Paramyotonia congenita (Eulenburg): clinical, neurophysiological and muscle biopsy observations in a Swedish family

A Swedish family with Paramyotonia congenita (Eulenburg) (PMC) is presented. Clinical neurological examination, neurophysiological examination (n = 5) and muscle biopsy (n = 4) were performed. Different clinical features were found in various combinations in the individual family members. The clinical symptoms were: (1) cold-induced myotonia, (2) attacks of weakness, (3) persistent weakness and (4) no symptoms but other signs of muscle affection. In the patients with myotonia, the neurophysiological examination showed spontaneous myotonic discharges which were frequent at room temperature but disappeared after cooling. Furthermore, the amplitude of M. abductor digiti minimi compound action potential, during supramaximal ulnar nerve stimulation, decreased significantly after cooling. In the patients with persistent weakness there were no spontaneous myotonic discharges, but myopathic abnormalities were found in proximal muscle. In the patients with myotonia as well as in the patients with manifest muscle weakness, muscle biopsy showed a variation of muscle fibre diameters, centrally located nuclei, occasional atrophic fibers and an atrophy of type IIB muscle fibres. These findings are unspecific but have been described in PMC patients in earlier studies. An ancestor to the family, who had myotonia, lived in the same town and at the same time as Albert Eulenburg, which may suggest that this family is a part of the originally described family (1).     

强直性肌营养不良Ⅰ型临床、病理、骨骼肌磁共振特点

目的总结11例强直性肌营养不良Ⅰ型(DM1)患者的临床、病理和双下肢肌肉受累的特点。方法回顾性分析2012年01月至2020年10月就诊于南京鼓楼医院神经内科的11例DM1患者的临床、骨骼肌活检病理及5例双下肢骨骼肌磁共振的特点。结果11例患者均有不同程度的肌强直、伴有肌无力/肌萎缩症状,肌无力/肌萎缩远端重于近端。骨骼肌病理特点:10/11例患者可见Ⅰ型肌纤维轻度萎缩,部分患者可见核内移、核聚集、肌浆块现象。双下肢肌肉磁共振:5例患者双下肢远端脂肪浸润重于近端,双侧肌肉受累程度不对称,大腿肌肉脂肪浸润以股中间肌最严重,小腿肌肉以腓肠肌、比目鱼肌、腓骨长肌最严重。结论骨骼肌磁共振对诊断强直性肌营养不良Ⅰ型有重要的提示意义。     

强直性肌营养不良症的临床与肌肉病理学特点

目的探讨强直性肌营养不良症(DM)的临床及肌肉病理学的特点。方法对6例DM患者的临床资料进行回顾性分析。结果6例患者均呈慢性病程,以肌无力、肌强直和肌肉萎缩为主要表现,多伴有脱发、白内障、心脏传导阻滞等多系统损害。肌电图检查结果为肌源性损害,6例均可见肌强直电位发放。病理学检查见肌纤维核内移、核袋及核链现象,部分患者可见肌质块及肌纤维分布异常。结论DM是一种以肌无力和肌强直为主要表现的多系统损害的遗传性疾病;特征性病理改变为肌纤维核内移、核链以及肌质块、肌纤维分布异常。     

Colchicine-induced myopathy with myotonia in a patient with chronic renal failure

Although colchicine induced myopathy has been described in patients with chronic renal failure, colchicine induced myopathy with myotonia has been reported very rarely. A 49-year-old man with chronic renal failure was hospitalised for investigation of fatigue, malaise and severe pain in all extremities. He was on colchicine therapy for 5 months. Neurological examination showed mildly decreased sensation in a distal symmetric pattern in lower extremities, moderate proximal limb weakness, hyporeflexia and severe myalgia on palpation. No clinical evidence of myotonia was present. Laboratory studies showed elevated creatine phosphokinase (CK), lactic dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. Electromyographic (EMG) findings were compatible with myopathy and abundant, widespread myotonic discharges were determined. Muscle biopsy was consistent with vacuolar myopathy. After withdrawal of colchicine, CK, LDH, AST and ALT levels were normalised and the symptoms were disappeared gradually. In conclusion, the detection of myopathic motor unit potentials with myotonic discharges on EMG in patients on colchicine therapy is an important finding and it is possible to suggest that this clue may lead to the invasive procedure of muscle biopsy unnecessary.     

强直性肌营养不良一家系临床分析

目的 探讨强直性肌营养不良(DM) 的临床特点,以提高对该病的认识.方法 对一DM 家系确诊的5例患者的临床资料进行收集分析,包括患者基本资料、临床表现、肌电图及肌肉活检等.结果 5例DM 患者均为慢性病程,以肌强直、肌无力、肌萎缩为主要表现,伴眼部、心脏、内分泌和神经等多系统损害,血清肌酶轻度增高或正常,肌电图具有特征性肌强直放电和肌源性损害,肌肉活检具有相对特异性肌病特征.结论 DM 是一种以肌强直、肌无力、肌萎缩为主要表现的多系统损害的遗传性疾病,临床表现复杂多样,肌肉活检有助于明确诊断.     

