This document provides an overview of the approach to evaluating and diagnosing myopathies. It discusses the types of muscle fibers and symptoms that may be present in patients with myopathies. The evaluation involves assessing temporal evolution, distribution of weakness, family history, and laboratory/diagnostic testing including CK levels, EMG, and muscle biopsy. Causes of myopathies include genetic, acquired, inflammatory/immune, and those associated with other systemic illnesses. Specific myopathies discussed include central core disease, nemaline myopathy, and centronuclear myopathy.

1. Approach to
myopathy
DR BHAVIN J PATEL
SR NEUROLOGY
GMC KOTA

2. Structure of muscle

3. Types of muscle fiber

4. Introduction
MYOPATHY means primary skeletal muscle dysfunction.

5. Evaluation
Symptoms of patient: Positive or Negative ?
Temporal evolution:- onset age,episodic/constant, progressive/static,
acute/chronic
Distribution of weakness
Associated systemic symptoms or signs(cardiac, respiratory,
hepatomegaly, skin changes)
Family history
Precipitating factors:-episodic weakness (drug, fever, cold, excersice,
high carbohydrate diet)

6. Etiology
Acquired
Endocrine
Drug induced
Toxic
Inflammatory/immune
Associated with systemic illness
Critical illness myopathy
Hereditary
Channelopathies
Congenital
Mitochondrial
Metabolic
Muscular dystrophy
Myotonia

7. Symptoms associated with myopathies
Negative symptoms
Fatigue
Exercise intolerance
Weakness
Atrophy
Positive symptoms
Cramp
Contracture
Hypertrophy
Myalgia
Stiffness

8. Temporal evolution: onset age

9. Temporal evolution: onset age

10. Temporal evolution: onset age

11. Temporal evolution: episodic or constant
weakness?
Causes of episodic weakness:-
Hypo and hyper kalemic periodic paralysis
Anderson- tawil syndrome
Secondary PP
Metabolic myopathy (glycolytic enzyme defect)

12. Temporal evolution: acute or chronic?
Acute onset myopathy
Viral myosistis
Polymyositis and dermatomyositis
channelopathies

13. Weakness

14. Weakness

15. Pattern of weakness:- proximal
Most dystrophies(dystrophinopathies, limb girdle, myotonic dystrophy 2, rare
FSHD)
Congenital myopathies( nemaline, central core)
Metabolic myopathies(glycogen and lipid storage)
Mitochondroal myopathy
PM, DM
Toxic myopathy
Endocrine myopathy

16. Pattern of weakness:- Distal
Myotonic dystrophy
Distal myopathies:-welander, marksberry, udd, nonaka, miyoshi, laing
Inclusion body myosistis
Centronuclear myopathy
Myofibrillar myopathy
Debrancher deficiency

17. Pattern of weakness:- scapuloperoneal
Proximal arm and distal leg:-
Facioscapulohumeral dystrophy
Scapuloperoneal dystrophy
Emery dreifuss humeroperoneal
dystrophy
LGMD 2A( calpin), 2C-F(sarcoglycan)
2I(KFRP)
Nemaline and central core myopathy
Acid maltase deficiency
 Distal arm and proximal leg:-
 IBM
 Myotonic dystrophy

18. Pattern of weakness:- axial
Cervico brachial myositis
hIBM
FSHD
MD 2
Hyperparathyroidism/vit d deficiency
Metabolic ( late onset pompe and mc ardle)

19. Pattern of weakness:- Ptosis
Ptosis without opthalmoparesis
Myotonic dystrophy
Nemaline myopathy
Central core myopathy
Myofibrillar myopathy
Ptosis with opthalmoparesis
OPMD
Mitochondrial myopathy
Centronuclear myopathy
NMJ disorder

20. Myopathies with neck extensor
weakness
Hyperparatyroidism
Myotonic dystrophy
FSHD
IBM, polymyositis
Carnitine deficiency
Isolated neck extensor myopathy

