29: Polyneuropathy Flashcards
Examples of small-fiber peripheral polyneuropathies?
DM, amyloidosis, toxins, drugs, Tangier, Fabry, AIDS, hypertriglyceridemia
Asymmetry of neuropathy symptoms would imply what?
- Mononeuropathy multiplex pattern
- Superimposed radic or entrapment neuropathy
- Variant of CIDP
When is mononeuropathy multiplex seen?
Vasculitis (e.g. polyarteritis nodosa, Churg-Strauss, Wegener’s, SLE, RA, Sjogren, hepatitis);
DM;
Inflammatory demyelinating polyneuropathy (Lewis-Sumner variant);
Multiple entrapments;
Infection (HIV, Lyme);
Infiltration (sarcoid, lymphoma, leukemia)
Example of hereditary demyelinating polyneuropathies?
CMT I, IV, CMTX;
Dejerine-Sottas (CMT III), Refsum disease;
HNPP, metachromatic leukodystrophy;
Krabbe, adrenoleukodystrophy;
Niemann-Pick; cerebrotendinous xanthomatosis
Acquired demyelinating polyneuropathies?
AIDP, CIDP (HIV, MGUS, osteosclerotic myeloma, Waldenstrom);
MMN with conduction block;
diphtheria;
Toxic (amiodarone, arsenic, glue sniffing)
What ratio could help detect underlying axonal polyneuropathy?
Sural/radial amplitude ratio (less than .21 may be the cutoff…)
in axonal polyneuropathy, what does involvement of proximal muscles as opposed to distal muscles suggest?
Possible porphyria, or combo of both peripheral nerve and nerve root pathology
One way to differentiate axonal and demyelinating slowing?
Could compare conduction velocities recording a distal and proximal muscles across the same segment of nerve (e.g. EDB vs. TA when stimulating fibular nerve)
What clinical clues could suggest primary demyelination disorder?
- Global areflexia
- Hypertrophic nerves
- Moderate-to-severe muscle weakness with relative preservation of muscle bulk
- Motor symptoms and signs more so than sensory
Possible causes of GBS?
Campylobacter, CMV, EBV, Zika, HIV;
vaccination, surgery, trauma,malignancy;
immune checkpoint inhibitors…
Signs and symps of GBS?
Rapidly ascending paralysis;
distal paresthesias, hypo/areflexia, bifacial weakness, bulbar weakness; autonomic dysfunction
What can porphyria cause?
A severe, acute axonal sensorimotor polyneuropathy
Why is there sural sparing in AIDP?
Preferential early involvement of the smaller myelinated fibers in AIDP (sural sensory fibers larger and have more myelin than the median and ulnar sensory fibers)
Best predictor of prognosis in AIDP?
Distal CMAP amplitude (if low, or < 20 % of LLN), this predicts poor outcome or prolonged course
Inheritance pattern of the different sub-types of CMT?
CMT1 is dominant and demyelinating;
CMT2 is dominant and axonal;
CMT4 is recessive and demyelinating;
CMTX is X-linked and demyelinating
(DDRX)
In CMT1, what muscles are affected first and what muscles are affected later?
Intrinsic foot and lower leg anterior compartment;
later distal thighs and intrinsic hand muscles
What does pathology of peripheral nerve in patient with CMT show?
Segmental demyelinating and Schwann cell proliferation with onion-bulb formation
What are average conduction velocities in CMTX vs. CMT1A vs. CMT1B
CMTX (25-38) > CMT1A (20-25)> CMT1B (15)
What is HNPP also known as?
Tomaculous neuropathy (due to sausage resemblance)
What ages are affected in CIDP? How does it come about? What muscles are affected? Symmetric or asymmetric?
Fifth and sixth decade;
Immune-mediated;
Proximal AND distal muscles;
Asymmetric
CIDP can respond to what treatments?
Plasma exchange, IVIG, immunosuppressive therapy;
prednisone, azathioprine, mycophenolate, cyclophosphamide, cyclosporine;
rituximab if IgM Ab’s present;
surg or radiation therapy for osteosclerotic myeloma
CIDP shows nerve conduction abnormalities that are often a/symmetric?
Asymmetric
What is characteristic of anti-MAG CIDP? What are these polyneuropathies associated with?
Markedly prolonged distal motor latencies (distal myelinopathy);
IgM monoclonal protein
What can be used to treat MMN?
IVIG;
cyclophosphamide or rituximab
