium transport within cells. Laboratory testing is confirmatory, which reveals notably low potassium levels, causing paralysis, which improves once the low potassium is restored. The patient generally complains of muscle weakness with difficulty in performing activities of daily living and impaired participation in functional tasks, with few suffering from coexisting sensory impairments. Physiotherapy generally plays a symptomatic role with motion exercises for the affected muscle groups. There is no standardized physiotherapy protocol for disease-specific impairments. A 46-year-old man complained of bilateral upper and lower limb muscular weakness and was admitted to the neurology ward. The patient also complained of having tingling numbness throughout their entire limbs and had experienced similar episodes of symptoms six months prior. During laboratory evaluation, a significantly low potassium level was found, leading to a diagnosis of hypoKPP. Following medical management, neurophysiotherapy was initiated. Physiotherapy strategy shows significant improvement in muscular strength and functional activities. Thus, this case report concludes that physiotherapy plays a vital role in managing hypoKPP by enhancing muscular strength, functional activities, and quality of life.

A Rare Case of Hypokalemic Periodic Paralysis With Acute Urinary Retention: Diagnosis and Management

Hypokalemic periodic paralysis (hypoPP) is a rare channelopathy caused by mutations in skeletal muscle ion channels that usually occurs in young individuals and adolescents. The etiology can be attributed to various factors, such as idiopathic or secondary causes. It is characterized by episodes of sudden flaccid muscle weakness. Timely detection may mitigate the risk of severe complications. Secondary causes of hypoPP, such as hyperthyroidism, should be ruled out, as this could lead to thyrotoxic periodic paralysis. We report the case of a 19-year-old boy who presented to the ED with severe weakness in both the upper and lower extremities. The weakness rapidly progressed to his trunk and was accompanied by acute urinary retention. The physical examination was significant for bilateral upper and lower extremity weakness. Subsequent laboratory investigations revealed markedly low serum potassium levels. The patient's symptoms resolved after the replacement of potassium, and he was discharged without neurological deficits. Although rarely accompanied by acute urinary retention, hypoPP must be differentiated from other causes of weakness and paralysis so that the proper treatment can be initiated quickly. The rarity of hypoPP, a condition seldom encountered in clinical practice, and the added rarity of its coexistence with acute urinary retention further underscore the uniqueness of this case report.

Case report: A novel CACNA1S mutation associated with hypokalemic periodic paralysis

Background

Hypokalemic periodic paralysis (HypoKPP) is a rare neuromuscular genetic disorder causing recurrent episodes of flaccid paralysis. Most cases are associated with CACNA1S mutation, causing defect of calcium channel and subsequent impairment of muscle functions. Due to defined management approaches early diagnosis is crucial for promptly treatment and prevention new attacks.

Materials and methods

We report a case of HypoKPP associated with previously unreported mutation in CACNA1S gene (p.R900M). Molecular modeling of CaV1.1 was applied to evaluate its pathogenicity.

Results

As a patient referred between attacks neurological status, laboratory and neurophysiological examination were unremarkable. Molecular modeling predicted that the p.R900M mutation affects the process of calcium channels activation.

Conclusion

Novel CACNA1S mutation, associated with HypoKPP was identified. Monte-Carlo energy minimization of the CaV1.1 model supported the association of this mutation with this disease.

An Instance of Hypokalemic Periodic Paralysis in Adolescent Brothers: A Case Report

Hypokalemic periodic paralysis (HypoPP) is a rare autosomal dominant disease caused by mutations in either calcium or sodium transmembrane voltage-gated ion channels of skeletal muscle or endoplasmic reticulum. Most cases of HypoPP are associated with a mutation in the gene encoding a calcium channel, the CACNA1S gene. Mutations in the channels create leakage currents that disrupt resting potential and depolarize the muscle fiber resulting in transient flaccid paralysis and low extracellular potassium (K+). Patients experience episodes of muscle paralysis typically provoked by exertion and diet. Treatment focuses on the prevention of such episodes with carbonic-anhydrase inhibitors or potassium-sparing diuretics as well as to treatment of acute episodes with oral K+ supplementation. Due to the rarity of the disease, the literature surrounding the disease and pharmacological management is limited. We present a case of two adolescent brothers who present with a confirmed diagnosis of periodic episodes of paralysis and are seeking treatment. Both brothers experience paralytic episodes provoked by acute changes in diet and exercise. However, the lack of literature and treatment guidelines surrounding the disease emphasizes the importance of documenting cases and the effectiveness of treatment outcomes. Additionally, it reminds providers to keep HypoPP on the differential when faced with a young patient experiencing paralytic episodes.

How is Guillain-Barre syndrome associated with COVID-19 infection differentiated from hypokalemic periodic paralysis? a case report

Patients with coronavirus disease 2019 (COVID-19)-associated Guillain-Barre syndrome (GBS) exhibit a range of clinical symptoms, such as cranial nerve paralysis and axonal or motor-sensory electrophysiological signals.

Case presentation

A 61-year-old retired black African female was brought into the emergency room on 13 May 2022, with a 4-day history of shortness of breath and high-grade fever and a 1-day history of global body weakness (bilateral paralysis of the upper and lower extremities). Motor examination indicated reduced muscular strength in all limbs, with a Medical Research Council score of 2/5 in the right arm of the upper extremities, 1/5 in the right leg of the lower extremities, 1/5 in the left leg of the lower extremities, and 2/5 in the left arm of the upper extremities. Her electrocardiogram revealed ST depression in the anterior-lateral leads and sinus tachycardia. For the COVID-related infection, azithromycin 500 mg per day for 5 days was begun. After cerebrospinal fluid findings supported the diagnosis of GBS, she underwent intravenous immunoglobulin 400 mg/kg every day for 5 days.

Clinical discussion

In the majority of COVID-19-related GBS cases, areflexic quadriparesis developed suddenly. A COVID-19 infection related to a GBS case was the only one that had preceding signs, including ageusia and hyposmia. By testing serum potassium levels, this study determined that there is no connection between GBS and hypokalemia, which can lead to diagnostic and therapeutic conundrums by evaluating serum potassium levels, which showed a normal value.