Proximal myotonial myopathy (PROMM): clinical and histology study

We report 13 French patients with proximal myotonic myopathy. PROMM is a recently delineated multisystem disorder with dystrophic myopathy, myotonia and cataracts. This syndrome is genetically distinct from myotonic dystrophy (DM) by the absence of abnormal CTG repeat expansion. The geographical origin varies but 4 families originated from Poland. Of late onset, muscle weakness is diffuse and predominantly affected proximal and axial muscles. Facial involvement and myotonia were moderate or absent, but in all cases myotonic discharges were detected on EMG. 6 patients suffered from myalgia. Cataracts occurred in 11 patients, mainly indistinguishable from those in DM. Cardiac arrythmia occurred in 7 patients. Muscle biopsy revealed rare structural changes of the muscle fibers and selective type I atrophy, common in DM, could not be found on morphometric analysis. PROMM has a distinct clinical spectrum from DM which includes a predominantly proximal muscle weakness, with troubling pain, a more favourable prognosis and a different histopathological pattern.     

强直性肌营养不良临床特点分析

目的分析强直性肌营养不良(DM)的临床特点,以提高对DM疾病的认识及诊断水平。方法对21例DM患者的临床资料进行回顾性总结与分析。结果 21例患者均为慢性起病,以双手无力,活动不灵活起病多见,其中5例有家族史,部分病例伴有心脏、眼部、内分泌及中枢神经系统等其他多系统损害。19例行肌电图检查提示肌源性损害,其中16例发现有肌强直电位。10例行肌活检,主要表现为部分肌纤维萎缩,变性、坏死肌纤维,核内移及肌浆块形成,部分萎缩纤维内可见无结构胞浆体。1例强直性肌营养不良蛋白激酶(DMPK)基因CTG重复序列分析发现拷贝数超过正常范围。结论 DM是一种主要累及肌肉系统,以肌强直、肌无力和肌萎缩为主要临床表现并伴有多系统损害的疾病。综合评估多系统损害并结合肌肉的电生理学及病理学检查,有助于提高对DM的认识;在有条件的医疗机构可以开展DM基因诊断,对DM确诊很有意义。     

Proximal myotonic myopathy: clinical, electrophysiological and pathological findings in a family

Proximal myotonic myopathy (PROMM) is an autosomal dominant muscle disorder characterized by proximal weakness, myotonia, muscle pain and cataract. It resembles Steinert myotonic dystrophy (MD), but weakness is proximal, without facial muscle involvement, and the chromosome 19 CTG trinucleotide repeat expansion characteristic of MD is not present. We describe a further family with PROMM. Affected members complained of weakness of lower limbs or of myotonia. EMG revealed diffuse myotonic discharges. Muscle histology showed dystrophic abnormalities. The PROMM phenotype varies, even in the same pedigree, and may mimic MD or limb-girdle muscle dystrophy. EMG is particularly useful, since it may disclose myotonic discharges even in the absence of overt myotonia. Thus far it is not known whether PROMM is a single entity, or if it represents a heterogeneous group of disorders. This question will probably soon be settled through genetic analysis.     

A case of myotonic dystrophy showing proximal dominant muscle involvement but not myotonia]

A 45-year-old female had progressive difficulty in climbing stairs and standing from a chair for 10 years. She had binocular cataracts which were operated at the age of 42 years. On examination, she had marked muscle wasting in the proximal limbs, scapular and sternomastoid muscles. She presented as marked muscle weakness in the proximal portion of the lower extremities and moderate in the upper extremities and the legs. Deep tendon reflexes were absent in all limbs. There was no grip myotonia, or percussion myotonia of the thenar muscle and tongue. Myotonia was not elucidated even after the hands were exposed to cold water. Moreover, none of the examined muscles revealed insertion myotonic discharge on electromyography. Serum CK level was normal and IgG value decreased to 546 mg/dl. Muscle biopsy of the left biceps muscle showed the variation in fiber size, increased central nuclei and many fiber with pyknotic nuclear clumps on HE staining. Sarcoplasmic mass and ring fibers were also found on HE staining. There were a few percents of ragged-red fibers on Gomori-trichrome staining, and type 1 fiber atrophy was found on pH 4.5 ATP-ase staining. The expansion of lymphocyte CTG trinucleotide repeats in the myotonin protein kinase gene was about 733, so that she was diagnosed as having myotonic dystrophy (MD). MRI of skeletal muscles exhibited marked atrophy especially in the femoral region and the biceps muscle. This patient had the proximal dominant muscle weakness, and absent myotonia even on electromyographic examination, which are unusual clinical features of adult onset MD.     

