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Neuro: Clin Med IIB > Peripheral Neuropathy: Part II > Flashcards

Peripheral Neuropathy: Part II Flashcards

1
Q

An acute inflammatory polyradiculoneuropathy with resultant weakness with a possibility of paralysis and diminished reflexes

A

Guillain-Barré Syndrome (GBS)

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2
Q

pathophys of Guillain-Barré Syndrome (GBS)

A
  • a post-infectious, immune-mediated process
  • infectious agents induce production of antibodies that breakdown myelin/damage axon in PNS
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3
Q

causes of GBS

A
  1. MC infectious illness (respiratory/GI) in wks prior to onset
  2. Campylobacter jejuni - MC identified etiology
  3. Cytomegalovirus (CMV) - 2nd MC
  4. Other: EBV, M. pneumoniae, VZV, HIV
  5. Vaccinations - GBS has been associated w/ Menactra, Covid vaccine, Shingrix
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4
Q

GBS is MC in who/when?

A
  1. Male-to-female ratio of 1.5:1
  2. Age risk is bimodal
    - young adulthood (ages 15-35 y)
    - middle-aged and elderly persons (ages 50-75 y)
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5
Q

MC GBS variant

A

Acute inflammatory demyelinating polyneuropathy (AIDP)

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6
Q

presentation of GBS

A
  1. Onset - 1-4 wks after a (benign) rsp or GI illness
  2. Presentation - 1 wk after onset of sx
  3. Initial sx
    - Paresthesias - finger/toes moving proximally - sensory before motor sx
    - Pain - throbbing/aching even w/ minimal movements - shoulder, back, buttocks, and thighs
    - Proximal muscle weakness of LE “rubbery legs”
    — 10% will have it begin in arms/face
    — weakness progresses over hrs-days ascending symmetrically to involve entire body
  4. later sx
    - Muscle weakness → paralysis
    — Legs →arms→truncal muscles→rsp→CN
    — Rsp muscles: DOE, SOB, poor inspiratory effort, diminished breath sounds
    — CN involvement: Facial droop, diplopia, ptosis, impaired EOM, ophthalmoplegia, pupillary dysfunction, dysarthria, dysphagia
    - ANS dysfunction (Dysautonomia) - in 70% of pts
    — tachycardia (MC), bradycardia, other arrhythmias, fluctuating BP, orthostatic hypotension, urinary retention, ileus, and anhidrosis
  5. PE
    - Diminished/absent DTRs early in course
    - Muscle weakness→paralysis
    - Impaired proprioception otherwise objective sensory findings are minimal
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7
Q

work up for GBS

A
  1. serum labs WNL; used to r/o DDX
  2. LP = albuminocytologic dissociation
    - elevated CSF protein w/ normal WBC
    - (+) within 1 wk of sx onset (MC)
  3. Electrodiagnostic Studies
    - Confirms polyneuropathy
    - Differentiates demyelinating vs axonal variants of GBS
    - Results most pronounced 2 wks after onset of weakness
    - nml study (early in course) does NOT r/o GBS = do serial studies
  4. MRI brain/spine w/ gadolinium - sensitive but not specific for GBS
    - spine - thickening & enhancement of intrathecal spinal nerve roots and cauda equina
    - brain - enhancement of CN roots
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8
Q

management for GBS

A
  1. Admit until plateau period has been reached
    - avg time to plateau - 12-28 d
    - ⅓ of pts require ICU d/t rsp failure
  2. Consults to consider
    - Neuro - will assist in dx & tx
    - pulm - rsp management & vent support - Serial bedside PFT - q4h assessing pulm muscle strength
    - cardio - cardiac arrhythmias or labile BP
    - Surgery - if need for trach or enteral feeding tubes
  3. ANS support
    - Cardiac monitor, frequent BPs, fluids
    - BP
    — HTN - esmolol or nitroprusside
    — Hypotension - IV fluids & supine
    - HR
    — Tachycardia - rarely severe enough for tx
    — Bradycardia - atropine or external pacemaker (severe)
    - Frequent assessment of BS (for ileus)
    - I&O’s - assessing urinary retention
  4. Immunotherapy - Plasmapheresis vs IVIG w/n 4 wks of sx onset
  5. Pain control
    - 1st: NSAIDs, anticonvulsants (gabapentin/carbamazepine) or TCA (amitriptyline)
    - careful w/ opiates if have dysautonomia - monitor for ileus
    - epidural morphine for severe refractory pain
  6. Motor dysfunction
    - PT & OT early on; inpatient rehab if persistent
    - Speech therapy for significant oropharyngeal weakness (dysphagia, dysarthria)
  7. DVT prophylaxis if unable to ambulate frequently - Lovenox, compression stockings and/or intermittent pneumatic compression
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9
Q

