Term
| what is the neuromuscular system composed of |
|
Definition
peripherial nerves (sensors)
skeletal muscles (effectors |
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Term
| what is the principal component of the motor system |
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Definition
|
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Term
| what is a motor unit made of 4ch |
|
Definition
1 lower motor neyron
peripherial axon
NMJ
muscle fiber |
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Term
| myelin: what makes it, anatomy, function |
|
Definition
made by schwann cells
one schwann cell per multiple nodes of axon
internodes reparated by nodes of ranvier
axon diabeter combined with myelin thicnkess determines velocity |
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Term
|
Definition
| meningeal like cell that maintains blood nerve barrier of fasicles |
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Term
| what type of nerves sense light toch |
|
Definition
thick myelin
large diameter axons |
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Term
| what type of nerves sense temp |
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Definition
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Term
| what are the 2 patterns of nerve injury |
|
Definition
axon injury
demyelinating injury |
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Term
| how does axonal injury occur |
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Definition
| damage causes distal portion of axon to degenerate |
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Term
| what are the three types of axonal injury, explain |
|
Definition
wallerian degeneration: secondary to myelin loss
axonal neuropathies: decrease axon density and amplitude of impulses
regeneration: regrowth of axon and remyelination of distal axon |
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Term
| what is a demyelinating injury, what does it do to conduction, where does it occur |
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Definition
damage of schwann cells or myelin with axon sparing causes thin myelin sheaths and short internodes
slows conduction velocity
occurs at random internodes (SEGMENTAL) |
|
|
Term
| what are the 3 demyelinating injuries |
|
Definition
polyneuritis
polyneuritis multiplex
mononeuropathy |
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Term
| polyneurmmetricopathy: define, location |
|
Definition
peripherial nerve affected in symmetrically length wise, more pronounced at distal segments
diffuse axonal loss |
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Term
| polyneuropathies: clinical presentation |
|
Definition
| stockin and glove distribution: loss of sensation and paresthesia starting in toes to knees and hands to elbows |
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Term
| polyneurs multiplex define |
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Definition
| demyelination randomly affects all portions of indivdual nerves |
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Term
| mononeuropathy define, when does this happen |
|
Definition
demyelination of a signle nerve
traumatic injury or entrapment |
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Term
| nutritional causes of demyelination 5 |
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Definition
| DM, neuremia, deficient thiamine, B6, B12 |
|
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Term
| toxic causes of demyelination 6 |
|
Definition
| drugs, alcohol, lead, aluminum, aresnic, mercury, acrylamide |
|
|
Term
| vascular causes of demylation 2 |
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Definition
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Term
| inflammatory causes of demyelination 4 |
|
Definition
| autoimmune: SLE, RA, sarcoidosis, sjogerns |
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|
Term
| infectious causes of demyelination 4 |
|
Definition
HSV (ganglioniitis)
leprosy
HIV
lyme (facial nerve palsy) |
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|
Term
| inherited causes of demyelination 4 (explain issue in each) |
|
Definition
charcot-marine-tooth (CMT) neuropathy 1: AD duplication in PMP22
CMT neuropathy 3: AD/AR point mutation in PMP22
CMT neuropathy X: X-linked connexin 32 gene mutation
hereditary neuropath with liability to pressure palsy: AD deletion in PMP22 |
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|
Term
| paraneoplastic causes of demyelination 1 |
|
Definition
|
|
Term
| what are the 6 demyelinating dosorders |
|
Definition
guillian barre syndrome
chronic inflammatory demyelinating polyneuropathy |
