Reply: Operculo-insular pain (parasylvian pain): a distinct central pain syndrome * Not all that glisters is gold--nor all that responds a primary sensory area

Abstract

Sir, The purpose of our recent paper in Brain (Garcia-Larrea et al ., 2010) was to attract attention to a central pain syndrome (operculo-insular pain), which, albeit mentioned in medical literature, had not yet been individualized by the neurological community. The pain is severe and difficult to treat, its characteristics allow unequivocal diagnosis and in our experience cortical neurostimulation could provide pain relief. We are glad that our work has so rapidly gained the attention of our distinguished colleague Dr Arthur D. Craig; however, his letter focuses on marginal aspects of our paper, which primarily aimed at outlining the clinical contours of this pain syndrome. Since some of the points that Dr Craig raises are of conceptual importance, and since his letter contains a number of debatable assertions, we are willing to respond, as follows. The last paragraph of our article proposes that the posterior insula contains ‘what can be conceived as a third somatosensory area, supporting the particular attribute of somatic sensation we call “pain” ’. Dr Craig wrongly reports our words as stating ‘… an area specifically supporting temperature sensation’. Apart from this faux pas , our proposal is not agreeable to Dr Craig, who considers that the dorsal posterior insula should be considered as ‘the primary cortical sensory representation of temperature and pain in humans’. Our view is, however, based on a currently accepted concept of cortical organization not limited to the somatosensory system. External world information reaches the cortex through a variety of channels, which transform physical energies into conscious perception. Visual, auditory and somatosensory perceptions each have attributes and, for instance, a compound of luminance, contrasts, edges, colour and movement perceptions have to integrate to make up our representation of the visual world. A number of these visual attributes have their own ‘labelled lines’ and …