Risk of malignant hyperthermia in patients carrying a variant in the skeletal muscle ryanodine receptor 1 gene.

Malignant hyperthermia is a life-threatening disorder, which can be prevented by avoiding certain anesthetic agents. Pathogenic variants in the skeletal muscle ryanodine receptor 1-gene are linked to malignant hyperthermia. We retrospectively studied 15 patients who presented to our clinic with symptoms of muscle dysfunction (weakness, myalgia or cramps) and were later found to have a variant in the skeletal muscle ryanodine receptor 1-gene. Symptoms, creatine kinase levels, electromyography, muscle biopsy and in vitro contracture test results were reviewed. Six out of the eleven patients, with a variant of unknown significance in the skeletal muscle ryanodine receptor 1-gene, had a positive in vitro contracture test, indicating malignant hyperthermia susceptibility. In one patient, with two variants of unknown significance, both variants were required to express the malignant hyperthermia-susceptibility trait. Neurologists should consider screening the skeletal muscle ryanodine receptor 1-gene in patients with myalgia or cramps, even when few to no abnormalities on ancillary testing.

A case of primary aldosteronism caused by unilateral multiple adrenocortical micronodules presenting as muscle cramps at rest: The importance of functional histopathology for identifying a culprit lesion.

Unilateral multiple adrenocortical micronodules (UMNs) constitute a rare subset of primary aldosteronism (PA) characterized by the hypersecretion of aldosterone derived from multiple small nodules in the zona glomerulosa of the unilateral adrenal grand. This case study describes a 49-year-old man with PA and UMNs who presented with muscle cramps at rest due to hypokalemia. The patient had a 6-year history of hypertension treated with antihypertensive drugs. Imaging studies revealed bilateral adrenal nodules as large as 5 mm. Adrenal venous sampling confirmed unilateral PA; therefore, the patient underwent the removal of the affected adrenal gland. Macroscopically, the removed adrenal gland exhibited irregular adrenocortical thickening accompanied by ill-defined, adrenocortical macronodules as large as 6 mm. The zona glomerulosa was histologically hyperplastic. However, an immunohistochemistry test of the steroidogenic enzymes revealed that these macronodules and the hyperplastic glomerular layer tested negative for CYB11B2. Moreover, we observed adrenocortical micronodules as large as 0.5 mm that tested immunohistochemically positive for CYP11B2 and HSD3B2 but negative for CYP17A1 and CYP11B1. Thus, UMNs were diagnosed. This case instructively indicates that a grossly or histologically detectable nodular lesion is not necessarily a culprit lesion for PA. Therefore, functional histopathology is indispensable for the correct subclassification of PA.

L-carnitine Reduces Muscle Cramps in Patients With Cirrhosis.

We performed a prospective study to evaluate the ability of L-carnitine, which is involved in the ß-oxidation of fatty acids, to reduce muscle cramps in patients with cirrhosis. Consecutive patients with cirrhosis and muscle cramps were given L-carnitine 300 mg, 3 times/day (900 mg/day, n = 19) or 4 times/day (1200 mg/day, n = 23) for 8 weeks. The frequency of muscle cramps was assessed by questionnaires, and the degree of muscle cramping was assessed by using the visual analogue scale (VAS). Muscle cramping was reduced in 88.1% of all subjects at the end of the 8-week study period and disappeared for 28.6% of patients. Overall VAS scores decreased significantly from 69.9 ± 22.5 at baseline to 26.2 ± 29.1 after 8 weeks (P < .0001). The dose of L-carnitine was significantly associated with percentages of patients with reduced muscle cramps after 8 weeks (43.5% in the 1200 mg/day group vs 10.5% in the 900 mg/day group, P = .037) and VAS scores at 8 weeks (9.9 ± 13.5 in the 1200 mg/day group vs 39.6 ± 31.9 in the 900 mg/day group, P = .003). No adverse events were reported. Therefore, L-carnitine appears to be safe and effective for reducing liver cramps in patients with cirrhosis.

Paroxysmal dyskinesia suspected as canine epileptoid cramping syndrome in a young Yorkshire terrier dog.

A 9-month-old intact female Yorkshire terrier dog was presented with episodic partial seizure-like cramping of the limbs. The patient's episodes began six months previously; the interval between episodes became shorter, and the duration of the episodes increased. Various tests including neurologic examination, blood examination, abdominal radiography, ultrasonographic examination, angiographic computed tomography (CT) and brain magnetic resonance imaging (MRI) detected no remarkable changes. After these tests were conducted, the patient's condition was suspected to be canine epileptoid cramping syndrome (CECS), which could be a form of paroxysmal dyskinesia (PD), and as a trial therapy, Science Diet k/d (Hill's Pet Nutrition, Topeka, KS, U.S.A.) was prescribed. The clinical signs were dramatically reduced after diet therapy, and we diagnosed the patient with CECS. This is the first case report of CECS in a Yorkshire terrier dog.

A verified spider bite and a review of the literature confirm Indian ornamental tree spiders (Poecilotheria species) as underestimated theraphosids of medical importance.