Conclusion

One of the neurological symptoms of the COVID-19 infection is GBS. Several weeks after a COVID-19 acute infection, GBS is frequently observed.

A Case of Sudden-Onset Flaccid Paralysis In a Previously Healthy Person

Flaccid paralysis is a neurological syndrome characterized by weakness and paralysis of the limbs, followed by reduced muscle tone. Common causes of flaccid paralysis include blockage of the anterior spinal artery, trauma to the spinal cord, cancer, arterial disease, or thrombosis. A potential differential diagnosis in a 35-year-old male presenting with sudden-onset flaccid paralysis with no history of trauma is hypokalemic periodic paralysis. Treatment with potassium can alleviate symptoms in affected patients. .

Case report: SCN4A p.R1135H gene variant in combination with thyrotoxicosis causing hypokalemic periodic paralysis

Hypokalemic periodic paralysis (HPP) is a heterogeneous group of diseases characterized by intermittent episodes of delayed paralysis of skeletal muscle with episodes of hypokalemia, caused by variants in CACNA1S or SCN4A genes, or secondary to thyrotoxicosis, Sjogren syndrome, primary aldosteronism, etc. HPP may be the only presentation in Andersen-Tawil syndrome in which the majority of cases are caused by pathogenic variants in the KCNJ2 gene. We present a case of a 29-year-old male with hypokalemic periodic paralysis. The patient began to experience recurrent weakness of the extremities at the age of 26, which was effectively treated with potassium supplementation. He had recently developed dry mouth, palpitations, weight loss, and even dyspnea, with a serum potassium level as low as 1.59 mmol/L. The results of auxiliary examinations showed Graves' disease, and genetic testing indicated a missense variant, NM_000334.4 (SCN4A):c.3404G>A (p.R1135H). He did not experience periodic paralysis during follow-up after lifestyle guidance and treatment of thyrotoxicosis with radioactive iodine. It is a rare case of SCN4A p.R1135H gene variant combined with hyperthyroidism resulting in HPP with respiratory muscle paralysis to raise awareness of the disease and avoid misdiagnosis and missed diagnosis.

Periodic paralysis due to cumulative effects of rare variants in SCN4A with small functional alterations

INTRODUCTION/AIMS

Mutations in the SCN4A gene encoding a voltage-gated sodium channel (Nav1.4) cause hyperkalemic periodic paralysis (HyperPP) and hypokalemic periodic paralysis (HypoPP). Typically, both HyperPP and HypoPP are considered as monogenic disorders caused by a missense mutation with a large functional effect. However, a few cases with atypical periodic paralysis phenotype have been caused by multiple mutations in ion-channel genes expressed in skeletal muscles. In this study we investigated the underlying pathogenic mechanisms in such cases.

METHODS

We clinically assessed two families: proband 1 with HyperPP and proband 2 with atypical periodic paralysis with hypokalemia. Genetic analyses were performed by next-generation sequencing and conventional Sanger sequencing, followed by electrophysiological analyses of the mutant Nav1.4 channels expressed in human embryonic kidney 293T (HEK293T) cells using the whole-cell patch-clamp technique.

RESULTS

In proband 1, K880del was identified in the SCN4A gene. In proband 2, K880del and a novel mutation, R1639H, were identified in the same allele of the SCN4A gene. Functional analyses revealed that the K880del in SCN4A has a weak functional effect on hNav1.4, increasing the excitability of the sarcolemma, which could represent a potential pathogenic factor. Although R1639H alone did not reveal functional changes strong enough to be pathogenic, Nav1.4 with both K880del and R1639H showed enhanced activation compared with K880del alone, indicating that R1639H may modify the hNav1.4 channel function.

DISCUSSION

A cumulative effect of variants with small functional alterations may be considered as the underpinning oligogenic pathogenic mechanisms for the unusual phenotype of periodic paralysis.

Hypokalemic Periodic Paralysis Secondary to Medullary Sponge Kidney Complicated With Renal Tubular Acidosis

Hypokalemic periodic paralysis has a high risk of life-threatening dysrhythmias. Hyperchloremic acidosis with hypokalemia is a dangerous condition. There are several causes of hypokalemia, in addition to common diseases, such as hyperthyroidism, hyperaldosteronism, and Cushing’s syndrome; the other rare diseases include renal tubular acidosis (RTA), Bartter’s syndrome, and Gitelman’s syndrome. We present an unusual case of hypokalemic periodic paralysis, which was caused by a medullary sponge kidney with distal RTA. The patient had no significant medical history and was not taking any conventional drugs. Investigations demonstrated a combination of hypokalemia, hyperchloremia, metabolic acidosis with a normal anion gap, relatively raised urinary pH, and decreased phosphate level. Results suggested a diagnosis of RTA with secondary hyperparathyroidism. After potassium citrate replacement and correction of acidosis, the patient’s condition was in remission. This case highlights the rare etiology of hypokalemia and the need to actively search for the pathogenesis of unexplained hypokalemia to avoid delaying the condition.

Lidocaine Ineffectiveness Suggests New Psychopharmacology Drug Target

Objectives

The mechanism of many neuropsychiatric disorders remains unknown, but the ineffectiveness of the sodium channel blocker lidocaine has been suggested to be a biomarker for Attention Deficit Hyperactivity Disorder (ADHD) and a severe form of Premenstrual Syndrome (PMS) that is considered psychiatric. We conducted single-arm double-blind clinical trials to test whether lidocaine ineffectiveness can be used as a biomarker to identify people with these conditions and provide a clue as to the molecular mechanism and potential psychopharmacological intervention.

Experimental Design

We developed a noninvasive taste test for lidocaine ineffectiveness, validated by comparing lidocaine injections to pain testing in 12 subjects, and assessed it in individuals with ADHD and PMS.

Principal Observations

Lidocaine ineffectiveness had a strong association in women with ADHD + PMS in a sample of 53 subjects and controls (p < 0.001).

Conclusions

These results suggest the possibility of the biological understanding of the combination of ADHD and PMS that is characteristic of the psychiatric disorder Premenstrual Dysphoric Disorder (PMDD). These results and comparison to family pedigrees of a neuromuscular channelopathy with overlapping symptoms suggest the possibility that the clinical phenotype in PMDD is produced by sensory overstimulation, and amenable to molecular understanding and treatment.