indications for immunotherapy for GBS

A

non-ambulatory pts and ambulatory pts not recovering w/n 4 wks of sx onset

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10
Q

which immunotherapy removes autoantibodies, immune complexes, cytotoxic constituents
more time consuming requiring 4-6 treatments over 8-10 days

GBS

A

Plasmapheresis

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11
Q

which immunotherapy is derived from donated plasma; supplements the pts immune response
requires less time - one tx daily x 5 d

GBS

A

IVIG

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12
Q

clinical course of GBS

A
  1. Average nadir is 12 d - can take up to 4 wk
  2. Followed by a plateau of unchanging sx
    - recovery begins 2-4 wks after progression stops
  3. Then gradual improvement of sx
    - mean time to recovery is 200 d
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13
Q

poor prognosis factors of GBS

A
  1. Older age
  2. Rapid onset (<7 d) prior to presentation
  3. Severe muscle weakness on admission
  4. Need for vent support
  5. avg distal motor response amplitude reduction to 20% of nml (2-4 wks after onset) on NCS
  6. Preceding diarrheal illness
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14
Q

2-5% of GBS patients will develop ____ resulting in a chronic relapsing weakness

A

chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)

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15
Q

long-term monitoring for GBS

A
  1. Pt ed on realistic recovery goals and possible relapse
    - 80% pts walk independently at 6 mo
    - 60% attain full recovery w/n 12 mo
  2. Monitor for depression and anxiety related to initial loss of quality of life
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16
Q

relapse of GBS occurs in ?% of pts, closing monitoring and pt education to recognize sx are important

A

10%

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17
Q

Motor nerve action potential releases ____ into the synaptic cleft (temporary depletion of presynaptic ____ - known as presynaptic rundown)

A

ACh

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18
Q

ACh attaches to the ACh receptor (AChR) on the postsynaptic fold of the muscle cell resulting in ?

A

muscle contraction

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19
Q

Acetylcholinesterase breaks down Ach to prevent ?

A

prolonged muscle contraction

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20
Q

An autoimmune disorder presenting with progressively reduced muscle strength with repeated use and recovery of muscle strength after a period of rest

A

Myasthenia Gravis (MG)

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21
Q

pathophys of Myasthenia Gravis (MG)

A
  1. antibodies against ACh nicotinic postsynaptic receptors (AChR) at neuromuscular junction (NMJ) of skeletal muscles = AChR destruction & loss of postsynaptic folds
  2. No receptors = over release of ACh from pre-synapsis to create adequate motor response
  3. repeated use of NMJ + presynaptic rundown = MG sx
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22
Q

cause of MG

Myasthenia Gravis

A

Idiopathic

  1. 2 types of autoantibodies
    - anti-AChR antibody (MC)
    - anti-MuSK (muscle-specific tyrosine kinase) antibodies
  2. Few pts will test negative for sero-antibody and still have clinical dx of MG
  3. Thymic disease is found in majority with AChR antibodies - thymoma, thymic hyperplasia
  4. Drugs - many shown to induce or exacerbate MG
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23
Q

MG is MC in who/when?

A

uncommon

  • Females - 20-30 y
  • Male - 50-70 y
  • Infantile - transient neonatal MG occurs in infants of myasthenic mothers who acquire anti-AChR antibodies via placental transfer of IgG
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24
Q

