What are the 4 types of peripheral neuropathy?
- Mononeuropathy: damage to a single nerve
- Polyneuropathy: damage to more than one nerve
- Radiculopathy: damage to affecting a spinal nerve
- Plexopathy: damage to one of theplexuses
Mononeuropathy vs polyneuropathy origin
mono- mechanical injury
poly- systemic/metabolic pathology- longest fibers are affected first
dysthesia:
abnormal sensations whether provoked by stimuli or not
hypoesthesia
a decrease in sensory perception
hyperesthesia
an increase in sensory perception
paresthesia
unusual feelings, such as pins and needles without any stimulus
hyperalgesia
normally painful stimuli are perceived as even more painful than usual
Allogynia
previously non painful stimuli are now painful (bed sheets on feet)
What are the 3 different levels of severity for a peripheral nerve injury?
- Neuropraxia- mild– axon remains intact myelin is just mildy effected
- Axonotmesis- severe, damage to axon but myelin is intact; can recovery slowly
- Neurotmesis- damage to myelin and axon; no myelinated path for the neuron to regrow
what are the clinical implications for a dymylenating peripheral injury in terms of : weakness, reflexes, distribution, infection, conduction velocity, symptom progression.
- weakness more diffuse
- early loss of reflexes
- non length dependant distribution
- rapid ascending symptoms
- preceding infection
- conduction velocity decreased
what are the clinical implications of an axonal peripheral injury in terms of: weakness, reflexes, distribution, symptom progression and conduction amplitude.
- weakness is more distal
- reflexes are less affected
-length dependant distribution - usually chronic progression
conduction amplitude decreased
What are the clinical implications of GBS (motor, sensory, autonomic)
- it is a demyelinating condition usually following a recent infection
- Sensory: numb/tingling feet that ascends; sometimes neuropathic pain in face and trunk; large fiber> small fiber impairment
- Motor: distal> proximal weakness, ascends; opthalomoplegia and/or ptosis in 5-15%
- Autonomic: hypertension/hypotension; cardiac arrhythmia
What causes diabetic neuropathy?
Due to axonal damage
stocking and glove symptoms because distal axonal damage is first (lack of blood supply to neurons due to blood damage)
What part of the spinal cord does poliomyelitis effect?
anterior horn of cell bodies (LMN)
What part of the spinal cord does Tabes Dorsalis effect?
dorsal column damage due to neurosyphillis
What is the neuroanatomical basis of ALS
chronic progressive disease of corticospinal tracts and neurons of anterior grey horn
Syringomyelia
tube like enlargement of the central canal due to buildup of CST
How many pairs of spinal nerves?
31
how many pairs of cranial nerves?
12
What is a nerve plexus? examples?
a reorganization of nerves- you end up with mixed terminal nerves that can do a variety of functions
Brachial plexus (C5-T1) Lumbar plexus (T1-L4)
what is the endoneurium of a peripheral nerve?
fills the space between a bunch of axons
what is the perineurium of a peripheral nerve? what does it form?
surrounds a bunch of neurons with the endoneurium around them
nerve fasicle- same modality- carrying either sensory or motor neurons
what is the epineurium of the PNS? what does it form?
surrounds a bunch of fasicles and forms a proper peripheral nerve
In terms of peripheral fibre types, earlier numbers and letters are what?
larger and more likely to be myelinated, therefore have faster conduction
