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Ocular myasthenia gravis is a not uncommon autoimmune disorder causing diplopia, ptosis, and weakness of lid closure. The predilection of myasthenia for the ocular muscles may be related to differences between limb and extraocular muscles in either physiological function or antigenicity. Clinically, ocular myasthenia can mimic any form of pupil-sparing ocular motility disorder. Dynamic abnormalities of myasthenic eye movements may reflect the primary hallmarks of the disease, which are fatigability and variability in strength, or secondary adaptive effects by the central nervous system. Tests to confirm the diagnosis include edrophonium challenge, repetitive nerve stimulation, single-fiber electromyography (EMG) of the frontalis, and assays for antibody directed against the acetylcholine receptor: all are less sensitive for ocular myasthenia than for generalized myasthenia. There is a higher incidence of other autoimmune conditions in myasthenia, notably thymoma and thyroid dysfunction. The differential diagnosis includes other diseases of the neuromuscular junction, such as Lambert-Eaton syndrome and botulism. Treatment consists of symptomatic use of acetylcholinesterase inhibitors and immunosuppression with steroids or azathioprine. Between 50 and 70% of patients with ocular myasthenia will eventually develop generalized disease: there is some retrospective data that steroids or azathioprine may reduce this by about 75%. The role of thymectomy in ocular myasthenia remains unclear.
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PMID:Ocular aspects of myasthenia gravis. 1087 73

This paper describes a case of myasthenia gravis in a 38-year-old woman who first consulted a dentist and then an oral surgeon because of chewing difficulty. Although myasthenia gravis commonly presents with diplopia, ptosis, or both as initial symptoms, chewing difficulty is rare. The patient was given steroid therapy and underwent thymectomy. Changes in bite force were monitored during treatment. The bite force was low when a high titer of anti-acetylcholine receptor antibody (11.0 nmol/l, normal <0.2) was found in the blood, but increased after the titer had decreased (1.5 nmol/l) in response to therapy.
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PMID:Myasthenia gravis associated with reduced masticatory function. 1107 Dec 45

We report a patient of polymyositis and myasthenia gravis as manifestations of chronic graft-versus-hot disease (GVHD). A 48-year-old man was diagnosed as having chronic myelogenous leukemia at the age of 42 years, and had bone marrow transplantation (BMT) two years after the onset of the disease. Since he suffered from mild liver dysfunction and cutaneous involvement manifesting chronic GVHD, he was placed on prednisolone and cyclophosphamide. As his condition improved, the prednisolone was gradually tapered. Forty-one months after the BMT, the patient developed muscle pain and muscle weakness. A diagnosis of polymyositis was made from muscle biopsy and laboratory findings. An increase in the prednisolone dose was effective but a few weeks later the patient noticed ptosis and recurrence of muscle weakness. A tensilon test and anti-acetylcholine receptor antibody produced positive results, leading to a diagnosis of myasthenia gravis. Only one case of polymyositis and myasthenia gravis as manifestations of chronic GVHD has been reported, and in our patient both symptoms appeared almost at the same time. Although neuromuscular symptoms as a manifestation of chronic GVHD are rare, all patients receiving BMT should be carefully followed up neurologically to detect neuromuscular complications.
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PMID:[A patient of chronic graft-versus-host disease presenting simultaneously with polymyositis and myasthenia gravis]. 1188 35

Nine patients over 5 generations developed progressive bilateral blepharoptosis from 40 to 50 years of age, suggesting that they had an autosomal dominantly inherited blepharoptosis. Except for the ptosis, they had no apparent neurological symptoms: normal ocular movement, no bulbar sign and no muscle weakness in the extremities. On laboratory examination, serum creatine kinase and blood lactate levels were within normal limits, and acetylcholine receptor antibody was not elevated. Electrophysiological studies including EMG and nerve conduction velocities were normal. Muscle biopsies from gastrocnemius and palpebral muscles were nondiagnostic with no ragged-red fibers nor rimmed vacuoles. Nuclear inclusions were not recognized by electron microscopy. Since none of patients examined had mitochondrial DNA deletions and GCG repeat expansion in the poly A binding protein P2 (PABP2) gene, this familial disorder is a unique blepharoptosis with no relationship to progressive external ophthalmoplegia or oculopharyngeal muscular dystrophy with PABP2 mutation.
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PMID:[Familial chronic progressive blepharoptosis without other neurological symptoms: a new clinical entity?]. 1235 44

