Trismus due to myotonia associated with hyperadrenocorticism in a dog

We present the report of trismus due to hyperadrenocorticism-associated myotonia diagnosed by electromyography in a dog. An intact female Miniature Dachshund, 13 years and 9 months old, presented with stiff gait and trismus as well as polyuria and polydipsia. Abdominal ultrasonography showed enlarged adrenal glands. An adrenocorticotropic hormone stimulation test revealed an exaggerated response. Based on these findings, this case was diagnosed with hyperadrenocorticism. Electromyography revealed myotonic discharge in the temporalis muscle and limbs. Therefore, trismus was considered to be caused by hyperadrenocorticism-associated myotonia, and the case was treated with oral trilostane (1.3 mg/kg, once daily). During the 4-month follow-up period, despite the partial improvement in stiff gait, trismus did not recover. Long-term data on more cases are warranted to assess the prognosis and clinical characteristics of trismus due to hyperadrenocorticism-associated myotonia.

Dental findings and muscular-skeletal features in Schwartz-Jampel syndrome: case report of two affected siblings

Schwartz-Jampel syndrome (SJS) is a rare, inherited disorder defined by myotonia, skeletal malformations, muscular stiffness, and growth retardation. The clinical signs and symptoms of SJS are seen in the maxillofacial region. The combination of skeletal and muscular abnormalities predisposes affected individuals to a number of primary and secondary orodental manifestations. Although several studies have discussed the clinical features of SJS from a medical perspective, few reports have addressed the oral findings or dental treatment in children and adolescents with the disorder. This article reviews the dental manifestations and impairments of Schwartz-Jampel syndrome. The case histories of two siblings diagnosed with this disorder are described as well as their dental care.

Schwartz-Jampel syndrome: surgical management of the myotonia-induced blepharospasm and acquired ptosis after failure with botulinum toxin A injections

A 6-year-old boy with Schwartz-Jampel syndrome and severe myotonia-induced blepharospasm and ptosis did not respond to botulinum toxin A injections in the orbicularis muscle. The clinical diagnosis was further supported by electromyography. Surgical management using a combination of techniques in one operation produced a satisfactory result for both function and appearance. Muscle biopsy was also done during surgery.

A rare form of painful nondystrophic myotonia

OBJECTIVE

In this paper we report a painful nondystrophic myotonia which has not been previously described. Pain is a rare symptom in myotonia. We report a myotonic disorder in a 34-year-old woman and her 14-year-old daughter. Painful cramps occur during and after exercise in the mother, and both patients can demonstrate unusual contractions in the tongue. In the present study we try to evaluate the mechanisms behind the unique finding of trains of high amplitude of positive waves, not seen in the earlier known myotonic conditions.

METHODS

Clinical investigations and electromyography with single and dual channel recordings and muscle morphometry were performed.

RESULTS

The electromyographic recordings reveal positive waves, fibrillation potentials and myotonic discharges. In addition, extraordinary findings were made of trains of high frequency positive potentials with very high amplitudes and with conduction block along the muscle fibres.

CONCLUSIONS

In this new form of myotonia with likely dominant heredity, the specific finding of trains of high amplitude positive waves indicates ephaptic transmission within bundles of neighbouring muscle fibres.

Equine muscular dystrophy with myotonia

OBJECTIVES

To describe a case of equine muscular dystrophy with myotonia.

METHODS

A 5-year-old horse presented with hypertrophy and delayed relaxation of the muscles of the hindlimbs from age 2 months. Testicular atrophy developed from 2 years of age. Action and percussion myotonia was associated with weakness in these muscles, and EMG showed diffuse myotonic discharges and myopathic features. Biopsy of the gluteal muscle showed adipose and connective tissue infiltration, marked variation in muscle fibre size, and moth-eaten, ring and whorled fibres.

RESULTS

Injection of apamin, a peptide blocker of calcium-activated potassium channels, which inhibits myotonia in human myotonic dystrophy, was ineffective in blocking myotonic discharges. Discharges promptly abated with 2% lidocaine injection.

CONCLUSIONS

Myotonia in this horse is associated with dystrophic changes similar to human myotonic dystrophy, though there are some pharmacological differences.

Myotonia associated with sarcoidosis: marked exacerbation with pravastatin

A 37-year-old man with sarcoidosis developed severe electrical and clinical myotonia while taking pravastatin for hypercholesterolemia. Myotonia associated with sarcoidosis is rare. Pravastatin is associated with myotonia in animals. This case suggests that sarcoidosis and pravastatin, two entities not frequently associated with myotonia, may interact in a synergistic manner to produce severe clinical myotonia in humans.