|
|
Term
| guillian barre syndrome: what caises damage disease, how does it present, location |
|
Definition
| mononuclear infiltrates cause rapidly progressive demyelination causing ASCENDING MOTOR WEAKNESS |
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Term
| how do people with guillian barre die |
|
Definition
| failiure of respiratory muscles during ascending motor weaness |
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|
Term
|
Definition
autoimmune response: humeral and cellular response triggered by infection or vaccine
infection: camplobacter jejuni, EBV, CMV, HIV |
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Term
| TX 3 and prognosis guillian barre |
|
Definition
plasmaphresis (remove offending antibody), ivig, supportive care (ventilation)
recovery is likley if patient survives initial acute phase |
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|
Term
| chronic inflammatory demyelinating polyneuropathy: cause, presentation |
|
Definition
| symetric demyelinating disease (MOTOR AND SENSORY) the is immune mediated |
|
|
Term
| what disorders is chronic inflammatory demyelinating polyneuropathy seen in 2 |
|
Definition
|
|
Term
| signs of chronic inflammatory demyelating polyneuropathy 7 |
|
Definition
chronic relapsing and remitting progressive course
difficulty walking, weakness, numbness, pain, tingling |
|
|
Term
| cellular changes in chronic inflammatory demyelinating polyneuropathy 2 |
|
Definition
segments of demyelination and remyelination
schwann cells wrap in ONION SKIN pattern |
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|
Term
| chronic inflammatory demyelinating polyneuropathy tx and prognosis |
|
Definition
tx: plasmapharesis and immunosupression
some pt recover completely, usually pt has recurrent bouts causing permanent loss of nerve function |
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|
Term
| peripherial neuropathy most common cause |
|
Definition
|
|
Term
| types of diabetic peripherial neuropathy 3, which is most common |
|
Definition
autonomic
lumbosacral
distal symmetric sensorimotor polyneuropathy - most common |
|
|
Term
| signs of autonomic neuropathy 4 |
|
Definition
| bowel, bladder, cardiac, or sexual dysfunction |
|
|
Term
| lumbosacral radiculopathy 3 |
|
Definition
| asymmetric pain, can progress to LE weakness and muscle atrophy |
|
|
Term
| dystal symmetric sensorimotor polyneuropathy - signs and why |
|
Definition
| sensory axons most affected (parasthesia and numbness) with features of axon injury AND demyelination |
|
|
Term
| causes of distal symmetric sensorimotor polyneuropathy 6 |
|
Definition
glycosylation end products
hyperglycemia
increased ROS
microvascular changes in axon metabolism
abnormal protein C levels
neurotropic factors |
|
|
Term
| tx distal symmetric sensorimotor polyneuroopathy |
|
Definition
|
|
Term
| how do drug and enivormental toxins cause damage to nerves, location |
|
Definition
interfere with axon transport or cytoskeletal function
longest axons most susceptible |
|
|
Term
| how does systemic vasculitis damage nerves, where |
|
Definition
patchy involvement
variation in degree of axon damage between fascivle within a nerve
mononeuritis multiplex: painful asymmetric sensory and motor peripherial neuropathy |
|
|
Term
| inherited diseases of peripherial nerves: when do they show up, what causes damage, most common |
|
Definition
demyelination of axon
show as adult and slowly progress
mutation in PMP22 gene encoding myelin sheath protein |
|
|
Term
| how does the NMJ normally work |
|
Definition
influx of Ca
release of ACh
diffuses across cleft
binds post-synaptic receptor
depolarizes membrane
depolarizes myofiber
contraction |
|
|
Term
| what are the 4 NMJ disorders |
|
Definition
myasthenia gravis
lambert eaton syndrome
congenital myasthenic syndromes
infection |
|
|
Term
|
Definition
autoantibodies develop self tolserance and allow generation of out reactive T and B cells
autoantibodies block post-synaptic ACh receptor causes degradation and depletion |
|
|
Term
| what are 3 diseases or common associations with myasthenia gravis |
|
Definition
mostly female
60% have reactive hyperplasia of intrathalamic B cells
20% have thymoma(epithelial cell tumor) that causes tolerance to self antigens and allows for mectomyautoreactive T and B cells |
|
|
Term
| clinical signs of myasthenia gravis: 5 |
|
Definition
ptosis
diplopia
fluctuating muscle weakness over short time
MORE WEAKNESS CAUSED WITH USE
CHOLINESTERASE INHIBITORS IMPROVE STRENGTH |
|
|
Term
| tx 4 and prognosis of myasthenia gravis |
|
Definition
tx: cholinesterase inhibitors, immune supression, plasmapharasis, thymectomy
