Neuropathy, Myopathy, Motor Neuro Disease Flashcards
Neuropathy is a board, generic term which refers to a variety of syndromes in which one more more nerves are affected by several know/unknow causes.
Mononeuropahty = invovlemnt of a _____ major named nerve usually by _____ or _____
Polyneuropathy/peripheral neuropathy is a disorder of ______.
Peripheral neuropathy symptoms/signs are ____ (asymmetrical/symmetrical), and _____ loss / impairment occurs early and often remains prominet.
some sx:
Sx usually begin ______ @ ….with later affecting _____
the pattern is called:
Reflexes?
Which nerves are affected first?
Peripheral neuropathy symptoms/signs are SYMMETRICAL and SENSORY loss / impairment occurs early and often remains prominet.
some sx: numbness, tingling, pain, paresthesia (spontaneous tingling), pins and needles sensation, dysestheia; weakness and muslce atropy [ANS sx too, if those nerves affected: orthostatic hypotension, incontinence, impotence, sweating abnormalities]
Sx usually begin DISTALLY @ toes and feet, with later affecting fingers and hands
the pattern is called: stocking and glove pattern
Reflexes? early loss or decrease
Which nerves are affected first? Longest nereves in the body
What is the pathology of neuropathy?
Is recovery possible?
What is Wallerian degeneration?
What are neuromas?
What is the pathology of toximetabolic causes of polyneurpathies?
Demyelination and axonal degeneration
Mild focal trauma to a nerve can recovery sooner and more completely once any swelling has resolved or any remyelinaiton of intact axons has occured
W/TRAUMA…If the neuropathy progresses over time or is initally servere, axonal degreneration may occur, with less chance for recovery, via Wallerian Degeneration - axons and myelin degenerate distal to the point of nerve injury; recovery takes longer and may be incomplete, depending on whether any remianing perineurium can “guide” regrowing or sprouing axons to their intended targets.
If there is an absence of “supporting” scaffolding of perineurium to guide regrowing/sprouting axons to their inteded targets, resprouting axons pile up in a bulbous neuroma, which could be painful
Most polyneuropathies from toximetabolic** causes have **axonal degeneration as the primary pathology, with demyelination as a secondary or additional process.
What are two examples of demyelination pathologies?
Demyelination usually focal compression…
Carpal tunnel syndrome: medial nerve is compressed at the wrist
Guillian-Baree Syndrome - acute type of polyneuropathy
How would you diagnose polyneuropathy?
Clinical pattern of nerve involvement:
Mononeuroapthies are usually due to trauma (hx!), or occur at typical sites of nerve compression or entrapment (medial nerve @ wrist, ulnar nerve @ wrist, common peroneal nerve @ fibular head)
*multiple moneuropathy syndrome may be due to a systemic illness - inflammatory or autoimmune (lupus), infiltrative (sarcoidosis) or infectious (leprosy)
*non-acute polyneuropathies dx are challenging
What are important parts of a patient’s history that may be sugggestive to non-acute polyneuropathy?
- Current or recent meds (ie- chemotherapy)
- Neurotoxins –> toxic neuropaties; such as organic solvents in the workplace or social habits like alcoholism
- Malnutrition and vitamin deficiences
- Positive family history - maybe a hereditary neuropathy (often begin early in life); limb weakness occurs early in growth/development thus look out for pes cavus (high-arched feet), hammertoes, scoliosis
What further diagnostic testing could be obtained?
1. Electromyogram (EMG), tests the electrical activity and function of nerves and muscles; sensory and motor nerves are electrically stimulated and their responses measures
Primary slowing of nerve conduction velocity suggestive of a demyelination problem while primary loss of amplitude suggest axonal loss
- distinguish any subtle neuropathic clinical signs
- detect abnormalities not found on clinical examination
- help distinguish a neuropathy from a radiculopathy or myopathy
-
2. Sural/Sensory nerve biopsy, helps confirm diagnosis when it is suspected that a chronic polyneuropathy is due to inflammatory, immune-mediated or vasculitic cause
[the sural nerve in the foot is bipsided which leaves permanent numbness along the lateral foot; motor nerves are NOT biopsied which leaves permanent numbness along the lateral foot]
3. CBC - helps to screen for nonspecific causes, possibly treatable ones, such as DM, liver or renal dysfunction, vitamin B12 defciencey and hypothyroidism, anemia or other blood disorders
Treatment of Neuropathy
Depends on underlying cause if one is found
Surgical decompression
Optimal glycemic control
braces, splints, use of cane/walker
Ankle-foot orthoses (AFOs) - prevent tripping int he setting of foot drop
Topical capsaicin, a substance P depleter or lidocaine patches can be applied over involved skin
Effective oral meds for neurpathic pain include: anticonvulsants (gabapentine, pregabalin, carbamazepine) and antidepressants (duloxetine, amitriptyline)
Guillain-Barre Syndrome:
most often following a recent ____illness but also after surgery or trauma
Pathogen: the immune system targets peripheral nerve ___, which was possibly modified by or antigentically resembles the virus encountered weeks earlier
Clinical SX:
Which part of the body is affected first?
