Demyelinating Disorders

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    Multiple Sclerosis

    • Diagnosis:
      • Diagnostic Criteria for MS:

        - Clinical and radiologic dissemination of lesions in space and time.

         

        (I.e. patient has transient arm weakness, and now has symptoms of optic neuritis (central scotoma, etc..).  MRI shows lesions (two disparate clinical events happening at separate times) - space and time.  Additional brain lesions (if shown by MRI) would satisfy criteria for dissemination in space.

    • Labs:
      • CSF evaluation is often part of the workup, but not in diagnostic criteria (see oligoclonal bands).
      • Note: ESR has no role
    • Optical Neuritis Treatment Trial:
      • Treat relapses and acute exacerbations with HIGH DOSE IV steroids
        • IV Methylprednisolone 1g/day for 3-5 days
        • (PO steroids led to worse outcomes!)
      • Helps speed recovery from MS attack, but controversial whether improves long-term disability outcomes.
    • Physical, OT, SLP assessment to help regain function.
    • Gabapentin for pain.
    • Interferon Beta-1a or Beta1-b.
    • For painful muscle spasms.
      • These muscle spasms usually have spastic, hyper-reflexic upper motor neuron findings.
      • Tizanidine (centrally-acting alpha2-adrenergic agonist)
    • Overactive bladder in MS:
      • Oxybutynin

    Guillain-Barre Syndrome

    • Introduction
      • Acute inflammatory demyelination of peripheral nerves (rapid symmetric weakness of upper & lower limbs)
        • Triggered by infection (particularly Campylobacter jejuni), trauma, or surgery (often 1-3 weeks apart)
      • Classified as an Inflammatory Polyradiculoneuropathy

     

    Clinical Features

    • Motor
      • Rapid Symmetric weakness of upper + lower limbs (progresses over days to weeks)
        • Patients reach their worst by week 4
      • Eventually facial, oropharyngeal, oculomotor, and diaphragmatic muscles involved.
    • Sensory:
      • Many have parasthesias/neuropathic pain
      • Objective sensory loss is mild (or absent)
      • Back pain!!! (active demyelination of spine - mistaken for compression)
    • Dysautomomia
      • labile BP
      • Severe constipation
      • Cardiac arrhythmias
    • Respiratory failure in 25% of cases  (if very advanced --> can get autonomic instability)
    • Resolves spontaneously in 80% (residual neuro deficits common)

     

    Workup

    • History (above)
    • Exam:
      • Weakness and decreased/absent deep tendon reflexes
      • Nerve Conduction Studies (neuropathy)
    • CSF analysis (elevated protein in 80%)
      • Normal cell count (if pleocytosis --> consider GBS mimics --> infection (Lyme, West Nile), vasculitis, leptomeningeal disease from sarcoid or cancer.
    • EMG
      • Demyelinating process (unless rare axonal variant 5-10% of GBS)
    • Pulmonary Function Testing
      • FVC
      • Negative inspiratory pressure (NIP)
    • Normal CK

     

    Treatment

    • Supportive
    • Plasmapheresis and IVIG (0.4 g/kg/day x 5 days) --> equally effective, start within 7-14 days.
      • Do not delay while waiting for tests (nerve conduction studies etc..)
      • Equally effective in short-term improvement.
      • IVIG preferred, b/c easy to administer
      • No role for steroids (can even slow recovery)

     

    Myesthenia Gravis

    • Can present in (Myesthenic Crisis)

      • Oropharyngeal weakness often accompanies (may need intubation).  

      • Triggered by infection, medications, surgery, pregnancy or natural hx.

      • Management:

        • Plasmapheresis or IVIG, and steroids for sustained control.

    • Normal Serum CK

     

    Critical Illness Myopathy

    • Seen in severely ill patients after a prolonged (>7 days) stay in the intensive care unit (ICU).
    • Inability to extubate
    • Predominantly proximal flaccid limb weakness are classic findings.
    • elevated serum creatine kinase (CK) level.
    • Predisposing factors:
      • Prolonged ICU stay, use of corticosteroids and neuromuscular junction–blocking agents, and hyperglycemia.

     

    Steroid Induced Myopathy

    • Predominantly proximal weakness
    • preserved reflexes
    • Normal serum CK level
    • Normal or only mildly myopathic findings on electromyography (EMG).
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