Dementia with Lewy bodies (DLB) is a type of dementia that presents with different clinical features such as Parkinsonism (tremor, bradykinesia, rigidity and postural instability), visual hallucinations, cognitive impairment, dysautonomia, sleeping disorders and neuroleptic sensitivity.
It may represent up to 4-30% of all dementias and it is the second most common type of degenerative dementia after Alzheimer disease.
Lewy bodies are neuronal inclusions that can be visualized using H&E stain. They are round, intracytoplasmic and eosinophilic, being surrounded by white halos. They are filled with ubiquitin and alpha-synuclein and are located mostly in the substancia nigra but may also be seen in other areas of the brain (limbic cortex, sympathetic neurons, dorsal vagal nuclei, pedunculopontine nucleus). Amyloid plaques may be visualized as well.
The diagnosis is suggested by history and physical examination and it can only be confirmed by pathological examination (which is not done in a regular basis). Having that in mind, it is possible to have a probable diagnosis of DLB or a possible diagnosis of DLB.
The consensus criteria for the clinical diagnosis of probable and possible dementia with Lewy bodies (DLB) are below:
- The central feature required for a diagnosis of DLB is progressive cognitive decline of sufficient magnitude to interfere with normal social or occupational function. Prominent or persistent memory impairment may not necessarily occur in the early stages but is usually evident with progression. Deficits on tests of attention and of frontal–subcortical skills and visuospatial ability may be especially prominent.
- Two of the following core features are essential for a diagnosis of probable DLB; one is essential for possible DLB.
a. Fluctuating cognition with pronounced variations in attention and alertness
b. Recurrent visual hallucinations that are typically well formed and detailed
c. Spontaneous motor features of Parkinsonism
- Features supportive of the diagnosis are the following:
a. Repeated falls
c. Transient loss of consciousness
d. Neuroleptic sensitivity
e. Systematized delusions
f. Hallucinations in other modalities
(Depression and REM sleep behavior disorder have been suggested as additional supportive features.)
- A diagnosis of DLB is less likely in the presence of
a. Stroke disease, evident as focal neurological signs or on brain imaging
- Evidence on physical examination and investigation of any physical illness, or other brain disorder, sufficient to account for the clinical picture
General measures to improve the quality of life should be discussed with the patient and family, such as visual or hearing aids if necessary, avoidance of dangerous or unfamiliar environments, fall prevention, cognitive exercises, hobbies stimulus, among others.
A challenging aspect of the pharmacological treatment is the fact that the antiparkinsonian drugs may worse the psychiatric symptoms, and the drugs for psychiatric symptoms may worse the Parkinsonism. The best balance among these two aspects of the disease and treatment should be decided in an individual basis.
Cognitive changes may be improved with acetylcholinesterase inhibitors (rivastigmine – EXELON – 6-12mg/day).
Parkinsonism may improve with dopamine agonists (carbidopa-levodopa – SINEMET – 25/100 mg TID).
Hallucinations should be managed ideally with non-pharmacological treatments. The investigation of infection or metabolic abnormalities that may be worsening the behavior may be relevant. Antipsychotics, particularly the typical ones, may cause neuroleptic malignant syndrome at higher rates in patients with DLB and should be avoided.
Autonomic dysfunction may be managed with reeducation regarding practical aspects of daily life to avoid syncope (proper hydration, slowly arising, and leg elevation when sitting), to avoid constipation (fiber ingestion, laxatives) or urinary symptoms (diapers or careful use of terazosin).
SOURCES & FURTHER READING:
- Zupancic M et al. Dementia With Lewy Bodies: Diagnosis and Management for Primary Care Providers. Prim Care Companion CNS Disord. 2011; 13(5): PCC.11r01190.
- Weisman D, McKeith I. Dementia with Lewy Bodies. Semin Neurol 2007; 27(1): 042-047.
- Neef D et al. Dementia with Lewy Bodies: An Emerging Disease. Am Fam Physician. 2006 Apr 1;73(7):1223-1229.
- McKeith IG et al. Dementia with Lewy Bodies. Neuropsychopharmacology: The Fifth Generation of Progress. Chapter 91: Dementia with Lewy Bodies. 1301-1315.