The insula, a grey matter of tastes: a volumetric MRI study in dementia with Lewy bodies.

BACKGROUND: Despite the growing number of discoveries during the past decades about its functions, the insula remains a mysterious 'island'. In addition to its involvement in basic functions such as gustation and interoception, the insular cortex is now considered a key region for integrated functions such as emotion/motivation processing, decision-making and self-consciousness. We hypothesized that this structure, standing at the crossroads of such functions, could ground personal tastes in general, beyond food preferences and aesthetic judgements. Given that dementia with Lewy bodies is characterized by a focal atrophy within the insular cortex from the early stages, this condition provides an opportunity to test such a hypothesis. METHODS: We developed a questionnaire to assess potential changes in personal tastes, submitted it to a cohort of 23 patients with early-stage dementia with Lewy bodies and compared their questionnaire results to those of 20 age-matched healthy controls. Furthermore, we performed a global and regional neuroimaging study to test for a potential correlation between the patients' scores for changes in personal tastes and their insular cortex volumes. RESULTS: Our results indicate that the patients presented significant changes in personal tastes compared to the controls, in both food and non-food domains. Moreover, imaging analyses confirmed the involvement of the insular cortex atrophy in the changes in personal tastes using global analysis, and in both food and non-food domains using regional analysis. CONCLUSIONS: These results bring new insights into the role of the insula as a 'grey matter of tastes', this structure supporting personal preferences in general, beyond the food domain. The insular cortex could be involved through its role in motivational processes by the representation of subjective awareness of bodily states during the phenomenological experience of stimulus appraisal. However, we also argue that it could support the abstract representations of personal tastes as self-concepts, acutely exemplifying embodied cognition. Finally, the questionnaire on changes in tastes could constitute an interesting tool to help early diagnosis of dementia with Lewy bodies and to assess insular dysfunction more generally.

Restless legs syndrome related to hemorrhage of a thoracic spinal cord cavernoma.

CONTEXT: Restless legs syndrome (RLS) is a common neurological disorder characterized by an irresistible urge to move the lower limbs often accompanied by unpleasant sensations in the legs, worsened at rest and in the evening. Symptoms are improved by movement. Its pathophysiology remains poorly understood. Lesion-related RLS has been reported, mainly in cases of stroke-related RLS involving the brainstem and lenticulostriate nuclei. Only few data of RLS in a context of spinal cord injury have been reported. FINDINGS: We report the case of a woman with secondary RLS due to hemorrhage of a spinal cord cavernoma located at T9-T10. Following recovery from the acute phase of the hemorrhage, the patient began to complain about restlessness in her legs causing impaired sleep and daytime somnolence. Polysomnographic investigations found a high index of periodic leg movements during sleep (71/hour), but no sleep disordered breathing. Iron stores were normal. Relief of symptom's severity was obtained with gabapentin 600mg in the evening. CONCLUSION/CLINICAL RELEVANCE: We hypothesize a possible involvement of the diencephalospinal pathway in the patient's RLS pathophysiology. A systematic study of focal lesions associated with RLS may contribute to improving our understanding of the pathophysiological mechanisms underlying this condition. The frequency of RLS associated with lesions of the spinal cord might be underestimated. Clinicians should be aware of spinal cord lesion-related RLS, especially as efficient treatments are available.

Insular cognitive impairment at the early stage of dementia with Lewy bodies: a preliminary study.

BACKGROUND: The anterior part of the insula appears atrophied in the early stage of dementia with Lewy bodies (DLB) whereas it is not the case in early Alzheimer's disease (AD). OBJECTIVE: The objective of this study was to develop neuropsychological markers supposed to reflect insular dysfunction, which would facilitate early diagnosis of DLB, namely in comparison to AD. METHODS: Twelve patients with DLB, 12 patients with AD, all at the stage of Mild cognitive impairment (MCI) or mild dementia, as well as 10 Controls subjects (CS) participated in the study. Cognitive functions supposedly related to the insula were evaluated with a battery of tests: a facial expression recognition test, a test assessing the feeling of disgust with images, a test evaluating idioms' comprehension, an empathy questionnaire and a questionnaire screening for disgusting behaviors. RESULTS: Compared to AD patients and CS, DLB patients experienced less disgust when they were shown disgusting images, whereas their ability to recognize emotional expression of disgust appeared to be preserved. Furthermore, DLB patients seemed less empathetic than AD patients. Finally, compared to CS, DLB patients were less effective to provide an intuitive decision about idioms' signification since they needed significantly more time to answer. CONCLUSION: This preliminary study suggests the existence of a potential « insular cognitive impairment ¼ profile in DLB at the early stage. These results provide interesting leads to develop tools facilitating the differential diagnosis of DLB and AD.