RESUMEN
BACKGROUND: Motor cortex stimulation (MCS) for neuropathic pain control induces focal cerebral blood flow changes involving regions with high density of opioid receptors. We studied the possible contribution of the endogenous opioid system to MCS-related pain relief. METHODS: Changes in opioid receptor availability induced by MCS were studied with PET scan and [(11)C]diprenorphine in eight patients with refractory neuropathic pain. Each patient underwent two preoperative (test-retest) PET scans and one postoperative PET scan acquired after 7 months of chronic MCS. RESULTS: The two preoperative scans, performed at 2 weeks interval, did not show significant differences. Conversely, postoperative compared with preoperative PET scans revealed significant decreases of [(11)C]diprenorphine binding in the anterior middle cingulate cortex (aMCC), periaqueductal gray (PAG), prefrontal cortex, and cerebellum. Binding changes in aMCC and PAG were significantly correlated with pain relief. CONCLUSION: The decrease in binding of the exogenous ligand was most likely explained by receptor occupancy due to enhanced secretion of endogenous opioids. Motor cortex stimulation (MCS) may thus induce release of endogenous opioids in brain structures involved in the processing of acute and chronic pain. Correlation of this effect with pain relief in at least two of these structures supports the role of the endogenous opioid system in pain control induced by MCS.
Asunto(s)
Encéfalo/metabolismo , Terapia por Estimulación Eléctrica/métodos , Corteza Motora/fisiología , Péptidos Opioides/metabolismo , Enfermedades del Sistema Nervioso Periférico/metabolismo , Enfermedades del Sistema Nervioso Periférico/terapia , Adulto , Unión Competitiva/efectos de los fármacos , Unión Competitiva/fisiología , Encéfalo/diagnóstico por imagen , Encéfalo/fisiopatología , Radioisótopos de Carbono , Cerebelo/diagnóstico por imagen , Cerebelo/metabolismo , Diprenorfina/farmacocinética , Femenino , Giro del Cíngulo/diagnóstico por imagen , Giro del Cíngulo/metabolismo , Humanos , Masculino , Persona de Mediana Edad , Sustancia Gris Periacueductal/diagnóstico por imagen , Sustancia Gris Periacueductal/metabolismo , Enfermedades del Sistema Nervioso Periférico/diagnóstico por imagen , Tomografía de Emisión de Positrones , Corteza Prefrontal/diagnóstico por imagen , Corteza Prefrontal/metabolismo , Receptores Opioides/efectos de los fármacos , Receptores Opioides/metabolismo , Resultado del TratamientoRESUMEN
Korsakoff-like amnestic syndromes have been rarely described following structural lesions of the central nervous system. In this report, we describe a case of acute Korsakoff-like syndrome resulting from the combination of a left anteromedian thalamic infarct and a right hippocampal hemorrhage. We also review the literature relevant to the neuropathology and pathophysiology of Korsakoff syndrome and anterograde amnesia.