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 Progressive static metabolic Dystrophy congenital

muscular dystrophy

    are inherited myopathy characterized by progressive muscles weakness °eneration &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

duchenne beckers Emery-dreifuss LGD Cong/CNS Cong/noCNS Distal MD bethlen disease inheritance

MD

X linked X linked AD/AR AR AR AD/AR AD FSH AD oculodystrophy AD Myotonic type1 AD Myotonic type 2 AD myofibrillar AD age 2y 5-15 dystrophin protein ..

childh emerin sacroglycan birth ..

merosin Child& adult 5 th dec 2th,3th decade desmmin

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

Common Features:



Clinical:



Muscle weakness

: main feature

Gower’s sign (

proximaly dominating deficit) 

Contractures

+/- severe: advanced stages 

Pain

: in inflamm. Disorders only 

Atrophy

(+/- pseudohypertrophy in X-linked) 

Deformity

: advanced disease 

DTR

: normal, diminished or absent 

Tone

: slightly  or normal  Other systems may be involved

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: normal  EMG: – Spontaneous activities +/- in inflammatory disorders – Interferential tracing – MUPs:    small A Short D polyphsics