European neurology
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Comparative Study
Central representation of somatic sensations in the parietal operculum (SII) and insula.
Four subjects with small restricted cerebral cortical infarcts have been examined. One had a lesion confined to the parietal operculum (SII), while in the second the SII lesion also encroached on the posterior insula; in the third subject, both banks of the sylvian fissure and the dorsal insula were involved, while in the fourth the lesion involved the upper bank of the sylvian fissure. In all cases, the postcentral gyrus (SI) was intact. ⋯ The possibility must nevertheless be considered that the presence of central pain in some way alters the cortical mechanisms for the perception of thermal stimuli. Certainly, as we had earlier observed, spontaneous pain only occurs when there is interference with thermal sensation. Functional MRI (fMRI) studies following thermal stimulation in subjects 1 and 2 showed these areas, particularly SII, to be concerned with the reception of innocuous and noxious thermal stimuli, mechanical (skinfold pinch) pain and sharpness (pinprick), implying that SI is principally concerned with the reception of low-intensity mechanical stimuli, although it was activated in 1 of our fMRI-studied subjects by innocuous cooling.
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The terms myofascial pain, fibromyalgia and fibrositis are critically examined. They constitute diagnostic labels for non-specific musculoskeletal aches and pains. Analysis of the evidence shows that none of these labels is substantiated by hard physical signs or by laboratory evidence of consistent pathological or biochemical abnormality. ⋯ They reflect no demonstrable pathology. It is therefore argued that none of these commonly used diagnoses represent distinct disease entities. A possible but unproven alternative hypothesis is that such symptoms relate to neural pain with both peripheral and central components, and in some instances psychological or wilful embellishment.