PNS LAB Flashcards
(37 cards)
Weakness
Paresis:
- Causes paresis of muscles distal to the knee, with resulting foot
drop, a steppage gait, frequent tripping, and muscle atrophy - As the disease slowly progresses, muscle atrophy and paresis
affect the hands. - Significant numbness is unusual
- Ability to sense heat, cold, and painful stimuli is decreased.
- Neuropathic pain, a frequent complaint, probably is related to the
loss of A delta fibers. - Onset typically occurs in adolescence or in young adulthood
Hereditary Motor and Sensory Neuropathy (Charcot-Marie-Tooth Disease)
generalized sensitivity to ACh, is spontaneous contraction
of individual muscle fibers. Not visible with eyes
Fibrillation
Encompasses a spectrum of acute inflammatory demyelinating
polyradiculopathies (AIDP)
- The motor system is more affected than the sensory system
- Weakness and areflexia or hyporeflexia in all four limbs
- Onset is rapid
- With paralysis typically progressing from distal to proximal
Guillain-Barré Syndrome
quick twitch of muscle fibers, visible with eyes
Fasciculations: q
- is loss of myelin limited to the site of injury
- Peripheral myelinopathies interfere with the function of:
- large-diameter axons, producing motor, light touch, proprioceptive, phasic
stretch reflex deficits, and cause neuropathic pain. - If not severe, autonomic function is intact and axons are not damaged.
- Recovery is possible because myelination is possible (Schwann Cells).
Traumatic Myelinopathy
If scar tissue intervenes between the stumps, sprouts may grow into a
tangled mass of nerve fibers, forming a _________
traumatic neuroma
Trophic Changes:
- Begin in the denervated tissues
- This includes: muscle atrophy, shiny skin, brittle nails, and thickening of
subcutaneous tissues. - Lack of movement: ____________
- Loss of sensation and Poor blood supply changes: Ulceration of
cutaneous and subcutaneous tissues, healing of wounds and
infections.
neurogenic joint damage
Are disorders intrinsic to muscle
MYOPATHY
Pain due to a stimulus that does not normally provoke pain
Allodynia
Common sites of Traumatic Myelinopathy
- (carpal tunnel), ulnar (ulnar groove), radial (spiral
groove), and peroneal (fibular head).
Autonomic Changes: If many nerves are involved:
difficulty regulating blood pressure,
heart rate, sweating, and bowel and bladder functions.
- Individual nerves are affected,producing a random, asymmetric presentation of
signs. - Causes: diabetes or vasculitis (Red flags)
Multiple Mononeuropathy
Causes of Traumatic Myelinopathy
- Repeated mechanical stimuli, including excessive pressure,
stretch, vibration, and/or friction may cause focal compression - Prolonged pressure from casts, crutches,or sustained positions
(e.g., sitting with knees crossed) may compress nerves.
Can cause an ordinary stimulus to be unpleasant or painful. It can also cause
insensitivity to a stimulus.
Dysesthesia
axons that are near the cell body
Proximal stump
- Begin in the denervated tissues
- This includes: muscle atrophy, shiny skin, brittle nails, and thickening of
subcutaneous tissues. - Lack of movement: neurogenic joint damage
- Loss of sensation and Poor blood supply changes: Ulceration of
cutaneous and subcutaneous tissues, healing of wounds and
infections.
Trophic Changes:
Autonomic Changes: Single Nerve:
- Lack of sweating
- Loss of sympathetic control of smooth muscle fibers in arterial
walls
an autoimmune disease that damages post-synaptic
ACh receptors at the neuromuscular junction
Myasthenia Gravis (
Symmetric involvement of sensory, motor, and autonomic fibers,
often progressing from distal to proximal,
the hallmark of
polyneuropathy.
- Axons and myelin are damaged.
- Usually sensation is affected most severely, often in a
stocking/glove distribution. - All sizes of sensory axons are damaged
- pain, paresthesias,and dysesthesias.
Diabetic Polyneuropathy
- Disrupts axons but leaves myelin intact
- Wallerian degeneration* occurs distal to the lesion
- Axonopathies affect all sizes of axons
- Absent/Significantly reduced: reflexes, somatosensation,and motor function
- Because the myelin and connective tissues remain intact, regenerating axons are
able to reinnervate appropriate targets. Axon regrowth typically proceeds at a rate
of 1 mm/day.
Traumatic Axonopathy
An increased sensitivity to feeling pain and an extreme response to pain
Hyperalgesia
- random muscle fibers degenerate, leaving motor units with
fewer muscle fibers than normal. - Activating a muscle that lacks a significant number of muscle
fibers produces less force than is produced by a healthy
motor unit.
Muscular dystrophy
