The new modifications of the clinical criteria for diagnosis of DLB are a beautiful contribution, especially the inclusion of RBD as a core clinical feature together with visual hallucinations, parkinsonism, and cognitive fluctuation. No doubt this change will increase the sensitivity of the clinical diagnosis to predict the pathological findings in this disease.
However, it would seem that there may be an error that should be amended in the criteria of probable DLB. In the case of a patient who has only one core clinical feature such as RBD, and the only supportive biomarker is REM without atonia in polysomnography, according to the criteria this patient should be considered probable DLB. In fact, the polysomnographic findings would only confirm the clinical report. Thus, a single criterion would ensure the diagnosis of probable DLB, and this would not be correct.
The new guidelines have rightly put greater emphasis on the diagnostic role of REM behavior disorder, which is likely to be the most specific among the “core features.” In addition, a greater diagnostic weight has been given to MIBG myocardial scintigraphy (which now has the same value of DAT-scan), in light of the results of multiple studies during the last decade which have highlighted the high sensitivity and specificity of this procedure. These modifications can increase the identification of this (still underdiagnosed) condition during life and undoubtedly represent an advance in the field.
Based on these new guidelines, at least two core features, or one core and one indicative biomarker, are required for a diagnosis of “probable DLB” while, as for prior formulations of Consortium Criteria, the presence of a single core feature only warrants the uncertain and unstable diagnosis of “possible DLB.” However, in terms of specificity, the core features have a different diagnostic weight (REM behavior disorder > visual hallucinations > fluctuations > parkinsonism), so that one can wonder whether the presence of RBD alone may be sufficient to warrant a diagnosis of probable rather than possible DLB. Perhaps the authors might have stressed that there is a hierarchy among the core features.
The authors have differentiated between indicative (previously suggestive) and supportive biomarkers on the basis of the greater specificity of the former in supporting the clinical diagnosis, but have not clarified which procedure should be preferred in particular circumstances. For example, when parkinsonism is the single core feature exhibited by the patient with dementia, MIBG myocardial scintigraphy or FDG-PET imaging are likely to be more appropriate diagnostic options than DAT-scan. That is because, in general, one would expect the latter exam to be abnormal in the context of parkinsonism, which means that DAT-scan abnormalities add no or negligible diagnostic extra value when parkinsonism is already present on examination.
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Hospital Italiano
The new modifications of the clinical criteria for diagnosis of DLB are a beautiful contribution, especially the inclusion of RBD as a core clinical feature together with visual hallucinations, parkinsonism, and cognitive fluctuation. No doubt this change will increase the sensitivity of the clinical diagnosis to predict the pathological findings in this disease.
However, it would seem that there may be an error that should be amended in the criteria of probable DLB. In the case of a patient who has only one core clinical feature such as RBD, and the only supportive biomarker is REM without atonia in polysomnography, according to the criteria this patient should be considered probable DLB. In fact, the polysomnographic findings would only confirm the clinical report. Thus, a single criterion would ensure the diagnosis of probable DLB, and this would not be correct.
View all comments by Angel GolimstokFondazione IRCCS Istituto Neurologico "C. Besta”
The new guidelines have rightly put greater emphasis on the diagnostic role of REM behavior disorder, which is likely to be the most specific among the “core features.” In addition, a greater diagnostic weight has been given to MIBG myocardial scintigraphy (which now has the same value of DAT-scan), in light of the results of multiple studies during the last decade which have highlighted the high sensitivity and specificity of this procedure. These modifications can increase the identification of this (still underdiagnosed) condition during life and undoubtedly represent an advance in the field.
Based on these new guidelines, at least two core features, or one core and one indicative biomarker, are required for a diagnosis of “probable DLB” while, as for prior formulations of Consortium Criteria, the presence of a single core feature only warrants the uncertain and unstable diagnosis of “possible DLB.” However, in terms of specificity, the core features have a different diagnostic weight (REM behavior disorder > visual hallucinations > fluctuations > parkinsonism), so that one can wonder whether the presence of RBD alone may be sufficient to warrant a diagnosis of probable rather than possible DLB. Perhaps the authors might have stressed that there is a hierarchy among the core features.
The authors have differentiated between indicative (previously suggestive) and supportive biomarkers on the basis of the greater specificity of the former in supporting the clinical diagnosis, but have not clarified which procedure should be preferred in particular circumstances. For example, when parkinsonism is the single core feature exhibited by the patient with dementia, MIBG myocardial scintigraphy or FDG-PET imaging are likely to be more appropriate diagnostic options than DAT-scan. That is because, in general, one would expect the latter exam to be abnormal in the context of parkinsonism, which means that DAT-scan abnormalities add no or negligible diagnostic extra value when parkinsonism is already present on examination.
View all comments by Cristina MuscioMake a Comment
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