Term
| what are the parts of the neuromuscular system |
|
Definition
| peripherial nerves (sensors) and skeletal muscles(effectors |
|
|
Term
| what are the parts of the motor unit |
|
Definition
peripherial component of the motor system
1 lower motor neuron
peripherial axon
NMJ
muscle fibers |
|
|
Term
| myelin: composition, amount, anatomy |
|
Definition
schwann cells
one schwann cell per internode of one axon
intenodes are seperated by nodes of ranvier |
|
|
Term
| what are perineural cells |
|
Definition
| meningeal like cells that maintain blood nerve barrier of fasicles |
|
|
Term
| what determines nerve velocity |
|
Definition
| axon diameter combined with myelin thickness |
|
|
Term
| what nerves sense light touch |
|
Definition
| thick myelin, large diameter |
|
|
Term
|
Definition
|
|
Term
| what are the 2 patterns of nerve injury |
|
Definition
axonal injury
demyelinating injury |
|
|
Term
| what are the 3 causes of axonal injury |
|
Definition
damage to axon causes distal portion to degenerate
wallerian degeneration
axonal neuropathies |
|
|
Term
| what is a wallerian degeneration |
|
Definition
|
|
Term
| what is an axonal neuropathy |
|
Definition
| decrease in axon density and amplitude of impulses |
|
|
Term
|
Definition
| regrowth of axon and remyelination of distal axons |
|
|
Term
| what are the 3 types of demyalinating injuries |
|
Definition
polyneuropathies
polyneuritis multiplex
mononeuropathy |
|
|
Term
| what are the consequence of demyelinating injury (4) |
|
Definition
damage of schwann cells or myelin with axonal sparing
slow conduction velocity
occurs within random individual internodes (segmental demyelination)
axons develop thin myelin and short internodes |
|
|
Term
| how can an axon with a demyelinating injury be identified (3) |
|
Definition
normal density
segmental demyelination
areas of repair |
|
|
Term
| polyneuropathies: clinical presentation |
|
Definition
loss of sensation and paresthesia starting in toes and spreading to knees (simillar in hands)
"stocking and glove distribution: |
|
|
Term
| polyneuropathies: histology (3) |
|
Definition
peripherial nerves affected in symmetric length dependent fashion
diffuse axonal loss
pronounced in distal segments of long nerves |
|
|
Term
| define polyneuritis multiplex |
|
Definition
| demyelinating injury randomly affects portions of individual nerves |
|
|
Term
|
Definition
| demyelinating injury affects single nerve |
|
|
Term
| most common cause of mononeuropathy (2) |
|
Definition
| most common in traumatic injury or entrapment |
|
|
Term
| causes of demyelinating injuries (13) |
|
Definition
DM
neuremia
thiamine deficiency
B6/B12 deficiency
drugs and toxins
vasculopltic: vasculitis, amyloidosis
inflammatory: autoimmune
infection
inherited
paraneoplastic: leukodistrophy |
|
|
Term
| what drugs cause demyelinating injuries (5) |
|
Definition
vinblastine
vincristine
paclitaxel
colchicine
isoniazid |
|
|
Term
| what toxins cause demyelinating injuries (6) |
|
Definition
alcohol
lead
aluminum
arsenic
mercury
acrylamide |
|
|
Term
| what autoimmune disorders cause demyelinating injuries (4) |
|
Definition
|
|
Term
| what infections cause demyelinating injuries (4) |
|
Definition
HSV (ganglionitis)
leprosy
HIV
lyme (facial nerve palsy) |
|
|
Term
| what inherited disorders cause demyelinating injuries |
|
Definition
charcot-marine tooth neuropathy 1, 3, X
hereditary neuropathy with liability to pressure palsy |
|
|
Term
| what are the causes of charcot-marine-tooth neuropathy 1, 3, X |
|
Definition
1: AD duplication in PMP22
3: AD or AR point mutation in PMP22
X: X-linked connexin 32 gene mutation |
|
|
Term
| what is the cause of hereditary neuropathy with liability to pressure palsy |
|
Definition
|
|
Term
| symptoms of guillian barre syndrome (3) |
|
Definition
rapidly progressive
ascending motor weakness
can cause death due to resp M failure |
|
|
Term
| guillian barre syndrome histology (3) |
|
Definition
injury more extensive in nerve roots and proximal segments
mononuclear infiltrates rich in macrophages
acute demyelination |
|
|
Term
| cause of guillian barre syndrome |
|
Definition
autoimmune response: humeral and cellular response triggered by infection of vaccine
infection: camplobacter, EBV, CMV, HIV |
|
|
Term
| guillian barre syndrome treatment |
|
Definition
plasmaphresis: remove offending antibodies
