A thorough neurological examination should be conducted by a clinician experienced in neurodegenerative disorders at the time of the initial assessment. Areas of importance include:
- Cognitive function, including language and speech
- Eye movements (can be abnormal in some types of atypical parkinsonism)
- Gait, balance, fine/coarse motor movements, reflexes
- Presence of involuntary movements such as tremor
- Cortical sensory findings, such as assessing sensory abilities to recognize writing on the skin (graphesthesia) or objects by touch (stereognosis)
- Alteration of smell
Blood pressure should be taken at every visit to assess whether blood pressure drops significantly when a person moves from sitting or lying to standing (a measure of an impaired autonomic nervous system). As hallucinations are common, evaluation of vision and hearing can establish baseline acuity. Assessment of a person’s functional status, including the ability to perform activities of daily living (bathing, dressing) and instrumental activities of daily living (managing money, shopping), can provide insight into the ability of patients to care for themselves.
Clinical follow-up should be done in 6-month intervals or whenever changes are reported by the patient or family.
Brief Cognitive Assessments
Select a brief standardized instrument sensitive for both amnestic and non-amnestic cognitive decline. The Montreal Cognitive Assessment (MoCA) has become the standard, whereas the Folstein Mini-Mental State Exam (MMSE) is also available, but is often not sensitive enough to detect initial, more-subtle cognitive deficits in LBD.1 Each of these tests take less than 10 minutes to administer. Any ambiguous abnormalities will require referral for a more in-depth evaluation by a neuropsychologist.
Psychiatric symptoms are common and may include anxiety, depression and psychotic features such as hallucinations and delusions. If visual or other hallucinations occur with mild dementia, it is suggestive of DLB over AD. The most common tool used to assess psychiatric symptoms is the Neuropsychiatric Inventory – Questionnaire (NPI-Q). This assessment gets information from a caregiver familiar with the patient’s behavior and determines the frequency and the severity of each behavior.
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REM sleep behavior disorder (dream enactment) frequently precedes the observed onset of LBD and the sleep partner should be asked about a history of acting out dreams. A polysomnogram is the gold standard in diagnosing RBD. The SCOPA-SLEEP assessment is a useful rating scale for night-time sleep and daytime sleepiness.
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There is not one standard test used to assess autonomic function in DLB, however, the Non-Motor Symptoms Scale or the Scales for Outcomes in Parkinson’s Disease (SCOPA) assessments can be used.
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Blood Tests and Imaging
Reversible causes of dementia (e.g. post-traumatic hydrocephalus, drug and alcohol toxicity, electrolytes, B12 deficiency, HIV, thyroid disorders), though rare in this setting, should be screened for and treated if confirmed.
Imaging by computed tomography (CT) or magnetic resonance (MRI) should be done to rule out stroke, brain tumors, intracranial bleeding, hydrocephalus or other structural causes of dementia. Imaging in DLB is usually normal. Dopamine transporter single-photon emission computed tomography (DaT SPECT) of the brain can be done when indicated to differentiate both DLB and PDD from AD. The scan in LBD usually shows reduced uptake of an injected radioactive compound that binds to the dopamine transporter compared with a normal result in AD.
Research is under way to identify neuro-imaging tests, as well as brain, spinal fluid and serum proteins (biomarkers) that can be used to help identify various types of dementia.
DLB Diagnostic Criteria
In 2017, the international DLB Consortium published updated diagnostic criteria2 (Table 1) for DLB in the journal Neurology.
Table 1: Revised Criteria for the Clinical Diagnosis of Probable and Possible DLB
|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
(NOTE: 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 (RBD) which may precede cognitive decline.
• One or more spontaneous cardinal feature of parkinsonism – these are bradykinesia (defined as slowness of movement and decrement in amplitude or speed), rest tremor, or rigidity
• Reduced dopamine transporter (DaT) uptake in basal ganglia demonstrated by SPECT or PET.
• Abnormal (low uptake) 123iodine-MIBG myocardial scintigraphy.
• Polysomnographic confirmation of REM sleep without atonia.
See open access article in Neurology2 for examples of abnormal scan results.
|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.
• Relative preservation of medial temporal lobe structures on CT/MRI scan.
• Generalized low uptake on SPECT/PET perfusion/ metabolism scan with reduced occipital activity +/- 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:
|Probable DLB should not be diagnosed on the basis of biomarkers alone.|
|Possible DLB can be diagnosed if:
|DLB is less likely:
|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 practice setting the term that is most appropriate to the clinical situation should be used and generic terms such as LB disease are often helpful. In research studies in which 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.|
PDD Diagnostic Criteria
A consensus statement by a task force from the Movement Disorder Society for the diagnosis of PDD was published in 20073, providing criteria (Table 2) for probable and possible PDD.
A diagnosis of probable PDD requires the core features and a typical presentation of clinical features that is defined as having deficits in at least two out of four cognitive domains. There may or may not be behavioral symptoms, although their presence would support a diagnosis of probable PDD. There must not be any features present from Groups III and IV, as the abnormalities and conditions described in these categories can cause too much uncertainty in a potential diagnosis.
A diagnosis of possible PDD also requires the core features, but can have a more non-characteristic pattern of symptoms in at least one of the cognitive domains. There may or may not be any behavioral symptoms. One or more features of Group III may be present, and none in Group IV.
Table 2: Features of dementia associated with Parkinson’s disease
|Group I – The core feature requires a prior diagnosis of Parkinson’s disease and dementia causing a decline in function severe enough to impair the patient in daily activities and in at least one cognitive domain.|
|Group II – The clinical features include both the cognitive and behavioral domains described below: Cognitive domains:
|Group III – The third category includes two features that will not rule out a diagnosis of PDD, but may make the diagnosis more uncertain:
|Group IV – The last domain contains two features which suggest that other existing conditions impair the patient’s cognitive functioning to such an extent that reliable diagnosis of PDD becomes impossible.
1. McKeith, I. G. et al. Diagnosis and management of dementia with Lewy bodies: third report of the DLB Consortium. Neurology 65, 1863–72 (2005).
2. McKeith, I. G. et al. Diagnosis and management of dementia with Lewy bodies: Fourth consensus report of the DLB Consortium. Neurology 89, 88–100 (2017).
3. Emre, M. et al. Clinical diagnostic criteria for dementia associated with Parkinson’s disease. Mov. Disord. Off. J. Mov. Disord. Soc. 22, 1689–1707; quiz 1837 (2007).