PERIPHERAL NERVES Flashcards
____ bacterial toxin
acts directly on the membranes of the Schwarm cells near
the dorsal root ganglia and adjacent parts of motor and
sensory nerves
diphtheria
____ causes occlusion of
vasa nervorum, resulting in multifocal nerve infarction
polyarteritis nodosa
_____ protein
synthesis of dorsal root ganglion cells is blocked with
subsequent neuronal destruction
doxorubicin toxicity,
which combines with the axoplasm of the largest sensory
and motor nerves via sulfhydryl bonds
arsenic
____which damages the microtubular transport system.
vincristine
toxicity,
mechanism of histopathological reactions of peripheral nerves
segmental
demyelination, wallerian degeneration, and axonal degeneration
Focal degeneration of the
myelin sheath with sparing of the axon is called _______
segmental
demyelination.
a reaction of both the axon and
myelin distal to the site of disruption of an axon
wallerian degeneration
when the axon degenerates
as part of a “dying-back” phenomenon in a more
generalized metabolically determined polyneuropathy, it
is termed _____
axonal degeneration.
Certain diseases affect the neuron primarily rather
than the axon and cause either a motor or sensory _______.
neuronopathy
By means of ________, the cell bodies receive signals to
increase their metabolic activity and to produce growth
factors and other materials needed for axonal regeneration.
retrograde
axonal transport
These
retrograde changes consist of swelling of the cell cytoplasm
and marginalization and dissolution of the Nissl
substance. The important point again is that despite the
destructive changes in the nerve fibers, the nerve cells,
while altered in histologic appearance, are left intact with
preservation of the apparatus required for recovery.
chromatolysis
T or F
recovery is much slower with
wallerian or axonal degeneration, often requiring months
to a year or more
T
Recurrent demyelination and remyelination lead
to ________formations and enlargement of nerves,
the result of proliferating Schwarm cells and fibroblasts
that encircle the axon and its thin myelin sheath
“onion bulb”
Regenerating axon filaments take
aberrant courses and, with fibroblastic scar formation,
they may form a disorganized clump of tissue termed
_____
pseudoneuroma
This represents the “length-dependent” pattern that is
typical of ______. The nutritional, metabolic,
and toxic neuropathies assume this
axonal degeneratio
By contrast, in demyelinating polyneuropathies, the _______ of lesions and blockage of electrical conduction
often leads to weakness of proximal limb and facial muscles
before or at the same time as distal parts are affected
multifocal
nature
The maximum degree of denervation
atrophy after an acute injury to the axons occurs in _____ and reduces muscle volume by 75 to 80 percent.
90 to
120 days
Ultimately in muscle
atrophy, there is degeneration and loss of the denervated
muscle fibers. This process begins in _________months; in 3 to
4 years,
6 to 12
_______, in which tendon reflexes
may be retained, even with marked loss of perception
of painful stimuli.
small-fiber neuropathies
An ________pattern of sensory
loss over the abdomen and thorax in severe axonal neuropathy
may be mistaken for the sensory level of a spinal cord lesion.
“escutcheon”
Loss of proprioception may also give rise to small
wavering, fluctuating movements of the outstretched fingers–
called _______ or “dancing fingers.”
pseudoathetotic,
Austin pointed out that foot deformity is
found in ___ of patients with hereditary polyneuropathy,
and spine curvature is found in 20 percent
30 percent
Unequal weakening
of the paravertebral muscles on the two sides of the spine
during early development leads to ______
kyphoscoliosis
In an
anesthetic and immobile limb, the skin becomes tight and
shiny, the nails curved and ridged, and the subcutaneous
tissue thickened____
(“trophic changes”)
_________ two o f the most
frequent manifestations of autonomic failure, predominate
in certain types of polyneuropathies.
