Neuromuscular

SPINAL MUSCULAR ATROPHY (5q)

SMA: General pathology
SMA, Congenital (Type 0)
SMA, Type 1
SMA, Type 2
SMA, Type 3

Also see
  Spinal muscular atrophy
  XBSMA pathology


SMA 5q: General Features


H&E stain

ATPase pH 9.4 stain
Grouped atrophy
  Small muscle fibers are often rounded
  Pyknotic nuclear clumps are not present.
Large muscle fibers are hypertrophied.
Large fibers: Hypertrophied & Type I
Small fibers: Type I or II


SMA, Type 2


H&E stain

H&E stain
Large grouped atrophy

H&E stain


ATPase, pH 9.4

ATPase, pH 9.4

ATPase, pH 4.3
Small muscle fibers may be varied types (Left) or mostly type II (Middle)
Clusters of large type I muscle fibers
Many small fibers are type 2C


Esterase

Esterase
Neuromuscular junctions on large (Left) and small (Right) muscle fibers.


VvG

Toluidine blue
Intramuscular nerve: Unremarkable Sensory nerve
  Normal numbers of axons
  Thinly myelinated axons consistent with young age.


NADH

NADH
Small muscle fibers stain darkly on NADH

SMA, Type 1


H & E

H & E
Many muscle fibers are small.
A few hypertrophied fibers are present

NADH

Some large & small muscle fibers have reduced or absent glycogen

PAS


SMA, Congenital (Type 0)


H & E

H & E
Only small muscle fibers are present.
Small fibers have moderate variation in size.

VvG
Many small fibers are Type 2C.

ATPase pH 4.3

COX
Mitochondrial stains are pale

SDH


SMA, Type 3


H & E
Grouped atrophy.
Larger muscle fibers are not promiently hypertrophied.


ATPase pH 9.4

NADH
Variable involvement of fascicles.
  Top: Scattered small fibers. Large fibers are type 1.
  Bottom: Few small fibers. Type 2 predominance.
        Abnormal intermediate-staining fibers.
Variable involvement of fascicles.
  Top: Scattered small fibers. Most fibers are dark-stained.
  Bottom: Few small fibers. Most fibers are pale-stained.



VvG
Grouped atrophy.
Larger muscle fibers are not promiently hypertrophied.
Intramuscular nerves have mildly reduced axon numbers.


Esterase
Neuromuscular junctions.
Present on large and small muscle fibers.
Mildly large, but not multi-segmented.


Also see: Active Denervation & Fiber type grouping


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8/14/2013