IVIG
supportive care: ventilation |
|
|
Term
| guillian barre syndrome prognosis |
|
Definition
| recovery is likley if patient survives initial acute phase |
|
|
Term
| cause of chronic inflammatory demyelination polyneuropathy |
|
Definition
symmetric demyelinating disease of motor and sensory due to immune factors
increased in autoimmune disorders: SLE, HIV |
|
|
Term
| signs of chronic inflammatory demyelinating polyneuropathy (6) |
|
Definition
chronic relapsing and remitting progressive course
difficulty walking, weakness, numbness, pain, tingling |
|
|
Term
| histolog of chronic inflammatory demyelinating polyneuropathy (2) |
|
Definition
segments of demyelinating and remyelinating
schwann cells wrap in onion skin pattern |
|
|
Term
| treatment of chronic inflammatory demyelinating polyneuropathy (2) |
|
Definition
plasmapharesis
immunosupressents |
|
|
Term
| prognosis of chronic inflammatory demyelinating polyneuropathy (2) |
|
Definition
some recover completely
usuallo they have recurrent bouts causing permanent loss of nerve function |
|
|
Term
| what are the three types of diabetic peripherial neuropathy, which is most common |
|
Definition
can occur alone or together
autonomic neuropathy
lumbosacral radiculopathy
distal symmetric sensorimotor polyneuropathy - most common |
|
|
Term
| signs of diabetic autonomic neuropathy (4) |
|
Definition
| change in bowel, cladder, cardiac, or sexual function |
|
|
Term
| signs of diabetic lumbosacral radiculopathy (3) |
|
Definition
asymmetric pain
can progress to LE weakness and muscle atrophy |
|
|
Term
| signs of diabetic distal symmetric sensorimotor polyneuropathy (10) |
|
Definition
sensory axons most affected: parasthesia, numbness
glycosylation end products
hyperglycemia
increased ROS
microvascular change sin axon metabolism
abnormal C protein levels
neurotrophic factors
axonal injury and demyelination |
|
|
Term
| tx distal symmetric sensorimotor polyneuropathy |
|
Definition
|
|
Term
| how do druges and toxins interfere with nerves (3) |
|
Definition
interfere with axon transport or cytoskeletal function
longest axons most susceptible |
|
|
Term
| systemic vasculitis: 3 signs |
|
Definition
patchy involvement
variation in degree of axonal damage between fasicles within nerve
mononuclear multiplex |
|
|
Term
| what is mononuclear multiplex |
|
Definition
| painful asymmetric sensory and motor preipherial neuropathy |
|
|
Term
| what are common signs of an inherited disease of peripherial nerves |
|
Definition
demyelination of axon
show as adult and slowly progress
mimic acquired polyneuropathies |
|
|
Term
| what is the most common cause of inherited disease of peripherial nerves |
|
Definition
| mutation of PMP22 encoding myelin sheath protein |
|
|
Term
|
Definition
influx of Ca
release of ACh
diffuses across cleft
binds post synaptic receptor
depolarizes membrane
depolarizes myofiber
contraction of msucle |
|
|
Term
| cause of myasthenia gravis |
|
Definition
autoantibodies block post-synaptic ACh receptor
degradation and depletion of receptors
can change self tolerance and allow generation of auto-reactive T and B cells |
|
|
Term
| who get smyasthenia gravis |
|
Definition
|
|
Term
| what conditions are associated with myasthenia gravis |
|
Definition
60% have reactive hyperplasia of intrathymic B cells
20% have thymoma (epithelial cell tumor) which causes tolerance to self antigens and allows for generation of autoreactive T and B cells |
|
|
Term
| clinical signs of myasthenia gravis |
|
Definition
ptosis
diplopia
fluctuating muscle weakness over short time
use causes more weakness
cholinesterase inhibitors improve strength |
|
|
Term
|
Definition
cholinesterase inhibitors
immunosupression
plasmaphresis
thymectomy |
|
|
Term
| prognosis myasthenia gravis |
|
Definition
| >95% 5 year survival with intervention |
|
|
Term
| cause of lambert-eaton syndrom |
|
Definition
| autoantibodies inhibit pre-synaptic Ca channels reducing ACh release |
|
|
Term
| signs of lambert-eaton syndrome |
|
Definition
weakness improves with stimulation
often begins as paraneoplastic disorder esp small cell lung cancer |
|
|
Term
| tx lambert eaton syndrome |
|
Definition
plasmaphresis
immunosupression |
|
|
Term
| prognosis lambert eaton syndrome |
|
Definition
| worse prognosis due to lung cancer association |
|
|
Term
| cause of congenital myasthenic syndrome |