presentation of MG

A
  1. Fluctuating msk weakness and true muscle fatigue
    - worsens w/ use and improves with rest
    - worse later in day/evening or after exercise
  2. Ocular (initial sx in > 50%) (CN III, IV, VI)
    - binocular diplopia & weak EOM testing
    — diplopia disappears when the patient closes one eye
    — EOM testing reveals a general weakness to all ocular muscles
    — Pupils are not affected in MG
  3. Ptosis - unilateral (can be alternating) or bilateral
  4. Weakness confined to eyes in 15% of pts
  5. Bulbar muscle weakness (CN IX-XII)
    - weakness w/ prolonged chewing
    - dysphagia: nasal regurg, difficulty in handling secretions, choking on liquids
    - dysarthria: slurring of speech
    - dysphonia: nasal sound to voice or soft voice
  6. Facial (CN VII)
    - flat affect
    - unable to smile or completely close eyes
  7. Neck muscle weakness
    - aching and fatigue often in the extensors first = “dropped head syndrome” later in day
  8. Limb
    - proximal muscle weakness w/ UE > LE with repetitive use
  9. Nml DTR, sensation and coordination
  10. Rsp muscles - “myasthenic crisis”
    - spontaneously or precipitated by event or meds
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25
Q

this presention of MG is the weakness of diaphragm and intercostal muscles lead to hypoventilation and rsp collapse requiring ventilation assistance
the muscle weakness will mask normal signs of rsp distress, such as accessory muscle use

A

myasthenic crisis

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26
Q

what is the “warning” sign of myasthenic crisis?

A

increasing generalized muscle weakness & bulbar muscle weakness

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27
Q

what events/meds can precipate myasthenic crisis?

A

infection, surgical procedure, pregnancy, childbirth, tapering of immunosuppressive medications

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28
Q

clinical course of MG

A
  1. sx may resolve spontaneously for wks or longer
  2. Relapses may result in new sx with a progression of recurrent sx becoming more persistent
  3. sx progression usually peaks within first 3 yrs of dz onset
    - eyes/face → neck→ upper limbs→ hands → lower limbs
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29
Q

DDX of MG

A
  1. Lambert Eaton Myasthenic Syndrome (LEMS)
  2. Botulism
  3. Thyroid disease
  4. Intracranial mass lesion (ocular symptoms only)
  5. Chronic Progressive External Ophthalmoplegia (ocular symptoms only)
  6. Medication induced myasthenia
  7. Congenital myasthenic syndrome
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30
Q

work-up for MG

A
  1. ice pack test - (+)MG if improvement of ptosis
  2. Serology
    - ACh receptor ab
    — present in 85% of pts w/ generalized disease
    — performed BEFORE immune modulating therapy to avoid false (-) ab results
    - MuSK ab (muscle specific receptor tyrosine kinase)
    — 35-50 % of pts w/ generalized MG (-) AChR-Ab
    — (+) MuSK ab = < likely thymic-related dz
    - Seronegative MG
    — 6-12% (-) for both ab
    - more likely to have purely ocular disease
  3. Additional Serology
    - anti–striated muscle (anti-SM) Ab
    — can be positive with (+) anti-AChR/anti-MuSK ab
    — (+) 30% of pts w/ MG
    — (+) 80% of pts w/ thymoma
  4. Imaging
    - CT chest w/o contrast to assess for thymoma
  5. Electrodiagnostic
    - Repetitive Nerve Stimulation (RNS) (MC) - smaller excitatory postsynaptic potentials (EPSPs) d/t repetitive stimulation of the NMJ depleting Ach
    - Single-fiber electromyography (SFEMG) (most sensitive) - increased interval between 1st & 2nd AP - NOT SPECIFIC FOR MG
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31
Q

a modified motor NCS that repetitively stimulates the NMJ of a specific muscle
most frequently used electrodiagnostic test for MG

A

Repetitive Nerve Stimulation (RNS)

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32
Q

normal response of Repetitive Nerve Stimulation (RNS)

A

all (EPSPs) exceed their threshold to generate an action potential

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33
Q

less readily available but the most sensitive diagnostic test for MG
records the action potentials of two muscle fibers innervated by the same motor axon

A

Single-fiber electromyography (SFEMG)

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34
Q

CI of Single-fiber electromyography (SFEMG)