21. Bulbar weakness
OPMD
Inflammatory myopathy
LGMD 1A

22. Stiffness: decrease ability to relax
Improve with exercise
Myotonia: Na or Ca channelopathy
Worsen with exercise/ cold
Paramyotonia
Brody disease
With fixed weakness
Myotonic dystrophy
Becker disease (AR Cl channelopathy
Other
Malignant hyperthermia
Neuromyotonia
Stiffperson syndrome

23. Myalgia

24. Other symptoms
Fatigue
NMJ
Glycolysis
Lipid abnormality
Mitochondrial
myopathy
Chronic myopathy
Calf
Hypertrophy
Calf
Pseudohypertrophy
Atrophy
LGMD 2c-f
LGMD 2i
LGMD 2G
miyoshi
DMD
BMD
Humeral muscle—FSHD
Gastrocnimius–
dysferlinopathies
Quadriceps and forearm
flexor- IBM

25. Family History

26. Examination
Muscle appearance – wasting ,atrophy (neurogenic)
ABSENT fasciculations (+Denervation)
 Tenderness on palpation
 Tone –normal ,decreased in advanced cases.
 Distribution of weakness –proximal,distal (distal myopathies)
 Tendon reflexes – normal /hypoactive in adv.cases
 Babinski sign negative
 SENSORY system is normal.
 GAIT – lordosis on stance,increased on toe walking
 Waddling gait – b/l pelvic girdle weakness
 Genu recurvatum –quadriceps weakness

27. Associated Cardiac disorder

28. Respiratory involvement

29. Creatinine kinase
Most useful lab investigation for myopathy
Degree of elevation is helpful
May be normal in:-
Slowly progressive form
Profound wasting
Steroid use
hyperthyroidism

30. Hyperckemia

31. Other laboratory test
Electrolytes including calcium and magnesium
S.myoglobin level
Urinanalysis:- myoglobinuria
ESR
TFT
ANA

32. EMG
Indication:-
To confirm muscle localization and rule out AHC, neuropathy
Guide for muscle biopsy
Common pattern:-
Brief duration small amplitude MUAP with early recruitment

33. Muscle biopsy
Should not be taken from muscle with grade 3 or less power
Avoid biopsy from EMG needle site insertion
Punch biopsy is preferred over open biopsy
Common site:- biceps, deltoid, vastus lateralis
Emergence of genetics has reduce need of biopsy

34. Muscle biopsy
Common pattern:-
Central nuclei, both small and large hypertrophic round fibers, split fibers, and
degenerating and regenerating fibers
 Inflammatory myopathy:-
Presence of mononuclear inflammatory cells in the endomysial and perimysial
connective tissue between fibers and occasionally around blood vessels
Dermatomyositis, atrophy of fibers located on the periphery of a muscle fascicle,
perifascicular atrophy, is a common finding
Chronic myopathies frequently show evidence of increased connective tissue and fat.

35. Stain used in myopathy

36. Genetic Testing

37. FSHD

38. Valley sign :-DMD

39. Diamond sign :- dysferlinopathy

40. Calf head sign:- Miyoshi myopathy

41. Fish mouth:- cong. Myotonic
dystrophy

42. Which myopathy?
Myotonic
dystrophy

43. Identify Myopathy?
Gottron papules
Shawl sign
V sign
Heliotrope rash
Mechanics hand
Dermatomyositis

44. Case scenario
68 yr old male, 5 year history of difficulty walking down stairs and weak right hand grip….
After 2 yr of onset pt evaluated…CPK:- 500, muscle biopsy(quadriceps) s/o polymyositis…
treated with immunosuppressant steroid and azathioprne… still progressive illness….at present
weakness in right finger and wrist flexion and left finger flexion with bilateral asymmetric knee
extension weakness…next step????
A) IVIG
B) Rituximab
C) look for systemic illness
D) Muscle biopsy

45. MCQ
Risk of myopathy with statins is potentiated by which of the
following factors?
A. Alcoholism
B. Concomitant therapy with fibrates
C. Hyperthyroidism
D. Younger age
E. Renal disease
A B E