worse prognosis due to lung cancer association |
|
|
Term
| lambert eaton syndrome: cause |
|
Definition
| autoantibodies inhibit PRE SYNAPTIC CA CHANNELS reducing ACh release |
|
|
Term
| signs of lambert eaton syndrome 2 |
|
Definition
WEAKNESS IMPROVES WITH STIMULATION
often begins as a paraneoplastic disorder (ESP SMALL CELL LUNG CANCER) |
|
|
Term
| lambert eaton syndrome tx 2 and prognosis |
|
Definition
tx: plasmapharesis, immunesupression
worse prognosis that myasthenia due to lung cancer association |
|
|
Term
| congenital myasthenic syndromes: inheritance, cause |
|
Definition
heterogenous group of disorders
mutations disrupt function of various NMJ proteins stopping pre-synaptic, synaptic OR post synaptic ACh activity |
|
|
Term
| what two infections cause NMJ disorders, how, what sign |
|
Definition
tetanus toxin: neuro toxin blocks action of inhibitor interneurons increasing ACh causing tetanospasm (sustained muscle contraction and spasm)
botulinium toxin: inhibitors ACh release causing FLACCID PARALYSIS |
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|
Term
| peripherial nerve sheath tumors: who usually gets them, causes, general clinical sign, 2 histological changes |
|
Definition
usually in adults
often familial association with NF1 and NF2
pain or loss of dunction due to impingement of nerve or surrounding structures
soft tissue mass, schwann cell differentiation |
|
|
Term
| what is the function of a schwann cell |
|
Definition
| schwann cells myelinate the PNS |
|
|
Term
|
Definition
90% sporadic
10% associated with NF2 |
|
|
Term
| what is the presentation of a schwannoma associated with NF2 |
|
Definition
multiple BILATERAL vestibular schwannoma
often affects CN 8 are cerebellar pontine engle decreasing hearing causing tinnitus |
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|
Term
| cause of sporadic schwannoma |
|
Definition
| loss of function mutation in ch22 merlin gene which is a cytoskeletal tuomor supressor via E-cadherin contact inhibition |
|
|
Term
|
Definition
| familial multiple schwannomas without vestibular schwannomas due to loss of function in Ch22 tumor supressor protein for chromatic structure regulation |
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|
Term
| histological changes in schwannoma 8 |
|
Definition
circumscribed mass adjacent to nerves
axons excluded from tumor
antoni A (Dense) areas
antoni B (loose) areas
uniform proliferation of neoplastic schwann cells
thick walled haylanized vessels
S100+ |
|
|
Term
| what are the 3 types of neurofibromas |
|
Definition
localized cutaneous neurofibromas
plexiform neurofibromas
diffuse neurofibromas |
|
|
Term
| localized cutaneous neurofibromas: what is it, cause |
|
Definition
superificial nodular polypoid tumors, solitary sporadic lesions
multiple in NF1 |
|
|
Term
| plexiform neurofobromas: what is it, cause, complication |
|
Definition
grow diffusley within nerve or nerve plexus
difficult to remove
pathognomic for NF1
small risk of malignant transformation |
|
|
Term
| diffuse neurofibromas: what is it, cause |
|
Definition
infiltrative proliferations
large disfiguring SC masses
associated with NF1 |
|
|
Term
| histological changes in neurofibromas |
|
Definition
not encepsulated
circumscribed: localized cuteneous neurofibromas
diffuse infiltrative
neoplastic schwann cells mixed with other cell types (mast cells)
loose wavy collagen or myxoid or dense collagen fiber
plexiform or diffuse |
|
|
Term
| describe a plexiform neurofibroma |
|
Definition
multiple fasicles of individual affected nerves
axons embedded within neoplastic proliferation
expand fascicles but leave perinerium intact |
|
|
Term
| describe a diffuse neurofibroma |
|
Definition
| infiltrative growth within dermis subcutis |
|
|
Term
| cause of malignant nerve sheath tumors |
|
Definition
originate from a peripherialnerve
transform from neurofibroma (usually plexiform)
50% associated with NF1
10% of NF1 have malignant nerve sheath tumor |
|
|
Term
| morphology of malignant tumors in adults 4 |
|
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) |
|
|
Term
| traumatic neuroma: cause, effect, symptom |
|
Definition
| previous injury of peripherial nerve goes through non neoplastic proliferation that is painful and localized |
|
|
Term
| morphology of traumatic neuroma |
|
Definition
axonal regeneration after transection causes spouting and elongation of processes from axonal stump
nodules: axons, schwann cells, CT
if perineurium is disrupted: processes may miss distal end of nerve
if processes induced: reactive schwann cell proliferation |
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