1. Polymyositis a rare entity in children
Dr Aisha Qaisar (Senior Registrar).
Children Hospital Lahore.
Dr Zahid Jamil ( Registrar).
Children
Hospital Lahore

2. 10 Year old Boy presented with Muscles weakness, Dysphagia and
Tip toe walk

3. History
 Name Usman
 Age 10 Year
 Resident Okara
 DOA 17-10-12
 MOA OPD

4. Presenting Complain
 weakness 25days
 Walk on tip of toe 07 Days
 Dysphagia 02 days
 Speech Nasal in quality 01 day

5. HOPC
Progressive weakness difficulty in performing every
day work.
 Getting up from bed
 Climbing stairs
 Unable to change his cloth
 Difficulty in keeping his head up (Head drop)
He had difficulty in walking(Unsteady).
 Tip toe walk 7 days
After admission during stay in ward dysphagia.
 Initially to liquid than s0lid
Nasal twang voice

6. Cont…….
No history of;
 Cutaneous lesion ,
o Rash over face , hands neck or shoulder.
 Heat or cold intolerance constipation ,diarrhea.
 Photosensitivity, oral ulcer, hair loss.
 Rhaynaud’s phenomenon
 Any drug intake

7. Cont…
 He is developmentally normal child Grade 4 doing
good at education
 Consanguineous marriage twin brother.
 No family h/o myopathy
 Vaccinated no h/o TB contact
 Poor socioeconomic class

8. Examination
 General physical examination
 Conscious ,Oriented, cooperative, but miserable look and
lying in agony in bed.
 Ht 150cm.
 Wt 30 kg.
 Temp 98F.
 BP 180/80.
• Generalized edema and muscle tenderness.
• No rash over body.
• No joint inflammation, deformity.
• No calf muscle hypertrophy
• No skin tightening or telangectasia

9. Central Nervous system
 Gcs 15/15
 Tone normal
 Power 3/5 in both upper and lower Proximal muscle weakness
limb at hip and shoulder joint fine
movements of hand were intact
 Reflexes were elicit able
 Sensation was intact cranial nerve
also intact
 No ocular facial or respiratory
muscle weakness were noted at
time of admission.
 Gower sign +ve
 He was walking on tip of his toes.
 GIT………………..normal
 CVS………………..normal
 Respiration ……normal

10. D/D
Based on these finding following diagnosis we initially
considered.
A. Acute Viral myositis
B. Polymyositis
C. dermyomyositis

11.  Proximal muscle weakness in the
absence of cutaneous lesion is
suggestive of Polymyositis.

12. Investigation
 CBC ESR……..45
• Hb………10 CRP………10
• TLC……..11OOO
• N………….63%
• L……………21% CPK………….2036
• Plt…………543 LDH............1613
ANA -VE
RAF -VE
 ECG Normal NCS Normal
 CXR Normal

13. EMG

14. Muscle biopsy

15. Inflammatory myopathy
 Group of disorder
characterized by;
 Proximal muscle weakness
 Non suppurative
inflammation of skeletal
muscle with predominantly
lymphocytic infiltrate

16. Inflammatory myopathy
 Clinical Classification
 Dermatomyositis
 Polymyositis
 Inclusion Body myositis

17. Epidemiology
 Rare disease in children
 Usualy seen after 18 yrs
 Incidence in USA is .5 to
8.4/million population.
 More common in female

18. Cause
 Autoimmune
in origin

19. T cell mediated Asso: other
myocytotoxity autoimmune dis:
Comliment
Auto antibodies
mediated
microangiopathy
Response to Histocompatibility genes
immunosuppressive therpy
Supported by

20. T cell mediated
cytotoxicty
Viral
Malignancies
C.T Disorders

21. Pathophysiology
Cytotoxic Cd8+T
Invade muscle tissue
Damaging Vescular endothelium
Virus
Muscle destruction
CK
Abnormal expression MCHC