The expanding clinical and genetic spectrum of the myotonic dystrophies

Core features of the dominantly inherited myotonic dystrophies are myotonia, muscle weakness and cataract. Classic myotonic dystrophy (Steinert's disease) has been defined as a genetic entity by the underlying CTG repeat expansion on chromosome 19q13.3 (= DM1 locus). Later on, another disorder similar to but different from myotonic dystrophy was described as proximal myotonic myopathy (PROMM). The majority of PROMM families have been linked to a recently discovered locus on chromosome 3q21 (= DM2 locus).--This article analyses the clinical features of 70 patients from 14 German PROMM families linked to the 3q locus. In contrast to Steinert's disease, these patients did not reveal mental deficiency; no congenital type was found; weakness was mainly located in the proximal leg muscles; clinical myotonia was very mild and sometimes absent; episodes of pain occurred. In the majority of patients, the disorder seems to be more benign compared to Steinert's disease. However, life threatening cardiac involvement is possible; rarely, muscle weakness may progress until the patient is bedridden.--Some families with a PROMM-like phenotype do not link to the locus on 3q. The group of the myotonic dystrophies will get new members in the future.     

Myotonic dystrophy with no trinucleotide repeat expansion

We report 3 patients from 2 families with myotonic dystrophy who do not show an abnormal expansion of CTG trinucleotide repeats within the myotonic dystrophy gene. Characteristic features of myotonic dystrophy in these patients were frontal balding, cataracts, cardiac conduction abnormalities, and testicular atrophy with myotonia and muscle weakness. Results of muscle histopathology were consistent with myotonic dystrophy. Genetic analysis of leukocyte and muscle DNA showed a normal number of CTG repeats. The demonstration of normal CTG repeat number for the myotonic dystrophy gene does not exclude the diagnosis of myotonic dystrophy.     

A patient with proximal myotonic myopathy and parkinsonism

INTRODUCTION: There are two case reports of patients who had proximal myotonic myopathy (PROMM)/myotonic dystrophy (DM) Type 1 and parkinsonism. The combination of myotonic myopathy and parkinsonism is so rare that it may appear to be just a coincidence. However, previous neuropathological examinations of patients who had myotonic dystrophy showed that there were intracytoplasmic inclusion bodies in the nigra and striatum, which raises the possibility that myotonic myopathy may be associated with parkinsonism. In this report we describe a patient with PROMM and a clinically definite parkinsonism to highlight this possibility. CASE REPORT: A 65-year-old man developed proximal muscle weakness, myotonia and atrophy around the age of 55 and was diagnosed as having PROMM at the age of 62. Needle electromyography and muscle biopsy supported the diagnosis. A gene study of the DM Type 1 showed a normal CTG repeat length. At age 63, he developed rest tremor, bradykinesia, hypomimia, stooped posture, and gait disturbance. The postural instability worsened rapidly. The tremor and rigidity were much worse in his right side, where myotonia was more severe. Levodopa therapy was only partially effective. CONCLUSION: This is a case report of a patient with PROMM that shows an association with a rapidly progressive form of parkinsonism. We suggest that this may be a novel form of a neurodegenerative disorder, which we name 'Parkinsonism-Myotonic Myopathy-Complex'.     

Myotonic dystrophy (DM/Curschmann-Steinert disease) and proximal myotonic myopathy (PROMM/Ricker syndrome). Myotonic muscle diseases with multisystemic manifestations

Myotonic disorders are characterised by slowed muscle relaxation and myotonic discharges in the electromyogram. "Pure" myotonic disorders affect only muscle and can be separated into ion channel disorders affecting either the chloride channel (myotonia congenita Thomsen or myotonia congenita Becker) or those affecting the sodium channel (paramyotonia, hyperkalemic periodic paralysis, and myotonia fluctuans). The genetic defects in these disorders are point mutations or deletions within the respective channel genes. A second group of myotonias consists of multisystem disorders with muscle weakness and atrophy plus extramuscular symptoms and signs including cardiac arrhythmias, cataracts, hypogonadism, and pain. Classic myotonic dystrophy (Steinert's disease or DM 1), and proximal myotonic myopathy (PROMM or Ricker's syndrome) are the major syndromes. PROMM is characterised by predominantly proximal muscle weakness and myalgias. Similarly to DM 1, anticipation also occurs in PROMM, but the disease course is usually milder. Steinert's disease belongs to the group of trinucleotide repeat-associated disorders. The DM 1 mutation is an unstable CTG trinucleotide repeat expansion on chromosome 19q13.3 which is diagnostic for the disease. A number of families with PROMM have been linked to a gene locus on chromosome 3q, but the mutation is still unknown. Therefore, direct molecular genetic testing for PROMM is not yet possible.     

