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Acute Peripheral Weakness

Acute Peripheral Weakness. Peter Shearer, MD Assistant Residency Director Mt. Sinai School of Medicine. Objectives. Acute Extremity Weakness Levels of potential involvement Key Elements of History and Physical for each level CNS PNS Diagnostic Options Therapy. Question #1.

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Acute Peripheral Weakness

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  1. Acute Peripheral Weakness Peter Shearer, MDAssistant Residency DirectorMt. Sinai School of Medicine

  2. Objectives • Acute Extremity Weakness • Levels of potential involvement • Key Elements of History and Physical for each level • CNS • PNS • Diagnostic Options • Therapy

  3. Question #1 At which level of the CNS can a lesion produce motor weakness without affecting mental status? A. Brainstem B. Dorsal root ganglia C. Spinal Cord D. Cerebellum

  4. Question #2 Which of the following can differentiate between acute transverse myelitis and Guillain-Barre Syndrome? A. ascending vs. descending paralysis B. presence of slight lymphocytosis in CSF C. increased vs. decreased reflexes D. acuity of onset E. presence of a preceding respiratory or GI illness

  5. Question #3 Which of the following does NOT produce a myelopathy? A. Spinal cord infarct B. Transverse Myelitis C. Spinal cord metastasis of lung cancer D. Tick Paralysis

  6. Question #4 Which of the following illnesses has a well evaluated, prospectively studied therapy? A. Guillain-Barre Syndrome B. Acute Transverse Myelitis C. Acute Spinal Cord Hemorrhage D. Botulism

  7. case-history • 30 year old woman • diffuse weakness • lower extremities > upper extremities • over 3 days • preceding diffuse vesicular rash • difficulty voiding

  8. case-history • 30 year old woman • diffuse weakness • lower extremities > upper extremities ascending • over 3 days • preceding diffuse vesicular rash • difficulty voiding

  9. case-details of the physical • BP 140/86, P 90, RR 18, T 99, 99%O2 sat • CN intact • Motor: 4/5 in UE, 3/5 in LE • Sensory intact but sharp/dull less pronounced in the LE • Reflexes 3+ in all extremities • palpable bladder

  10. Case - summary • Acute ascending symmetrical paralysis following a recent infection with slight sensory impairment and hyperreflexia.

  11. Could this be a CNS lesion?

  12. Could this be a CNS lesion? Yes Can a CNS lesion produce bilateral weakness and sensory deficits and have a normal mental status?

  13. Could this be a CNS lesion? • CNS = Upper motor neuron • cerebral cortex to, but not including the anterior horn cell • UMN lesions produce: • increased tone • increased DTR • extensor plantars • no fasiculations

  14. levels of the CNS • Cerebral Cortex • Cerebellum • Brainstem • Spinal Cord up to the Anterior Horn Cell

  15. Could this be a PNS lesion?

  16. Could this be a PNS lesion? Yes Where?

  17. levels of the PNS • Spinal cord - Anterior horn cell of the Lateral Corticospinal tract • Peripheral nerve • NMJ • Muscle

  18. Myelopathy • A Lesion in the cord produces A Level of deficit • Division of labor • Dorsal columns - position/vibration • Lateral corticospinal tract - motor function • Lateral spinothalamic tract - pain/temperature • Preserved mental status

  19. Myelopathy - etiology • Infarct • Trauma • Brown-Sequard • Central cord syndrome • Anterior cord syndrome • Mass lesions • Inflammation/Infection

  20. myelopathy - details of history • Acuity of onset • Trauma • Distal > Proximal • Pain at site • Preceding Illness

  21. myelopathy - details of physical • Weakness • Spasticity • Atrophy • Fasciculations • Bowel and bladder complaints • Increased tone • Sensory findings • DTR’s may be increased (not if ALS)

  22. Cord Infarct • Anterior Spinal Artery • anterior cord - dissociation of sensory findings • symmetric flaccid paralysis • loss of sphincter tone • Dorsal columns prevail • Posterior Spinal Artery • proprioceptive and vibratory sensation

  23. Acute Peripheral Neuropathy • Motor and/or sensory • disorder of transmission along peripheral nerve • axon • myelin • Guillain-Barre • Tick Paralysis • Toxic

  24. Acute Peripheral Neuropathy - details of physical • Weakness • Absent DTR’s (all outflow from the cord is affected) • Affects longer nerves first - ascending

  25. Guillain-Barre Syndrome • Post infectious • mononuclear inflammatory infiltrate of myelin • dymyelinating • may be axonal injury and degeneration

  26. Guillain-Barre Syndrome • Symmetric ascending paralysis • areflexic • possible sensory - paresthesias, position and vibration • Progression over 1 - 3 weeks - may be more rapid • 1/3 progress to respiratory failure

  27. Guillain-Barre Syndrome • CSF - Albuminocytologic dissociation • Stool for C. jejuni

  28. NMJ • Presynaptic - disorder of ACh release • will affect nicotinic and muscarinic • weakness • anticholinergic symptoms • Postsynaptic - will just be nicotinic • weakness • NO anticholinergic findings

  29. NMJ - details of history • Exposure • botulism • snake bites • fatigue

  30. NMJ - details of physical • Proximal>distal muscles • Bulbar muscles • May have anticholinergic signs if presynamptic • Fatigability

  31. Examples of NMJ disorders • Myasthenia Gravis • Botulism • Tick Paralysis

  32. Myopathies • Periodic Paralyses • Electrolyte Abnormalities • Hypermagesemia • Hypophosphatemia

  33. Metabolic Abnormalities • Periodic Paralyses • Hypermagesemia • Hypophosphatemia

  34. Work up • CBC and serum chemistry • CSF for signs of GBS or myelitis • Radiography • MRI vs CT

  35. Management • Corticosteroids • not supported by prospective placebo controlled studies

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