Multichannel EEG Frequency Analysis and Somatosensory-Evoked Potentials in Patients with Different Types of Organic Dementia

110

Objective: To investigate the relationship between quantitative EEG (qEEG) measurements in frontotemporal dementia (FTD), Alzheimer’s disease (AD) and healthy controls and to study to what extent qEEG in FTD and AD or neuropsychological test results of FTD and AD patients or a combination of both contribute to classification accuracy. Method: The FTD sample consisted of 19 patients, the AD sample of 16 patients, and the control group of 19 subjects. Groups were matched on the group level with respect to demographic variables. For qEEG the global field power was calculated for six frequency bands: δ (1.0–3.5 Hz), Θ (4.0–7.5 Hz), α (8.0–11.0 Hz), β1 (12.0–15.5 Hz), β2 (16.0–19.5 Hz), β3 (20.0–23.5 Hz), and spectral ratio as the ratio of the sum of fast frequency bands α + β1 + β2 + β3 and slow frequency bands δ + Θ. Results: In comparison to controls FTD patients were marked by an absence of an increase in slow qEEG activities and a decrease in fast activities, whereas AD patients were marked by an increase in slow activities and a smaller decrease in fast activities. According to the Mann-Whitney U test the cognitive functions of attention, visuospatial thinking and episodic memory were significantly better in FTD than in AD. Using logistic regression analysis the best predictors of FTD and AD were in a model using the δ and Θ activities, and high levels of visuospatial ability and episodic memory. Classification accuracy of the model was 93.3%. Conclusion: FTD patients reveal a different pattern of qEEG changes than AD patients. This result demonstrates the importance of qEEG for FTD diagnosis. Cognition is selectively better in FTD than in AD. A combination of qEEG and neuropsychology is recommended for differential diagnoses of FTD and AD.

Section: Discussioncontrasting

confidence: 99%

Quantitative EEG Abnormalities and Cognitive Dysfunctions in Frontotemporal Dementia and Alzheimer’s Disease

Lindau

Jelić

Johansson

et al. 2003

110

“…There are few neurological symptoms in FTD, although primitive reflexes may appear comparatively early as may urinary incontinence, while rigidity and tremor are late phenomena. Epileptic seizures are rare and EEG often remain normal despite clinically evident dementia [27,28]. Low and labile blood pressure are prevalent in FTD as also orthostatic blood pressure drops and syncopal attacks.…”

Section: Discussionmentioning

confidence: 99%

Magnetic Resonance Imaging and Histopathology in Dementia, Clinically of Frontotemporal Type

Larsson

Passant²,

Sundgren³

et al. 2000

Self Cite

The magnetic resonance imaging (MRI) and computed tomography findings in 28 patients with the clinical diagnosis of frontotemporal dementia (FTD) were compared with the findings in a control group of 76 individuals without dementia or stroke. A pattern of frontal and temporal atrophy with predominantly frontal white matter changes was found in the FTD patients, and this was significantly different from the radiological findings in the control group. Six of the FTD patients have undergone autopsy. Histopathological evaluation showed a primary cortical degenerative disease (frontal lobe degeneration of non-Alzheimer type) in 3 of them, and primary white matter disorder, mainly frontal, of basically ischemic type (selective incomplete white matter infarction) in 3 of them. MRI could be a helpful tool to support the clinical diagnosis FTD, especially in young patients. MRI may also be helpful for the differentiation of a primary neurodegenerative from a mainly ischemic-vascular type of dementia.

“…The effect on quantitative EEG of single intravenous doses of scopolamine has been suggest ed as a test of the degree of cholinergic deficiency in Alz heimer's disease [86], EEG in P ic k 's Disease and Frontal Lobe Dem entias EEG in patients with histologically verified frontotem poral cortical atrophy were found to be normal or moder ately abnormal despite prolonged dementia of increasing severity [37,68]. Quantified EEG showed a moderate and diffuse increase of relative 9 activity in a group of fronto temporal dementia patients, identified by their clinical Electroencephalography as a Diagnostic Tool in D em entia features and rCBF [57], Further observations in a larger group of patients [Passant et al, unpubl. data] localized the maximum 0 abnormality over the posterior parts of the brain.…”

Section: Differentiation Between D a T And Cerebrovascular Dementiamentioning

confidence: 93%

“…The heterogeneity of DAT was further illus trated with multichannel brain mapping applied to two groups of DAT patients, one with predominant memory deficit, and one group with progressive spatial impairment [54,55] with differences located to the parietal region. Mapping studies usually show a widespread increase of 0 and 8 activity, and a more localized decrease of a and [3 activity [28, [55][56][57], Breslau el al. [58] found marked asym metry' of8 activity over temporal lobes, in correspondence with the PET findings ofFricdland ct al.…”

Section: Eeg In Dementia Of Alzheim Er Typementioning

confidence: 99%

Electroencephalography as a Diagnostic Tool in Dementia

Rosén

1997

Self Cite

Clinical electroencephalography is a relatively simple and inexpensive diagnostic tool with a high sensitivity for diffuse organic encephalopathy of various aetiologies but with a rather low specificity for the type of diagnosis. The highest sensitivity is shown in DAT and Parkinson dementia, and in these conditions the degree of EEG abnormality is correlated with the disease severity. Quantification of EEG makes these correlations more reliable and provides a method for monitoring therapeutic effects. Dementias with predominantly frontal pathology show much less EEG abnormality, and in these conditions the EEG is often normal despite obvious clinical dementia. Also, alcohol dementias often show normal EEG patterns. At an early stage of clinical evaluation, EEG may be useful in the discrimination of organic dementia from pseudodementia, because EEG is usually normal in depression, confusion, agitation and other psychiatric conditions. In pseudodementia due to intoxication with sedatives the EEG is usually dominated by diffuse β activity. At the stage of differential diagnosis of an organic brain disorder, EEG cannot reliably discriminate between encephalopathies secondary to hydrocephalus, AIDS, cerebrovascular disease, B12 deficiency and primary degenerative diseases such as DAT. More specific EEG patterns are seen in acute cerebrovascular lesions, metabolic encephalopathies, i.e. of hepatic origin, Creutzfeldt-Jakob disease, herpes encephalitis, and nonconvulsive status epilepticus as possible causes of a rapidly deteriorating mental and neurological condition. Repeated EEG recordings over time would add significantly to the diagnostic information. New techniques such as topographical brain mapping, analysis of the EEG during REM sleep, coherence analysis of the EEG activity, and the combination of quantified EEG techniques with evoked potentials and event-related potentials will presumably add to the sensitivity as well as the specificity of the electrophysiological methods in the diagnosis of dementia.