Spinal cord diseases/Peripheral nerve/Myopathy Flashcards
Spinal Muscular Atrophy: SMA-1
Pathophysiology: SMA1 infantile: manifests within 3 months (autosomal recessive) Clinical: - hypotonia - difficulty suckling, swallowing -atrophy, fasciculations of the tongue -absent plantar response -wasting/weakness of extremities - kyphoscoliosis
Dx/Rx:death by age 3
Spinal Muscular Atrophy: SMA-2
Pathophysiology: SMA2 intermediate: latter half of first year of life (autosomal recessive)
Clinical: gradually progressive proximal muscle weakness
Dx/Rx: supportive
Spinal Muscular Atrophy: SMA-3
Pathophysiology: SMA3 juvenile: hereditary vs. sporadic (autosomal recessive)
Clinical: gradually progressive proximal muscle weakness
Dx/Rx:
Amyotrophic Lateral Sclerosis
Pathophysiology:
- umn and lmn signs in bulbar + spinal cord distribution
- SOD1 mutation
Clinical:
- bulbar involvement: dysphagia, dysarthria, wasting/fasciculations of tongue
- UE/LE weakness: fatiguability, weakness, stiffness, twitching, wasting, cramps
Dx/Rx:
- riluzole: blocks glutaminergic transmission
- PEG tube for dysphagia
- fatal within 3-5 years
Poliomyelitis
Pathophysiology: RNA picornavirus, fecal-oral transmission
Clinical:
- prodrome: fever, myalgia, malaise
- weakness, asymmetric, focal, or unilateral
- DECREASED tone/reflexes
- CSF: increased pressure, pleocytosis
Dx/Rx:
- dx: stool culture
- rx: supportive care
Diphtheric Polyneuritis
Pathophysiology:
- corynebacterium diphtheria infection as URI or in skin wound
- neuropathy 2/2 neurotoxin elaboration
Clinical:
- palatal weakness
- impaired pupillary responses
- sensorimotor polyneuropathy
- +/- respiratory paralysis
Dx/Rx:
- diphtheria antitoxin
- penicillin/azithromycin
Porphyria
Pathophysiology: attacks precipitated by drugs: barbiturates, estrogen, sulfonamides
Clinical:
- colicky abdominal pain preceding neurologic involvement
- +/- acute confusion/convulsions
- weakness 2/2 polyneuropathy that is symmetric
- decreased reflexes
- fever, tachycardia, hyponatremia, peripheral leukocytosis
Dx/Rx:
- dx: increased porphobiliogen and d-aminolevulinic acid in the urine
- rx: IV dextrose to suppress heme pathway, propanolol to control tachycardia/hypotension
Lead toxicity
Pathophysiology: often occupational exposure
Clinical:
- acute encephalopathy in kids 2/2 ingestion
- painless peripheral neuropathy in arms > legs in adults
- anemia, constipation, abdominal pain, nephropathy
Dx/Rx: EDTA
Multifocal motor neuropathy
Pathophysiology:
- progressive asymmetric weakness with EMG evidence of demyelination
- 2/2 antiglycolipid antibodies (anti-GM1 IgM)
Clinical:
- pure motor multineuropathy beginning in arms
- insidious onset with chronic course
- conduction block on EMG
Dx/Rx: cyclophosphamide
Bell’s palsy
Pathophysiology:
- LMN facial weakness without widespread CNS disease
- common in pregnancy, DM
Clinical: facial weakness often preceded by pain around the ear
Dx/Rx: corticosteroids
Myasthenia Gravis
Pathophysiology:
- a/w thymoma, thyrotoxicosis, RA, SLE
- F>M
- 2/2 immune mediated decrease in # of functioning Ach receptors
- -> 80% v. nicotinic receptor; can have MuSK ab (muscle specific kinase)
Clinical:
- exacerbated by infection
- slowly progressive course
- ptosis, diplopia, limb weakness with diurnal variation
- extraocular muscle invovlement (90%)
- sustained muscle activity temporarily increases weakness
Dx/Rx:
dx: anticholinesterase trial (edrophonium?)
rx: neostigmine, thymectomy, corticosteroids, azathioprine, myfortic (mycophenolate)
Eaton-Lambert Myasthenic syndrome
Pathophysiology:
- antibodies against presynaptic voltage-gated calcium channels
- a/w neoplasm
Clinical:
- proximal muscle weakness
- spares ocular muscles!
