Difference between revisions of "Neuromuscular pathology"

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Neuromuscular pathology (view source)

Revision as of 02:47, 26 October 2010

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|-
| Small fibres  
| Small fibres  
| groups ("group atrophy")
| groups <br>("group atrophy")
| singular
| singular
|
|
| [http://neuropathology.neoucom.edu/chapter9/images9/13-7.jpg group atrophy]<ref>URL: [http://neuropathology.neoucom.edu/chapter9/chapter9fALS.html http://neuropathology.neoucom.edu/chapter9/chapter9fALS.html]. Accessed on: 25 October 2010.</ref>
| [http://neuropathology.neoucom.edu/chapter9/images9/13-7.jpg group atrophy]<ref>URL: [http://neuropathology.neoucom.edu/chapter9/chapter9fALS.html http://neuropathology.neoucom.edu/chapter9/chapter9fALS.html]. Accessed on: 25 October 2010.</ref>
|-
|-
| Large fibres
| Large fibres<br>
| No
| No
| +/-Scattered
| +/-Scattered
|
| "hypercontracted fibres"
| [http://commons.wikimedia.org/wiki/File:Duchenne-muscular-dystrophy.jpg DMD (WC)]
| [http://commons.wikimedia.org/wiki/File:Duchenne-muscular-dystrophy.jpg DMD (WC)]
|}
|}
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#Myopathy - something is wrong with the muscle fibres.
#Myopathy - something is wrong with the muscle fibres.


==Muscle anatomy==
==Muscle structure/histology==
===Macro to micro===
Organization:<ref>URL: [http://commons.wikimedia.org/wiki/File:Skeletal_muscle.jpg http://commons.wikimedia.org/wiki/File:Skeletal_muscle.jpg]. Accessed on: 25 October 2010.</ref>
Organization:<ref>URL: [http://commons.wikimedia.org/wiki/File:Skeletal_muscle.jpg http://commons.wikimedia.org/wiki/File:Skeletal_muscle.jpg]. Accessed on: 25 October 2010.</ref>
*Muscle.
*Muscle - surrounded by epimysium.
**Fascicle.
**Fascicle - surrounded by perimysium.
*
***Muscle fibre - muscle cell.
****Myofibrils - contractile elements within the muscle cell.
 
===Fibre types===
{{familytree/start}}
{{familytree | | | |A11| | | | |A11 =Types          }}
{{familytree | |,|-|-|^|-|-|.|}}
{{familytree | B11 | | | | B12 |B11=Type 1<br>slow twitch|B12=Type 2<br>fast twitch }}
{{familytree/end}}
 
====List====
Type 1 - [[AKA]] slow twitch:
*Predominantly oxidative metabolism, i.e. have lots of mitochondria.
 
Type 2 - AKA fast twitch:
*Predominantly glycolytic metabolism.
 
Mnemonic ''Slow red fat ox'': '''Slow''' twitch fibres are (grossly) more '''red''' (due to mitochondria),
lipid rich ('''fat''') and primarily have '''oxidative''' metabolism.
 
===Abnormal findings===
*Ragged red fibres = mitochondrial pathology.
*Rimmed vacuoles = inclusion body myositis.
*PAS +++ = glycogen storage disease.
 
===Approach===
General:
#Size variation - in groups (neurogenic) vs. singular (myogenic).
#Shape - angulated (neurogenic) vs. round (myogenic).
#Position of nuclei.
#Necrosis - suggests myogenic.
#Fibrosis - suggests myogenic.
#Inflammation.
Other:
#Obvious abnormality vs. minimal change.
#Diffuse vs. focal change.
 
==Processing of muscle biopsies==
#Formulin.
#Frozen section.
#Frozen for biochemistry.
#Fragment for electronmicroscopy (glutaraldehyde fixative).
 
==Stains for muscle biopsies==
Common/standard:
*H&E stain.
*Gomori trichrome - Good for nemaline rods, mitochondrial pathology (red).
*PAS.
*Congo red - find [[amyloid]]; seen in inclusion body myositis.
*Oil Red O - type 1 more lipid.
*ATPase - should have checkerboard pattern in normal.
*NADH-TR - should have checkerboard pattern in normal.
 
Special - mitochondrial pathology.:
*SDH.
*COX.
*COX-SDH.
 
Enzymatic/genetic stuff:
*Phosphorylase.
*Adenylate deaminase.
*Acid phosphatase.
*Alkaline phosphatase.
 
Dunno:
*Toluidine blue.
 
IHC:
*Dystrophy panel.
*Lymphocytic markers (CD45, CD3, CD4, CD8, CD20).
*MAC - inclusion body myositis.
*APP - inclusion body myositis.
*Ubquitin - inclusion body myositis.
 
===ATPase stain pattern/fibre type===
{| class="wikitable"
|
| '''Type 1<br>slow twitch'''
| '''Type 2<br>fast twitch'''
|-
| '''pH 4.2'''
| '''dark'''
| light
|-
| '''pH 9.4'''
| light
| '''dark'''
|}
 
==Inflammatory myopathy==
DDx:
#Polymyositis.
#Inclusion body myositis.
#Dermatomyositis.
 
==DDx==
Neurogenic:
*Amyotrophic lateral sclerosis.
*Spinal muscular atrophy.
*Trauma.
*Vascular disease.
*Infective process.
*?Motor neuron disease.
 
Myopathic:
*Inflammatory:
*#Polymyositis.
*#Inclusion body myositis.
*#Dermatomyositis.
*Duchenne muscular dystrophy.
*Becker muscular dystrophy.
*Limb-girdle muscular dystrophy.
*Myotonic dystrophy.
*Metabolic - glycogen storage disease.
 
Other:
*Myasthenia gravis.
*Mitochondrial myopathy.
*Congenital fibre type disproportion.
*Periodic paralysis.
 
==Amyotrophic lateral sclerosis==
===General===
*Abbreviated ''ALS''.
*Affects - corticospinal tract - gliosis.
 
===Microscopic===
Features:
*Neurogenic pattern:
**Group atrophy.
**+/-Target fibre.
 
==Dermatomyositis==
===General===
*Complement mediated disease... membrane attach complex.
===Microscopic===
Features:
*Perifascicular inflammation with perifascicular atrophy - '''key feature'''.
 
==Inclusion body myositis==
===Microscopic===
Features:
*Inflammation.
*Vacuolated fibres (with proteineous aggregates) - '''key feature'''.
 
DDx: polymyositis.
 
IHC: APP +ve, ubiquitin +ve, tau +ve.
 
==Polymyositis==
===General===
*Tx: steroids.
===Microscopic===
Features:
*Inflammation.
 
DDx: Inclusion body myositis.
 
==Muscular dystrophy==
===General===
*DDx: lots.


===Microscopic===
Features:
*Endomysial fibrosis.
*Hypercontracted fibres (large muscle fibres).


==References==
==References==
Michael
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