A

had botox within last 12 mo

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35
Q

tx for MG

A
  1. symptomatic therapy - AChI (1st line) - pyridostigmine
  2. chronic immunomodulators - glucocorticoids, immunosuppressives
    - Prednisone - reduce the production of antibodies
    — High dose steroids only used in hospitalized pts undergoing rapid immunomodulating therapy
    — Stress dosing may be needed
    - Immunomodulators - if CI or not controlled w/ corticosteroids
  3. rapid immunomodulators - Effects last 3-6 wks
    - Plasmapheresis
    - IVIG
  4. surgery - Thymectomy - May result in complete remission
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36
Q

dosing for pyridostigmine

A
  1. Onset - 15 to 30 minutes
  2. Duration - 3-4 hours
  3. Dosing is patient dependent:
    - often dosed 3-4x daily
    - dosed before meals or other activities that result in muscle fatigue
    - may be dosed later in the day depending on when symptoms begin
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37
Q

indications for rapid immunomodulating therapy

A
  • Myasthenic crisis
  • Pre-op tx in MG - helps prevent post-op “crisis”
  • Bridging to slower acting immunotherapy
  • Assist in maintaining remission in MG who are not well controlled on other tx
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38
Q

indications for thymectomy in MG

A
  1. thymoma on imaging
  2. No thymoma
    - young patient
    - +/- AChR ab
    - generalized MG
    - disabling ocular MG
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39
Q

management plan for Mild-Moderate Generalized MG

A

1st symptomatic therapy
chronic immunomodulating therapy if remains uncontrolled

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40
Q

management plan for Severe generalized or rapidly progressing MG

A

rapid immunomodulating + chronic immunomodulating + symptomatic

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41
Q

management plan for ocular MG

A
  1. Symptomatic + chronic immunologic pharm
  2. Thymectomy if indicated
  3. Adjunct sx therapy for ptosis
    - Ptosis crutches/eyelid adhesive strips - ensure adequate corneal lubrication by using lubricating drops and periods of abstinence from device
  4. Adjunct sx therapy for diplopia
    - unilateral eye patch, opaque contact lens or eyeglass lens occlusion
  5. Refer to ophthalmology for surgical intervention for ptosis & diplopia
    - Indicated if stable ptosis or ophthalmoparesis
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42
Q

management for refractory MG

A

Patients who do not respond well to symptomatic and standard chronic immunomodulating therapy may benefit from monthly IVIG

43
Q

management for myasthenic crisis

A
  1. admission to ICU w/ ventilation assistance as needed
  2. Rapid immunotherapy bridging w/ chronic immunotherapy
    - high dose glucocorticoids preferred if no CI due to short onset of clinical effect
44
Q

pt ed for MG

A
  1. Avoid excessive chewing
  2. Thicken liquids to prevent nasal regurgitation or aspiration
  3. Remain physically active w/ frequent rests but avoid sustained physical activity
  4. Education on myasthenic crisis and develop a written plan of care for the patient to follow if this occurs
  5. Educate pts to avoid medications that can worsen MG
  6. Women of childbearing age
    - discuss teratogenicity of meds and increased risk of birth defects in children born to MG mothers
45
Q

An inherited group of progressive myopathic disorders resulting from defects in a number of genes required for normal muscle function (w/o central or peripheral nerve abnormality) characterized by progressive muscle weakness and wasting
Categorized by mode of inheritance, age at onset, and clinical features

A

Muscular Dystrophy

46
Q

most well-known muscular dystrophy

A

Duchenne and Becker Muscular Dystrophies

47
Q

what is Duchenne and Becker Muscular Dystrophies (DMD & BMD)

A
  1. Genetic defect on short arm of X chromosome
    - X-linked recessive disorder - MC Males
    - Defective protein dystrophin - responsible for muscle fiber strength
  2. DMD - reduced/absent dystrophin = rapid muscle damage with early use and more severe s/s
  3. BMD - dystrophin lvls may be normal, but protein is altered (misshapen) yet still functional = later onset & milder course of disease than DMD
48
Q

presentation of DMD

A
  1. Onset - usually 2-3 yrs of age
  2. Progressive weakness
    - Difficulty running, jumping, walking up steps
    - Affects proximal muscles
    - Affects LE before UE
    - Gower’s sign - use hand support to push themselves upright when arising from floor
  3. PE
    - Unusual waddling gait, lumbar lordosis
    - Pseudohypertrophy of calf
    - Shortened achilles tendons
    - Decreased or absent DTR
    - Often varying degrees of mild cognitive impairment
49
Q