Literature on bird spider or tarantula bites (Theraphosidae) is rare. This is astonishing as they are coveted pets and interaction with their keepers (feeding, cleaning the terrarium or taking them out to hold) might increase the possibility for bites. Yet, this seems to be a rare event and might be why most theraphosids are considered to be harmless, even though the urticating hairs of many American species can cause disagreeable allergic reactions. We are describing a case of a verified bite by an Indian ornamental tree spider (Poecilotheria regalis), where the patient developed severe, long lasting muscle cramps several hours after the bite. We present a comprehensive review of the literature on bites of these beautiful spiders and conclude that a delayed onset of severe muscle cramps, lasting for days, is characteristic for Poecilotheria bites. We discuss Poecilotheria species as an exception from the general assumption that theraphosid bites are harmless to humans.

Muscle cramps in liver disease.

Muscle cramps are common in patients with liver disease and adversely influence quality of life. The exact mechanisms by which they occur remain unclear, although a number of pathophysiological events unique to liver disease may contribute. Clinical studies have identified alterations in 3 areas: nerve function, energy metabolism, and plasma volume/electrolytes. Treatments have focused on these particular areas with varied results. This review will focus on the clinical features of muscle cramps in patients with liver disease and review potential mechanisms and current therapies.

Myokymia and neuromyotonia in veterinary medicine: a comparison with peripheral nerve hyperexcitability syndrome in humans.

Involuntary muscle hyperactivity can result from muscle or peripheral nerve hyperexcitability or central nervous system dysfunction. In humans, diseases causing hyperexcitability of peripheral nerves are grouped together under the term 'peripheral nerve hyperexcitability' (PNH). Hyperexcitability of the peripheral motor nerve can result into five different phenotypic main variants, i.e. fasciculations, myokymia, neuromyotonia, cramps and tetany, each with their own clinical and electromyographic characteristics. This review focuses on the most commonly described expressions of PNH in veterinary medicine, i.e. myokymia and neuromyotonia, in particular in young Jack Russell terriers. Data from 58 veterinary cases with generalized myokymia and neuromyotonia were analyzed, including unpublished treatment and follow-up data on eight Jack Russell terriers from a previous study and seven additional Jack Russell terriers. A dysfunction of the potassium channel or its associated proteins has been found in many human syndromes characterized by PNH, in particular in generalized myokymia and neuromyotonia, and is suspected to occur in veterinary medicine. Potential pathomechanisms of potassium channel dysfunction leading to signs of PNH are broad and include genetic mutations, antibody-mediated attack or ion channel maldistribution due to axonal degeneration or demyelination. A more accurate classification of the different PNH syndromes will facilitate a more rapid diagnosis and guide further research into natural occurring PNH in animals.

Phosphoglycerate mutase deficiency with tubular aggregates in a patient from Panama.

INTRODUCTION: Phosphoglycerate mutase deficiency (PGAM) is a rare metabolic myopathy that results in terminal block in glycogenolysis. Clinically, patients with PGAM deficiency are asymptomatic, except when they engage in brief, strenuous efforts, which may trigger myalgias, cramps, muscle necrosis, and myoglobinuria. An unusual pathologic feature of PGAM deficiency is the association with tubular aggregates. METHODS: We report an African-American patient from Panama with partial deficiency of PGAM who presented with asymptomatic elevation of creatine kinase levels and tubular aggregates on muscle biopsy. RESULTS: Muscle biopsies showed subsarcolemmal and sarcolemmal tubular aggregates in type 2 fibers. Muscle PGAM enzymatic activity was decreased and gene sequencing revealed a heterozygous mutation in codon 78 of exon 1 of the PGAM2 gene, which is located on the short arm of chromosome 7. CONCLUSIONS: PGAM deficiency has been reported in 14 patients, 9 of whom were of African-American ethnicity, and in 5 (36%) tubular aggregates were seen on muscle biopsy. Contrary to previously reported cases, our patient was initially asymptomatic. This further expands the PGAM deficiency phenotype.

[Patient of myofibrillar myopathy associated with muscle cramp and distal muscle involvement].

A 53-year-old man presented mild, but gradually worsening, distal-dominant upper bilateral limbs weakness and muscle cramp in both legs from the age of 30. He had no obvious muscle atrophy during the course of the disease. Muscle biopsy of the right lateral vastus muscle showed myopathic changes with round or helical hyaline inclusions in eosinophilic on H&E staining and dark green on modified Gomori trichrome. There were also non-rimmed vacuoles. NADH-TR showed lack of enzymic activity in areas corresponding to the inclusions. Immunohistochemistry demonstrated abnormal accumulation of desmin and myotilin in fibers with inclusions. Given these pathological findings, he was diagnosed with myofibrillar myopathy (MFM). Because MFM is genetically heterogeneous, its clinical manifestations are reported as variable. While MFM patients are sometimes reported to develop serious conditions such as severe weakness, cardiomyopathy or respiratory failure, which require a pacemaker or mechanical ventilator, our case only had mild distal dominant limb weakness and muscle cramps. Our patient suggests that we must consider MFM as a differential diagnosis in adult onset distal myopathies.

