缺血性中風病患腦波的時頻分析與小波轉換

Abstract

現行對於缺血性中風的治療多以手術或血栓溶解劑rt-PA的方式來進行治療，但這兩種方式皆有其時效限制。而根據腦中風醫學會的資料指出大部分國人的中風皆發生於睡眠中，而延誤治療的黃金時間，甚至由於無法確認中風確切發生的時間，故只能以就寢時間為基準判定中風時間，導致無法使用rt-PA進行缺血性中風的治療，影響缺血性中風病患的預後。 在相關文獻的探討中，發現有研究者中風患者與正常人的腦波在頻域上的alpha to delta ratio及alpha peak frequency會有差異，進一步的文獻指出缺血性中風腦波的頻率變化與大腦血流量相關。但是在目前的研究結果中尚未看到針對時域、頻域在各波段完整的特徵值分析。故本論文探討20位中風病患，依照中風位置將大腦分為中風區域半影區域及這兩個區域對稱區域的特徵值，分為四個頻段進行時域、頻域及時頻域，總共16個特徵值進行分析比較。並嘗試利用所得到的分析結果進行中風及非中風的演算法判讀。 本論文研究結果發現，中風區的slow alpha ADR、theta FR，半影區的fast alpha PKF、delta PKF在與其對稱區域的比較上皆有顯著差異(p<0.05)。各波段的特徵值中在與正常人腦波特徵值的比較上也有顯著差異。並以theta波的firing rate及delta波段的peak frequency當作偵測缺血性中風演算法的判斷特徵值，在十個包含正常人及缺血性中風病患的判讀實測中其sensitivity為75%、specificity為66.67%。

It is well established in clinics now to use surgical treatment or recombinant tissue plasminogen activator(rt-PA) approach to treatment for ischemic stroke, but both ways have their limitation. According Taiwan Stroke Association data indicate most people in Taiwan stroke in sleep, and miss an opportunity to use rt-PA in ischemic stroke treatment. It will seriously affect patients prognosis. In literature review, some researchers found that there are some significant different between normal person and stroke patient’s Electroencephalograph (EEG), such as alpha to delta ratio and alpha peak frequency in frequency domain. Further studies found that frequency in stroke patient’s Electroencephalograph have strongly correlate with cerebral blood flow. However, in the current study we haven’t seen the complete results analysis the time domain, frequency domain features in each frequency band. Therefore, this paper discusses 20 stroke patients Electroencephalograph(EEG) signal , according to the stroke area of the brain is divided into four regions, stroke region, penumbra region and these two areas symmetrical region, and divided into four bands in time domain, frequency domain and time-frequency domain, and a total of 16 characteristic values were analyzed and compared. Analysis of the results and try to use in ischemic stroke detection algorithm. This paper found that, slow alpha to delta ratio(slow alpha ADR) and theta firing rate(theta FR) in stroke area; fast alpha peak frequency(fast alpha PKF) and delta peak frequency(delta PKF) in penumbra area compare with the symmetrical region have significant difference(p <0.05). Each band eigenvalues also have significant differences in comparison with the normal people. And theta firing rate and delta peak frequency are use in ischemic stroke detection algorithm. In the algorithm test, ten people are classify in the algorithm including normal and ischemic stroke patients, the sensitivity was 75% , specificity was 66.67%.