Restless legs syndrome and painful neuropathy-retrospective study. A role for nociceptive deafferentation?
OBJECTIVE
Restless legs syndrome (RLS) occurs in polyneuropathy with small fiber involvement, possibly as a peculiar form of neuropathic pain; however, the relationship between pain and RLS has been poorly investigated in polyneuropathy.


METHODS
We evaluated retrospectively the occurrence of RLS in 102 consecutive patients with polyneuropathy manifesting with neuropathic pain or dysesthesia, referred to the Neuromuscular Center, using the National Institutes of Health criteria for RLS. The patients were classified in subgroups characterized respectively by allodynia (hyperphenomena), with reported unpleasant sensations evoked by tactile stimuli, and hypoalgesia (hypophenomena), with absent pain sensation to pinprick, according to putative mechanisms of pain.


RESULTS
RLS was present in 41/102 patients (40.2%). It was significantly more frequent in the "hypoalgesia" (23/37) than in the "allodynia" subgroup (9/31; P = 0.008) and in the not classifiable cases (9/34; P = 0.004).


CONCLUSIONS
RLS is frequent in painful polyneuropathy and is significantly associated with decreased small fiber input, thus nociceptive deafferentation may represent a factor interacting with RLS "generators," possibly at spinal level. We suggest that overactivity of the spinal structures implicated in RLS may be triggered by nociceptive deafferentation in a subgroup of patients with painful polyneuropathy. Our findings, prompting a mechanistic characterization of RLS associated with painful polyneuropathy, have to be confirmed in a prospective study.
Gemignani
Franco
F
Department of Neurosciences, Section of Neurology, University of Parma, Parma, Italy.
Brindani
Francesca
F
Vitetta
Francesca
F
Marbini
Adriana
A
D000344:Afferent Pathways / Q000503:physiopathology*; D000368:Aged; D000927:Anticonvulsants / Q000494:pharmacology / Q000627:therapeutic use; D015984:Causality; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009619:Nociceptors / Q000473:pathology / Q000502:physiology*; D010147:Pain Measurement / Q000379:methods; D017288:Pain Threshold / Q000502:physiology; D010525:Peripheral Nerves / Q000503:physiopathology; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D012148:Restless Legs Syndrome / Q000209:etiology* / Q000503:physiopathology*; D012189:Retrospective Studies; D016896:Treatment Outcome
D000927:Anticonvulsants