Hyperemesis Gravidarum Presenting as Severe Hypokalemic Periodic Paralysis and Type II Respiratory Failure: A Different Form of Thyroid Storm?

Hyperthyroidism in pregnancy is a condition that results from an excess of beta-human chorionic gonadotropin hormone resulting in gestational thyrotoxicosis. This thyrotoxicosis of pregnancy might be linked with hyperemesis gravidarum and is usually a self-limiting disease. Hyperthyroidism can cause hypokalemic periodic paralysis, which presents as pure motor areflexic flaccid paralysis. In severe cases, it may involve respiratory muscles and cause hypercapnic respiratory failure requiring invasive ventilation. A positive feed-forward cycle of hypokalemia could be triggered by the loss of function of inward rectifier potassium channel 18 (Kir2.6) along with the increased activity of sodium, potassium-adenosine triphosphatase (Na⁺/K⁺-ATPase). Hyperthyroid periodic paralysis is characterized by biochemical hyperthyroidism, normal urine potassium excretion, and electrocardiography abnormalities.

We report a case of a 23-year-old female (G2P0L0A1) who had severe hyperemesis gravidarum and later on developed flaccid quadriplegia. Her thyroid profile revealed hyperthyroidism. She later developed hypercapnic respiratory failure and was managed by potassium replacement and invasive ventilation.

Atypical Fracture of Femur in Association with Familial Hypokalemic Periodic Paralysis: A Case Report

INTRODUCTION

Hypokalemic periodic paralysis (HPP) is an important and a reversible but rare cause of paralysis. Periodic paralyses are of two types. The first one is primary which is also known as familial type and the second one is secondary periodic paralysis which is due to other underlying pathologies [1]. Important secondary causes can be categorized as metabolic, infectious and losses from the body, etc. [2]. HPP associated with bony abnormalities in form of spontaneous atypical fractures in femoral shaft with coxa vara is an unusual presentation.

CASE REPORT

Here is a case report of 26 year old lady who presented with pain in the proximal part of right thigh and weakness in both the upper and the lower limbs. She was diagnosed as familial HPP (FHPP) with atypical fracture of proximal third diaphysis of femur. Confirmation of the expected diagnosis was done with history, laboratory tests, and plain radiographs. Previously also, she had similar episode of weakness and opposite side femur atypical fracture.

CONCLUSION

Association of atypical femur diaphysis fracture and FHPP is a rare presentation of an uncommon disease but should be kept in mind whenever treating any HPP patient. The patient complaining of pain in limbs should be taken seriously as atypical fractures are prone to be missed. In future, further genetic studies are required to establish this rare association.

Osteoporosis Complicating Renal Tubular Acidosis in Association With Sjogren's Syndrome

Chronic metabolic acidosis increases alkali mobilization from the bone and promotes the development of osteoporosis. We report the case of a 35-year-old Caucasian female who presented for surgical fixation of a left femoral fracture sustained six months previously from a ground level fall with known primary hypothyroidism (for 12 years, on thyroxine replacement) with history of hypokalemia for the last 13 years (on regular oral potassium supplements). There was no history of fracture in past. There was no history of renal stones. There was positive history of hypokalemic periodic paralysis twice in past (12 and 13 years back). There was no history of recurrent oral or ocular ulcers. On examination there was no uveitis, oral ulcers, lacrimal or parotid gland enlargement. Upon workup the patient was diagnosed with left-sided femur fracture (neck) and was admitted for surgical management. She underwent left dynamic hip screw fixation under general anesthesia which she tolerated well. Upon further workup she had normal anion gap with hyperchloremic metabolic acidosis, low vitamin D level and dual-energy x-ray absorptiometry (DEXA) scan revealed osteoporosis at femur and hip joint. Vitamin D was replaced, she was started on Ibandronate and calcium supplements. Her further workup revealed positive anti-SSA. Our final clinical diagnosis in this case is possible or incomplete Sjogren's syndrome causing type-1 renal tu-bular acidosis (RTA; distal RTA) with osteoporosis.

Hyperemesis Gravidarum With Paraparesis and Tetany

Subacute-onset muscle weakness can result from channelopathies, inflammatory myopathies, thyroid dysfunction, hypoparathyroidism, vitamin D deficiency, and dyselectrolytemias like hypokalemia, hypocalcemia, and hypomagnesemia. We report a curious and extremely rare case of a 29-year-old woman with hyperemesis gravidarum presenting with disabling muscle weakness involving her lower limbs and trunk, and concurrent features of tetany. Following voluminous vomiting over the last two months, she presented with history of weakness of her lower limbs of 14 days duration, resulting in difficulty in her getting out of bed or walking unassisted. On examination, she was hypotensive (80/60 mmHg) and tachycardic (110 bpm), with flaccid weakness of her lower limbs (proximal weakness more than distal weakness - power of 1/5 at the hips bilaterally, and 3/5 at the knees and ankles bilaterally) and diminished deep tendon reflexes. She also had positive Trousseau’s sign and Chvostek’s sign. Interestingly, she also had thinned-out bluish sclerae, a high-arched palate, short stature, and bilateral conductive hearing loss. Laboratory evaluation revealed anemia, hyponatremia, hypokalemia, hypomagnesemia, hypochloremia, hypophosphatemia, and low vitamin D levels. Electrocardiogram showed prolonged QT interval. Her thyroid function test and parathyroid levels were normal. With parenteral replenishment of the electrolytes and vitamin D, her power improved and she was discharged on oral supplements. Thus, this case report demonstrates the importance of aggressive, early, and adequate management of hyperemesis gravidarum to prevent dyselectrolytemia-associated paraparesis.

Thyrotoxic Periodic Paralysis in a Young Hispanic Male With Newly Diagnosed Grave's Disease

Thyrotoxic periodic paralysis (TPP) is a unique cause of hypokalemia from transcellular shift into muscle in the setting of active thyrotoxicosis. It is essential to recognize TPP, given the specific management considerations, which would otherwise easily go unaddressed. TPP can also be clinically indistinguishable from other causes of hypokalemia. In particular, familial periodic paralysis can present similar to TPP. This case illustrates a young Hispanic male who presented with paralysis and was found to be hypokalemic. Patient was also found to have thyromegaly with further testing consistent with Grave's disease, despite no hyperthyroid symptoms. Ultimately, identifying TPP early will allow for swift and appropriate treatment, avoid unnecessary interventions and testing, and reduce cost of care.

