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

Longlife

Progressive
 Dystrophy

fluctuation
acquired
MG
periodic P
metabolic
static
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

disease inheritance
duchenne
X linked
age
protein
2y dystrophin
beckers
MD
X linked
Emery-dreifuss
X linked
LGD
AD/AR
Cong/CNS
AR
Cong/noCNS
AR
Distal MD
AD/AR
bethlen
AD
FSH
AD
oculodystrophy
AD
5th dec
Myotonic type1 AD
2th,3th
decade
5-15
..
childh emerin
sacroglycan
birth
.. merosin
Child&
adult
Myotonic type 2 AD
myofibrillar
AD
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