Lewy Body Dementia: Symptoms and Diagnostic Imaging - Neurology

Dr. Hong Weibin reply Neurology

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Hello:
1.
Dementia with Lewy Bodies (DLB) must first meet the criteria for dementia, defined as a decline in daily functioning due to cognitive impairment.
Other possible symptoms include significant daily fluctuations in the patient's consciousness, bradykinesia and unsteady gait, well-defined visual hallucinations, as well as memory impairment, delusions, visuospatial deficits, sleep disturbances, and autonomic dysfunction, among others.
If interested, you can refer to the following explanation, which outlines the diagnostic criteria for DLB (using Google Translate from English to Chinese may sometimes lead to misunderstandings compared to the original text).
This is taken from McKeith IG, Boeve BF, Dickson DW, et al.
Diagnosis and management of dementia with Lewy bodies: Fourth consensus report of the DLB Consortium.
Neurology.
2017;89(1):88-100.
doi:10.1212/WNL.0000000000004058.
Essential for a diagnosis of DLB is dementia, defined as a progressive cognitive decline of sufficient magnitude to interfere with normal social or occupational functions, or with usual daily activities.
Prominent or persistent memory impairment may not necessarily occur in the early stages but is usually evident with progression.
Deficits on tests of attention, executive function, and visuoperceptual ability may be especially prominent and occur early.
Core clinical features (The first three typically occur early and may persist throughout the course):
- Fluctuating cognition with pronounced variations in attention and alertness.
- Recurrent visual hallucinations that are typically well-formed and detailed.
- REM sleep behavior disorder, which may precede cognitive decline.
- One or more spontaneous cardinal features of parkinsonism: these are bradykinesia (defined as slowness of movement and decrement in amplitude or speed), resting tremor, or rigidity.
Supportive clinical features:
- Severe sensitivity to antipsychotic agents; postural instability; repeated falls; syncope or other transient episodes of unresponsiveness; severe autonomic dysfunction, e.g., constipation, orthostatic hypotension, urinary incontinence; hypersomnia; hyposmia; hallucinations in other modalities; systematized delusions; apathy, anxiety, and depression.
Indicative biomarkers:
- Reduced dopamine transporter uptake in the basal ganglia demonstrated by SPECT or PET.
- Abnormal (low uptake) 123-iodine-MIBG myocardial scintigraphy.
- Polysomnographic confirmation of REM sleep without atonia.
Supportive biomarkers:
- Relative preservation of medial temporal lobe structures on CT/MRI scan.
- Generalized low uptake on SPECT/PET perfusion/metabolism scan with reduced occipital activity and the cingulate island sign on FDG-PET imaging.
- Prominent posterior slow-wave activity on EEG with periodic fluctuations in the pre-alpha/theta range.
Probable DLB can be diagnosed if:
a.
Two or more core clinical features of DLB are present, with or without the presence of indicative biomarkers, or
b.
Only one core clinical feature is present, but with one or more indicative biomarkers.
Probable DLB should not be diagnosed on the basis of biomarkers alone.
Possible DLB can be diagnosed if:
a.
Only one core clinical feature of DLB is present, with no indicative biomarker evidence, or
b.
One or more indicative biomarkers are present but there are no core clinical features.
DLB is less likely:
a.
In the presence of any other physical illness or brain disorder, including cerebrovascular disease, sufficient to account in part or in total for the clinical picture, although these do not exclude a DLB diagnosis and may serve to indicate mixed or multiple pathologies contributing to the clinical presentation, or
b.
If parkinsonian features are the only core clinical feature and appear for the first time at a stage of severe dementia.
DLB should be diagnosed when dementia occurs before or concurrently with parkinsonism.
The term Parkinson's disease dementia (PDD) should be used to describe dementia that occurs in the context of well-established Parkinson's disease.
In a clinical setting, the term that is most appropriate to the clinical situation should be used, and generic terms such as Lewy body disease are often helpful.
In research studies where a distinction needs to be made between DLB and PDD, the existing one-year rule between the onset of dementia and parkinsonism continues to be recommended.
2.
According to the diagnostic criteria mentioned above, currently helpful examinations for diagnosing dementia with Lewy bodies include dopamine transporter imaging (SPECT or PET), 123-iodine-MIBG myocardial scintigraphy, polysomnography to assess for REM sleep without atonia, CT/MRI scans, EEG, and PET scans for cerebral blood flow.
However, these examinations are used to assist in diagnosis and are not considered the gold standard for diagnosis.

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Reply Date: 2020/09/26