Complications/Comorbidities of DMD

A
  1. dilated cardiomyopathy (DCM) - cardiac arrhythmias
  2. frequent bone fractures
  3. progressive scoliosis
  4. respiratory muscle weakness
  5. most patients are wheelchair bound by age 12
50
Q

presentation of BMD

A
  1. Less severe mutation results in less severe disease
  2. Later onset, milder clinical s/s than DMD
    - cognitive deficit is less and muscle weakness is less severe
    - able to ambulate at least until age 15 and commonly into adult life
    - retained strength allows for clinical distinction between BMD and DMD
    - cardiac complications more evident in BMD > DMD d/t retained ability to exercise
51
Q

work up for Muscular Dystrophy

A
  1. Serum CK - elevated prior to clinical signs
  • peaks age 2, usually >10-20x ULN, then falls over 3-4 yrs
  • increased in DMD/BMD carriers but lesser extent (3x ULN)
  • normal CK = r/o disease
52
Q

primary care management for muscular dystrophy

A
  1. Refer to neuromuscular specialist/muscular dystrophy center for confirmation of dx and multidisciplinary tx
    - Specialists involved in care: neurology, cardiology, orthopedics, pulmonology, genetic counselor, dietician, psychiatry
53
Q

how to confirm musclar dystrophy disease

A
  1. Genetic analysis - 1st line, confirms dx in majority of cases
  2. Muscle bx - Rarely used
    - muscle cell degeneration, regeneration, isolated “opaque” hypertrophic fibers, replacement of muscle by fat and CT
    - Dystrophin analysis
    — Normal pts have easily detectable dystrophin
    — DMD - most have total/near-total absence (< 5% of normal quantity) of dystrophin
    — BMD - 20-50% normal level (mild-mod), 5-20% normal level (severe)
54
Q

mainstay therapy for musclar dystrophy

A

Glucocorticoids (prednisone)

  • Decreases inflammation and influence repair of weakened muscle cell membranes - Provides significant improvement in muscle strength, cardiac and pulm function
  • Stress dosing might be needed during periods of high physical/mental stress
  • Monitor for SE of long-term therapy
55
Q

genetic therapy for musclar dystrophy

A

Eteplirsen (Exondys 51)

  1. induces new dystrophin protein expression in patients who have a gene mutation = exon 51 skipping
  2. Indicated only for DMD patients with specific gene mutation
  3. EMB outcome
    - increased walking performance
    - increased dystrophin on muscle bx

Golodirsen & Vitolarsen

  1. induces new dystrophin protein expression in patients who have a gene mutation = exon 53 skipping
  2. Indicated only for DMD patients with specific gene mutation

Casimersen

  1. induces new dystrophin protein expression in patients who have a gene mutation = exon 45 skipping
  2. Indicated only for DMD pts with specific gene mutation
  3. EMB outcome
    - increased walking performance
    - increased dystrophin on muscle bx

Delandistrogene moxeparvovec

  1. genetic therapy that introduces code on how to create microdystrophin which works similar to dystrophin but is smaller in size
  2. For ambulatory boys with DMD ages 4-5 years
  3. FDA approved based upon increase in microdystrophin production in two small trials
  4. benefit has not yet been established
56
Q

cardiac management in musclar dystrophy

A
  1. steroids may reduce new-onset and progressive cardiomyopathy, lower deaths related to heart failure
  2. ARB/ACEI beginning at age 10 to reduce progression of heart failure
  3. Echo yearly at onset and cardiac MRI yearly after age 7
57
Q

pulmonary management in musclar dystrophy

A
  1. Use of CPAP at night can be used to treat symptomatic nocturnal hypoventilation
  2. Early and aggressive treatment of lower respiratory infections
  3. Maintain immunizations
58
Q

bone health management in muscle dystrophy

A
  1. steroids reduce risk of scoliosis and prolong independent ambulation
  2. increase risk of osteoporosis and long bone & vertebral compression fractures
  3. Prevention of osteoporosis
    - Consider calcium & vitamin D supplementation
    - IV bisphosphonates if compression fracture of vertebra; PO bisphosphonates controversial (CI if unable to sit/stand upright for 30 minutes)
    - PT & exercise
  4. Orthotics and leg braces
  5. Surgical release of contractures
59
Q

mental health management in musclar dystrophy

A
  1. routine neuropsych eval for developmental, emotional or behavioral delays are necessary at each visit
  2. referral to psychiatrist/psychology if needed
  3. recommend support groups, summer camps
60
Q

