Why are eye muscles frequently involved in myasthenia gravis?

Kaminski, Henry J.; Maas, E. F.; Spiegel, Peter H.; Ruff, Robert L.

doi:10.1212/wnl.40.11.1663

Cited by 109 publications

(61 citation statements)

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“…It has been suggested that the susceptibility of extraocular muscles to myasthenic weakness reflects the presence of fetal AChR on the multiply innervated tonic fibers (27). Although there is some expression of AChR ␥ subunit mRNA in extraocular muscle (26), there is more AChR ⑀ subunit mRNA (MacLennan, C., D. Beeson, A. Vincent, J. Newsom-Davis, manuscript submitted for publication), and the lack of any ocular symptoms in AMC-M1 and AMC-M5 argues against antibodies to fetal AChR causing ocular muscle weakness.…”

Section: Discussionmentioning

confidence: 99%

Association of arthrogryposis multiplex congenita with maternal antibodies inhibiting fetal acetylcholine receptor function.

Riemersma¹,

Vincent²,

Beeson³

et al. 1996

J. Clin. Invest.

149

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Section: Discussionmentioning

confidence: 99%

Association of arthrogryposis multiplex congenita with maternal antibodies inhibiting fetal acetylcholine receptor function.

Riemersma¹,

Vincent²,

Beeson³

et al. 1996

J. Clin. Invest.

149

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“…Muscles with the lowest safety margin, such as the extraocular muscles, could be preferentially involved. 40 Indeed, a clinical electrophysiologic case study suggests that motor nerve terminal block may induce muscle weakness in MFS. 41 In MFS patients, however, we did not observe abnormal fatigability and fluctuation of muscle weakness as one might expect in assuming a myasthenia-like action of blocking antibodies.…”

Section: Presynaptic Blockade By Mfs-iggmentioning

confidence: 99%

Combined pre- and postsynaptic action of IgG antibodies in Miller Fisher syndrome

Buchwald¹,

Bufler²,

Carpo³

et al. 2001

Neurology

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Article abstract-Background: Miller Fisher syndrome (MFS), a variant of the Guillain-Barré syndrome, is associated with the presence of neuromuscular blocking antibodies, some of which may be directed at the ganglioside GQ1b. Materials and Methods:The authors investigated the in vitro effects of serum and purified immunoglobulin (Ig) G in a total of 11 patients with typical MFS during active disease, and in three of those patients after recovery. From one patient's serum, we prepared an IgG fraction enriched in anti-GQ1b antibodies by affinity chromatography. For combined pre-and postsynaptic analysis, endplate currents were recorded by a perfused macro-patch clamp electrode. Postsynaptic nicotinic acetylcholine receptor channels were investigated by an outside-out patch clamp technique in cultured mouse myotubes. Results: All MFS-sera depressed evoked quantal release and reduced the amplitude of postsynaptic currents. Five of the 11 sera were additionally examined by outside-out patch clamp analysis and caused a concentration-dependent and reversible decrease in acetylcholine-induced currents. The time course of activation and desensitization of nicotinic acetylcholine receptor channels was not altered by MFS-IgG. Nine patients (82 %) were positive for anti-GQ1b antibodies in ELISA and dot-blot. The enriched anti-GQ1b antibody fraction had a similar effect as whole serum. After recovery from MFS, blocking activity was lost and sera originally positive for anti-GQ1b antibodies became negative. Conclusion: Circulating IgG antibodies induce both pre-and postsynaptic blockade and may play a pathogenic role in acute MFS. NEUROLOGY 2001;56:67-74 Miller Fisher syndrome (MFS) is characterized by the triad of gait ataxia, external ophthalmoplegia, and areflexia.1 As a variant of the Guillain-Barré syndrome (GBS), MFS is thought to be an immunopathologic disorder of the peripheral nervous system. Immunoglobulin (Ig) G autoantibodies directed at the ganglioside GQ1b are found in the acute phase sera of more than 90% of patients with MFS.2-4 Gangliosides are present in high concentrations in peripheral nerve axons and myelin, and several studies indicated that different gangliosides (e.g., GM1) are present at nodes of Ranvier and at neuromuscular junctions. 5 The distal motor nerve terminal lacks the blood-nerve barrier, making it accessible for circulating antibodies and a suitable site to investigate the functional effects of serum-antibodies experimentally.There is evidence that MFS sera block neuromuscular transmission in the mouse hemidiaphragm. [6][7][8][9] Using intracellular microelectrode techniques, a marked increase in spontaneous release (i.e., miniature endplate potential frequency) after application of MFS sera, followed by inexcitability of the muscle upon phrenic nerve stimulation has been demonstrated. 6,9 In that study, the effects depended entirely on the presence of complement, 9 and miniature endplate potential (MEPP) amplitudes appeared unchanged. 6,9 With a perfused macro-patch clamp electrode, we...

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“…Tal fato tem mudanças a cada dia e flutuação no curso diário, melhorando com repouso e com anticolinesterásicos [1][2][3][4][5][6][7][8][9][10]12,16,20 .…”

Section: Discussão Discussão Discussão Discussão Discussãounclassified

“…Os músculos bulbares, mastigatórios e a musculatura cervical tiveram frequência menor 9 . Tem sido descrito que o envolvimento da musculatura extra-ocular, destacando diplopia e/ou ptose, é mais frequente e pode ser observado na metade dos casos durante a apresentação e na sua maior parte durante a evolução da doença 2,4,5,8,16 . Assis estudou 372 pacientes, sendo a diplopia isolada, acompanhada ou seguida de ptose unilateral, a manifestação clínica inicial mais frequente, vindo após ptose uni ou bilateral.…”

Section: Discussão Discussão Discussão Discussão Discussãounclassified

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Miastenia grave: avaliação clínica de 153 pacientes

Cunha

Scola

Werneck

1999

Arq. Neuro-Psiquiatr.

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RESUMO -São analisados, retrospectivamente, os prontuários dos doentes miastênicos diagnosticados e seguidos no período de fevereiro de 1973 a março de l995. Os principais achados clínicos foram ptose palpebral, diplopia, disfagia, disfonia ou disatria, dificuldade de mastigação, dispnéia, astenia, paresia da musculutura cervical e das extremidades. A partir das informações coletadas, os pacientes foram classificados clinicamente pela escala de Osserman-Genkins modificada, mas considerando o aspecto não dinâmico dessa escala, adotou-se a escala funcional de Niakan modificada, na qual os doentes são colocados nas seguintes condições: remissão, controlado, compensado, controle parcial, controle precário, sem resposta. Na casuística foram estudados 153 pacientes: 104 (68,0%) do sexo feminino e 49 (32,0%) do sexo masculino, numa proporção de 2,1:1. O tempo de doença variou de sete dias a 27 anos, com média de 6,26 anos (± 5,44). A idade dos primeiros sintomas variou entre 24 horas a 80 anos, com média de idade de 32,13 anos (±19,48). Até os 15 anos foram observados 30 doentes; entre 15 e 50 anos, 91 doentes; com idade acima de 50 anos, 32 doentes; após os 60 anos, a doença tem nítido predomínio entre os homens (1,5:1). Na amostra estudada, a forma auto-imunoadquirida foi a mais frequente, com comprometimento muscular generalizado, porém o envolvimento da musculatura ocular com ptose e diplopia se constituiu nas manifestações clínicas mais frequentes.PALAVRAS CHAVE: miastenia grave, avaliação clínica. Myasthenia gravis: clinical evaluation of 153 patientsABSTRACT -We have retrospectively analysed the records of patients diagnosed as having myasthenia gravis and followed up in our departament from February 1973 to March 1995. The main clinical findings were ptosis, diplopia, dysphagia, disphonia or dysarthria, mastigatory impairment, dyspnea, asthenia, weakness of the cervical muscles and of the extremities, as well as findings of the physical and neurological examination. Based on the information collected, the patients were classified clinically according the modified Osserman-Gerkins scale, but considering the non-dynamic aspects of that scale, we used the modified functional scale of Niakan and classified the patients clinically as follows: remission, controled, stable, partially controled, poorly controled, no response. We collected 153 patients, 104 (68.0%) females and 49 (32.0%) males producing a female/male ratio of 2.2:1. The duration of the disease varied from seven days to 27 years, mean 6.26 years (±5.44). Age at the first symptoms varied between 24 hours to 80 years, mean of 32.13 years (±19.48). We had 30 patients ranging from 0 to 15 years of age, 91 patients were observed between 15 and 50 years and 32 patients after the age of 50 years. Above the age of 60 years, the disease aflicts males more than females with a ratio of 1.5:1. The acquired autoimmune form with generalized weakness was the most frequent presentation. However, ocular muscle weakness with ptosis and diplopia were the most commom clinic...

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Why are eye muscles frequently involved in myasthenia gravis?

Cited by 109 publications

References 0 publications

Association of arthrogryposis multiplex congenita with maternal antibodies inhibiting fetal acetylcholine receptor function.

Association of arthrogryposis multiplex congenita with maternal antibodies inhibiting fetal acetylcholine receptor function.

Combined pre- and postsynaptic action of IgG antibodies in Miller Fisher syndrome

Miastenia grave: avaliação clínica de 153 pacientes

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