Is bariatric surgery effective in the treatment of the neurological motor deficit syndromes?

BACKGROUND

Persons who suffer from neurological motor deficit syndromes, such as multiple sclerosis, postpolio syndrome, cerebral palsy, myotonia or stroke, are at a particular disadvantage if they are also morbidly obese. There appears to be little in the medical literature describing the role of bariatric surgery and the management of these conditions.

METHODS

We offer our experience with six such patients. All had variations of the gastric bypass procedure.

RESULTS

Weight loss was quite good, in comparison to other morbidly obese patients. All six noted improved function, usually dramatically improved.

CONCLUSIONS

Long-term weight maintenance and functional improvement cannot be assessed in this group of patients. One should expect difficulty in making a long-term assessment in the presence of a progressing debilitating disease. Short-term results were good, and we believe that bariatric surgery should be offered to these patients on an individual basis.

A case of Hodgkin's lymphoma producing neuromyotonia

The syndrome of neuromyotonia produces muscle stiffness, cramps, and frequently, excessive sweating. Most cases are idiopathic, but some are associated with neoplasms, especially immune cell cancers. Voltage-gated potassium channels may be the target of an autoantibody attack in idiopathic generalized neuromyotonia (Isaacs' syndrome). The cases associated with neoplasms may also have an autoimmune etiology. We report the first case of neuromyotonia as the presenting feature of Hodgkin's lymphoma and propose a paraneoplastic mechanism that would link the purported autoimmune etiology in Isaacs' syndrome with the cancer-associated cases.

The spectrum of arthrogryposis in 33 chinese children

The clinical profile of 33 children (19 boys, 14 girls) with multiple congenital contractures has been studied. The majority (54%) belong to arthrogryposis multiplex congenita with a static clinical course. Children were classified into three groups: group I (limb involvement only; n = 21) having arthrogryposis multiplex congenita (n = 18), distal arthrogryposis syndrome (n = 2) and Streeter syndrome (n = 1); group II (limb involvement with other malformation or anomalies; n = 7) having congenital contractural arachnodactyly (n = 3), Larsen syndrome (n = 1), multiple pterygium syndrome (n = 1), craniocarpotarsal dystrophy (n = 1), and Schwartz Jampel syndrome (n = 1); and group III (limb involvement with central nervous system dysfunction or mental retardation; n = 5) having myotonia dystrophica (n = 2), congenital muscular dystrophy (n = 1), foetal alcohol syndrome (n = 1) and Pena-Shokeir syndrome (n = 1). Three children died, one each of arthrogryposis multiplex congenita, congenital contractural arachnodactyly and myotonia dystrophica. The majority had a good prognosis with independent function and mobility.

Ocular neuromyotonia in Graves dysthyroid orbitopathy

OBJECTIVES

To describe 2 patients with ocular neuromyotonia in association with Graves orbitopathy and to consider the possible underlying mechanisms.

DESIGN

Description of the clinical findings in 2 patients with these conditions.

SETTING

Neuro-ophthalmology referral centers.

PATIENTS

Two patients, aged 55 and 52 years, had episodic, involuntary periods of vertical diplopia and dysthyroid orbitopathy.

INTERVENTION

Treatment with carbamazepine in one patient and external beam radiation therapy in the second patient.

MAIN OUTCOME MEASURES

Frequency and duration of episodic spasms of the extraocular muscles.

RESULTS

Although radiation therapy is the most common association with ocular neuromyotonia, it cannot explain the involuntary contractions of extraocular muscles in all affected patients. Other mechanisms must be involved, such as those discussed in this article.

CONCLUSION

Ocular neuromyotonia is described in 2 patients with dysthyroid orbitopathy, confirming previous findings. Possible mechanisms are given.

A newly-described myotonic disorder (proximal myotonic myopathy--PROMM): personal experience and review of the literature

The aim of this study is to describe the essential characteristics of a family affected by the newly-described proximal myotonic myopathy (PROMM) The clinical, laboratory and genetic findings are described and compared with those reported in the literature, and the clinical spectrum of the manifestations that are similar to but distinct from myotonic dystrophy (MD) is also explored. This has practical implications because the cases so far described suggest that the long-term prognosis with PROMM seems to be more favourable than that of patients with MD.