46. MCQ
Creatine kinase
A. Levels should be routinely monitored for patients receiving statins
B. Is less specific than aldolase for diagnosis of myopathy
C. Can be elevated in Afro–Caribbean men
D. Can lead to renal failure, if levels are grossly elevated
E. Can be normal in patients with corticosteroid-induced myopathy
C D E

47. MCQ
Which of the following clinical features are not suggestive of
proximal myopathy?
A. Loss of deep tendon reflexes
B. Episodic weakness
C. Myalgia
D. Fasciculations
E. Dysphagia
A D

48. MCQ
Which of the following statements regarding management of proximal myopathy
are true?
A. Double-blind, randomised controlled trials have demonstrated efficacy of
corticosteroids for inflammatory myopathy
B. Statin should be discontinued when creatine kinase levels start to rise
C. Hypothyroid myopathy responds promptly to thyroxine replacement therapy
D. Randomised controlled trials have demonstrated that physiotherapy is helpful
for patients with inflammatory myopathy
E. Southeast Asian patients with dermatomyositis should always be referred to an
otolaryngologist to screen for nasopharyngeal carcinoma
D E

49. Thank you

50. myalgia
fibromyalgia,myofascial
syndrome,Polymyalgia rheumatic,
temporal arteritis
Muscle
weakness
No muscle
weakness
Local
trauma
Cramp +
Muscle
contracture +
Stiffnaess +
NMJ
BMD
Glycolytic
EMD
Stiffperson syn
neuromyotonia

51. Endocrine myopathy
Muscle fatigue is more common than true weakness.
Serum CK LEVELS are normal.
Muscle histology –atrophy rather than destruction.
All respond to treatment

52. LIPID LOWERING
AGENTS
FIBRATES ,HMG COA ,NIACIN,EZETIMIBE
• MYALGIA,MUSCLE TENDERNESS.
• MUSCLE PAIN RELATED TO EXERCISE
• RHABDOMYOLYSIS,MYOGLOBINURIA
• ELEVTED CK LEVELS –TOXICITY – 3 TIMES – STOP THE
DRUG
• MYOPATHIC EMG-MUSCLE NECROSIS ON BIOPSY
• IMPROVEMENT –SEVERAL WEEKS
• NO RESPONSE – IMMUNE MEDIATED MYOPATHY
GLUCOCORTICOIDS
GLUCOCORTICOID
MYOPATHIES
HIGH DOSE IV GLUCOCORTICOIDS
• >30 MG/DAY USE OF PREDNISOLONE
• FLUORINATED GLUCOCORTICOIDS -TRIAMCINOLONE
• SERUM CK NORMAL IN CHRONIC CASES
• LOSS OF MYOSIN IN ACUTE ONSET.
• RECOVERY SLOW IN ACUTE QUADRIPLEGIC
MYOPATHY
D –
PENICILLAMINE
DRUG RELATED INFLAMMATORY OR ANTIBODY
MEDIATED
• WILSON’S,SCLERODERMA,RA,PBC
• DRUG INDUCED POLYMYOSITIS -1%
• MYASTHENIA GRAVIS – 7%
• IMPROVE ON DRUG WITHDRAWAL

53. Central core disease
 Breech presentation
 Legs>arms
 CHD,scoliosis,pescavus
 Non progressive
 Suspectible to malignant
hyperthermia
 CPK NORMAL
 CORES ON BIOPSY DEVOID OF
OXIDATIVE ENZYMES
NEMALINE MYOPATHY
 Rods /threads in muscle fibers type 1
fibers
 long narrow facies,high arched
palate,open mouth appearance
 pectus excavatum,pes
cavus,kyphoscoliosis
 five genes –thin
filament proteins
CENTRONUCLEAR
MYOPATHY
 marfanoid habitus
 progressive external
ophthalomplegia,eom weakness
 Myotubularin
 ARR –childhood
 no specific treatment