PNS LAB Flashcards
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
Weakness and paresthesias affecting the face and sparing
all four limbs
Bifacial weakness GBS
- Occurs when nerves are physically divided by excessive stretch or laceration.
- causing immediate loss of sensation and/or muscle paralysis in the area
supplied - Wallerian degeneration begins distal to the lesion 3 to 5 days later.
- 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
Severance
Loss of control/movement
Paralysis
hyporeflexia with weakness of the upper limbs,
oropharynx, and cervical muscles
Pharyngeal-cervical-brachial weakness GBS
axons near the axon terminal
Distal stump:
an autoimmune disease that damages pre-synaptic
ACh receptors at the neuromuscular junction
Lambert-Eaton Myasthenic Syndrome
Symptoms typically begin in the feet and then appear in the hands. The distal pattern of symptoms is called?
stocking/glove distribution
denervated muscle -> no activity for approximately 1
week following injury.
Electromyography:
is a common compression injury of the median nerve in the space
between the carpal bones and the flexor retinaculum
- Initially pain and numbness are noted at night.
- Chronically, throughout the day, and sensation is decreased
or lost in the lateral 3 1/2 digits and the adjacent palm of the
hand.
- Paresis and atrophy of the thumb intrinsic muscles (abductor
pollicis brevis, opponens pollicis, first and second lumbricals,
and half of the flexor pollicis brevis)
- Pain from carpal tunnel syndrome may radiate into the forearm and
occasionally to the shoulde
Carpal Tunnel Syndrome
When the distal segment of an axon degenerates, the myelin sheath pulls
away from that segment
Wallerian degeneration
- Is used therapeutically in people with spasticity or
dystonia to weaken overactive muscles. - Interferes with the release of ACh at the neuromuscular
junction
Botulinum toxin
An abnormal touch sensation, such as burning or prickling, that occurs without an
outside stimulus.
Paresthesia
weakness affecting only the lower limbs and sparing
the upper limbs
Paraparetic GBS