Neuromyotonia, peripheral neuropathy and myasthenia gravis

A patient with neuromyotonia, peripheral neuropathy and myasthenia gravis (MG) is described. Neurophysiological studies, at rest, showed continuous muscle discharges of motor unit action potentials (MUAPs) in duplets and triplets. Motor (MNCV) and sensory (SNCV) nerve conduction studies revealed mild axonal and demyelinating peripheral neuropathy. Plasma exchange was followed by disappearance of clinical and electrophysiological signs of neuromyotonia and MG, as well as peripheral neuropathy.

[Syringomyelia in orthopedic practice]

Three females with syringomyelia and atrophic shoulder arthropathy, in one patient associated also with hypertrophic elbow arthropathy and Morvan syndrome have been presented. Despite long duration and apparent symptoms the condition has been diagnosed only during hospitalization.

Intermittent diplopia and strabismus caused by ocular neuromyotonia

PURPOSE

Two cases illustrate the symptoms, signs, etiologies, and treatment of ocular neuromyotonia (ONM).

METHODS

The histories, neuroradiologic tests, and/or biopsy revealed the etiologies of ONM in both patients. Clinical observations, videotaping, and electronic eye movement recordings documented the eye movements.

RESULTS

A 72-year-old man with chronic arachnoiditis following myelography with thorium dioxide (Thorotrast) developed intermittent diplopia and a partial right third nerve palsy. Left gaze induced spasm of the right medial rectus. Right gaze produced right lateral rectus spasm. A 66-year-old woman, who had radiation treatment for a pituitary tumor and acromegaly, had intermittent spasm of the left medial rectus muscle and left esotropia. The episodes occurred spontaneously and were induced by right gaze. A left internuclear ophthalmoplegia was also found. Carbamazepine (Tegretol) abolished the ONM in both patients.

CONCLUSIONS

Although ONM is an unusual cause of intermittent diplopia and strabismus, its distinctive clinical features identify it. Injury to the peripheral cranial nerves probably leads to segmental demyelination, axonal hyperexcitability, and a self-perpetuating, reverberating circuit, which causes spasms of the extraocular muscles.

Neuromyotonia in association with malignant hyperpyrexia

Images

Association of neuromyotonia with peripheral neuropathy, myasthenia gravis and thymoma: a case report

A case of neuromuscular hyperactivity syndrome associated with a thymoma, high serum titres of anti-acetylcholine receptor and anti-DNA antibodies is reported. The study of peripheral nerve conduction revealed a peripheral neuropathy. Repetitive stimulation showed a decrease in the fifth M response. Myasthenic symptoms were anamnestically reported but were absent at clinical observation. The clinical picture and EMG examination improved after phenytoin administration.

Proximal myotonic myopathy: a new dominant disorder with myotonia, muscle weakness, and cataracts

We describe three families with a dominantly inherited disorder. Affected individuals have myotonia, proximal muscle weakness, and cataracts. There was no abnormal CTG repeat expansion of the myotonic dystrophy (DM) gene in DNA from blood and muscle. The structure of the three families permitted linkage analysis, and there is no linkage to the gene loci for DM or to the loci for the muscle chloride channel disorders or muscle sodium channel disorders. The collection of symptoms in these three families seems to represent a new disorder.

Hyperkalaemic periodic paralysis and anaesthesia

Hyperkalaemic periodic paralysis is the rarer of the two forms of potassium-associated familial paralysis. We report a family with hyperkalaemic periodic paralysis with paramyotonia and the anaesthetic management of four affected members. In three of these, paralytic episodes had been precipitated by previous anaesthesia, but this was avoided in the anaesthetics described. We conclude from our experiences that with depletion of potassium before surgery, prevention of carbohydrate depletion, avoidance of potassium-releasing anaesthetic drugs and maintenance of normothermia, patients with hyperkalaemic periodic paralysis can be anaesthetised without complications. We have no evidence that they exhibit abnormal sensitivity to nondepolarising neuromuscular relaxants.

Are myotonias and periodic paralyses associated with susceptibility to malignant hyperthermia?

