Axonal excitability in primary amyloidotic neuropathy.
BACKGROUND
Acquired and hereditary amyloidosis can cause peripheral neuropathy, but the mechanisms by which this occurs have not been established. Threshold tracking techniques allow in vivo assessment of the properties of the axonal membrane and may shed light on pathogenetic mechanisms underlying neuropathic disorders.


METHODS
We studied 10 subjects with primary amyloidosis using conventional nerve conduction studies and quantitative sensory, autonomic, and axonal excitability testing of median motor and sensory fibers.


RESULTS
As expected, subjects with amyloidosis had evidence of small- and large-fiber neuropathy on conventional testing. There was no significant difference in axonal excitability between subjects and controls apart from the stimulus required to activate sensory fibers.


CONCLUSIONS
Amyloid-related neuropathy does not produce a change in membrane potential as either a primary or secondary event. This suggests that ischemia and axonal compression are unlikely mechanisms for the neuropathy.
Department of Neurology and Clinical Neurophysiology, Royal North Shore Hospital, Reserve Road, St Leonards, New South Wales, 2065, Australia.
Jessica
J
Hafner
Roula
R
Ghaoui
Luke
L
Coyle
David
D
Burke
Karl
K
Ng
D000200:Action Potentials / Q000502:physiology*; D000368:Aged; D000369:Aged, 80 and over; D000686:Amyloidosis / Q000175:diagnosis* / Q000503:physiopathology*; D001369:Axons / Q000502:physiology*; D005260:Female; D006801:Humans; D000075363:Immunoglobulin Light-chain Amyloidosis; D008297:Male; D008875:Middle Aged
amyloidosis; autonomic testing; axonal excitability; peripheral neuropathy; quantitative sensory testing