EMG shows…
Prognosis?
Treatment:
Guillain-Barre Syndrome: acute polyneuropathy - ASCENDING, areflexic paralysis
Most often following a recent VIRAL illness but also after surgery or trauma
Pathogen: the immune system targets peripheral nerve MYELIN, which was possibly modified by or antigentically resembles the virus encountered weeks earlier –> pathological inflammation and demyelination of peripheral nerves or roots (if severe, secondary axonal loss can occur)
Clinical SX:
Which part of the body is affected first? ascending - legs first
EMG shows…demyelination
Elevated protein in CSF, with few if any WBCs
Prognosis? overall good with optimal medical care
Treatment: plasmapheresis, IVIG
Unlike Guillain-Barre syndrome, most polyneuropathies are chronic and develop over months to years,
what are other causes of polynueropathies?
Diabetes Mellitus –> isolated or multiple mononeuropathies, autonomic neuropahties (diabetic gastroparesis or orthostatic hypotension), and cranial neuropaties (diabetic third nerve palsy)
Metabolic/endocrine disorders - uremia, hypothyroidism
Rheumatologic disease - RA, SLE
Cancer or myeloma
Infection - AIDS, leprosy
Nutritional deficiences - B vitamins
Toxins - alcohol, lead, solvents, drugs
Myopathies are several diseases of various causes where the primary pathology affects muscle directly.
Most myopathies have ____ [distal/proximal] weakness or fatigue, ___ sensation, and ____ reflexes only after signification atrophy has occured; pain…
How are myopathies diagnosed?
1 Historical Findings
Myopathies are several diseases of various causes where the primary pathology affects muscle directly.
Most myopathies have PROXIMAL weakness or fatigue, NORMAL sensation, and LATE LOSS of reflexes only after signification atrophy has occured; pain is usually not prominent but can happen with muscle cramps or spasms during activity
How are myopathies diagnosed?
+ diagnositic testing: serum creatine kinase (CK, msulce enzyme often nonspecifically elevated in diseases of muscle), EMG, muscle biopsy
What are some examples of myopathies? (4)
Influenza –> breakdown of muscle fibers –> kidney failure (myoglobinuria, rhabdomolysis)
Medications - ie) statins, corticosteriods
Endocrine disorders - Cushing’s, hypothyroidism
Hereditary - sx including muscle pain and weakness developing primarily during exercise
Polymyositis = _____ disorder affecting muscles, usually in ____ [age].
SX: ______ [proximal/distal] weakness, ________ [skin/muslce involvement lesion]
DX testing….what would a biopsy show?
RX and prognosis
Polymyositis = AUTOIMMUNE disorder affecting muscles, usually IN ADULTHOOD
SX: PROXIMAL weakness, DERMATOMYOSITIS [rash involving the periorbital areas and knuckles, where both skin and muslces are involved]
DX: EMG + biopsy which shows inflammatory cell infilatrates amidst necrotic and regenerating muscle fibers
RX: oral corticosteriods or other immunosuppressant meds
Prognosis: most patients recover with RX
Muscular dystrophies are _____ myopathies of variable progression and severity
Prognosis of children vs adults
Muscular dystrophies are HEREDITARY myopathies of variable progression and severity
Patients may be midly affected or asymptomatic by adulthood
Children or teenagers may die from teh more severe muscular dystrophies (ie-Duchenne’s)
Duchenne’s muscular dystrophy is an _____ -linked dystrophy, involveing ______ of muslce _______, an important structural protein
Early sx:
RX and prognosis
Duchenne’s muscular dystrophy is an X -linked dystrophy, involving virtually TOTAL DEFICIENCY of muscle DYSTROPHIN, an important structural protein
Early sx: young boys could have trouble running, climbing or walking; GOWER’s MANEUVER (child attempting ot get off the floor using upper limbs to compensate for weak truck/pelvin muscles), pseudohypertrophy (calf muscles seem to be enlarged as it is replaced by fat and connective tissue)
RX and prognosis: death occurs after weakening of the respiratory muslces or from the associated cardiomyopathy
