A dangerous food binge: a case report of hypokalemic periodic paralysis and review of current literature.

BACKGROUND: Hypokalemic periodic paralysis is a rare neuromuscular genetic disorder due to defect of ion channels and subsequent function impairment. It belongs to a periodic paralyses group including hyperkalemic periodic paralysis (HEKPP), hypokalemic periodic paralysis (HOKPP) and Andersen-Tawil syndrome (ATS). Clinical presentations are mostly characterized by episodes of flaccid generalized weakness with transient hypo- or hyperkalemia. CASE PRESENTATION: A teenage boy presented to Emergency Department (ED) for acute weakness and no story of neurological disease, during the anamnestic interview he revealed that he had a carbohydrates-rich meal the previous evening. Through a focused diagnostic work-up the most frequent and dangerous causes of paralysis were excluded, but low serum potassium concentration and positive family history for periodic paralyses raised the diagnostic suspicion of HOKPP. After the acute management in ED, he was admitted to Pediatric Department where a potassium integration was started and the patient was counselled about avoiding daily life triggers. He was discharged in few days. Unfortunately, he presented again because of a new paralytic attack due to a sugar-rich food binge the previous evening. Again, he was admitted and treated by potassium integration. This time he was strongly made aware of the risks he may face in case of poor adherence to therapy or behavioral rules. Currently, after 15 months, the boy is fine and no new flare-ups are reported. CONCLUSION: HOKPP is a rare disease but symptoms can have a remarkable impact on patients' quality of life and can interfere with employment and educational opportunities. The treatment aims to minimize the paralysis attacks by restoring normal potassium level in order to reduce muscle excitability but it seems clear that a strong education of the patient about identification and avoidance triggering factors is essential to guarantee a benign clinical course. In our work we discuss the typical clinical presentation of these patients focusing on the key points of the diagnosis and on the challenges of therapeutic management especially in adolescence. A brief discussion of the most recent knowledge regarding this clinical condition follows.

Hyperkalaemic periodic paralysis in pregnancy.

Hyperkalaemic periodic paralysis is a rare skeletal muscle disorder which is characterised by episodic muscle paralysis associated with hyperkalaemia. Although it is an autosomal-dominant disease, cases of de novo mutations have been reported. We report the case of a 30-year-old woman, gravida 5 para 3+1, who was planned for an elective repeated caesarean section at 38 weeks and 3 days of pregnancy. She developed recurrent episodes of hyperkalaemic periodic paralysis after receiving corticosteroids. Intravenous calcium gluconate was administered to normalise potassium levels (from 6.3 mmol/L to 4.1 mmol/L). Extra anaesthetic precautions were taken during the caesarean delivery. Postoperatively, she was well and discharged from the ward. She encountered similar symptoms in her third pregnancy, and there was no family history of muscle weakness which suggested a de novo mutation. Pregnancy seemed to result in vulnerability to hyperkalaemic attacks as she was never symptomatic outside pregnancy.

Long-term effectiveness of acetazolamide on permanent weakness in hyperkalemic periodic paralysis.

Acetazolamide is commonly used as an empirical treatment for inherited periodic paralyses although some patients may develop deleterious effects. We report a 65 year-old man with hyperkalemic periodic paralysis and late-onset permanent weakness in association with the common T704M mutation in α-subunit, skeletal muscle voltage-gated sodium channel gene. He rapidly recovered from weakness after acetazolamide treatment. Magnetic resonance imaging of thighs comparing pre- and post-treatment revealed a significant increase in muscle bulk. The patient has been without any type of weakness for over 6 years. This data show the remarkable benefit of acetazolamide on permanent weakness of hyperkalemic periodic paralysis in association with the T704M mutation.

The impact of permanent muscle weakness on quality of life in periodic paralysis: a survey of 66 patients.

The periodic paralyses are hereditary muscle diseases which cause both episodic and permanent weakness. Permanent weakness may include both reversible and fixed components, the latter caused by fibrosis and fatty replacement. To determine the degree of handicap and impact of permanent weakness on daily life, we conducted a 68-question online survey of 66 patients over 41 years (mean age, 60 ± 14 years). Permanent weakness occurred in 68%, muscle pain in 82% and muscle fatigue in 89%. Eighty-three percent of patients reported themselves as moderately to very active between ages 18-35. At the time of the survey only 14% reported themselves as moderately to very active. Contrary to the literature, only 21% of patients reported decreased frequency of episodic weakness with increased age. Sixty-seven percent had incurred injuries due to falls. Mobility aids were required by 49%. Strength increased in 49% of patients receiving professional physiotherapy and in 62% performing self-managed exercise routines. A decline of strength was observed by 40% with professional and by 16% with self-managed exercise routine, suggesting that overworking muscles may not be beneficial. There is an average of 26 years between age at onset and age at diagnosis indicating that diagnostic schemes can be improved. In summary our data suggests that permanent muscle weakness has a greater impact on the quality of life of patients than previously anticipated.