A Case of Hypokalemic Periodic Paralysis in a Young Athlete

Hypokalemic periodic paralysis (HPP) is one of the group muscle disorders that can cause sudden onset paresis or paralysis. It is a quite rare, yet, potentially life-threatening condition that, if appropriately and promptly diagnosed and treated, can be completely reversed. Other forms of periodic paralysis include thyrotoxic periodic paralysis, hyperkalemic periodic paralysis, and Anderson syndrome. We are presenting a case of a young male who presented to the emergency department (ED) with sudden paralysis to shed light on such a diagnosis and on other differential diagnoses.

A 29-year-old Bodybuilder with Liothyronine-induced Thyrotoxic Hypokalaemic Periodic Paralysis

We describe a 29-year-old male bodybuilder with recurrent attacks of myalgia and muscle weakness associated with hypokalaemia and thyrotoxicosis due to abuse of liothyronine. The attacks quickly resolved after potassium supplementation and liothyronine cessation. We concluded that the patient had thyrotoxic hypokalaemic periodic paralysis (TPP). Although muscle weakness and hypokalaemia are prominent symptoms of TPP, underlying thyrotoxicosis may be overlooked. Up to 25% of androgen abusers also abuse thyroid hormone. Lack of recognition of thyroid hormone abuse as a cause of hypokalaemic periodic paralysis may result in unnecessary, potentially harmful medical investigations and improper treatment and advice.

LEARNING POINTS

In patients with bouts of muscle weakness and hypokalaemia, thyrotoxic hypokalaemic periodic paralysis should be suspected and thyroid function should be evaluated.In bodybuilders and strength athletes, undisclosed abuse of performance and image-enhancing drugs, including thyroid hormone, should be suspected.

Thyrotoxic Hypokalemic Periodic Paralysis: A Success Story of a Diagnostic Challenge

Thyrotoxic hypokalemic periodic paralysis (THPP) is a rare but life-threatening complication of hyperthyroidism seen predominantly in males. It is generally characterized by hypokalemia and skeletal muscle paralysis requiring intensive care admission. Hypokalemia occurs due to the massive intracellular shift of potassium because of the hyperactivity of the sodium-potassium adenosine triphosphates pump (Na⁺ K⁺ ATPase). Its differential diagnosis from the other common causes of hypokalemic paralysis is essential to provide targeted therapy. We present a rare case of THPP in a female patient with no prior history of thyroid disease. THPP in this patient was precipitated by trauma and emotional stress, which served as a diagnostic challenge. Both hypokalemia and elevated levels of T3 and T4 are important diagnostic features during the acute episode. Treatment of THPP includes nonselective beta-blockade, which prevents the shift of intracellular potassium, and potassium replacement. THPP is curable once a euthyroid state is achieved.

A rare case of cephalexin-induced acute interstitial nephritis with hypokalemic periodic paralysis

Drug-induced acute interstitial nephritis (AIN) is often encountered in clinical practice. Cephalexin is a first-generation cephalosporin with antimicrobial sensitivity ranging from Gram-positive to Gram-negative organisms. Cephalexin-induced AIN presenting with hypokalemic periodic paralysis (HPP) has been rarely reported. A 34-year-old female with recent history of oral cephalexin intake presented with acute onset paraplegia with deranged renal parameters and hypokalemia. She was treated conservatively with mechanical ventilator support. HPP could be a rare clinical presentation for cephalexin-induced AIN.

Association study in Mexican patients with thyrotoxic hypokalemic periodic paralysis

Hypokalemic periodic paralysis type 1 (OMIM; HOKPP1) and type 2 (OMIM; HOKPP2) are diseases of the muscle characterized by episodes of painless muscle weakness, and is associated with low potassium blood levels. Hyperthyroidism has been associated with thyrotoxic periodic paralysis (TTPP) (OMIM; TTPP1 and TTPP2), and genetic susceptibility has been implicated. In the present study, the clinical and epidemiological characteristics of patients with TTPP are described, together with their association with genetic variants reported previously in other populations. A prospective and a retrospective search of the medical records of patients who attended the emergency department at the Hospital Universitario ‘Dr. Jose E. Gonzalez’ in Monterrey, Nuevo León, Mexico, and were diagnosed with TTPP was performed. A total of 16 gene variants in the genes MUC1, CACNA1S, KCNE3 and SCN4A, and nine ancestry informative markers (AIMs), were analysed by Multiplex TaqMan™ Open Array assay, and a genetic association study was performed. A total of 11 patients were recruited, comprising nine males and two females (age range, 19-52 years) and 64 control subjects. Only two cases (18%) had a previous diagnosis of hyperthyroidism; the rest were diagnosed subsequently with Graves' disease. Based on the analysis, two DNA variants were found to potentially confer an increased risk for TTPP: S1PR1 rs3737576 [odds ratio (OR), 4.38; 95% confidence interval (CI), 1.08-17.76] and AIM rs2330442 (OR, 4.50; 95% CI, 1.21-16.69), and one variant was suggested to be possibly associated with TTPP, namely MUC1 rs4072037 (OR, 3.08; 95% CI, 0.841-1.38). However, there were no statistically significant associations between any of the 24 DNA variants and TTPP in a population from northeast Mexico.

Unusual Clinical Presentation of Periodic Paralysis: Case Report and Literature Review

We are presenting a case of hypokalemic paralysis in a patient who presented to the emergency department (ED) with a unique clinical picture that did not fully fit with other causes of periodic paralysis (hypokalemic periodic paralysis, thyrotoxic periodic paralysis, hyperkalemic periodic paralysis, and Anderson syndrome). The patient presented to the ED complaining of two days of severe flaccid paralysis in both legs and left arm; his right arm was completely normal. Initially, he was treated as a stroke alert patient and had head and spine computed tomography (CT) scans and both showed no acute pathologic changes. Initial labs showed a potassium level of 1.9 and a magnesium level of 1.8. Electrocardiography (EKG) showed prolonged QTc of 534 ms. The patient was admitted to the ICU and started on intravenous and oral potassium replacement. Over the next 24 hours, he started to regain his muscle power gradually until it came back to his baseline. Repeat EKG also showed QTc back to normal. We compared our patient's initial presentation to other published case reports with periodic paralysis and found that his initial presentation was different than other published cases.

