No adrenergic sensitization of afferent neurons in painful sensory polyneuropathy.
BACKGROUND
The aim of the present study was to determine (1) if an adrenergic sensitivity of afferent neurons is present in patients with painful polyneuropathy as compared with non-painful polyneuropathy and (2) if there is a correlation between adrenergic sensitisation and the severity of afferent and sympathetic small fiber damage.


METHODS
10 patients with painful and non painful polyneuropathy and 10 healthy controls were included. The function of small afferent and efferent sympathetic neurons was evaluated. Adrenergic sensitivity of afferent neurons was assessed by cutaneous iontophoresis of norepinephrine. Spontaneous pain, mechanical hyperalgesia as well as warm and heat pain thresholds were measured.


RESULTS
Iontophoresis of norepinephrine did not induce or enhance spontaneous pain or mechanical allodynia, either in painless or painful polyneuropathies. There was no difference in norepinephrine-induced heat hyperalgesia between both neuropathy groups and healthy controls. The response of afferent neurons to norepinephrine was not correlated with the severity of damage to afferent small fibers or efferent sympathetic vasoconstrictor neurons.


CONCLUSIONS
The results do not support the assumption that in painful polyneuropathies afferent neurons acquire an adrenergic sensitivity after nerve injury and that adrenergic stimulation leads to an exacerbation of spontaneous pain and thermal and mechanical hyperalgesia.
Schattschneider
Jörn
J
Klinik für Neurologie, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Schittenhelmstr. 10, 24105 Kiel, Germany. j.schattschneider@neurologie.uni-kiel.de
Uphoff
Jens
J
Binder
Andreas
A
Wasner
Gunnar
G
Baron
Ralf
R
D000368:Aged; D016022:Case-Control Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology; D007478:Iontophoresis / Q000379:methods; D008297:Male; D008875:Middle Aged; D009475:Neurons, Afferent / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D010146:Pain / Q000473:pathology / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects* / Q000502:physiology; D010465:Perception / Q000187:drug effects; D010523:Peripheral Nervous System Diseases / Q000473:pathology / Q000503:physiopathology*; D012039:Regional Blood Flow / Q000187:drug effects; D012720:Severity of Illness Index; D012867:Skin / Q000187:drug effects / Q000294:innervation / Q000503:physiopathology; D018709:Statistics, Nonparametric
D009638:Norepinephrine