Although myasthenia gravis (MG) has frequently been associated with other autoimmune disorders, it has only rarely been reported in conjunction with diseases of the nervous system. A 74-year-old patient with hypertension suddenly presented left unilateral ptosis and mastication disorders. Clinical examination showed a concomitant loss of strength distally and reduced deep tendon reflex. Electrophysiologic data indicated a diagnosis of MG and chronic inflammatory demyelinating polyneuropathy; acetylcholine receptor antibody was elevated at 4.1 nmol/L (normal < 2 nmol/L). Improvement was rapid after initiation of pyridostigmine in association with corticosteroid (1 mg/kg/day). One month later, the cranial nerve deficit disappeared and strength was normal. It is likely that a basic abnormality of immune regulation was responsible for the emergence of diseases with different clinical presentations, but similar immunopathogenesis. Corticosteroid seemed to be the most effective treatment.
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PMID:[Ptosis and mastication disorders revealing concurrent myasthenia gravis and chronic polyradiculoneuritis]. 1248 7

We report a rare case of a 70-year-old woman diagnosed as having blepharospasm with positive anti-acetylcholine receptor antibody. Blepharospasm developed in November, 2000, and increased in frequency, and worsened toward the evening. She complained of difficulty in her eyelid opening from October, 2002. Neurological examinations revealed blepharospasm and mild ptosis in both eyes. Tensilon test was negative. Waning and waxing were not detected in bilateral orbicularis oculi muscles by Harvey-Masland test. However, anti-acetylcholine receptor antibody was positive and thymoma in the anterior mediastinum was also found by the computed tomography of the chest. After the thymectomy, frequency of blepharospasm decreased. When blepharospasm worsened toward the evening, the co-existence of myasthenia gravis should be borne in mind.
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PMID:[Blepharospasm in a patient with thymoma and positive anti-acetylcholine receptor antibody]. 1465 4

We contrast the phenotypes associated with hereditary acetylcholine receptor deficiency arising from mutations in either the acetylcholine receptor epsilon subunit or the endplate acetylcholine receptor clustering protein rapsyn. Mutational screening was performed by amplification of promoter and coding regions by PCR and direct DNA sequencing. We identified mutations in 37 acetylcholine receptor deficiency patients; 18 had acetylcholine receptor-epsilon mutations, 19 had rapsyn mutations. Mutated acetylcholine receptor-epsilon associated with bulbar symptoms, ptosis and ophthalmoplegia at birth, and generalized weakness. Mutated rapsyn caused either an early onset (rapsyn-EO) or late onset (rapsyn-LO) phenotype. Rapsyn-EO associated with arthrogryposis and life-threatening exacerbations during early childhood. Rapsyn-LO presented with limb weakness in adolescence or adulthood resembling seronegative myasthenia gravis. Awareness of distinct phenotypic features of acetylcholine receptor deficiency resulting from acetylcholine receptor-epsilon or rapsyn mutations should facilitate targeted genetic diagnosis, avoid inappropriate immunological therapy and, in some infants, prompt the rapid introduction of treatment that could be life saving.
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PMID:Distinct phenotypes of congenital acetylcholine receptor deficiency. 1514 36