The expanding phenotype of hypokalemic periodic paralysis in a Japanese family with p.Val876Glu mutation in CACNA1S

BACKGROUND

Hypokalemic periodic paralysis (HypoPP) is an autosomal dominant disease characterized by the episodic weakness of skeletal muscles and hypokalemia. More than half patients with HypoPP carry mutations in CACNA1S, encoding alpha-1 subunit of calcium channel. Few reports have documented the non-neuromuscular phenotypes of HypoPP.

METHODS

The proband is a Japanese woman who developed HypoPP at 6 years of age. An excessive insulin secretion with the oral glucose tolerance test rationalized that she had experienced frequent attacks of paralysis on high-carbohydrate diets.

RESULTS

Voglibose and acetazolamide effectively controlled her paralytic episodes. Her 8-year-old son and 2-year-old daughter started showing the paralytic symptoms from 4 and 2 years of age, respectively. Laboratory tests revealed high concentrations of creatinine kinase in serum and elevated renin activities in plasma of these children. The targeted sequencing confirmed that these three patients had an identical heterozygous mutation (p.V876E) in CACNA1S.

CONCLUSION

Our data indicate that the p.V876E mutation in CACNA1S contributes to the early onset of neuromuscular symptoms and unusual clinical phenotypes of HypoPP.

Periodic Paralysis Syndromes: A T3 Thyrotoxicosis Case and Review of Literature

Description Periodic paralysis is a group of muscle diseases that are related to transmembrane ion channels. Dysfunction of these channels causes an increase in sodium-potassium (Na-K) adenosine triphosphatase (ATPase) activity that pushes potassium into the cells that result in serum hypokalemia that manifests as muscle weakness. Beta-adrenergic stimulation and insulin sensitivity might also play a role. Periodic paralysis is divided into hereditary and acquired forms. Thyrotoxic periodic paralysis is an acquired form of periodic paralysis that manifests as muscle weakness, hypokalemia, and hyperthyroidism. The onset of the symptoms is mainly over the age of 20 and can be triggered by intense physical activity, stress, and excessive carbohydrate intake. This review presents the different types of this disease (hypokalemic, hyperkalemic, thyrotoxic, and Andersen-Tawil syndrome) while presenting a unique case of T3 thyrotoxicosis causing periodic paralysis.

Abduction range: A potential parameter for the long exercise test in hypokalemic periodic paralysis during inter-attack periods

BACKGROUND

The abduction range of the little finger in the long exercise test (ET) has rarely been reported in patients with hypokalemic periodic paralysis (HypoPP) during inter-attack periods, and the diagnostic value requires clarification.

METHODS

The long ET was performed in 43 HypoPP patients during inter-attack periods and in 20 healthy controls (HCs). The compound muscle action potential (CMAP) and the abduction range of the little finger were recorded concurrently.

RESULTS

There were significant differences in the percent changes of the CMAP amplitudes and the abduction ranges after exercise between HypoPP patients and the HCs. The curve of percent changes in abduction ranges overlapped substantially with that of the CMAP amplitudes, and the sensitivity, specificity, and cutoff values were 0.860, 0.900, and 22.6%, respectively.

CONCLUSIONS

The abduction range of the little finger can serve as a novel parameter in the long ET for the diagnosis of HypoPP during inter-attack periods.

Clinical and Etiological Spectrum of Hypokalemic Periodic Paralysis in a Tertiary Care Hospital in Pakistan

Introduction Hypokalemic periodic paralysis (HPP) is characterized by muscle weakness secondary to low serum potassium levels. It may be primary in origin or there may be secondary causes like thyrotoxic periodic paralysis, renal or suprarenal causes, or non-renal causes like gastroenteritis. Aim To study the etiology, clinical manifestations, and outcome after therapy of patients with hypokalemic paralysis. Methodology The study was conducted from January 2016 to December 2016. Patients fulfilling the diagnostic criteria for hypokalemic paralysis, i.e., flaccid muscle weakness involving two or more limb muscles due to serum potassium < 3.5 mmol/L and with no objective sensory signs were included in the study. Relevant investigations were done. Those with other causes of flaccid weakness or on diuretic therapy were excluded from the study. Data was analyzed using SPSS Version 20.0 (IBM Corp., Armonk, NY). Results In our study, 14 patients out of a total of 18 (14/18, i.e., 77.78%) were male and 4/18 (22.22%) were female [Male: Female ratio: 3.5:1]. The mean age of onset of HPP in males (29.5±10.14 yrs.) was lesser than that of females (41±10.8 yrs.), but this difference was statistically not significant (p<0.066). In the entire sample there were 15/18 cases (83.33%) of primary and 3/18 (16.67%) cases of secondary HPP [2/3 had thyrotoxic periodic paralysis and 1/3 had gastroenteritis]. Furthermore, 12/18 patients (66.66%) had symmetrical weakness (five cases of paraparesis and all were male; seven cases of quadriparesis: six males and one female) and 6/18 (33.33%) had asymmetrical weakness (two paraparesis: one male, one female; four quadriparesis: two males, two females). Statistically, no significant difference (p<0.709) was seen in those with symmetrical versus those with asymmetrical weakness. In this study 7/18 (38.89%) cases had absent, 1/18 (5.55%) had diminished, and 10/18 (55.55%) cases had intact deep tendon reflexes. None of the cases had cranial, bulbar, or respiratory involvement. The mean serum potassium of sample was 3.18±0.5 standard deviation (SD). The reduction in serum potassium was moderate (2.5-3.5 mmol/L) in primary and severe (<2.5 mmol/L) in secondary HPP. Those with quadriparesis had severe hypokalemia with a mean serum potassium of 2.1 mmol/L. Only 3/18 patients had concomitant magnesium deficiency. Patients given intravenous potassium replacement (except one with moderate hypokalemia and given oral replacement) recovered dramatically. The mean recovery time was 38.6±20.3 hours. The recovery time in quadriparesis was about 24 hours and in paraparesis was 12 hours. Only one patient with thyrotoxic periodic paralysis (TPP) and with severe serum potassium deficiency (0.9 meq/L) died due to cardiac arrhythmia. No atypical presentation was seen. Conclusion HPP has male preponderance. The age of onset of HPP is earlier in males than in females. Moreover, males are more prone to have symmetrical weakness. Asymmetrical weakness has almost an equal gender distribution. Primary hypokalemic paralysis is more frequent than secondary. Thyrotoxic periodic paralysis is the commonest cause of secondary periodic paralysis. The recovery time in quadriparesis is almost double the recovery time in paraparesis. Respiratory involvement is rare. HPP is an important differential in the diagnosis of acute flaccid muscle weakness. It should be promptly addressed to prevent recurrence of paralysis.

