6. Neuropathology 2 Flashcards
How are neuropathologies classified?
- Inherited (genetic) or Acquired
- Infections (e.g. viruses, bacteria, other)
- Inflammation (e.g. vasculitis, paraneoplastic, idiopathic, MS) • Toxic (e.g. drugs, chemicals etc)
- Metabolic (e.g. DM, vitamin deficiency, thyroid problems etc)
- Degenerative (idiopathic)
- Trauma
- Other
Problems of relying on pathology
- Sampling error
- Accessibility of tissue
- Often tissue only available late in disease process (i.e. post-mortem)
Vitamin D and MS
- vitamin D deficiency prior to MS onset predisposes individuals to increased risk of MS
- Vitamin D as an immunomodulator
Which disease are MS patients of?
EBV
(Due to high level in general pop)
Virtually all subjects with MS (>99%) are infected with EBV compared to only ~90% of control subjects.
In ALS there is degeneration of..
- Cortico-spinal tracts
- Hypoglossal nuclei of medulla
*Dorsal column preserved
Parkinson’s disease pathology
Lewy-body presence in dopaminergic pathway of substantia nigra
Prion diseases
Related to abnormal prion protein.
Pathology of Alzheimer’s disease
Presence of tangles and plaques
Initial presentation of peripheral neuropathy
Numbness spread up from feet/hands due to axonal or demyelinating degeneration
Causes of peripheral neuropathy?
Diabetes (*scotland) Leprosy (* world) Idiopathic (*clinic) Toxic-alcohol, drug Vit def Post inefction (Guillain-barre syndrome)
Other name for inherited peripheral neuropahties?
Presentation
Charcot-Marie-Tooth
Presentation:
- Distal wasting
- Inverse champagne bottle legs
- Sensitive to trauma
Contractile Properties
• Slow twitch (I) fibers innervated by _____ 2 motor neurons, smaller of the two α motor neurons
• Fast twitch (II) fibers innervated by alpha 1 motor neurons, ____ of the two α motor neurons
• Fast twitch (II) fibers have _____ excitation threshold and faster conduction velocity
Contractile Properties
• Slow twitch (I) fibers innervated by alpha 2 motor neurons, smaller of the two α motor neurons
• Fast twitch (II) fibers innervated by alpha 1 motor neurons, larger of the two α motor neurons
• Fast twitch (II) fibers have higher excitation threshold and faster conduction velocity
Motor unit recruitment?
• Motor neurons recruited in order of size: Size Principle
• Smallest alpha motor neurons, α2, which belong to slow twitch recruited first
• Largest alpha motor neurons, α1, which belong to fast twitch recruited last
09/11/2017
Difference in staining properties of alpha type I and II fibres?
- Slow twitch (type I) have myosin isoforms with low ATPase activity.
- Fast twitch (type II) have myosin isoforms with high ATPase activity that promotes rapid breakdown of ATP for energy of high-speed muscle shortening.
Difference in distribution properties of alpha type I and II fibres?
- All muscle composed of ST & FT fibers
- Distribution varies from muscle to muscle within an individual
- Most individuals possess between 45 and 55% ST