Approach to myopathy

Dr omid yaghini

MUSCLES DISORDERS

Definition:

Diseases involving the muscle fibers (myogenic)Unlike: neuronopathies: secondary to LMN Heterogenous etiology, genotype, phenotype…

No specific treatment for most of them

Myoblasts fusing to form large multi-nucleate muscle cells

white = fast (speed)

red = slow (endurance)

ETIOLOGY / CLASSIFICATION

Inherited myopathies– Muscular dystrophies – Congenital myopathies– Inherited channelopathies – Periodic paralysis – Inherited metabolic myopathies

Disorders of glycolysis

Disorders of oxidative metabolism

Lipid myopathies

Mitochondrial myopathies

Acquired myopathies

Inflammatory myopathies

Acquired metabolic myopathies

Toxic myopathies

Weakness Constant fluctuation

Longlife acquired MG periodic P metabolic

Progressive static Dystrophy congenital

muscular dystrophy

are inherited myopathy characterized by progressive muscles weakness &degeneration &subsequent replacement by fibrous & fatty connective tissue

Historically were categorized by their: Age onset /distribution of weakness&

pattern of inheritance The genetic mutation &abnormal gene

product were defined for many of them

MDprotein age inheritance disease

dystrophin 2y X linked duchenne

.. 5-15 X linked beckers

emerin childh X linked Emery-dreifuss

sacroglycan AD/AR LGD

birth AR Cong/CNS

merosin .. AR Cong/noCNS

AD/AR Distal MD

AD bethlen

Child&adult

AD FSH

5th dec AD oculodystrophy

2th,3th decade

AD Myotonic type1

AD Myotonic type 2

desmmin AD myofibrillar

Congenital myopathy

Are distinguished from dystrophy in three respect:

Characteristic morphologic alteration At birth Non progressive However there are exception to all

these generalization Inheritance: are variable

c/p: hypotonia with subsequent developmental delay Reduce muscles bulk, slender body build &long narrow face Skeletal abnormalities: high arched palate ,pectus

exacavitum, kyphscliosis, dislocated hip, pes cavus)

Absent or reduced muscle stretch reflex

Weakness: limb girdle mostly, but distal weakness exist CK &EMG may be normal Muscle biopsy: the diagnostic method

Metabolic myopathy

Glucose/glycogen metabolism Fattay acid metabolism mitochondrial

Calf Pseudohypertrophy

Gowers' Sign

“Climbing up himself”

Gowers’ sign always denotes proximal muscle weakness

Clinical: Muscle weakness: main feature

Gower’s sign (proximaly dominating deficit)Contractures +/- severe: advanced stagesPain: in inflamm. Disorders onlyAtrophy (+/- pseudohypertrophy in X-linked) Deformity: advanced diseaseDTR: normal, diminished or absentTone: slightly or normal Other systems may be involved

Common Features:

Common Features:

Laboratory Investigations:

CBC, LFT.. Normal ESR: high in inflammatory only U&E: abnormalities in some endocrinopathies and

periodic paralysis C.K & aldolase: generaly: raised (normal in few

sittings: metabolic, endocrine…) Lactic acid Genetic study: location & type of chromozomal

abnormalities:

Common Features:

Neurophysiology

NCS: normalEMG:

– Spontaneous activities +/- in inflammatory disorders– Interferential tracing

– MUPs: small A Short D

polyphsics