Parálisis periódica hiperpotasémica / Hyperpotassemia periodic paralysis

La parálisis periódica hiperpotasémica es una canalopatía del músculo esquelético que se caracteriza por episodios recurrentes de debilidad muscular que pueden ser desencadenados por el ejercicio, el frío, el reposo poco después del ejercicio y el aporte de potasio. Se presenta el caso de una paciente de 13 años de edad, con diagnóstico de parálisis periódica hiperpotasémica, sin antecedentes familiares de esta entidad y sin miotonía asociada. Los ataques de debilidad muscular sucedían en ocasiones diariamente y cada 2 o 3 días, con duración variable desde media hora hasta 24 a 48 h. Durante un episodio de debilidad muscular se constataron concentraciones de potasio en sangre de 7,14 mmol/L y el electromiograma mostró un patrón miopático. Se observó una disminución de la frecuencia de los episodios de debilidad muscular a los 2 meses de iniciado el tratamiento con acetazolamida por vía oral(AU)

The periodic hyperpotassemia paralysis is a striated muscle channelopathy characterized by recurrent episodes of muscular asthenia that may to be triggered by exercise, cold, not rest after exercise and potassium support. This the case of a female patient aged 13 diagnosed with hyperpotassemia periodic paralysis without family backgrounds of this entity and also without associated myotonia. The seizures of muscular asthenia occurred almost daily and each 2 or 3 days with a variable length from a half hour to 24 to 48 hours. During a episode of muscular asthenia there were blood potassium concentrations of 7,14 mmol/L and the electromyogram showed a myopathic pattern. There was a frequency decrease of episodes of muscular asthenia at 2 months of treatment onset with oral acetazolamide(AU)

Treatment for periodic paralysis.

BACKGROUND: Primary periodic paralyses are rare inherited muscle diseases characterised by episodes of flaccid weakness affecting one or more limbs, lasting several hours to several days, caused by mutations in skeletal muscle channel genes. OBJECTIVES: The objective of this review was to systematically review treatment of periodic paralyses. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group Trials Register, MEDLINE (from January 1966 to July 2007), and EMBASE (from January 1980 to July 2007) and any other available international medical library sources from the University of Milan for randomised trials. SELECTION CRITERIA: We included randomised (including cross-over studies) and quasi-randomised trials in participants with primary periodic paralyses, in which any form of treatment, including physical therapy and alternative therapies, was compared to placebo or another treatment. DATA COLLECTION AND ANALYSIS: Our primary outcome measure was the change in attack severity or frequency by eight weeks from the start of treatment. Our secondary outcome measures were: change in muscle strength and mass; change in Quality of Life, using Short Form 36 (SF36) or similar; preference of treatment strategy; adverse effects at eight weeks. MAIN RESULTS: Three studies met our inclusion criteria. In one study dichlorphenamide (DCP) vs placebo was tested in two groups of participants: 42 with hypokalemic periodic paralysis (HypoPP) and 31 with hyperkalemic periodic paralysis (HyperPP), based on clinical criteria. Thirty-four of 42 participants with hypokalemic periodic paralysis completed both treatment phases. For the 34 participants having attack rate data for both treatment phases, the mean improvement in attack rate (P = 0.02) and severity-weighted attack rate (P = 0.01) on DCP relative to placebo were statistically significant. Fifteen preferred DCP, three placebo and six their baseline medication. Twenty-four of 31 participants with hyperkalemic periodic paralysis completed both treatment phases: for the 16 participants who had attack rate data for both treatment phases, the mean improvement in attack rate (P = 0.006) and in severity-weighted attack rate (P = 0.02) on DCP relative to placebo were significant. Fifteen preferred DCP, one placebo and five their baseline medication. Acetazolamide proved to improve muscle strength in eight participants with HypoPP in one other study and pinacidil, a potassium channel opener, also improved muscle strength in 2/4 participants with HypoPP in a third study. AUTHORS' CONCLUSIONS: The largest included study that met our inclusion criteria suggested that DCP was effective in the prevention of episodic weakness in both hypokalemic and hyperkalemic periodic paralyses. The other two studies provide some evidence that either acetazolamide or pinacidil may improve muscle strength. However we still lack sufficient evidence to provide full guidelines for the treatment of people with periodic paralysis.