Dx/Rx:
dx: ab titers
rx: corticosteroids, azathioprine, Ca screening
Botulism
Pathophysiology:
- prevents release of Ach at NMJ and autonomic synapses
- 2/2 home canned foods
- A, B, E toxin
Clinical:
- fulminating weakness 12-72h after ingestion
- diplopia, ptosis, facial weakness, dysphagia, respiratory failure
- weakness in limbs
- blurry vision, dry mouth, hypotension
Dx/Rx: antitoxin A, B,E
Duchenne Muscuar Dystrophy
Pathophysiology:
- X-linked disorder
- M>F
- symptomatic onset by age 5
- 2/2 absent/reduced dystrophin
Clinical:
- early sx: toe walking, waddling, inability to run
- Gower’s sign, +/- cardiac problems, +/- MR (mental retardation?)
- pseudohypertrophy of the calves
- increased creatine kinase
- wheelchair bound by age 12
Dx/Rx: prednisone
Becker Muscular Dystrophy
Pathophysiology:
- X-linked
- symptomatic onset around 11 y
- normal dystrophin levels, but ABNORMAL protein
Clinical:
- early sx: toe walking, waddling, inability to run
- Gower’s sign, +/- cardiac problems, +/- MR
- pseudohypertrophy of calves
- increased CK
- wheelchair by age 12
Dx/Rx:
Myotonic dystrophy I?
Pathophysiology:
- AD inheritance
- manifests in 20s and 30s
- 2/2 expanded CTG repeat on chromosome 19 myotonin protein kinase
Clinical:
- myotonia (abnormal stiffness) + weakness/wasting in distal muscles
- +/- cataracts, frontal balding, DM, cardiac abnormalities, ptosis, dysphagia, testicular atrophy, insulin resistance, cognitive changes
Dx/Rx:
- increased CK (mild)
- quinine sulfate
- procainamide
- phenytoin (myotonia)
Polymyositis
Pathophysiology:
- onset at any age with variable rates
- muscle fibers that express MHCI are invaded by CD8 T cells resulting in necrosis
- commonly associated with other autoimmune syndrmes
Clinical:
- muscle pain, tenderness
- weakness, wasting in proximal limbs
- a/w raynaud’s phenomenon
- increased CK
Dx/Rx: prednisone
Dermatomyositis
Pathophysiology:
- microangiopathy of skin, muscle
- lysis of capillaries 2/2 activation and deposition of complement –> muscle ischemia
Clinical:
- associated w cancer
- heliotrope rash, Gottron’s papules
- increased CK
- cardiac conduction problems, myocarditis, CHF, etc.
- ILD (interstitial lung disease) in patients with Jo-1 antibodies
Dx/Rx: prednisone
Inclusion body myositis
Pathophysiology: M>F; onset s/p 50 yo
Clinical:
- painless proximal muscle weakness with lower>upper extremities
- a/w autoimmunity, DM, peripheral neuropathy
Dx/Rx:
Polymyalgia Rheumatica
Pathophysiology:
- F>M; age > 50
- variant of giant cell arteritis
Clinical:
- muscle pain/stiffness in head and neck
- h/a, anorexia, weight loss, fever
- increased ESR
Dx/Rx: DRAMATIC response to steroids
Acute necrotizing myopathy
Pathophysiology: 2/2 heavy binge drinking
Clinical:
- muscle pain, weakness, dysphagia
- muscles are swollen, tender, and weak
- proximal weakness that may be asymmetric or focal
- increased CK +/- myoglobinuria
Dx/Rx: Etoh abstinence
Stiff person syndrome
Pathophysiology:
- rare, sporadic
- may be a/w autoimmune disorders, diabetes
- glutamic acid decarboxylase (GAD) antibodies
Clinical:
- tightness, stiffness, and rigidity of axial and proximal limb muscles with superimposed spasms
- distinguish from tetanus by absence of lockjaw
Dx/Rx:
- baclofen
- vigabatrin
- sodium valproate
- gabapentin
Neuromyotonia
Pathophysiology:
- rare, sporadic vs. paraneoplastic vs. autosomal dominant
- can be 2/2 voltage-gated K+ channel antibodies if acquired
Clinical:
- continuous muscle stiffness
- rippling muscle movement (myokymia)
- delayed relaxation
Dx/Rx: phenytoin or carbamazepine
Malignant Hyperthermia
Pathophysiology:
- autosomal dominant
- defect of ryanodine receptor gene on Chr 19
- results in excitation-contraction coupling
- precipitated by NMJ blocking agents (succinylcholine) or inhalational anesthetics
Clinical:
- rigidity
- hyperthermia
- metabolic acidosis
- myoglobinuria
Dx/Rx:
- cessation of offending agent
- Dantrolene
Upper motor neuron lesion
- weakness
- spasticity
- increased reflexes
- babinski present
- (-) atrophy
Lower motor neuron lesion
- weakness/paraparesis
- fasciculations
- hypotonicity
- decreased reflexes
Cerebellar dysfunction
- hypotonia
- decreased reflexes
- ataxia, dysarthria
- gait disturbance
- eye mvmt problems
Neuromuscular transmission
- normal or decreased tone
- normal or decreased reflexes
- (-) sensory symptoms
- patchy weakness distally
Myopathic disorder
- proximal weakness
- no muscle wasting
- normal plantar responses
- no sensory loss
- increased CK
Total spinal cord transection
Pathophysiology:
- acute stage
- spastic plegia
- terminal
Clinical:
- flaccid paralysis, (-) tendon reflexes, sensory loss, urinary/fecal retention
- brisk reflexes, extensor plantar responses
- bladder/bowel regain function
- flexor/extensor spasms in legs
Dx/Rx:
- immobilization
- corticosteroids
- baclofen
Multiple Sclerosis
- F > M; age of onset 20-46
Pathophysiology: - lesions separated in space/time
- HLA-DR2
- immune mediated attack vs. myelin antigens
- relapsing/remitting vs. secondarily progressive
Clinical:
- focal weakness, numbness, tingling, optic neuritis, diplopia
- relapses triggered by infection, pregnancy, etc.