Myotonia fluctuans

Autosomal-dominantly inherited nondystrophic myotonic disorders are an interesting group of muscle diseases that provide considerable opportunity for future molecular genetic studies to identify the genes responsible for specific membrane functions. A family with such a myotonic disorder is described with features that are distinctly different from myotonia congenita and paramyotonia congenita. Five members were affected in three generations. The myotonia fluctuated to an unusual degree. It did not worsen with cold but increased markedly with potassium loading. Muscle weakness never occurred. Analysis of the contraction force of the flexor digitorum muscle showed a unique type of myotonia, namely, exercise-induced delayed-onset myotonia. Microelectrode studies done on one muscle biopsy specimen revealed a normal chloride conductance of the muscle fiber membrane.     

Myotonic dystrophy: Correlation of clinical symptoms with the size of the CTG trinucleotide repeat

An unstable DNA sequence of a gene encoding a protein kinase has been identified as the molecular basis of myotonic dystrophy. The correlation between different symptoms of myotonic dystrophy and the size of this unstable base triplet (CTG)_n repeat was investigated in 14 patients. DNA was prepared from whole blood by standard procedures. Detailed clinical, psychological, electrophysiological (quantified measurement of myotonia, electrocardiography) and other laboratory examinations (muscle biopsy in 4 patients, slit lamp examination) were performed. Triplet size correlated significantly with muscular disability and inversely with age at onset of the disease. A greater frequency of mental and gonadal dysfunction could be observed in patients with a larger repeat size. Other symptoms, however, such as cataract, myotonia, gastrointestinal dysfunction and cardiac abnormalities were not correlated with repeat size. Somatic mosaicism with different amplification rates in various tissues might be one possible explanation for the variable phenotypes. Furthermore, other factors such as different expression of the myotonic dystrophy gene might contribute to the clinical variability of the disease at a given triplet size.     

Unclassified familial myopathy resembling Steinert disease, without myotonia

A familial myopathy with predominantly proximal muscle atrophy is described. Although several clinical features such as sternomastoid and brachioradialis muscle involvement suggested Steinert disease, myotonia was not demonstrated by clinical examination or EMG. Histological data were consistent with myotonic dystrophy.     

A large German kindred with cold-aggravated myotonia and a heterozygous A1481D mutation in the SCN4A gene

Muscle sodium-channel disorders cover a spectrum of rare myotonic diseases. In a German family with 17 affected individuals in four generations, we identified a heterozygous missense mutation in exon 24 A1481D (c.4442 C>A) of the voltage-gated sodium channel gene (SCN4A) alpha subunit. Phenotypes of 12 family members were characterized by a mild myotonia with cold sensitivity but without paramyotonia. The index patient presented with fluctuating cold- and exercise-induced stiffness of ocular, facial, and distal muscles. The myotonia became more severe at the age of 22 years. His father had had cold- and exercise-induced periodic weakness with fluctuating myotonia since age 10. Later he developed a more severe, purely exercise- and cold-aggravated myotonia of arms, hands, and facial muscles. The father's mother presented with cold-induced myotonia until age 65, when progressive weakness of proximal limb muscles developed. Her muscle biopsies revealed considerable myopathic changes with a variety of fine structural alterations. This study presents a family with cold-aggravated myotonia and progression of myopathic changes in the muscle biopsy with increasing age. In older patients, sodium channelopathies may mimic the phenotypic features of myotonic dystrophy type 2.     

Myotonic dystrophy type 2 with focal asymmetric muscle weakness and no electrical myotonia

Genetically proven myotonic dystrophy type 2 (DM2) was found in a 61‐year‐old woman with creatine kinase (CK) elevation and only isolated weakness of one triceps. There was no clinical or electrical myotonia. Electromyography (EMG) showed only scattered fibrillation potentials and short duration motor unit potentials. Muscle biopsy showed nonspecific myopathic features and highly atrophic fibers with nuclear clumps. DM2 should be considered in patients with focal proximal weakness and abnormal EMG without myotonic discharges. Muscle Nerve 39: 383–385, 2009     

A case of Becker type congenital myotonia with myalgia

We reported a case of Becker type congenital myotonia with myalgia. A 28 year-old woman admitted to our hospital because of right anterior chest pain and back pain. She was diagnosed as myotonic dystrophy by other university hospital when she was 16 years old. Physical examination revealed only myotonia and could not find muscle atrophy or cataracta which were usually found in myotonic dystrophy. The quadriceps muscle biopsy revealed complete absence of type IIB muscle fiber. We diagnosed her Becker type congenital myotonia by the clinical course and family history and the histopathological findings of quadriceps muscle. Myalgia which she complained seemed to have some connection with this disease. But we could not prove the pathogenesis of this myalgia.     

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.