Cerebrovascular reactivity in patients under long-term acetazolamide treatment.

BACKGROUND AND PURPOSE: The acetazolamide (AZA) test is a well-accepted method for measuring the vascular reactivity of the cerebral arteries. In order to investigate the nature of this reactivity after long-term daily AZA treatment, the cerebral blood velocity (CBV) was measured using transcranial Doppler in patients under continuous AZA treatment after a single AZA 1 g intravenous (IV) dose. METHODS: Thirteen patients (eight women, five men) on long-term daily AZA (750 mg/day, mean treatment duration 68 +/- 12+ months) were included in the study. The CBV of the middle cerebral artery (MCA) and the basilar artery (BA), including the values of peak velocity, mean velocity and pulsatility index (PI) were measured. The examination was performed twice - with the initial IV administration of AZA and 20 min later. The results were compared with those of 10 age matched volunteers. RESULTS: A consistent significant increase of CBV in the right and left MCA (P < 0.001 for both arteries) was found in all study participants. A highly significant decrease of peak CBV in the BA (P < 0.001) was found in the post-AZA velocities of the patient's group. In the control group, a consistent significant increase in all post-AZA tests was demonstrated (P < 0.001). CONCLUSIONS: A mild elevation of blood velocity in the MCAs concomitant with a highly significant decrease of velocity in the BA was present in all examined patients. These patterns of CBV changes indicate the presence of a 'steal phenomenon' from the posterior to the anterior circulation and stress the necessity for caution when evaluating the indications for performance of the AZA test in patients under continuous AZA therapy.

[A case of potassium-sensitive periodic paralysis with cardiac dysrhythmia controlled with imipramine and acetazolamide].

We report a patient with potassium-sensitive periodic paralysis with cardiac dysrhythmia. The patient was a 16-year-old man. He presented with asymptomatic ventricular dysrhythmia and periodic paralysis when he was 6 and 12 years old, respectively. Physical examination revealed slight dysmorphic features such as hypoplastic mandible, low-set ears and clinodactyly. Through an exercise test, a potassium tolerance test and a muscle biopsy, his illness was diagnosed as potassium-sensitive periodic paralysis with cardiac dysrhythmia. For the treatment of his episodic paralysis, we started acetazolamide, which improved both the incidence and the severity of paralysis. However, the incidence of cardiac dysrhythmia was increased after the use of acetazolamide. Routine anti-arrhythmic drugs such as lidocaine failed to control his ventricular dysrhythmia. Only imipramine showed its efficacy by improving the degree and the incidence of cardiac dysrhythmia without aggravating periodic paralysis. This syndrome is relatively rare and there have been no standard protocols for the treatment. We propose the combination of acetazolamide and imipramine as the first choice for this clinical entity. We also discussed the efficacy of the exercise test. It enabled us to confirm the diagnosis of periodic paralysis safely and easily by recording the change of compound muscle action potential amplitudes.

[Hypokalemic pareses secondary to renal tubular acidosis]. / Hypokalemisk induserte pareser sekundaert til renal tubulaer acidose.

A 24 year old woman presented with flaccid paralysis, severe hypokalaemia and hyperchloremia, metabolic acidosis. Immunological tests and labial glandular biopsy indicated primary Sjögren's syndrome as the underlying cause of her distal renal tubular acidosis. The patient recovered after alkali and potassium substitution and was put on oral treatment with potassium citrate.

[Ion-channel related muscular diseases]. / Les maladies musculaires des canaux ioniques.

INTRODUCTION: Though ion channel-related muscular disorders were described long ago, better understanding of their underlying mechanisms has been more recently achieved. These mechanisms include myotonic syndromes that may be caused by mutations in sodium and chloride channels, as well as periodic paralysis which is due to mutations in sodium and calcium channels. CURRENT KNOWLEDGE AND KEY POINTS: Knowledge of the involved pathophysiological mechanisms has led to better clinical description of these disorders, as well as more efficacious treatment. In some cases, it is now possible to establish the diagnosis, using genetic tests. FUTURE PROSPECTS AND PROJECTS: Other neuromuscular disorders might be related to ion channel mutations.