Additional Demyelinating Diseases and Autoimmune Neuropathies Flashcards
Differential for an acute polyneuropathy
- Gullian-Barre syndrome
- Toxins
- Organophosphates, thallium, arsenic
- Acute intermittent porphyria
- Similar but not true polyneuropathies:
- Botulism
- Transverse myelitis
Gullian-Barre syndrome
- An overarching term for acute-onset and rapidly progressive immune-mediated polyneuropathy
- Underlying pathophysiology can be either demyelinating (AIDP) or axonal (AMAN orAMSAN)
- Axonal variants can be associated with anti-GM1 antibodies
- Often preceded by diarrheal or respiratory illness or vaccination
Core clinical syndrome of Gullian-Barre
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Rapid progression of symmetric paresthesias and/or weakness in the extremities and loss of reflexes
- Facial weakness is common and usually bilateral
- Autonomic instability: Common, manifesting as fluctuations in HR and BP
- SIADH may be present
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“Ascending paralysis” in axonal form - Sx begin in lower extremities, then appear in upper extremities
- However, since AIDP is demyelinating, Sx are not length-dependent and this pattern may not hold
- Maximal disability is usually reached at 2–3 weeks into the illness
Anti-GQ1B antibody syndrome of GBS
- Also called Miller Fisher variant
- ophthalmoplegia, ataxia, and areflexia but with no or minimal weakness
Anti-GT1a antibody syndrome of GBS
- Also called pharyngeal-cervical-brachial variant
- Dysphagia, neck weakness, proximal upper extremity weakness, and areflexia that is often limited to the upper extremities
- Sometimes w/ ptosis
Diagnosing Gullian-Barre
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LP and CSF analysis:
- Albuminocytologic dissociation (elevated protein, but low/normal WBC)
- In AIDP, nerve conduction studies show a demyelinating pattern with slowed velocities/increased latencies, conduction block
- MRI in GBS, if obtained due to clinical concern for spinal cord pathology, may show enhancement of nerve roots.
Treating Gullian-Barre
- Fear for respiratory paralysis – Vital capacity and negative inspiratory force should be assessed upon presentation and monitored serially
- Neck flexion and extension musculature testing as proxy for C3-C5 diaphragm innervation
- GBS that progresses rapidly and/or causes gait impairment is treated with IV immunoglobulin (IVIg) or plasmapheresis – equally effective
- Does not lead to acute improvement, but shorter course and better recovery
- Treatment requires intensive supportive care, usually in an ICU setting except in mild cases
Assessing diaphragmatic involvement in cervical radiculopathy
Neck flexion and extension musculature is supplied by C3-C5 as is the phrenic nerve, so evaluating for neck flexion/extension weakness can serve as a measure of muscles innervated by the same roots as the diaphragm
Critical Illness Polyneuropathy and Myopathy
Patients hospitalized in ICUs for sepsis or other critical illnesses can develop an axonal sensorimotor polyneuropathy and/or a myopathy over an acute to subacute period.
Both cause diffuse symmetric weakness of the extremities. Facial weakness may occur, but occulomotor involvement is very rare.
Neuromuscular blockade and high-dose steroids used to treat the underlying critical illness may increase the risk of the development of critical illness myopathy.
There is no treatment for either aside from rehabilitation.
Acute disseminated encephalomyelitis
- Multifocal CNS demyelinating syndrome more common in children and young adults
- “CNS analogue of Gullian-Barre”
- Both acute inflammatory conditions preceded by infection or vaccination
- May present as multifocal neurologic deficits and/or an encephalopathy
- Characterized by “incomplete ring enhancement” on MRI
- CSF shows elevated protein and lymphocytosis
- Oligoclonal bands may be present
Treating ADEM
- IV corticosteroids
- IVIg or Plasma exchange when steroids fail
Rarely, ADEM may progress to ___.
Rarely, ADEM may progress to multiple sclerosis
Transverse myelitis
- Refers to an inflammatory demyelinating disease of the spinal cord
- Like optic neuritis, may occur idiopathically or as a flare in patients with MS or another autoimmune disease (sarcoid, Lupus, etc), or as a paraneoplasm
- Rapidly evolving myelopathy that leads to weakness and sensory changes in the extremities and bowel and/or bladder dysfunction
- May be symmetric or asymmetric depending on lesion size
- Reflexes may be decreased or absent initially, but hyperreflexia typically emerges over time
- CSF shows elevated protein and modestly elevated (<l00>
<li style="text-align: center;">High pleocytosis (<100) should suggest infectious etiology instead</li>
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Telling acute-onset transverse myelitis apart from acute-onset Gullian-Barre
- Both may appear hyporeflexive or areflexive acutely, but TM patients gradually develop hyperreflexia
- Bowel/bladder dysfunction extremely uncommon in GB, but common in TM
- Continued progression of symptoms in the legs with no symptoms or signs in the arms make thoracic/lumbar TM more likely than GB (which usually progresses to upper extremities rapidly)