Etiological Search and Epidemiological Profile in Patients Presenting with Hypokalemic Paresis: An Observational Study

INTRODUCTION

Hypokalemia is associated with increased morbidity and at times mortality. "Hypokalemic paralysis", particularly if recurrent, has often been considered synonymous with "hypokalemic periodic paralysis (HPP)"; however, diseases such as Gitelman syndrome (GS), Bartter syndrome (BS), and renal tubular acidosis (RTA) can have identical presentation. We have tried to explore the etiological spectrum along with epidemiological and certain clinical, biochemical, and electrophysiological features in patients with hypokalemic paralysis.

MATERIALS AND METHODS

In this observational study, 200 appropriate patients with hypokalemic paralysis (serum K⁺ <3.5 mmol/L) were evaluated for transcellular shift, extra-renal or renal loss of K⁺ as the underlying etiology of hypokalemia. We took urinary potassium >25 mmol/day as the cutoff for inappropriate renal loss of potassium in presence of hypokalemia. Serum and urinary osmolality along with arterial blood gas analysis were performed in all patients with renal loss of potassium. Serum and urinary sodium, potassium, calcium, magnesium, chloride, and creatinine were measured in normotensive patients with metabolic alkalosis. Hypertensive patients were evaluated with plasma aldosterone and renin activity.

RESULTS

Probable GS topped the list involving 28% individuals of the entire cohort while probable BS, distal RTA, and HPP were diagnosed in 20%, 22%, and 19% cases, respectively. Rural tribal population (61%) and age group of 30-40 years suffered the most (48%) with concentration of cases in hot and humid summer months.

CONCLUSIONS

We suggest that patients with hypokalemic paresis should be evaluated thoroughly to unmask the underlying etiology that may have a different therapeutic and prognostic connotations and not to use the term "periodic" in cases of recurrent hypokalemic paralysis.

When muscle Ca2+ channels carry monovalent cations through gating pores: insights into the pathophysiology of type 1 hypokalaemic periodic paralysis

Patients suffering from type 1 hypokalaemic periodic paralysis (HypoPP1) experience attacks of muscle paralysis associated with hypokalaemia. The disease arises from missense mutations in the gene encoding the α1 subunit of the dihydropyridine receptor (DHPR), a protein complex anchored in the tubular membrane of skeletal muscle fibres which controls the release of Ca²⁺ from sarcoplasmic reticulum and also functions as a Ca²⁺ channel. The vast majority of mutations consist of the replacement of one of the outer arginines in S4 segments of the α1 subunit by neutral residues. Early studies have shown that muscle fibres from HypoPP1 patients are abnormally depolarized at rest in low K⁺ to the point of inducing muscle inexcitability. The relationship between HypoPP1 mutations and depolarization has long remained unknown. More recent investigations conducted in the closely structurally related voltage-gated Na⁺ and K⁺ channels have shown that comparable S4 arginine substitutions gave rise to elevated inward currents at negative potentials called gating pore currents. Experiments performed in muscle fibres from different models revealed such an inward resting current through HypoPP1 mutated Ca²⁺ channels. In mouse fibres transfected with HypoPP1 mutated channels, the elevated resting current was found to carry H⁺ for the R1239H arginine-to-histidine mutation in a S4 segment and Na⁺ for the V876E HypoPP1 mutation, which has the peculiarity of not being located in S4 segments. Muscle paralysis probably results from the presence of a gating pore current associated with hypokalaemia for both mutations, possibly aggravated by external acidosis for the R1239H mutation.

Spider toxin inhibits gating pore currents underlying periodic paralysis

Gating pore currents through the voltage-sensing domains (VSDs) of the skeletal muscle voltage-gated sodium channel Na_V1.4 underlie hypokalemic periodic paralysis (HypoPP) type 2. Gating modifier toxins target ion channels by modifying the function of the VSDs. We tested the hypothesis that these toxins could function as blockers of the pathogenic gating pore currents. We report that a crab spider toxin Hm-3 from Heriaeus melloteei can inhibit gating pore currents due to mutations affecting the second arginine residue in the S4 helix of VSD-I that we have found in patients with HypoPP and describe here. NMR studies show that Hm-3 partitions into micelles through a hydrophobic cluster formed by aromatic residues and reveal complex formation with VSD-I through electrostatic and hydrophobic interactions with the S3b helix and the S3-S4 extracellular loop. Our data identify VSD-I as a specific binding site for neurotoxins on sodium channels. Gating modifier toxins may constitute useful hits for the treatment of HypoPP.

Periodic paralysis

The periodic paralyses are a group of skeletal muscle channelopathies characterizeed by intermittent attacks of muscle weakness often associated with altered serum potassium levels. The underlying genetic defects include mutations in genes encoding the skeletal muscle calcium channel Ca_v1.1, sodium channel Na_v1.4, and potassium channels K_ir2.1, K_ir3.4, and possibly K_ir2.6. Our increasing knowledge of how mutant channels affect muscle excitability has resulted in better understanding of many clinical phenomena which have been known for decades and sheds light on some of the factors that trigger attacks. Insights into the pathophysiology are also leading to new therapeutic approaches.

Is thyrotoxic periodic paralysis a disease caused by muscle membrane dysfunction?