Mild clinical and histopathological features in patients who carry the frequent and causative malignant hyperthermia RyR1 mutation p.Thr2206Met.

OBJECTIVE: Malignant hyperthermia (MH) is a classically unapparent pharmacogenetic disorder of the skeletal muscles triggered by inhalational anesthetics or depolarizing muscle relaxants. The disposition to MH is inherited in an autosomal-dominant manner and is primarily due to mutations in the gene for the ryanodine receptor type 1 (RyR1). The present study intended to analyze whether mild muscular symptoms (elevation of the resting CK, cramps in the calves, slight calf hypertrophy) may be associated with susceptibility to MH and/or with histopathological changes. METHODS: A muscle biopsy was taken from 12 out of 44 blood relatives (three generations) of a large family and was investigated with the halothane/caffeine in vitro contracture test (IVCT). Afterwards a histological, histochemical and immunhistological examination was performed. Altogether in 29 persons the DNA was analyzed for mutations in the RyR1-gene. RESULTS: Eight persons were diagnosed as susceptible to MH (MHS) by the IVCT, 4 were MH negative. All MHS persons carried the MH causative c.6617C > T (Thr2206Met) mutation and showed slight clinical signs of a myopathy as well as mild biopsy changes with isolated hypotrophic fibers and disseminated small areas with reduction of oxidative staining (multi-minicore like lesions). The Thr2206Met mutation was identified in another further 9 relatives who also experienced mild myopathological features. Clinical MH incidents were not reported in this large family. CONCLUSION: The RyR1 Thr2206Met mutation is one of the most frequent mutations in the European MH population but carriers are normally healthy. In this study we could demonstrate that the MH causative Thr2206Met mutation may also be associated both with clinical symptoms of a mild myopathy and histopathological changes in the oxidative inter myofibrillar network.

Discharge properties of motor units of the abductor hallucis muscle during cramp contractions.

We analyzed individual motor units during electrically elicited cramp contractions with the aim of characterizing the variability and degree of common oscillations in their discharges. Intramuscular and surface electromyographic (EMG) signals were detected from the abductor hallucis muscle of 11 healthy subjects (age 27.0+/-3.7 yr) during electrically elicited cramps. In all, 48 motor units were identified from the intramuscular EMG. These motor units were active for 23.6+/-16.2 s, during which their average discharge rate was 14.5+/-5.1 pulses/s (pps) and their minimum and maximum rates were, respectively, 6.0+/-0.8 and 25.0+/-8.0 pps (P<0.001). The coefficient of variation for the interspike interval (ISI) was 44.6+/-9.7% and doublet discharges constituted 4.1+/-4.7% of the total number of discharges. In 38 motor units, the SD of the ISI was positively correlated to the mean ISI (R2=0.37, P<0.05). The coherence spectrum between smoothed discharge rates of pairs of motor units showed one significant peak at 1.4+/-0.4 Hz for 29 of the 96 motor unit pairs and two significant peaks at 1.3+/-0.5 and 1.5+/-0.5 Hz for 8 motor unit pairs. The cross-correlation function between pairs of discharge rates showed a significant peak (0.52+/-0.11) in 26 motor unit pairs. In conclusion, motor units active during cramps showed a range of discharge rates similar to that observed during voluntary contractions but larger ISI variability, probably due to large synaptic noise. Moreover, the discharge rates of the active motor units showed common oscillations.

[Muscle cramps--differential diagnosis and therapy]. / Wadenkrämpfe--Differenzialdiagnose und Therapie.

Calf cramps are sudden, involuntary, painful contractions of part of or the entire calf muscle that are visible, persist for seconds to minutes and then spontaneously resolve. They can occur with no identifiable cause, and are then referred to as common calf cramps. They may also be symptoms associated with diseases of the peripheral and central nervous system and muscle diseases. They also occur in association with metabolic disorders. In such cases the cramps are more extensive, intense and persist for longer. Cramp-fasciculation-myalgia syndrome additionally involves paresthesias and other signs of hyperexcitability of peripheral nerves. The recommended treatment for patients with frequent calf cramps causing significant impairment of well-being is oral administration of quinidine and/or botulinum toxin treatment of the calf muscles. During pregnancy both products are contraindicated, while probatory administration of magnesium is indicated.

Bertolotti's syndrome: a case report.

STUDY DESIGN: A case report and literature review is presented. OBJECTIVE: To review relevant data for the management of Bertolotti's syndrome and to determine whether the transverse process-ilium articulation may be a pain generator. BACKGROUND: Bertolotti's syndrome is associated with axial low back pain secondary to arthritic changes; the pain generator in the disorder is unclear. METHODS: We present a case report of symptomatic Bertolotti's syndrome managed with intra-articular steroid injections. RESULTS: A patient with Bertolotti's syndrome had significant relief of axial pain after steroid injection of the ilium-transverse process articulation. CONCLUSIONS: Steroid therapy may be a non-surgical alternative for the treatment of symptomatic Bertolotti's syndrome.