OVERVIEW
Dementia with Lewy bodies (DLB) is a group of neurodegenerative disorders characterized by fluctuating cognitive dysfunction, visual hallucinations, and Parkinson’s syndrome, with Lewy bodies as a pathognomonic feature, which overlap clinically and pathologically between Parkinson’s disease and Alzheimer’s disease. Most scholars believe that this disease has constituted an independent disease, and it is more common in the elderly, with a slight increase in males than females.
Etiology
The etiology and pathogenesis are unclear. It has been found that DLB and Parkinson’s disease Lewy bodies are abnormal aggregates of α-synuclein from soluble to insoluble, factors affecting the expression and metabolism of α-synuclein may be related to the pathogenesis of DLB, and DLB usually has little family genetic predisposition. Experimental evidence suggests that cholinergic and monoaminergic neurotransmitter impairment in DLB may be associated with cognitive impairment and extrapyramidal movement disorders.
Symptoms.
The course of the disease is slowly progressive, culminating in full-blown dementia after several years. In the early stages, most cases have a temporoparietal type of cognitive functioning, characterized by impairments in memory, language, and visuospatial skills, similar to those seen in Alzheimer’s disease (AD).Fluctuating impairments in cognitive functioning are seen in DLB. Most patients with DLB have true visual hallucinations, and the hallucinatory images are often vivid and vivid. Hallucinatory objects tend to be familiar characters or animals, and these visual images are often moving, talking, or making sounds, and occasionally the hallucinatory images are distorted. Some patients with DLB may have myoclonus, choreiform movements and other motor abnormalities, and patients with DLB are more likely to experience syncope.
Examination
1. Measurement of cerebrospinal fluid
Measurement of APOE polymorphism Tau protein quantitative β-amyloid fragment in serum has diagnostic and differential significance.
2. CT and MRI examination
No characteristic changes, diffuse cerebral atrophy or focal frontal lobe atrophy to a lesser extent can be seen in some cases.MRI coronal scan helps to differentiate DLB from AD, which can have medial temporal lobe atrophy and DLB is not obvious.
3.18F-dopaPET examination
Dopamine uptake in the substantia nigra and striatum can be found to be reduced. PET shows that the glucose metabolic rate of temporal-parietal-occipital cortex is reduced more severely than that of AD, which may be related to visuospatial disorders and visual hallucinations of DLB, etc. In AD, it is mainly the glucose metabolic rate of temporal lobe and cingulate gyrus that is reduced.
4. Early EEG
Most of them are normal, and a few of them show reduced background wave amplitude, visible 2-4Hz periodic discharges, and slowing down of basic rhythm. More patients can see reduced alpha wave and transient slow wave in temporal lobe area, and transient frontotemporal lobe bursting activity can be seen. The presence of abnormal rapid eye movement phase in sleep EEG is informative for diagnosis.
Diagnosis
1. Requirements for clinical diagnosis of DLB
Including progressive cognitive decline, affecting social and work ability; with 2 of the following 3 items:
(1) Fluctuating cognitive dysfunction, with the most pronounced fluctuations in attention and alertness;
(2) Recurrent visual hallucinations;
(3) concurrent or subsequent onset of Parkinson’s syndrome.
2. Conditions supporting the diagnosis of DLB
(1) Recurrent falls;
(2) Syncope;
(3) Transient loss of consciousness;
(4) Sensitivity to tranquilizers;
(5) other forms of hallucinations.
3. MRI coronal scan
DLB temporal lobe atrophy is not obvious, and AD medial temporal lobe atrophy, which helps to differentiate. early EEG of DLB is mostly normal, with a few background wave amplitude reduction, visible 2-4Hz periodic discharges, temporal lobe alpha wave reduction and transient slow wave. The presence of abnormal rapid eye movement periods on sleep EEG is of some value in the diagnosis.
Questions you may be concerned about
What are the diagnostic criteria for dementia with Lewy bodies?