Advanced planning and palliative care in muscle dystrophy

A
  1. discuss long term prognosis with patient/family
  2. gently discuss treatment options, advanced care planning, advanced directive, palliative care
  3. DMD
    - improvement w/ tx seen between 3-6 y/o followed by gradual but relentless deterioration
    - wheelchair confinement by age 12
    - avg life span is mid 30’s (much improved from previous years due to advancements in care)
  4. BMD
    - remain ambulatory until mid-teens and often adulthood
    - avg life span is mid 40’s
    - MCC of death is HF from DCM
61
Q

spectrum of disorders caused by a specific mutation in one of several myelin genes (> 80 genes affected) = defects in myelin structure, maintenance, and formation

A

Charcot-Marie-Tooth (CMT)

62
Q

MC type of hereditary neuropathy

A

CMT

63
Q

what type of mutation(s) can happen in CMT

A

a variety of mutations exist ranging from point mutations to whole gene deletions/duplications

64
Q

CMT is MC in who?

A
  1. autosomal dominant inheritance
    - often a strong FHx
    - May be sporadic, recessive, or X-linked
  2. Male to female ratio of 3:1
65
Q

presentation of CMT

A
  1. Onset - 1st-3rd decade of life with slow, progressive, distal leg weakness
    - LE before UE
  2. LE
    - foot drop - inability to dorsiflex
    - pes cavus - high arch and hammer toes
    - foot deformities or gait disturbances are noted during childhood or early adult life
    - weakness = atrophy
    - Atrophy of muscles below knee
    — “inverted champagne bottle legs” or “stork leg deformity”
    — Hx of frequent sprained ankles, “clumsy”, trips easily
  3. UE
    - hand weakness presents with poor finger control, poor handwriting, difficulty using zippers and buttons, and clumsiness in manipulating small objects
    - claw hand
  4. Diminished/absent DTRs
  5. Diminished proprioception and vibration sense
    - do not complain of subjective sensory sx
  6. Sensory gait ataxia and (+) Romberg d/t lack of distal sensation
  7. +/- tremor
  8. +/- palpable enlargement of peripheral nerves - noted late in disease
66
Q

work up for CMT

A
  1. Electrodiagnostic Studies: EMG/NCS
    - confirms evidence of neuropathy
    - if negative for neuropathy reconsideration of diagnosis is needed
  2. Genetic testing - confirms the dx of CMT (after electrodiagnostics)
    - less invasive but expensive
    - genetic counseling for all pts/family w/ suspected hereditary neuropathy
67
Q

tx for CMT

A

Supportive; no specific disease-modifying therapy

  1. PT
    - daily stretching exercises early in disease course may help delay contracture development
    - Non-weight-bearing exercise
  2. Ankle-Foot Orthotics (AFO) - help stabilize ankles
  3. Orthopedic foot surgery - treat the pes cavus deformity and hammer toes
    - Often needed between 10-20 years of age
68
Q

Meds to avoid in CMT

A

metronidazole, nitrofurantoin, fluoroquinolones, amiodarone, colchicine

due to their neurotoxic potential

69
Q

prognosis and monitoring for CMT

A
  1. Slow progression that eventually leads to disability
  2. Often live full life span but may have impaired quality of life
  3. Disease exacerbation can occur in pregnancy

Monitoring

  1. Screen periodically for conditions that can exacerbate neuropathy
    - DM
    - vitamin deficiencies
    - immune-mediated neuropathies
70
Q

MC DM complication

A

Diabetic Neuropathy

71
Q

MC cause of peripheral neuropathy in developed countries

A

DM

72
Q

how does diabetic neuropathy happen?

