Diego Lopergolo1, Baris Isak2, Maria Gabriele1, Emanuela Onesti1, Marco Ceccanti1, Gelsomina Capua1, Laura Fionda1, Antonella Biasiotta1, Giulia Di Stefano1, Silvia La Cesa1, Vittorio Frasca1, Maurizio Inghilleri3. 1. Department of Neurology and Psychiatry, University "Sapienza", Viale dell'Università 30, 00185 Rome, Italy. 2. Marmara University Hospital School of Medicine, Department of Neurology, Fevzi Cakmak Mah. Mimar Sinan Cad. No: 41, 34899 Ust Kaynarca/Pendik, Istanbul, Turkey; Department of Clinical Neurophysiology, Aarhus Universitets hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark. 3. Department of Neurology and Psychiatry, University "Sapienza", Viale dell'Università 30, 00185 Rome, Italy. Electronic address: maurizio.inghilleri@uniroma1.it.
Abstract
OBJECTIVE: To investigate the cutaneous silent period (CSP), a spinal inhibitory reflex mainly mediated by A-delta fibres, in demyelinating and axonal polyneuropathy (PNP) and evaluate whether CSP parameters differ between patients with and without neuropathic pain. METHODS: Eighty-four patients with demyelinating PNP, 178 patients with axonal PNP and 265 controls underwent clinical examination, DN4 questionnaire, standard nerve conduction study, motor-root stimulation and CSP recordings from abductor digiti minimi. We calculated the afferent conduction time of CSP (a-CSP time) with the formula: CSP latency-root motor evoked potential latency. RESULTS: In the demyelinating PNP group the a-CSP time was significantly longer; in the axonal PNP group, CSP duration was shorter than the demyelinating group (p=0.010) and controls (p=0.001). CSP parameters were not different between patients with and without neuropathic pain. CONCLUSIONS: The abnormality of a-CSP time in the demyelinating PNP group suggests the crucial role of A-delta fibres in the mechanism of CSP; the shorter CSP duration in the axonal PNP group supports the strong influence of the number of axons on this parameter. Our study suggests that neuropathic pain could be related to pathophysiological mechanisms differing from mere A-delta fibre loss. SIGNIFICANCE: CSP evaluation is effective in detecting A-delta fibre dysfunction in axonal as well as demyelinating PNP.
OBJECTIVE: To investigate the cutaneous silent period (CSP), a spinal inhibitory reflex mainly mediated by A-delta fibres, in demyelinating and axonal polyneuropathy (PNP) and evaluate whether CSP parameters differ between patients with and without neuropathic pain. METHODS: Eighty-four patients with demyelinating PNP, 178 patients with axonal PNP and 265 controls underwent clinical examination, DN4 questionnaire, standard nerve conduction study, motor-root stimulation and CSP recordings from abductor digiti minimi. We calculated the afferent conduction time of CSP (a-CSP time) with the formula: CSP latency-root motor evoked potential latency. RESULTS: In the demyelinating PNP group the a-CSP time was significantly longer; in the axonal PNP group, CSP duration was shorter than the demyelinating group (p=0.010) and controls (p=0.001). CSP parameters were not different between patients with and without neuropathic pain. CONCLUSIONS: The abnormality of a-CSP time in the demyelinating PNP group suggests the crucial role of A-delta fibres in the mechanism of CSP; the shorter CSP duration in the axonal PNP group supports the strong influence of the number of axons on this parameter. Our study suggests that neuropathic pain could be related to pathophysiological mechanisms differing from mere A-delta fibre loss. SIGNIFICANCE: CSP evaluation is effective in detecting A-delta fibre dysfunction in axonal as well as demyelinating PNP.
Authors: Isabella A Mota; João B Fernandes; Marcio N Cardoso; Xavier Sala-Blanch; Markus Kofler; Josep Valls-Solé Journal: Exp Brain Res Date: 2015-05-30 Impact factor: 1.972