Knowledge Vault 3/72 - G.TEC BCI & Neurotechnology Spring School 2024 - Day 8
Brain assessment parameters for stroke
Sebastian Sieghartsleitner, g.tec medical engineering GmbH (AT)
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Concept Graph & Resume using Claude 3 Opus | Chat GPT4 | Llama 3:

graph LR classDef main fill:#f9d4d4, font-weight:bold, font-size:14px; classDef stroke fill:#d4f9d4, font-weight:bold, font-size:14px; classDef eeg fill:#d4d4f9, font-weight:bold, font-size:14px; classDef recoveries fill:#f9f9d4, font-weight:bold, font-size:14px; classDef limitations fill:#f9d4f9, font-weight:bold, font-size:14px; A[Sebastian Sieghartsleitner] --> B[PhD: EEG, stroke recovery. 1] A --> C[Stroke: leading cause of
mortality, disability. 2] C --> D[2/3 survivors can't perform
daily activities. 3] C --> E[Recovery substantial early,
plateaus after 6 months. 4] A --> F[Scales evaluate function,
EEG detects brain changes. 5] F --> G[QEEG extracts parameters
describing brain function. 6] A --> H[Study: resting EEG vs
motor imagery with Recoveries. 7] H --> I[QEEG: DAR, PRI, BSI,
laterality coefficients. 8] I --> J[DAR, PRI: resting state,
lower is better. 9] I --> K[BSI: brain symmetry,
lower is better. 10] I --> L[Laterality: ERD/ERS in
contralateral vs ipsilateral. 11] H --> M[EEG parameters correlate
with clinical scales. 12] H --> N[Age doesn't affect BSI,
males less symmetric. 13] H --> O[Cortical/subcortical lesions:
less symmetry than healthy. 14] O --> P[Lower BSI correlates with
better upper extremity function. 15] H --> Q[Mu laterality correlates with
tremor, gross motor skills. 16] Q --> R[More negative laterality:
better motor function. 17] A --> S[EEG during Recoveries: potential
assessment parameter. 18] S --> T[Laterality decreases over
Recoveries sessions. 19] S --> U[Stronger ERD during
paretic motor imagery. 20] U --> V[ERD increase over premotor
areas: greater improvement. 21] A --> W[Recoveries limitations: wounds,
understanding, wakefulness, metal. 22] A --> X[EEG biomarkers correlate
with fMRI BOLD signal. 23] A --> Y[More BSI variability in
cortical vs subcortical lesions. 24] A --> Z[Presentation expanded on
Mark's earlier talk. 25] class A main; class C,D,E stroke; class F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,X,Y eeg; class W limitations; class B,Z recoveries;


1.- Sebastian Sieghartsleitner is doing a PhD analyzing EEG data from stroke patients undergoing recovery treatment with Recoveries.

2.- Stroke is a leading cause of mortality and disability, with prevalence decreasing but absolute numbers increasing due to aging population.

3.- Two-thirds of stroke survivors do not recover sufficiently to perform daily living activities, especially with upper extremity function.

4.- Recovery can be substantial in first months after stroke but plateaus after 6 months. However, recovery is still possible even in chronic stroke.

5.- Assessment scales evaluate motor function and changes but cannot directly detect changes in the brain. EEG can track neuroplastic changes.

6.- Quantitative EEG (QEEG) extracts parameters that describe brain function. Changes in EEG should relate to changes in clinical scales.

7.- The study compared resting state EEG in 32 healthy participants to EEG during motor imagery with Recoveries in 34 stroke patients.

8.- QEEG parameters included delta-alpha ratio (DAR), power ratio index (PRI), brain symmetry index (BSI), and laterality coefficients.

9.- DAR and PRI are based on resting state EEG. Lower values indicate better motor function. This was confirmed in stroke patients.

10.- BSI measures brain symmetry between hemispheres during rest. Lower values (more symmetry) are better. Stroke patients had higher BSI than healthy controls.

11.- Laterality coefficients measure ERD/ERS during motor imagery, comparing activity in contralateral vs ipsilateral hemispheres. More negative values indicate better motor function.

12.- Strong correlations were found between the EEG parameters and various clinical motor function scales in the stroke patients.

13.- Age did not significantly affect BSI in the healthy controls, but males had less brain symmetry than females.

14.- Stroke patients with cortical and/or subcortical lesions had significantly less brain symmetry than healthy controls based on BSI.

15.- Lower brain symmetry on BSI correlated with greater upper extremity motor function on the Fugl-Meyer assessment in stroke patients.

16.- The laterality coefficient for the mu (8-12 Hz) band correlated with tremor, gross motor skills, and upper/lower extremity motor function.

17.- More negative laterality coefficients, indicating greater activity in the contralateral hemisphere, related to better motor function in stroke patients.

18.- EEG data during Recoveries therapy can potentially provide an assessment parameter of motor function at baseline and improvement over time.

19.- The laterality coefficient decreased over the course of Recoveries therapy sessions, indicating increasing lateralization to the contralateral hemisphere and improved motor function.

20.- Event-related desynchronization (ERD) during paretic side motor imagery was stronger (more negative) in stroke patients with greater motor function.

21.- An increase in ERD strength over premotor areas from early to late Recoveries sessions related to greater improvement in motor function.

22.- Limitations of Recoveries include open scalp wounds, inability to understand instructions, staying awake, and metal implants interfering with stimulation or EEG.

23.- There is correlation between EEG biomarkers like the laterality coefficient and the BOLD signal on fMRI in stroke patients.

24.- More variability was seen in brain symmetry index for patients with cortical lesions compared to subcortical lesions, but the sample size was small.

25.- The presentation summarized work from papers published by Mark, who gave an earlier talk. Sebastian expanded on the EEG analysis.

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