A

Neuropathy develops because of long-standing, poorly controlled DM
morphologic abnormalities of the vasa nervorum are present early in the course of the disease

73
Q

3 types of diabetic neuropathy

A
  1. Distal symmetric polyneuropathy
  2. Isolated peripheral neuropathy
  3. Autonomic neuropathy
74
Q

MC form of diabetic peripheral neuropathy
Due to axonal neuropathy - long nerves esp vulnerable

A

Distal symmetric polyneuropathy

75
Q

presentation of Distal symmetric polyneuropathy

A
  1. Sensory sx appear 1st in stocking-glove pattern - Bilateral, symmetric - dulled perception of vibration, pain, temp, light touch
  2. Decreased/absent ankle DTR followed by widespread loss of reflexes
  3. Calluses & ulcerations in high pressure areas (metatarsal heads) results from:
    - Denervation of small muscles of foot
    - Clawing of toes and displacement of submetatarsal fat pads
    - Increased plantar pressures and decreased pain
    - Repetitive stress (e.g. walking)
76
Q

management for distal symmetric polyneuropathy

A
  1. Strict glycemic control in all patients
  2. Pharmacologic options
    - TCA: amitriptyline (Elavil)
    - SNRI: duloxetine (Cymbalta)
    - Anticonvulsants: pregabalin (Lyrica) or gabapentin (Neurontin)
77
Q

Least common of the diabetic neuropathies - seen mostly in older patients
Secondary to vascular ischemia or trauma

A

Isolated peripheral neuropathy

78
Q

presentation of Isolated peripheral neuropathy

A

Only mononeuropathy or mononeuropathy multiplex

  1. Often involves CN (III,IV,VI) or femoral nerves
    - diplopia, pain/weakness in the distribution of the involved nerve
    - Sudden onset with recovery in 6-12 wks of most or all function
  2. Diabetic amyotrophy aka (lumbosacral radiculoplexus neuropathy)
    - severe pain in anterior thigh followed by weakness and quadriceps wasting within a few days-weeks followed by improvement in pain
    - Improves in 6-18 months
79
Q

management for isolated peripheral neuropathy

A

same as distal symmetric polyneuropathy for analgesia + lidocaine patches

80
Q

DM of long duration affects visceral functions (BP, HR, GI, bladder, ED)

what subtype of diabetic neuropathy?

A

Autonomic neuropathy

81
Q

presentation of Autonomic neuropathy

A
  1. GI dysfunction → N/V/C/D, early satiety, reflux, fecal incontinence
  2. Bladder dysfunction - often leads to urine retention
  3. orthostatis
  4. ED
82
Q

tx for GI dysfunction in autonomic neuropathy

A
  1. Diarrhea
    - broad spectrum abx (suspected bacterial overgrowth)
    - loperamide (Imodium)
    - diphenoxylate/atropine (Lomotil)
  2. Constipation - increased fiber, fluids, stool softener, laxatives
83
Q

tx for bladder dysfunction in autonomic neuropathy

A
  1. bethanechol (Urecholine) - cholinergic agonist increases detrusor muscle tone
  2. Alt: catheter decompression, surgical severance of vesical sphincter
84
Q

tx for orthostatis in autonomic neuropathy

A
  1. compression stockings, tilting head of bed, arising slowly from supine position
  2. Persistent sx despite conservative therapy
    - fludrocortisone (Florinef) - mineralocorticoid
    - Alt: midodrine - alpha agonist
85
Q

tx for ED in autonomic neuropathy

A
  1. multifactorial: neurological, vascular and/or psychological
  2. Tx - PDE-5 inhibitors - sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis)
  3. May also try other non-pharmacologic ED treatments
86
Q

Primarily an axonal neuropathy d/t chronic alcohol neurotoxicity
* sensory, motor, and autonomic
* more marked in legs than arms

A

Alcoholic Neuropathy

87
Q

pathophys of Alcoholic Neuropathy

A
  • Acetaldehyde, (a metabolite of ethanol), is neurotoxic
  • Ethanol impairs axonal transport
  • Complicated by demyelination d/t vitamin deficiency
88
Q

presentation of Alcoholic Neuropathy

A
  1. Hx of chronic consumption of alcohol
  2. Insidious onset of distal lower extremity paresthesias, dysesthesias, or weakness
    - MC presenting complaint is paresthesias of the feet and toes
    - Progresses proximally and symmetrically
  3. Generalized weakness +/- gait ataxia
  4. Diminished or absent DTR
  5. Altered sensory exam (touch, vibration)
89
Q

management of alcoholic neuropathy

A
  1. Supportive; specific tx not available
  2. Physical and occupational therapy
  3. Improved nutrition and cessation of drinking
  4. Thiamine supplementation (thiamine deficiency is often coexisting)
  5. Low doses of TCAs or gabapentin may help with dysesthesia
90
Q

Thiamine pyrophosphate is the biologically active form of thiamine and functions as a ____

A

coenzyme in carbohydrate metabolism

91
Q

a deficiency of thiamine pyrophosphate

A

beriberi

92
Q

Exogenous thiamine is water-soluble, found in mostly where?