Anhidrosis and orthostatic hypotension,
In GBS
A mild respiratory or gastrointestinal infection or immunization
precedes the neuropathic symptoms by 1 to
3 weeks in approximately _____ percent of cases
60
______ is the most frequent identifiable
antecedent infection, but it accounts for only a relatively
limited proportion of cases
Campylobacter jejuni
viruses associated with GBS
(cytomegalovirus [CMV], Epstein-Barr virus
[EBV], HIV), and less often, bacterial infections other
than Campylobacter (Mycoplasma pneumoniae, Lyme disease
Only the______reflexes may be lost
during the first week of illness.
ankle
Urinary
retention occurs in approximately _____percent of patients
soon after the onset of weakness, but catheterization is
seldom required for more than a few days
15
rapid evolution
of polyneuropathy and slow and poor recovery.
muscle atrophy
became apparent relatively early in the axonal form
axonal
pathologic mechanism of Acute Axo n a l F o r m
complement and
the presence of macrophages in the periaxonal space, a
humoral antibody directed against some component of the
axolemma was postulated by
A proportion of axonal cases, perhaps up to one-fifth,
are associated with circulating antibodies to the ______
of peripheral nerve, and some of these reflect recently
preceding infection with C. jejuni
G M1 ganglioside
2 types of axonal
The acronyms AMAN
(acute motor) and AMSAN (acute motor-sensory axonal
neuropathy) are equivalents to axonal GBS.
prognosis of axonal
prolonged and incomplete recovery
what variant of GBS
causing difficulty
in swallowing with neck and proximal arm weakness
(Ropper, 1 986a) . Ptosis, often with ophthalmoplegia,
may be added.
plu!ryngeal-cervical-brachial
Ophthalmoplegia, whether occurring alone or
with weakness or ataxia of other parts, is almost uniformly
associated with a specific antineural antibody, ______
antiGQ1b.
CHON in CSF of GBS
The protein content is usually normal during the first few
days of illness, but then it rises, reaching a peak in ____
4 to
6 weeks
NCV findings in early GBS
- reduction in the amplitude of muscle action
potentials, - slowed conduction velocity, and
- conduction block in motor nerves
- Prolonged distal latencies and reduced distal amplitudes (reflecting distal conduction block) and
- prolonged or absent F responses (indicating involvement
of proximal parts of motor nerves and roots)
The acute motor axonal variety has a tendency to
be associated with antibodies to _____a and the
pharyngeal-cervical-brachial syndrome, to ______
GM1 or GD1
GTla.
pathologic findings in GBS
endoneural perivascular (mainly perivenous) lymphocytic infiltrates.
earliest change that could be detected
by Hafer-Macko and colleagues was the deposition of ___
complement on the inner layer of myelin.
______s early in their course, corresponding
in most instances to a predominantly motor presentation
and to axonal damage
antiGM1 antibodie
About ____
of our patients have required mechanical ventilation
one-quarter
A rough estimate of breathing capacity may be obtained
by having the patient count quickly on one deep breath.
The ability to reach 20 generally corresponds to a vital
capacity of greater than ____
1.5 L
the vital capacity
diminishes to below about ____endotracheal intubation
and mechanical ventilation are usually necessary
10 mL/kg,
Hypotension from dysautonomia, which occurs in
approximately ____ of paralyzed patients
10 percent
With tracheostomy and intensive
care, the mortality from the disease can be reduced to
approximately __
3 percent
In patients who are treated within 2 weeks with TPE,there
is an approximate
1.halving of the period of hospitalization,
- duration of mechanical ventilation, and of
the - time required to achieve independent ambulation
The most important predictors of responsiveness
to plasma exchange treatment are the same as for the
overall prognosis, namely:
the patient’s age (responders
are younger) and the preservation of motor compound
muscle action potential amplitudes prior to instituting
treatment
The advised regimen of plasma exchange removes a
total of_______ treatments
on alternate days, or over a shorter period if there is no
coagulopathy.
200 to 250 mL/ kg of plasma in 4 to 6
________
manifested most often by severe headache, are infrequent
complications of IVIg
Renal failure, proteinuria, and aseptic meningitis,
After the use of either plasma exchange or IVlg,
_____ of patients who initially improve will have
a relapse that becomes apparent several days or up to
3 weeks after completion of treatment.
5 to 10 percent