Ocular problems are common in recipients of stem cell transplantation (SCT), but ptosis is rarely reported and investigated. Among 346 consecutive SCT recipients, severe bilateral ptosis was noticed or reported in six cases (five women and one man), all with acute graft-versus-host disease (aGVHD) and chronic graft-versus-host disease (cGVHD). On univariate analysis, both aGVHD (P=0.001) and cGVHD (P<0.001) were associated with post SCT ptosis, while a trend was shown for female sex (P=0.086). The median level of anti-acetylcholine receptor antibody was significantly higher in ptosis cases than controls with cGVHD (student's t-test, P=0.01). Antistriated muscle antibody was detected in three cases and was not significantly different from controls (Fisher's exact test, P=0.29). Tensilon tests were uniformly negative. However in five cases, single fibre electromyogram at frontalis muscle showed irregular recruitment effort, suggesting localized neuromuscular transmission defect reminiscent of ocular myasthenia gravis (MG). Two patients were observed, while three patients did not respond to mestinon or steroids treatment and one patient underwent aponeurosis advancement surgery. Transplant physicians and ophthalmologists should be aware of the problem of post SCT ptosis, which may be related to alloimmune causes of neuromuscular transmission block. Diagnosis can be difficult to confirm even with invasive SF-EMG testing. Most cases warrant conservative treatment due to chronicity, benign course and poor response to medication.
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PMID:Immunological and electrophysiological investigations of severe ptosis after bone marrow transplantation. 1524 30

The slow-channel syndrome is one of the congenital myasthenic syndromes attributed to inherited kinetic disorders of the ion channel of the acetylcholine receptor of the neuromuscular junction. This is a case report of 25-years-old man with progressive ptosis and limitation of ocular movements since infancy, presented a 6-years history of worse of the external ophthalmoparesis and muscular weakness in the shoulders and hands. The motor nerve conduction studies after a supramaximal single stimulus disclosed a double compound muscle action potential (CMAP) that disappeared after a voluntary contraction of 30 seconds. Repetitive stimulation of facial and spinal accessory nerves showed a CMAP decrement greater than 10% with disappeared of the second potential. The patient received fluoxetine with mild improvement of muscular weakness, but persisted with: ptosis, limitation of ocular movements and repetitive CMAP in the motor nerve conduction study. The characteristic of disease are discussed.
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PMID:[Neurophysiological study in slow-channel congenital myasthenic syndrome: case report]. 1679 78

The properties of neuromuscular junctions (NMJs) were studied in motor-point biopsy samples from eight patients with congenital myasthenic syndromes affecting primarily proximal limb muscles ['limb-girdle myasthenia' (LGM)]. All had moderate to severe weakness of the proximal muscles, without short-term clinical fatigability but with marked variation in strength over periods of weeks or months, with little or no facial weakness or ptosis and no ophthalmoplegia. Most had a characteristic gait and stance. All patients showed decrement of the compound muscle action potential (CMAP) on repetitive stimulation at 3 Hz, and increased jitter and blocking was detected by SFEMG, confirming the presence of impaired neuromuscular transmission. None of the patients had serum antibodies against acetylcholine receptors (AChRs). Two of the patients had similarly affected siblings. Intracellular recording from isolated nerve-muscle preparations revealed that the quantal content (the number of ACh quanta released per nerve impulse) was only approximately 50% of that in controls. However, the quantal size (amplitude of miniature end-plate currents) and the kinetic properties of synaptic potentials and currents were similar to control values. The area of synaptic contact and extent of post-synaptic folding were approximately 50% of control values. Thus, the quantal content per unit area of synaptic contact was normal. The number of AChRs per NMJ was also reduced to approximately 50% of normal, so the local AChR density was normal. Immunolabelling studies revealed qualitatively normal distributions and abundance of each of 14 proteins normally concentrated at the NMJ, including components of the basal lamina, post-synaptic membrane and post-synaptic cytoskeleton. DNA analysis failed to detect mutations in the genes encoding any of the following proteins: AChR subunits, rapsyn, ColQ, ChAT or muscle-specific kinase. Response of these patients to treatment was varied: few showed long-term improvement with pyridostigmine and some even deteriorated with treatments, while others had intolerable side-effects. Several patients showed improvement with 3,4-diaminopyridine, but this was generally only transient. Ephedrine was helpful in half of the patients. We conclude that impaired neuromuscular transmission in these LGM patients results from structural abnormalities of the NMJ, including reduced size and post-synaptic folding, rather from any abnormality in the immediate events of neuromuscular transmission.
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PMID:Pre- and post-synaptic abnormalities associated with impaired neuromuscular transmission in a group of patients with 'limb-girdle myasthenia'. 1687 Aug 82


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