8/8/2019 Inflammatory Myositis

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Inflammatory myositis

-Prof. Rukmani M.D.

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Definition

A group of acquired inflammatory myopathies

affecting skeletal muscles«

Three groups Polymyositis

dermatomyositis

Inclusion Body myositis [IBM]

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Common Clinical Featur es

Progressive and sym. prox. muscle weakness; expt IBM [distal]

Fine motor movements relatively spared; except IBM ±inv. early

Ocular muscles spared in even untreated and advanced cases

Pharyngeal and neck muscles commonly involved

Respiratory muscles affected in advanced stages

Sensations preserved

Tendon reflexes preserves until late stages

Weakness can be accompanied by muscle wasting

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ExtraMuscular Manif estations

Systemic symptoms ± fever, malaise, wt loss,

arthralgias, raynaud¶s

Joint contractures

Dysphagia and GI symptoms

Catrdiac ± conduction defects, cardiomyopathies

Pulmonary - Pulmonary HT and ILD

Subcutaneous Calcifications

Arthralgias

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Overlap Syndromes

Inflammatory myopathies associated withconnective tissue disorders

DM most commonly asssociated with systemicsclerosis or MCD

R A, SLE, Sjogrens are very rarely associated

Overlap syndromes may have  ANA, anti PM/Sclantibodies in addiation to Jo 1 antibodies

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Featur e Polymyositis Dermatomyositis IBM

 Age at onset

Familial  Assoc

Extra

Musc.manif.

 Asssoc. Conn.

Tissue Dis

Malignancy

Viruses

Drugs

Parasites andbacteria

< 18 years

No

Yes

Yes

No

Yes

Yes

yes

 Adult and childhood

No

Yes

Scleroderma and MCD

Yes

Unproven

Rarely

yes

>50 years

No

Yes

Yes

No

Yes

No

No

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Skin Manif estation-

Dermatomyositis

Heliotrope rash

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Gottron¶s sign and mechanic hands

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Shawl sign

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Nail &Cuticle changes

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Diagnosis

Clinical suspiscion

Creatinine Kinase

Needle EMG

Muscle Biopsy

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Criteria Polymyos. Dermatomyo. IBM

Myopathic

muscle

weakness

EMG findings

Muscle enzymes

Muscle Biopsy

Rash /Calcinosis

Yes

Myopathic

Elevated [upto 50fold]

Primary

inflammation with

CD8/MHC1complex and no

vacoules

 Absent

Yes

Myopathic

Elevated [upto 50fold]

Perifascicular,

perimysial or 

perivascular infilatrates

present

Yes, slow

onset, distal

Myopathic

with mixed

potentials

Elevated upto

10 fold

Primary

inflammation

with

CD8/MHC1 complex, 

vacoulated

fibr es with

amyloid

 Absent

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Tr eatment

1. Glucocorticoids Initial treatment of choice

Started at 1 mg/kg/day-continued for 3-4 weeks

Then tapered to alternate day regimen and then

maintained at lowest possible dose

Other immunosuppressives started if there is no

improvement by 3 months

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Other Drugs

Azothioprine- 3mg/kg/day

Methotrexate ± 7.5 mg/week Mycophenolate mofetil 2.5 mg/day

Anti CD20 antibodies ± Rituximab

Cyclosporine

Cyclophosphamide

Immunomodulators ± IV Ig 2g/kg divided doses

over 5 days

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