INTRODUCTION

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.

Weakness in the Emergency Department: Hypokalemic Periodic Paralysis Induced By Strenuous Physical Activity

Hypokalemic periodic paralysis is a rare but serious disorder that is typically caused by a channelopathy. Thyrotoxicosis, heavy exercise, high carbohydrate meal and some drugs can trigger channelopathy in genetically predisposed individuals. A 33-year-old male patient presented to the emergency department with weakness in the lower extremities. He stated that he had done heavy physical activity during the previous week. The patient exhibited motor weakness in the lower extremities (2/5 strength) during the physical examination. Initial laboratory tests showed a potassium level of 1.89 mEq/L. The initial electrocardiogram demonstrated T wave inversion and prominent U waves. The patient was treated in the emergency department with oral and intravenous potassium. The physical and ECG symptoms resolved within 16 hours of potassium supplementation and biochemical tests showed normal serum potassium levels. The patient was discharged shortly after the resolution of the symptoms. Weakness is an important but nonspecific symptom that may be brought on by a number of underlying physiological processes. Hypokalemic periodic paralysis is a rare disease that may be triggered by heavy physical activity and presents with recurrent admissions due to weakness.

Mutations of SCN4A gene cause different diseases: 2 case reports and literature review

SCN4A encodes the Nav1.4 channel and mutations in SCN4A lead to different ionic channelopathies. In this study, one sporadic individual of periodic paralysis, one paramyotonia family and 200 normal healthy controls are enrolled. Genomic DNA was extracted from peripheral blood leukocytes, followed by polymerase chain reaction and DNA sequencing of candidate genes, including SCN4A and CACNA1S. As a result, heterozygous mutations c.2024G>A (R675Q) and c.1333G>A (V445M) of gene SCN4A were identified in the hypokalemic periodic paralysis patient and the paramyotonia congenita family respectively. Both mutations were not detected in healthy controls. Compared with reported cases, patients with mutation R675Q usually do not present hypokalemic periodic paralysis but hyperkalemic or normokalemic periodic paralysis. The mutation V445M was first reported in Chinese patients with nondystrophic myotonias. In addition, we carried out literature review by summarizing clinical features of the 2 mutations and establish the genotype-phenotype correlations to provide guidance for diagnosis.

Domain III S4 in closed-state fast inactivation: insights from a periodic paralysis mutation

Heterologous expression of sodium channel mutations in hypokalemic periodic paralysis reveals 2 variants on channel dysfunction. Charge-reducing mutations of voltage sensing S4 arginine residues alter channel gating as typically studied with expression in mammalian cells. These mutations also produce leak currents through the voltage sensor module, as typically studied with expression in Xenopus oocytes. DIIIS4 mutations at R3 in the skeletal muscle sodium channel produce gating defects and omega current consistent with the phenotype of reduced excitability. Here, we confirm DIIIS4 R3C gating defects in the oocyte expression system for fast inactivation and its recovery. We provide novel data for the effects of the cysteine mutation on voltage sensor movement, to further our understanding of sodium channel defects in hypokalemic periodic paralysis. Gating charge movement and its remobilization are selectively altered by the mutation at hyperpolarized membrane potential, as expected with reduced serum potassium.

Cardiac arrhythmias in hypokalemic periodic paralysis: Hypokalemia as only cause?

It is unknown how often cardiac arrhythmias occur in hypokalemic periodic paralysis (HypoPP) and if they are caused by hypokalemia alone or other factors. This systematic review shows that cardiac arrhythmias were reported in 27 HypoPP patients. Cases were confirmed genetically (13 with an R528H mutation in CACNA1S, 1 an R669H mutation in SCN4A) or had a convincing clinical diagnosis of HypoPP (13 genetically undetermined) if reported prior to the availability of genetic testing. Arrhythmias occurred during severe hypokalemia (11 patients), between attacks at normokalemia (4 patients), were treatment-dependent (2 patients), or unspecified (10 patients). Nine patients died from arrhythmia. Convincing evidence for a pro-arrhythmogenic factor other than hypokalemia is still lacking. The role of cardiac expression of defective skeletal muscle channels in the heart of HypoPP patients remains unclear. Clinicians should be aware of and prevent treatment-induced cardiac arrhythmia in HypoPP.

Reversible electrophysiological abnormalities in hypokalemic paralysis: Case report of two cases

Compound muscle action potential (CMAP) amplitude declines during a paralytic attack in patients with hypokalemic periodic paralysis (HPP). However, serial motor nerve conduction studies in hypokalemic paralysis have not been commonly reported. We report two cases with hypokalemic paralysis, who had severely reduced CMAPs in all motor nerves at presentation during the episode of quadriparesis. However, the amplitude of CMAPs increased and reached normal levels, as the serum potassium concentration and motor power returned to normal state.

A 32-year-old Man with Normokalemic Thyrotoxic Periodic Paralysis

Thyrotoxic Periodic Paralysis (TPP) is a rare and life threatening condition commonly occurring in young Asian males. It is characterized by acute paralytic attacks and hypokalemia in association with thyrotoxicosis. Serum potassium levels may be normal in rare cases of TPP. The diagnosis of normokalemic TPP may be overlooked and/or delayed in most cases. Here, we describe a 32-year-old Iranian man with normokalemic TPP misdiagnosed as somatization disorder with the correct diagnosis made one year after the onset of symptoms.

Comparative study of thyrotoxic periodic paralysis from idiopathic hypokalemic periodic paralysis: An experience from India

OBJECTIVE

There is paucity of reports on thyrotoxic periodic paralysis (TPP) from India. We report the patients with TPP and compare them with idiopathic hypokalemic periodic paralysis (IHPP).

MATERIALS AND METHODS

Patients with hypokalemic periodic paralysis (HPP) treated during the past 11 years were evaluated retrospectively. Their demographic parameters, family history, clinical features, precipitating factors, severity of weakness, laboratory parameters and rapidity of recovery were recorded. The demographic, clinical and laboratory parameters of TPP and IHPP were compared.

