Anesthetic experiences in a family with hypokalemic familial periodic paralysis

Diverse phenotype of hypokalaemic periodic paralysis within a family

Hypokalaemic periodic paralysis typically presents with intermittent mild-to-moderate weakness lasting hours to days. We report a case with an uncommon phenotype of late-onset myopathy without episodic paralytic attacks. Initial work-up including muscle biopsy was inconclusive. A subsequent review of the right deltoid biopsy, long exercise testing and repeated family history was helpful, followed by appropriate genetic testing. We identified a heterozygous pathogenic mutation in calcium ion channel (CACNA1S:c.1583G>A p.Arg528His) causing hypokalaemic periodic paralysis. Myopathy can present without episodic paralysis and the frequency of paralytic episodes does not correlate well with the development and progression of a fixed myopathy. Our report also highlights the intrafamilial phenotypic variation of hypokalaemic periodic paralysis secondary to a CACNA1S gene mutation.

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.

Severe prognosis in a large family with hypokalemic periodic paralysis

Hypokalemic periodic paralysis (HypoPP) is a channel disorder caused primarily by mutations in the human skeletal muscle alpha1 subunit (CACNA1S) of the dihydropyridine-sensitive calcium channel. Molecular, clinical, and biochemical studies were aimed at establishing genotype/phenotype correlations in a large Italian family affected by a severe form of HypoPP. Whereas patients with HypoPP usually show a normal life span, in this family three male patients died young, one of them from anesthetic complications resembling malignant hyperthermia. Our patients carried the c1583G>A genetic lesion (R528H), which has been associated with a mild phenotype and with incomplete penetrance in women. Surprisingly, the R528H amino acid substitution in the family presented here correlated with an unfavorable prognosis in both male and female patients. We conclude that genetic characterization is an important requirement to alert physicians about the management of similar patients, especially when anesthesia is considered.

Total intravenous anaesthesia in a patient with familial hypokalaemic periodic paralysis

A 35-year-old woman with known familial hypokalaemic periodic paralysis received general anaesthesia for reduction of bilateral breast hyperplasia. Uncomplicated general anaesthesia was performed using a propofol target-controlled infusion, remifentanil infusion and bolus doses of mivacurium with neuromuscular function monitoring. Plasma potassium concentrations were controlled intermittently in the peri-operative period and supplemented to achieve normokalaemia. Despite continuous substitution, an episode of low plasma potassium concentration occurred during the recovery period; this was without any clinical signs of muscle paralysis or respiratory distress.

Familial hypokalemic periodic paralysis and Wolff-Parkinson-White syndrome in pregnancy

PURPOSE

To describe the anesthetic and obstetrical management of a pregnant patient with co-existing Familial Hypokalemic Periodic Paralysis (FHPP) and Wolff-Parkinson-White syndrome (WPW).

CLINICAL FEATURES

A 29 yr-old primigravida with FHPP and WPW presented to the antenatal clinic at 18 wk gestation, for consideration of her anesthetic and obstetrical management during labour and delivery. A plan was constructed to avoid the known precipitating factors of FHPP including carbohydrate loading, cold, mental stress and exercise, which could lead to acute attacks of weakness. She presented for induction of labour at 41 wk and three days. An epidural catheter was sited early in labour. The second stage was limited to less than one hour. She had a rotational forceps delivery for which the epidural was extended to provide anesthesia. A healthy male baby was delivered. The patient made an uncomplicated recovery and was discharged home on the second postnatal day. The peripartum potassium was kept within the normal range with intravenous as well as oral potassium supplementation. No arrhythmias were reported.

CONCLUSION

Assessment of the patient at an early stage in her pregnancy allowed for a multidisciplinary approach to this patient and her medical problems. A plan was made to avoid known precipitating factors during labour, delivery and the postnatal period well in advance of her date of confinement, leading to a successful outcome for mother and child.

Genotype-phenotype correlations of DHP receptor alpha 1-subunit gene mutations causing hypokalemic periodic paralysis

Hypokalemic periodic paralysis (hypoKPP) is an autosomal dominant or sporadic disorder characterized by periodic, reversible attacks of muscle weakness. Mutations in the skeletal muscle dihydropyridine receptor alpha 1-subunit that functions as a calcium channel (CACNL1A3) cause hypoKPP. We studied a group of 45 hypoKPP probands and demonstrated mutations in 30 of them. When compared with patients in whom CACNL1A3 mutations were not identified, those with mutations had an earlier age of onset and more often had a family history of hypoKPP. To date, three mutations have been identified. The R1239G mutation has only been found in one family. Of the 30 probands with recognized mutations, R528H accounted for 43% and R1239H was seen in 53%. Age of onset and potassium levels during attacks were lower in patients with the R1239H mutation than those with R528H. Cardiac dysrhythmias co-segregated with hypoKPP in one small kindred with the R528H mutation. No mutations were identified in exons of the gene encoding the S4 segments of domains one and three or the cytoplasmic loop between domains two and three. In addition to the 45 hypoKPP probands, an additional 11 probands with clinical variants of hypoKPP (three thyrotoxic hypoKPP and eight Andersen syndrome patients) were examined for CACNL1A3 mutations and none were found.

Anaesthetic management of a patient with familial normokalaemic periodic paralysis

PURPOSE

We describe the anaesthetic management of a patient with the autosomal dominant inherited disease, normokalaemic periodic paralysis. The disease results in intermittent bouts of limb and respiratory muscular weakness in association with hypothermia, stress, prolonged fasting or exercise. Unlike hypokalaemic and hyperkalaemic periodic paralysis, the more common variants of the disease, normokalaemic periodic paralysis is not accompanied by alterations in the plasma potassium concentration.

CLINICAL FEATURES

A five-year-old boy presented for emergency scrotal exploration. He had a family history of periodic paralysis and had experienced previous episodes of weakness, two of which had required hospitalization for respiratory distress. On admission there was no evidence of weakness and serum potassium concentration was 4.2 mMol.L-1. A spinal anaesthetic was performed and the procedure was uncomplicated by muscle paralysis above the level of the spinal block.

CONCLUSION

Avoidance of known precipitating factors and judicious use of neuromuscular blocking drugs has been advocated in patients with this disorder presenting for surgery. In appropriate circumstances, spinal anaesthesia represents a useful option in patients with normokalaemic periodic paralysis.

Atracurium use in a patient with familial periodic paralysis

We describe a patient with the hypokalemic type of familial periodic paralysis (FPP) who received atracurium for muscle relaxation as required for diagnostic laparoscopy. Electrocardiographic (EKG) T-wave changes suggestive of hypokalemia were not supported by blood determinations. Arterial blood measurements of potassium (K+), pH, and arterial carbon dioxide tension (PaCO2) and the patient's esophageal temperature were maintained within normal limits. The degree of muscle relaxation was closely monitored by a peripheral nerve stimulator and train-of-four (TOF) measurement of muscle twitch height. At the conclusion of the surgical procedure, no reversal to the muscle relaxant was needed or given. The patient regained preoperative muscle strength, and her postoperative course was uneventful.