- CSF: oligoclonal bands, lymphocytosis
Dx/Rx:
- 2+ CNS lesions at 2 diff times
- MRI
- rx: interferon b-1A to prevent relapses
- corticosteroids for acute rx of relapses
ADEM
Pathophysiology:
- single episode that develops s/p viral illness (varicella, measles, chickenpox)
- perivascular demyelination w/ associated inflammatory rxn
Clinical:
- HA, fever, confusion, +/- seizures
- CSF: pleocytosis, normal glucose/protein
Dx/Rx:
Epidural abscess
Pathophysiology:
- sequelae of skin infection, sepsis, osteomyelitis, IVDU, trauma, etc.
- 2/2 S.aureus, Strep pneumo, gram neg bacilli
Clinical:
- fever, backache, tenderness
- spinal root distribution of pain
- neurologic emergency
Dx/rx:
- MRI with contrast
- abx + sx
Vacuolar Myelopathy
Pathophysiology:
- vacuolation of white matter most pronounced in lateral/posterior columns
- thought to be 2/2 HIV-infection of cord
- comorbid AIDS/dementia
Clinical:
- early incontinence, leg weakness, ataxia, ED, paresthesias, spasticity, (+) Babinski, decreased vibration/position sensation
Dx/rx:
HTLV-1
Pathophysiology:
- tropical spastic paraperesis
- transmitted in breast milk, sex, blood
Clinical:
- spastic paraperesis
- decreased position/vibration sense
- bowel/bladder dysfunction
Dx/rx:
Tetanus
Pathophysiology:
- clostridium tetani
- elaborates neurotoxin that is transported retrograde to spinal cord
- toxin interferes with release of NT
Clinical:
- trismus (lockjaw)
- difficulty swallowing
- facial spasm (risus sardonicus)
- muscle spasms/ rigidity
- +/- increased CK, myoglobinuria
Dx/rx: PPx: tetanus toxoid Rx: debridement - tetanus Ig if high risk wound - penicillin or metronidazole for infection
Spinal cord infarction
Pathophysiology:
- 2/2 anterior spinal artery territory
- s/p trauma, aortic aneurysm, polyarteritis nodosa, hypotension
Clinical:
- acute onset flaccid paraparesis
- evolves into spastic paraperesis
- pain/temp lost
- position/vibration retained
Dx/rx: symptomatic
AVM
Pathophysiology:
- usually involve the lower part of the cord –> motor/sensory disturbances in the legs
Clinical:
- may present with subarachnoied hemorrhage or myelopathy
- bruit audible over the spine
Dx/rx:
- MRI appearance suggests dx
- extramedullary lesions treated with embolization and excision
Cervical spondylosis
Pathophysiology: 2/2 chronic disk degeneration with herniation and secondary calcification
Clinical:
- pain/stiffness in the neck, arms, +/- motor deficits
- present with neck pain and limitation of head movement
- affects C5/C6 nerve roots
Dx/rx:
dx: x-ray
rx: cervical collar
Spinal tumor
Pathophysiology: intramedullary [ependymoma] vs. extramedullary [neurofibroma, meningioma]
Clinical:
- insidious onset of symptoms
- radicular pain
- motor symptoms may develop
- CSF: xanthrochromia, increased protein
Dx/rx:
