thaise agra teixeira. generalidades thaise agra teixeira

MIASTENIA GRAVESTHAISE AGRA TEIXEIRA

MIASTENIA GRAVES

GENERALIDADES

THAISE AGRA TEIXEIRA

MIASTENIA GRAVES

QUADRO CLINICO FRAQUEZA MUSCULAR FLUTUANTE FADIGABILIDADE MUSCULATURA ESQUELETICA ESTRIADA


MIASTENIA GRAVES

QUADRO CLINICO ENVOLVIMENTO MUSCULAR

▪ MUSCULOS OCULARES▪ MEMBROS▪ EXTENSORES DO PESCOÇO▪ TRONCO


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CLASSIFICAÇÃO IDADE

▪ NEONATAL – 10-15% sintomatico▪ ADULTO

ANTICORPOS ANTI-AchR▪ POSITIVO

▪ 85% GENERALIZADA▪ 50-60% OCULAR

▪ NEGATIVO-10-20% ▪ ANTICORPOS ANTI- MUSK(muscle specific protein

kinase)

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CLASSIFICAÇÃO


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CLASSIFICAÇÃO ETIOLOGICA

▪ AUTOIMUNE ADQUIRIDA▪ NEONATAL TRANSITORIA▪ MEDICAMENTOSA▪ CONGENITA


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CLASSIFICAÇÃO ETIOLOGICA

▪ MEDICAMENTOSA

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Schema of normal neuromuscular junction.

Thanvi B R , Lo T C N Postgrad Med J 2004;80:690-700

Copyright © The Fellowship of Postgraduate Medicine. All rights reserved.

Schema of neuromuscular junction in myasthenia gravis (note: widened synaptic cleft, reduced number of acetylcholine receptors, and simplification of postsynaptic membrane).

Thanvi B R , Lo T C N Postgrad Med J 2004;80:690-700

Copyright © The Fellowship of Postgraduate Medicine. All rights reserved.

MIASTENIA GRAVES

FATORES QUE PIORAM QUADRO CLINICO CALOR ESTRESSE INFECÇÃO HIPERTIREOIDISMO GRAVIDEZ ALTERAÇÕES K/Ca


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Box 1: Characteristic clinical features of myasthenia

gravis

Ocular muscle weakness is usually the initial presentation

and may be the only feature throught the course in about

10% of patients. The ptosis (and diplopia) is exacerbated

by the prolonged upward gaze toward a fixed target for one

minute.

In most cases, weakness progresses from ocular muscles to

involve other muscles in a craniocaudal direction. The

weakness of intercostal muscles and diaphragm leads to

dyspnoea on exertion or at rest. The orthopnoea with rapid

resolution on sitting up and diaphragmatic paradox are

important clinical signs of neuromuscular breathlessness.

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Box 1: Characteristic clinical features of myasthenia

gravis

Deep tendon reflexes are intact or may be brisk.

There are no objective sensory deficits.

In severe cases, respiratory failure may ensue, needing

intubation and mechanical ventilation.

Symptoms may fluctuate and there may be remissions of

variable periods, particularly at early stages.

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DIAGNOSTICO LABORATORIAL

Edrophonium (Tensilon test

▪ Easy to administer, no need for expensive

equipment. Limitations: false positives and false

negatives, occasional serious side effects, for

example, hypotension and arrhythmias


MIASTENIA GRAVES


Ice test

▪ Nearly 80% sensitive and highly specific to diagnose

myasthenic ptosis, no need for cardiac monitoring,

can be done in an office setting. Not commonly used,

applicable only when ptosis is present


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AChR antibody in serum

▪ Nearly 80%–85% sensitive in generalised and 60%–70% in

ocular myasthenia gravis, highly specific, non-invasive, now

widely available. May be the diagnostic “gold standard”.

Titres do not always correspond with the severity of

myasthenia gravis


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Repetitive nerve stimulation

▪ Sensitivity around 75%. Uncomfortable to patient,

not specific. Not reliable if the limb is cold, or

patient on acetylcholinesterase inhibitors


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A typical recording of compound muscle action potentials with repetitive nerve stimulation at low frequency in a patient with myasthenia gravis. Note the gradual decline in the amplitude of the compound muscle action potential with slight improvement after the fifth or sixth potential.


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Single fibre electromyography

▪ Most sensitive test. Needs costly equipment, not

specific


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Single-fiber electromyography showing so-called jitter phenomenon (second action potential wave group).


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Anti-MuSK antibodies

▪ Found in a subset of seronegative myasthenia gravis.

Only recently described; not widely available yet


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Computed tomography/MRI of chest

▪ To diagnose associated thymic tumours. Non-invasive.

Greater yield in patients >40 years of age. May be used

post-thymectomy to look for residual thymic tissue in

patients who deteriorate unexpectedly


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CT scan of chest showing an anterior mediastinal mass (thymoma) in a patient with myasthenia gravis.


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Cogan sign. Patient changes gaze from downward position (A) to primary position (B). Both lids are seen to overshoot in twitch (B) before gaining their initial ptotic position (D). In this case, Cogan sign is seen more obviously on right, whereas left lid is more ptotic.


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Increasing left ptosis developing upon sustained upward gaze in patient with myasthenia gravis (A through F). Note limited elevation of left eye, denoting superior rectus palsy (A). A initially, C after around 20 seconds, F after 1 minute.


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TRATAMENTO ANTICOLINESTERASICOS IMUNOSSUPRESSORES

▪ CORTICOIDES SISTEMICOS▪ AZATOPRINA▪ CICLOSPORINA▪ METOTREXATO▪ CICLOFOSFAMINA

TIMECTOMIA PLASMAFERESE IMUNOGLOBULINA


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TRATAMENTO ANTICOLINESTERASICOS


Efeitos dos anticolinesterásicos Bradicardia Hipotensão Secreções excessivas Broncoconstrição Sufocamento Hipermotilidade gastrintestrinal Redução da pressão intra-ocular Miose

neostigminepiridostigmineedofrônio

MIASTENIA GRAVES

TRATAMENTO IMUNOSSUPRESSÃO

▪ CORTICOIDES SISTEMICOS▪ AZATIOPRINA▪ CICLOSPORINA▪ METOTREXATO▪ CICLOFOSFAMINA


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TRATAMENTO TIMECTOMIA


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TRATAMENTO PLASMAFERESE IMUNOGLOBULINA


Figure. (A) A 61-year-old woman with marked generalized myasthenia gravis, 2 days after plasma exchange treatment, with only minimal spontaneous ptosis at baseline.

Toyka K V Neurology 2006;67:1524-1524

©2006 by Lippincott Williams & Wilkins

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