PNS disorders Flashcards
Paresthesia-
a morbid or abnormal sensation as burning, prickling, pins, and needles, numbness
ephase-
pathological contact between parallel nerve fibers where electrical nerve impulses can
negative symptoms of PNS lesions
muscle weakness, loss of tendon reflexes, ANS defecits, impared sensation
cuases of loss of function of PNS lesions.
conduction failure in efferents and/or afferents
mergence or exaggerated symptoms
paresthesias caused by ephaptic transmission between adjacent damaged sensory nerve fibers that have become hyper exciteable -pain caused by compression of nerves
mean conduction velocities
55 m/s
Motor neuron soma lesion affect on velocity
slight or no change, in motor and no change in sensory
compression affect on velocity
slowing of motor and sensory
Demyelination affect on velocity
marked reduction of motor and senory
mild axonal degenration effect on velocity
no or light reduction in velocity
NMJ effect on velocity
No change in motor or sensory
Muscle
no change in motor or sensory
Carpal tunnel syndrome
compression of the median nerve through the carpal tunnel causes weakness and numbness of the hand and wrist. pain that radiates up the arm. Women are more vulnerable than men.
Wallerian degneratino
degeneration of the distal part of the axon
anterograde transneural degeneration
degeneration of distal nerve cells
Retragrade transneural degeneration
degeneration of proximal nerve cells.
for regeneration axons my use
lingering schwann cells as a guide
sprouting errors causes
aberrant motor output during attempts at volitional movement.
axonal regrowth is facilitated by
nerve growth facotr, laminins and adhesion molecules. and grow at 1 mm/day
Gliosis occurs
when astrocytes multiply in regions of trauma and form a glial scar. This is a mechanical barrier to sprouting axons
an inhibitory chemical messengers tells the CNS
not to grow axons
regrowing axons differentiate into nerve terminals when
they contact the basal lamina
complications of guillain- barre syndrome
respiratory failure, aspiration, pneumonia, deep vein thrombosis
treatment for guillain Barre syndrome
plasmapheresis and intravenous immune globulin.
Leprosy
causes damage to peripheral nerve, sensory loss, muscle weakness may loose protective nociception.
lead toxicity
symmetric muscle weakness in distal regions, feet worst of all. focal weakness of extensor meucle fingers wrist and arms. bilateral weakness and wasting in chronic situations. motor neuropathy in adults but encephalopathy in infants. no sensory symptoms.
Alcoholic polyneuropathy
numbness, tingling, burning feet, weakness, more at risk if alcoholism is present for 10 years. associated with B1 deficiency
diabetes mellitus
usually express symmetric sensory, assymetric motr, and autonomic deficits. sensory usually begin in both legs due to abnormalities in unmylienated axons,