RESULTS

During the study period, we managed 52 patients with HPP; nine (17.3%) of whom had TPP and 27 (52%) had IHPP. The demographic, precipitating factors, number of attacks and severity of limb weakness were similar between the TPP and IHPP groups, except in the IHPP group, bulbar weakness was present in four and respiratory paralysis in six, needing artificial ventilation in two patients. Serum potassium was significantly lower in TPP (2.21 ± 0.49) compared with IHPP (2.67 ± 0.59, P = 0.04). Four patients with TPP had subclinical thyrotoxicosis and two had subclinical hyperthyroidism. Rebound hyperkalemia occurred in both TPP and IHPP (three versus eight patients). The recovery was faster in IHPP (26.7 ± 15.4 h) compared with TPP (34.0 ± 14.0 h), but was statistically insignificant.

CONCLUSION

TPP constitutes 17.3% of HPP, and absence of clinical features of thyrotoxicosis and subclinical hyperthyroidism in TPP is not uncommon. Clinical features, demographic profile and rebound hyperkalemia are similar in both TPP and IHPP. The serum potassium level is significantly low in the TPP compared with the IHPP group.

Concurrence of thyrotoxicosis and Gitelman's syndrome-associated hypokalemia-induced periodic paralysis

A 16-year-old Japanese boy with a history of truancy had been treated at a psychiatric clinic. When the patient was referred to us for hypokalemia-associated paralysis, the diagnosis of thyrotoxic hypokalemic periodic paralysis was made, common in Asian men. Subsequently, the patient was found to have persistently high plasma renin and aldos-terone levels. Thus, solute carrier family 12 member 3 gene (SLC12A3) analysis was performed. A novel missense homozygous mutation CTC->CAC at codon 858 (L858H) was found for which the patient was homozygous and his non-consanguineous parents heterozygote. These findings indicated that the patient developed hypokalemia-associated paralysis concurrently with thyrotoxicosis and Gitelman's syndrome. This case underscores the importance of careful examinations of adolescents with complaints of truancy as well as of precise determinations of the causes of hypokalemia-associated paralysis.

A patient suffering from hypokalemic periodic paralysis is deficient in skeletal muscle ATP-sensitive K channels

Hypokalemic periodic paralysis (HOPP) is a rare disease associated with attacks of muscle weakness and hypokalemia. In the present study, immunoprecipitation/Western blotting has shown that a HOPP patient was deficient in sarcolemmal K(ATP) channels. Real-time RT-PCR has revealed that HOPP has decreased mRNA levels of Kir6.2, a pore-forming K(ATP) channel subunit, without affecting the expression of other K(ATP) channel-forming proteins. Based on these findings, we conclude that HOPP could be associated with impaired expression of Kir6.2 which leads to deficiency in skeletal muscle K(ATP) channels, which may explain the symptoms and clinical signs of this disease.

The genotype and clinical phenotype of Korean patients with familial hypokalemic periodic paralysis

Familial hypokalemic periodic paralysis (HOPP) is a rare autosomal-dominant disease characterized by reversible attacks of muscle weakness occurring with episodic hypokalemia. Mutations in the skeletal muscle calcium (CACNA1S) and sodium channel (SCN4A) genes have been reported to be responsible for familial HOPP. Fifty-one HOPP patients from 20 Korean families were studied to determine the relative frequency of the known mutations and to specify the clinical features associated with the identified mutations. DNA analysis identified known mutations in 12 families: 9 (75%) were linked to the CACNA1S gene and 3 (25%) to the SCN4A gene. The Arg528His mutation in the CACNA1S gene was found to be predominant in these 12 families. Additionally, we have detected one novel silent exonic mutation (1950C>T) in the SCN4A gene. As for a SCN4A Arg669His mutation, incomplete penetrance in a woman was observed. Characteristic clinical features were observed both in patients with and without mutations. This study presents comprehensive data on the genotype and phenotype of Korean families with HOPP.

A Korean family of hypokalemic periodic paralysis with mutation in a voltage-gated calcium channel (R1239G)

Hypokalemic periodic paralysis (HOPP) is a rare disease characterized by reversible attacks of muscle weakness accompanied by episodic hypokalemia. Recent molecular work has revealed that the majority of familial HOPP is due to mutations in a skeletal muscle voltage-dependent calcium-channel: the dihydropyridine receptor. We report a 13-yr old boy with HOPP from a family in which 6 members are affected in three generations. Genetic examination identified a nucleotide 3705 C to G mutation in exon 30 of the calcium channel gene, CACNA1S. This mutation predicts a codon change from arginine to glycine at the amino acid position #1239 (R1239G). Among the three known mutations of the CACNA1S gene, the R1239G mutation was rarely reported. This boy and the other family members who did not respond to acetazolamide, showed a marked improvement of the paralytic symptoms after spironolactone treatment.

The human skeletal muscle Na channel mutation R669H associated with hypokalemic periodic paralysis enhances slow inactivation

Missense mutations of the human skeletal muscle voltage-gated Na channel (hSkM1) underlie a variety of diseases, including hyperkalemic periodic paralysis (HyperPP), paramyotonia congenita, and potassium-aggravated myotonia. Another disorder of sarcolemmal excitability, hypokalemic periodic paralysis (HypoPP), which is usually caused by missense mutations of the S4 voltage sensors of the L-type Ca channel, was associated recently in one family with a mutation in the outermost arginine of the IIS4 voltage sensor (R669H) of hSkM1 (Bulman et al., 1999). Intriguingly, an arginine-to-histidine mutation at the homologous position in the L-type Ca(2+) channel (R528H) is a common cause of HypoPP. We have studied the gating properties of the hSkM1-R669H mutant Na channel experimentally in human embryonic kidney cells and found that it has no significant effects on activation or fast inactivation but does cause an enhancement of slow inactivation. R669H channels exhibit an approximately 10 mV hyperpolarized shift in the voltage dependence of slow inactivation and a twofold to fivefold prolongation of recovery after prolonged depolarization. In contrast, slow inactivation is often disrupted in HyperPP-associated Na channel mutants. These results demonstrate that, in R669H-associated HypoPP, enhanced slow inactivation does not preclude, and may contribute to, prolonged attacks of weakness and add support to previous evidence implicating the IIS4 voltage sensor in slow-inactivation gating.