title: Thalamic pain: anatomical and physiological indices of prediction.
abstract: Thalamic pain is a severe and treatment-resistant type of central pain that may develop after thalamic stroke. Lesions within the ventrocaudal regions of the thalamus carry the highest risk to develop pain, but its emergence in individual patients remains impossible to predict. Because damage to the spino-thalamo-cortical system is a crucial factor in the development of central pain, in this study we combined detailed anatomical atlas-based mapping of thalamic lesions and assessment of spinothalamic integrity using quantitative sensory analysis and laser-evoked potentials in 42 thalamic stroke patients, of whom 31 had developed thalamic pain. More than 97% of lesions involved an area between 2 and 7 mm above the anterior-posterior commissural plane. Although most thalamic lesions affected several nuclei, patients with central pain showed maximal lesion convergence on the anterior pulvinar nucleus (a major spinothalamic target) while the convergence area lay within the ventral posterior lateral nucleus in pain-free patients. Both involvement of the anterior pulvinar nucleus and spinothalamic dysfunction (nociceptive thresholds, laser-evoked potentials) were significantly associated with the development of thalamic pain, whereas involvement of ventral posterior lateral nucleus and lemniscal dysfunction (position sense, graphaesthesia, pallaesthesia, stereognosis, standard somatosensory potentials) were similarly distributed in patients with or without pain. A logistic regression model combining spinothalamic dysfunction and anterior pulvinar nucleus involvement as regressors had 93% sensitivity and 87% positive predictive value for thalamic pain. Lesion of spinothalamic afferents to the posterior thalamus appears therefore determinant to the development of central pain after thalamic stroke. Sorting out of patients at different risks of developing thalamic pain may be achievable at the individual level by combining lesion localization and functional investigation of the spinothalamic system. As the methods proposed here do not need complex manipulations, they can be added to routine patients' work up, and the results replicated by other investigators in the field.
authors.affiliation: 1 Central Integration of Pain in Humans (NeuroPain), Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5092, University Claude Bernard Lyon 1, France larrea@univ-lyon1.fr.
authors.forename: Nuutti
authors.initials: N
authors.lastname: Vartiainen
authors.affiliation: 1 Central Integration of Pain in Humans (NeuroPain), Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5092, University Claude Bernard Lyon 1, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Perchet
authors.affiliation: 1 Central Integration of Pain in Humans (NeuroPain), Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5092, University Claude Bernard Lyon 1, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Magnin
authors.affiliation: 1 Central Integration of Pain in Humans (NeuroPain), Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5092, University Claude Bernard Lyon 1, France 2 Department of Neurology, University Hospital St Etienne, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Creac'h
authors.affiliation: 1 Central Integration of Pain in Humans (NeuroPain), Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5092, University Claude Bernard Lyon 1, France 2 Department of Neurology, University Hospital St Etienne, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Convers
authors.affiliation: 3 Neurology Vascular Unit, Neurological Hospital, Hospices Civils de Lyon, France.
authors.forename: Norbert
authors.initials: N
authors.lastname: Nighoghossian
authors.affiliation: 1 Central Integration of Pain in Humans (NeuroPain), Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5092, University Claude Bernard Lyon 1, France 4 Pain Clinic (CETD) and Department of Neurology, Neurological Hospital, Hospices Civils de Lyon, France.
authors.forename: François
authors.initials: F
authors.lastname: Mauguière
authors.affiliation: 1 Central Integration of Pain in Humans (NeuroPain), Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5092, University Claude Bernard Lyon 1, France 2 Department of Neurology, University Hospital St Etienne, France.
authors.forename: Roland
authors.initials: R
authors.lastname: Peyron
authors.affiliation: 1 Central Integration of Pain in Humans (NeuroPain), Lyon Neuroscience Research Center, Inserm U1028, CNRS UMR 5092, University Claude Bernard Lyon 1, France 4 Pain Clinic (CETD) and Department of Neurology, Neurological Hospital, Hospices Civils de Lyon, France.
authors.forename: Luis
authors.initials: L
authors.lastname: Garcia-Larrea
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000175:diagnosis* / Q000209:etiology*; D010147:Pain Measurement / Q000379:methods*; D011237:Predictive Value of Tests; D020521:Stroke / Q000150:complications* / Q000175:diagnosis*; D013788:Thalamus / Q000033:anatomy & histology* / Q000502:physiology*
keywords: CPSP; LEPs; laser-evoked potentials; thalamic pain; thalamus