22. Auto antibodies
dectected in 60-80%
Types:
Myositis associated Ab
Myositis Specific Antibody

23. Myositis associated Autoantibodies:
• Shared with other
autoimmune dis:
• Found in 20-50% of
Patients

24. Myositis Specific antibodies
• Unique to myositis.
• Found in 40% of cases.
• Three main types:
Anti -jo -1 Ab
Anti - Mi-2
Anti-SRP

25. ILD
Arthritis Acute onset
Fever Good Prognosis
Good Response to
Therpy.
Cardiac Involvewment
PoorPrognosis
Poor response to therapy

26. Ocular And Facial Muscles
never Involved
Dysphagia and dysphonia may occur
Neck muscles are involved in
50 %
of cases Shoulder and Pelvic muscles Most
severly affected
Distal muscles are spared
In majority and early in the course
Usually insidious in onset Toe walking
No identified precipitant
Skin Rash always absent

27. Arthritis
arthlalgia
Dysphagia
Nasal regurgitation
Reflux oesophagitis
SLE
Sarcoidosis
Sjogren
Abdominal Bloating
Odynophagia
Constipation

28. Myocarditis
Tachyarrythmias
Interstitial Pneumonitis
Ariovent
conduction
defect
Interstitial fibrosis

29. Dignosis.
 Muscles enzymes
 EMG
 Muscles biobsy
 Antibodies dectection
 Imiging studies
 Complete bld count

30. CK inc; up to 50 times ALT
AST
Aldolase
LDH

31. Imaging studies
MRI
USG
To Localize the
extent of muscle
involvement.

32. CBC
Leucocytosis or thrombocytosis >50%
ESR
 increased
CRP
Increase in >50%

33. Shared
features
Both
Inflamatory
Myopathies Distinct
Develop over Features
Wks to months.
Response to
Steriod
Demographic
Dermatomyositis Features.
vs Peculiar
Dematological
Polymyosits
finding.
Muscle biopsy
features.
Calcinosis

35. ACR Ctitaria for PM/DM (Bohan & Peter (1975) NEJM)
 Diagnostic Critaria.
1. Proximal muscle weakness
2. Elevated serum CK
3. Myopathic changes on EMG
4. Muscle biopsy demonstrating
Lymphocytic infiltration
5. Typical skin rash of
Dermatomyositis eg Gottron,
Shawl,Helitrop

36. ACR Ctitaria for PM/DM (Bohan & Peter (1975) NEJM)
• Using these criteria,
polymyositis is defined as
 Definite
All of criteria 1-4
 Probable
Any three of criteria 1-4
 Possible
Any two of criteria 1-4
• Dermatomyositis defined as
 definite
5 plus any three of criteria 1-4
 Probable
5 plus any two of criteria 1-4
 Possible
5 plus any one of criteria 1-4

37. Exclusion criteria for PM/DM
 Evidence of any central or peripheral neurologic disease
 Muscle weakness with slowly progressive course, and family history of
calf enlargement to suggest muscular dystrophy
 Biopsy with granulomatous myositis, such as with sarcoidosis
 Evidence of active infection
 Recent use of drugs known to be toxic to muscles
 cocaine, statins, fibrates, etc.
 Overt rhabdomyolysis
 Glycogen storage disorders (i.e. McArdle’s)
 Endocrinopathies
 hypo-/hyper- thyroid/parathyroid, diabetes, Cushing’s
 Myasthenia Gravis

38. Treatement
• Prednisone
• 1mg /kg/day 4to 6
weeks
 Tapering
 5 to 10 mg
monthly
 Improve in muscle
strength
 Decrease CK level

39. Cont…..
• Immunosupperesive
• If do not improve
• Steroid side effect
• Poor prognostic factor
 Methotrexate
IVIG
Rituximab

40. Cont…
• High Protien Diet
• Activity and Exercise
should be encouraged