Excised muscles from patients with myotonia or periodic paralysis were subjected to the in vitro contracture test for susceptibility to malignant hyperthermia (MH). In a group of 44 patients, this standard test gave four positive, 10 equivocal and 30 negative results. The results for 27 control muscles from normal subjects were negative. When the test was performed with less than normal concentrations of contracture-triggering substances (caffeine less than or equal to 2 mmol litre-1, less than or equal to 2% halothane), 70% of the muscles from the patients and only 15% of the controls responded with small contractures (less than 0.2 g). These results should not be taken to indicate that the patients have the genetic trait for MH. The positive and equivocal test results, in addition to the slight contractures, may be accounted for by the electrical after-activity in the cases of pure myotonia, and by increased resting myoplasmic [Ca2+] in myotonic dystrophy. This shows that the in vitro contracture test lacks specificity.

Electrical myotonia and cataract in X-linked muscular dystrophy (mdx) mouse

An X chromosome-linked mouse mutant (mdx) has been investigated as an animal model of Duchenne's muscular dystrophy, and has been found to have the same defect of dystrophin in the muscle surface membrane. Intracellular recordings from the mdx mouse hemidiaphragm preparations revealed low resting membrane potentials and electrical myotonia which occurred at the time of microelectrode insertion and withdrawal. Electrical myotonia of the mdx mouse was observed in 30-50% of the impaled muscle fibers at low temperature, which decreased to only 7.8% at 37 degrees C. Electrical myotonia of mdx mice was not abolished by (+)-tubocurarine. Though there was no behavioral myotonia in mdx mice, repetitive bursts of action potentials in mdx mice were based on the abnormalities of the muscle membrane since neuromuscular blockade did not abolish the repetitive bursts. Also close observation of the lenses of mdx mice revealed cataracts from the newborn stage to the adult age. Slit lamp examination of the lenses of the mdx mice revealed nuclear cataracts followed by anterior subcapsular cataract as they grew. The cataract of mdx mice is different from that of myotonic dystrophy which is usually posterior subcapsular.

[Infantile spinal amyotrophy with myotonia. Electromyographic study]

An unusual feature was observed in a 7-year-old boy presenting with type II infantile spinal muscular atrophy: percussion myotonia, clinical expression of pseudomyotonic volleys (bizarre high frequency discharge or complex repetitive discharge).

Adynamia episodica hereditaria with myotonia: a non-inactivating sodium current and the effect of extracellular pH

To study the mechanism of periodic paralysis, we investigated the properties of intact muscle fibers biopsied from a patient who had adynamia episodica hereditaria with electromyographic signs of myotonia. When the potassium concentration in the extracellular medium, [K]e, was 3.5 mmol/l, force of contraction, membrane resting potential, and intracellular sodium activity were normal, but depolarizing voltage clamp steps revealed the existence of an abnormal inward current. This current was activated at membrane potentials less negative than -80 mV, reached a maximum within 50 msec, and was not inactivated with time. The inward current was completely and reversibly blocked by tetrodotoxin, which indicates that it was carried by sodium ions. In a solution containing 9 mmol/l potassium, normal muscle would depolarize to -63 mV and yet be capable of developing full tetanic force upon stimulation. The muscle from the patient depolarized to -57 mV and became inexcitable, i.e., it was paralyzed. A contracture did not develop. Lowering of the extracellular pH did not influence the resting potential, but it effectively antagonized or prevented the paralytic effect of high [K]e by changing the inactivation characteristics of the sodium channels. Hydrochlorothiazide, which had a therapeutic effect on the patient, did not prevent paralysis in vitro. An abnormal rise of the intracellular sodium activity was recorded when the extracellular potassium concentration was raised to 10 mmol/l.

Adynamia episodica and paralysis periodica paramyotonica

We studied hyperkalemic attacks in one family with adynamia episodica (AE) and one family with paralysis periodica paramyotonica (PPP). Under exercise, serum potassium increased as in healthy subjects. Thiazide did not affect this increase. Thirty minutes after exercise, a second potassium increase occurred, but could be prevented by thiazide and not by mexiletine. After cooling, muscle relaxation time was normal in AE but increased up to 100 times in PPP; this cooling effect was prevented by mexiletine. Although hyperkalemic attacks are similar in AE and in PPP, the membrane defect in PPP seems more complex.