|
Definition
heterogenous disorders
mutations dirupt function in various NMJ proteins (pre-synapse, synapse, post-synapse ACh activity) |
|
|
Term
| what produces tetanus toxin |
|
Definition
|
|
Term
|
Definition
| neurotoxin blocks action of inhibitor interneurons increasing ACh |
|
|
Term
|
Definition
| tetanospasm: sustained muscle contraction and spasm |
|
|
Term
| MOA and effect of botulinium toxin |
|
Definition
inhibits ACh release
flaccid paralysis |
|
|
Term
| what are the NMJ disorders |
|
Definition
myasthenia gravis
lambert eaton syndrome
congenital myasthenic syndromes
tetanus toxin
botulinium toxin |
|
|
Term
| what are the periperhail nerve sheath tumors |
|
Definition
schwannoma
neurofibromas
malignant |
|
|
Term
|
Definition
| non-neoplastic proliferation caused by pervious injury to peripherial nerves |
|
|
Term
| traumatic neuroma: clinical sign |
|
Definition
|
|
Term
| traumatic neuroma: morphology |
|
Definition
axonal regeneration after transection causes aprouting and elongation of processes from axonal stump
nodules: axons, schwann cells, CT
if perinerum is disrupted: processes may miss distal end of nerve
if processes are induced: reactive schwann cell proliferation occurs |
|
|
Term
| in general, who gets peripherial nerve sheath tumors |
|
Definition
usually adults
often familial association with NF1 and NF2 |
|
|
Term
| in general, what are signs of nerve sheath tumors |
|
Definition
| pain or loss of function due to impingement of nerve or surrounding structures |
|
|
Term
| in general, waht are histological signs of nerve sheath tumors |
|
Definition
soft tissue mass
schwann cell differentiation |
|
|
Term
| schwannoma; location, spread |
|
Definition
benign encapsulated tumors
in soft tissue, internal organs, spinal nerve roots |
|
|
Term
| statistics on schwannoma cause |
|
Definition
10% associated with NF2 (multiple and bilateral vestibular schwannoma)
90% sporadic |
|
|
Term
|
Definition
due to loss of function mutation in CH22 merlin gene which is a cytoskeletal tumor supressor via E-cadherin contact inhibition
schwanomatosis |
|
|
Term
|
Definition
| familial multiple schwanoma without vestibular schwanomas due to loss of function in CH22 tumor supressor protein for chromatin structure regulation |
|
|
Term
|
Definition
circumscribed masses adjacent to nerves
axons excluded from tumor
antoni A dense areas
antoni B loose areas
uniform proliferation of neoplastic schwann cells
thick walled hyalinized vessels |
|
|
Term
| antoni A area composition |
|
Definition
| spindle cells, buckled nuclei in fasicles, align to make bands of verocay bodies (aneuclar mass) |
|
|
Term
|
Definition
localized cutaneous neurofibromas
plexiform neurofibromas
diffuse neurofibromas |
|
|
Term
| localized cutaneous neurofibroma signs |
|
Definition
superificial nodular polypoid tumors
solidary sporadic lesions
multiple NF1 |
|
|
Term
| plexiform neurofibromas: location, association, risks |
|
Definition
grow diffuse in nerve or nerve plexus
difficult to remove without neurological deficits
pathognomic for NF1
small risk of malignant transformation |
|
|
Term
| difuse neurofibromas: describe, associations |
|
Definition
infiltrative proliferations
large disfiguring SC masses
associated with NF1 |
|
|
Term
|
Definition
not encapsulated
circumscribed when localized, can be diffuse
neoplastic schwann cells mised with other cells (like mast cells)
loose wavy vollagen or myxoid, dense collagen filler |
|
|
Term
| histology of diffuse neurofibromas |
|
Definition
| infiltrative growth within dermis and subcutis |
|
|
Term
| histolog of plexiform neurofibromas |
|
Definition
multiple fasicles of individual affected nerves
axons embedded within neoplastic proliferation
expand fasicles but leave perinerium intact |
|
|
Term
| malignant nerve sheath tumor associations |
|
Definition
50% of malignant nerve sheath tumors nave NF1
10% of NF1 have nerve sheath malignancy |
|
|
Term
| cause of malignant nerve sheath tumors |
|
Definition
origin from peripherial nerve
transformation of neurofibroma (usually plexiform) |
|
|
Term
| histolog of nerve sheath malignancy |
|
Definition
schwann cell derivation
large poorly defined soft tissue mass
malignant features (anaplasia, necrosis, infiltrative growth, pleomorphism)
alternating areas of high and low cellularity (marbling) |
|
|
