3.14 Ch. 12.2 Flashcards
types of peripheral neuropathies
- mononeuropathy
- multiple mononeuropathy
- polyneuropathy
mononeuropathy
Involves a single nerve and is considered a focal dysfunction
multiple mononeuropathy
- Involves several nerves
- is multifocal (i.e., asymmetrically involves individual nerves).
polyneuropathy
- Involves many nerves
- is a generalized disorder that typically has a distal and symmetrical presentation.
3 categories of traumatic injuries
- traumatic myelinopathy
- traumatic axonopathy
- severance
traumatic myelinopathy refers to the loss of
- myelin
- limited to the site of injury
peripheral myelinopathies interfere with
function of large-diameter axons
What causes traumatic myelinopathy?
focal compression of a peripheral nerve
What can cause focal compression?
repeated mechanical stimuli
Where does traumatic axonopathy occur?
distal to the lesion
What does traumatic axonopathy disrupt?
- axons
- Wallerian degeneration
What does traumatic axonopathy affect?
- all sizes of axons
- reflexes
- somatosensation
- motor functions
**reduced or absent
traumatic axonopathy and regenerating axons
Regenerating axons are able to reinnervate appropriate targets because myelin and connective tissues remain intact.
When does severance occur?
- when nerves are physically divided by excessive stretching or laceration
- axons and connective tissue are completely interrupted
What does severance result in immediately?
- loss of sensation
- muscle paralysis in area supplied
What happens if proximal and distal nerve stumps are apposed and scarring does not interfere?
some sprouts enter the distal stump and are guided to their target tissue in the periphery
What does multiple mononeuropathy involve?
two or more nerves in different parts of the body
What may cause multiple mononeuropathy?
vasculitis
What should be done if vasculitis is suspected?
an urgent referral should be made for an electrodiagnostic evaluation
nerves affected with multiple mononeuropathy
What does this produce?
- individual nerves are affected
- produces a random, asymmetrical presentation of signs
hallmark signs of polyneuropathy
- symmetrical involvement of sensory, motor, and autonomic fibers
- often progresses from distal to proximal
Polyneuropathies are NOT the result of
- trauma
- ischemia
causes of polyneuropathies (Categories)
- toxic
- metabolic
- autoimmune
Most common causes of polyneuropathies
- diabetes
- nutritional deficiencies 2˚ to alcoholism
- autoimmune diseases
(also some therapeutic drugs, industrial and agricultural toxins, and nutritional disorders)
polyneuropathy in Guillain-Barré has more severe effects on (motor/sensory) than (motor/sensory) system
motor
sensory
Guillain-Barré: proximal
paresis may be worse
Guillain-Barré: onset
- rapid with progressive paralysis
- urgent dx and tx required to prevent respiratory failure
Guillain-Barré: patients requiring a ventilator
1/3 of pts will need a ventilator
most common inherited form of polyneuropathy
Charcot-Marie-Tooth disease
Charcot-Marie-Tooth disease: onset
typically occurs in adolescence or in young adults but varies with type
Charcot-Marie-Tooth disease: presentation
paresis of muscles distal to knee with
- foot drop
- steppage gait
- frequent tripping
- muscle atrophy
in progression, atrophy and paresis affect hands