Cardiac involvement in myotonic muscular dystrophy

Cardiac illness in myotonic muscular dystrophy (MyD) is infrequent, but subclinical cardiac involvement in MyD is very common (found in 42 of 46 subjects) and may be responsible for sudden death. In this series, we found ECG abnormalities in 72%, left ventricular dysfunction in 70%, mitral valve prolapse in 37%, and sudden death in 4%. Four deaths during the study period were due to acute left ventricular failure, one to sepsis and respiratory insufficiency, and one was unexplained. We did not find ominous bradyarrhythmias or atrioventricular block, evidence of congestive heart failure, noninvasive evidence of coronary artery disease, or any correlation of type or amount of cardiac involvement with any clinical parameter such as age, sex, or severity of systemic dystrophy. We feel tachyarrhythmias may play as important a role in sudden death of myotonic muscular dystrophy subjects as bradyarrhythmias, and coronary artery disease in addition to cardiac dystrophy may produce arrhythmias and myocardial dysfunction in myotonic muscular dystrophy. In addition, some subjects have an unusual form of resting left ventricular dysfunction which improves with exercise. The most important problem in the clinical management of myotonic muscular dystrophy subjects is sudden death, and the solution does not appear to be empiric ventricular pacing. Our recommendations for prophylaxis of sudden death in myotonic muscular dystrophy are noninvasive investigation of coronary artery disease in subjects with significant risk factors, with angiography and surgery if indicated: detailed evaluation of syncopal and presyncopal events, including electrophysiologic testing, with pacemaker or antiarrhythmic drug therapy if indicated; and consideration of ventricular pacing of asymptomatic subjects if severe bradycardia or marked intraventricular conduction delay develops during follow-up, serial 12-lead ECGs. The documentation of tachyarrhythmias during sudden death and syncopal episodes in myotonic muscular dystrophy subjects makes ventricular pacing alone an uncertain modality for prevention of sudden death in subjects with only mildly lengthened PR or QRS intervals, and suggests a combination of pacemaker and antiarrhythmic drug therapy for the myotonic muscular dystrophy subject with syncope of no apparent cause.

The child with a stiff neck

The child with a stiff neck can be a challenging diagnostic exercise. Four unusual examples of acute neck stiffness, not associated with meningitis, are presented to illustrate the various pathologic conditions which may produce this symptom. A differential diagnostic schema is suggested on the basis of pathologic and physiologic alterations of cervical and paracervical anatomic structures.

Electromyographic and nerve conduction findings in a patient with neuromyotonia, normocalcemic tetany and small-cell lung cancer

A 57-year-old man with neuromyotonia and normocalcemic tetany as probable paraneoplastic symptoms of small-cell lung cancer was examined neurophysiologically. In EMG, spontaneous action potential generation was demonstrated in peripheral motor axons. There were also time-locked high-frequency discharges after some voluntarily activated motor unit potentials. After electrical stimulation of motor axons, the M-response as well as spinal F-response or H-reflex was often followed by a sequence of oscillating potentials which could last several hundred msec. There was no evident peripheral polyneuropathy. Tetany subsided when carbamazepine therapy was started. The only striking abnormality in extensive laboratory studies was an increase in the plasma noradrenaline value.

[Hypertrophic neuropathy with myotonia (author's transl)]

A case of distal amyotrophia is reported, in which there was associated isolated clinical and electrical myotonia. Nerve conduction rates were very reduced. The nerves showed rarefaction of nerve fibers with segmentary demyelinization and the formation of bulbar swellings. The signification of this observation is discussed, and it would not appear to be related to peripheral nerve lesions of the type sometimes seen in Steinert's disease or from an association of this affection with Charcot-Marie's disease. It would seem more reasonable to suggest the hypothesis of a particular type of association of a peroneal hypertrophic neuropathy and a myotonia similar to certain cases reported in the published literature.

Myokymia, muscle hypertrophy and percussion "myotonia" in chronic recurrent polyneuropathy

Three unusual features were observed in a patient with chronic relapsing polyneuropathy: myokymia, muscle hypertrophy, and prolonged contraction in response to muscle percussion. Low nerve conduction velocity and conduction block were demonstrated in all motor nerves tested, indicating a demyelinating peripheral neuropathy. Myokymia was caused by spontaneous motor unit activity which was shown to originate in peripheral nerves, since it persisted after nerve block and was abolished by regional curarization. Muscle hypertrophy was attributed to increased peripheral nerve activity, and the prolonged contraction of muscle in response to direct percussion was attributed to irritability of intramuscular nerve terminals.

Prolonged muscle rigidity following administration of succinylcholine

Succinylcholine should be avoided in any patient with known myotonia because of the possibility of an abnormal rigid response. In addition, the possibility of undiagnosed myotonia should be considered in any myopathic patient. While not all myotonic responses are associated with malignant hyperthermia, the anesthetic should be discontinued immediately and the patient should be closely observed for elevation of temperature.