The diagnostic criteria of dementia with Lewy bodies mainly include the following two aspects, i.e. the necessary conditions for diagnosis and some symptoms that support the diagnosis.
1. Requirements for diagnosis: Progressive cognitive decline, with impact on society or family and work.
(1) Cognitive functioning is mainly characterized by impairments in attention, executive functioning, and visuospatial functioning.
(2) Recurrent visual hallucinations.
(3) Symptoms of Parkinson’s syndrome are present at the same time as or after the onset of the disease.
If two of the above three symptoms are present, the diagnosis of dementia with Lewy bodies is likely. If only one of these symptoms is present, the diagnosis of dementia with Lewy bodies is likely.
2. Symptoms that support the diagnosis: recurrent falls, syncope, transient loss of consciousness, sensitivity to tranquilizers, or other forms of hallucinations. The three core symptoms are fluctuating cognitive dysfunction, recurrent detailed visual hallucinations, and spontaneous Parkinson’s syndrome.
If you feel unwell, you should go to a regular hospital in time and take active treatment under the guidance of a specialized doctor.
Differential Diagnosis
1. Alzheimer’s disease (AD)
The main manifestation of progressive cognitive impairment, often due to forgetting, fictional hallucinations depicted ambiguous, mental behavioral abnormalities, advanced patients may have extrapyramidal symptoms, not easy to distinguish from DLB, DLB cognitive impairment manifested fluctuating, depending on the content of the hallucination is specific, vivid, the patient can be image descriptions and convinced; there is a clear visual impairment, extrapyramidal manifestations appear earlier, CT and MRI examination shows Diffuse cortical atrophy.
2. Parkinson’s disease (PD)
Some patients with PD may develop dementia in the late stage, and visual hallucinations can be produced during drug treatment, which is clinically similar to DLB. However, dementia symptoms of patients with PD appear several years after the onset of the disease, characterized by subcortical dementia, with prominent dyskinesia, which disappears with levodopa. patients with DLB have fluctuating cognitive deficits in the early stage, and dyskinesia manifests itself in the form of tonic hypokinesia and seldom typical resting tremor, which usually responds poorly to the treatment with levodopa. The response to levodopa treatment is usually poor.
3. Vascular dementia
There is often a clear history of stroke and neurological focal signs, with stepwise progression, clear neuroimaging, suggesting infarctive or hemorrhagic foci, which is easy to differentiate from DLB.
4. Creutzfeldt-Jakob disease (CJD)
Characterized by dementia and extrapyramidal damage, with rapid progression, diverse extrapyramidal signs, myoclonus and seizures, typical EEG changes help diagnosis.
5. Progressive supranuclear palsy (PSP)
Before the appearance of eye movement disorder, PSP and DLB are more difficult to distinguish. PSP dementia is subcortical dementia with no fluctuating symptoms, and visual hallucinations are rare.
Treatment
The principle of treatment for DLB is the same as that for other dementias, and the main objectives are to improve cognitive function, relieve psycho-behavioral symptoms and improve social life ability. However, psychobehavioral symptoms and extrapyramidal symptoms are more prominent in DLB patients and often become the main focus of treatment.
Currently there is no specific treatment for DLB, patients may respond well to anticholinesterase drugs such as tacrine and donepezil, which may improve cognitive function and behavioral deficits.DLB is particularly sensitive to side effects of tranquillizers and antipsychotics, and susceptible to drowsiness and coma, which is a characteristic that distinguishes it from other types of dementia, and is not used or used with caution. Newer antipsychotics such as Visteon and olanzapine are more effective for visual hallucinations. Depressive symptoms can be treated with selective 5-HT receptor reuptake inhibitors such as fluoxetine and citalopram.
Prognosis
Patients have a poor prognosis, with a disease duration of 5 to 10 years, and most die from complications.
Prevention
There is no effective prevention method, early diagnosis and early treatment may slow down the irreversible process of dementia.