A

animal and plant tissues
Best sources - unrefined cereal grains, wheat germ, yeast, soybean flour, and pork

93
Q

RF for thiamine deficiency

A
  1. Chronic alcohol abuse, recurrent vomiting, TPN, bariatric surgery, inappropriately restrictive diets
    - common in underdeveloped countries in populations who have limited access to an adequate diet
94
Q

presentation subtypes of thiamine deficiency

A
  1. Dry beriberi - symmetric peripheral sensorimotor neuropathy, loss of reflexes
    - occurs in pts who are inactive and have a low caloric intake
    - “Wernicke-Korsakoff Syndrome”: when CNS involvement occurs
    — Wernicke encephalopathy - nystagmus progressing to ophthalmoplegia, truncal ataxia and confusion
    — Korsakoff syndrome - amnesia, confabulation and impaired learning impairment
95
Q

how to dx thiamine deficiency

A
  1. Diagnostic testing is not necessary prior to treatment in an emergency setting
    - Ex: pt presenting to ED with Wernicke-Korsakoff Syndrome
  2. Direct thiamine levels - normal 70 to 180 nmol/L
    - can be assessed but may be falsely reduced during systemic inflammation
  3. Thiamine loading test - most reliable test (but not readily available)
    - assess erythrocyte transketolase activity (ETKA) before and after administration of thiamine pyrophosphate (TPP)
    - Expected results: increase ETKA by 10-25% after administration of thiamine
  4. Nerve Conduction Study - axonal sensorimotor polyneuropathy
96
Q

management for thiamine deficiency

A
  1. Thiamine replacement until proper nutrition is restored
    - IV or IM, 50 - 100 mg/d, followed by oral dosing of 5-10 mg/d
  2. neurology if evidence of Wernicke-Korsakoff Syndrome
97
Q

A lack of Vit B 12 results in ?

A

damage to the myelin sheath

98
Q

MCC of B12 deficiency

A

Pernicious anemia

Other causes:
* Diet (vegetarian/vegan)
* Gastrectomy or gastric bypass²
* IBD
* Pancreatic insufficiency
* H2 blockers and PPIs³
* Bacterial overgrowth
* Malabsorptive diseases (elderly)
* ETOH

99
Q

presentation of B12 deficiency

A
  1. Paresthesias of the hands followed by LE
  2. Sensory changes - diminished proprioception, vibration, DTR’s
  3. Unsteady gait → sensory ataxia
  4. Anemia - fatigue, pallor, shortness of breath
  5. Red swollen tongue or angular cheilitis ( glossitis)
    - complaints of tongue discomfort, change in taste
  6. Optic atrophy
  7. Behavioral changes in severe cases
    - mild irritability - dementia/ psychosis
100
Q

how to dx of B12 deficiency

A
  1. Confirm with reduced serum cobalamin (B12) levels
  2. May order CBC
    - 40% of pts - no anemia or macrocytosis
  3. Pernicious anemia
    - Intrinsic factor ab - 60% of pts
    - Antiparietal cell ab - 90% of pts
  4. NCS → axonal sensorimotor neuropathy (often not needed)
101
Q

tx for B12 deficiency

A

various regimens of cobalamin
1. Standard regimen - 1000 mcg cyanocobalamin IM/wk x 1 mo, then 1000 mcg/mo
- does not completely reverse manifestations

102
Q

Polyneuropathy may occur following ____ for ulcer, cancer, weight loss
Associated with rapid, significant weight loss and recurrent, protracted vomiting

A

gastric surgery

103
Q

Initial manifestations of Neuropathy Associated with Gastric Surgery are ?

A

numbness and paresthesias in the feet

104
Q

management for Neuropathy Associated with Gastric Surgery

A
  1. parenteral vitamin supplements, esp thiamine
    - improves w/ supplementation, parenteral nutritional support, and reversal of surgical bypass

Neuro: Clin Med IIB (13 decks)

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