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This Concept Map, created with IHMC CmapTools, has information related to: Peripheral Nerve, Peripheral Nerve Acquired Metabolic, Toxic MALIGNANCY -compression or infiltration -can be presenting Sx of CA -eg brachial plexopathy, obturator palsy, CN palsies, polyradiculopathies (c equina) Paraneoplastic-diffuse, symm neuropathy -mostly sensorimotor n'pathy -worse in lower limb -esp SMALL CELL CA OF LUNG Plasma cell dyscrasias->n'pathy 1. deposit AL amyloid in nn. 2. bind IgM to myelin-ass'd GP, Peripheral Nerve Inflammatory/Immune Neuropathies CHRONIC INFLAM DEMYELINATING POLYRADICULONEUROPATHY -relapses/remissions over years -symmetric, mixed sensorimotor polyneuropathy -ONION BULBS Tx-steroids, plasmapheresis, Peripheral Nerve Infectious Polyneuropathies VARICELLA-ZOSTER VIRUS -latent infx of spinal/stem sensory ganglia -after chicken pox -mononuc infiltrate, dmg -death to neurons, axon degen -no intranuclear inclusions -reactivation->painful, vesicular skin eruption -along dermatomes -active infx in epidermal cells -SHINGLES, Peripheral Nerve Hereditary HMSN II- AD - less common -neuronal form -no nerve enlargement -later age at onset, less severe GENETICS-1p35-p36 in some MORPH-lose myelinated axons -primary focus is NERVE, SEGMENTAL DEMYELINATION -injury to Schwann cells ->disintegrating myelin -eaten by Schwanns, then macs -replacement cells from endoneurium -w/ demyelination->remyelination ->ONION BULBS of more cells -if chronic->axonal injury General Rxns of Motor Unit RXNS OF MM FIBER 1. Segmental necrosis ->myophagocytosis ->coll deposition, fatty infiltrate 2. Vacuolation, altered struc proteins, accum of deposits in cells 3. Regeneration 4. Fiber hypertrophy, mm splitting -exercise or pathology, SEGMENTAL DEMYELINATION -injury to Schwann cells ->disintegrating myelin -eaten by Schwanns, then macs -replacement cells from endoneurium -w/ demyelination->remyelination ->ONION BULBS of more cells -if chronic->axonal injury General Rxns of Motor Unit NERVE REGENERATION REINNERVATION OF MM -2mm/day growth -use scaffold of old Schwanns -regeneration cluster -many small axons -reinnervation by nearby, healthy motor unit ->type grouping (same type as new unit), Peripheral Nerve Acquired Metabolic, Toxic PERIPH NEUROPATHY IN DM-II Distal Symm Sensorimotor/Sensory -most common-sens. more profound ->lose pain sensation->ulcers -axonal neuropathy, seg demyelin -esp small fibers -endoneurial aa'oles w/ hyalinization CLINICAL-in 50% after 25 yrs of DM Autonomic-20-40% of diabetics -usually w/ stocking-glove Focal/multifocal asymmetric -esp elderly, Peripheral Nerve Hereditary HERED MOTOR, SENSORY - AD NEUROPATHY I (HMSN I, CMT I) Charcot-Marie-Tooth dz Hypertrophic Form -progressive mm atrophy of calf -distal weakness -secondary foot orthopedic problem -pes cavus, steppage gait GENETICS-AD-duplicated 17p11.2-12 -segmental trisomy->PMP22 -Chrom 1 - MPZ-myelin prot zero MORPH-demyelination, onion bulbs -DISTAL>PROXIMAL -onion-bulb->"hypertrophic" -palpable nodules CLINICAL-slowly progressive -typical life span, Peripheral Nerve Hereditary DEJERINE-SOTTAS DZ (HMSN III)-AR -slowly progressive -delayed development-begin in kids -trunk, limb mm involved -enlarged periph nn -depressed DTRs GENETICS-PMP2 or MPZ in some fams MORPH-onion bulbing, Peripheral Nerve Infectious Polyneuropathies LEPROSY Lepromatous-bac invade Schwanns -seg demyelination -loss of un- and myelinated axons ->symmetric polyneuropathy -esp pain fibers-lose sensation Tuberculoid-CMI against M. leprae -granulomas in dermis ->injure nearby cutaneous nerves -peri-, endoneurium fibrosis -more localized, but some ABNL sens, Peripheral Nerve Acquired Metabolic, Toxic METABOLIC/NUTRITIONAL Uremic neuropathy- in 65% of renal failure before dialysis -distal, symmetric -axonal degeneration -2ndary demyelination Tx-dialysis->regeration Chronic liver dz Chronic resp insufficiency Thyroid dysfcn Thiamine def-axonal neuropathy -BERIBERI -also in vit B12, B6, E def, Peripheral Nerve Inflammatory/Immune Neuropathies GUILLAIN-BARRE-immune (Acute inflam demyel'ing Polyradiculoneuropathy) -pretty common -DISTAL -> PROX WEAKNESS -2/3 preceded by acute, flu-like illness (esp viral) Pathogenesis-sensitization to myelin -Tcell response->seg demyelination -via macs, maybe ABs MORPH-inflam of periph nn. -lymphos, macs, few plasmas -axon dmg in severe cases -most intense in spinal/cranial roots CLINICAL-ASCENDING PARALYSIS -symmetric -DTRs gone early -elevated CSF protein, not cells Tx-plasmapheresis, IV Ig, SEGMENTAL DEMYELINATION -injury to Schwann cells ->disintegrating myelin -eaten by Schwanns, then macs -replacement cells from endoneurium -w/ demyelination->remyelination ->ONION BULBS of more cells -if chronic->axonal injury General Rxns of Motor Unit AXONAL DEGENERATION MUSCLE FIBER ATROPHY -can be focal or neuronopathy or axonopathy ->wallerian degeneration (distal) ->denervation atrophy of mm -down-reg'n of myosin, actin -angulated cells (triangular) -smaller but viable -disorganized filaments -target fiber Type 2 fiber atrophy w/ inactivity, Peripheral Nerve Infectious Polyneuropathies DIPHTHERIA -exotoxin enters sensory ganglia ->selective demyelination -ant. and post. roots -mixed sensorimotor nn too ->paresthesias, weakness -lose proprioception, vib sense early, Peripheral Nerve TRAUMATIC LACERATIONS-cutting nn. AVULSIONS-tension on nn. -regenerates slowly -harder if misaligned -or discont. BM ->traumatic neuroma -small axon bundles COMPRESSION NEUROPATHY -entrapment -easiest to regenerate -eg carpal tunnel syndrome -median n compressed by transverse carpal ligament -bilateral, mostly women Sx-numb, paresthesis of tips of thumb, first 2 digits Morton Neuroma-metatarsalgia -interdigital n at intermetatarsal, Peripheral Nerve Tumors In CNS section, Peripheral Nerve Acquired Metabolic, Toxic TOXIC NEUROPATHIES -esp heavy metals-Pb, As -also organic cmpds