Patients
A total of 137 patients with acute lacunar stroke hospitalized in Changzhou No.2 people's Hospital from February 2019 to July 2020 were collected. Inclusion criteria:(1) Patients with first lacunar stroke; (2) age between 50 and 80 years at the inclusion; (3) Hearing is normal; (4) No history of dementia. (6) Be able to complete the MRI examination of the skull and P300 ERP detection. Exclusion criteria: (1) Known history of stroke, epilepsy, depression (excluded by self-rating depression scale) or other neurological or mental disorders (excluded by clinical evaluation and known history); (2) hearing loss and inarticulate; (3) weakness of the right limb. (4) Cognitive disorders that may be caused by other diseases (e.g. cancer, hepatorenal insufficiency, anemia, hypothyroidism). (5) Take drugs that affect cognitive function, such as anti-anxiety drugs.
Among these subjects, 3 subjects had hearing loss, 12 subjects had weakness of the right limb, and 8 subjects had inarticulate. Finally, 114 subjects performed P300 ERP and MRI examination and neuropsychological assessment. Dividing the total number of H-EPVS≥ 7 into extensive H-EPVS group (n = 61) and non-extensive H-EPVS group (n = 53). Physiologically right-handed. This study was approved by the Instituted Ethics Committees of the Changzhou No.2 people's Hospital Affiliated to Nanjing Medical University (NO.2018-KY032-01). Informed consent was obtained from all participants.
EPVS and other markers
We used GE 3.0T MR (Discovery MR750, USA) imaging system scan the T1WI, T2WI and T2 Flair sequence of all subjects. EPVS showed round, oval and linear structures with clear boundaries consistency in the direction of perforating arterioles (due to differences in location and section) on MRI. T1WI and FLAIR sequences showed low signal intensity, T2WI showed high signal intensity, and was the same as cerebrospinal fluid signal. EPVS usually occurs in BG, CSO, hippocampus and brainstem. Visual quantification was used to count the largest number of EPVS in unilateral BG and CSO plane [6] : grade 0, was non-EPVS; grade 1 was EPVS≤ 10; grade 2 was EPVS 11~20; grade 3 was EPVS 21~40; grade 4 was EPVS>40. Grade 0~1 was defined as mild EPVS, Grade 2~4 was defined as moderate -severe EPVS [6] (Fig1 B~C). We calculate total count of left and right hippocampus, H-EPVS≥ 7 was defined as extensive H-EPVS, H-EPVS< 7 was defined as non-extensive H-EPVS [7, 8] (Fig1 A). We only calculate the maximum diameter < 3mm EPVS, because the EPVS of > 3mm may have different pathogenesis.
The white matter hyperintensities (WMH) was the speckled or patchy high signal changes of the paraventricular or deep white matter on the FLAIR sequence. Fazekas score ≤ 2 was defined as mild WMH, Fazekas score ≥ 3 as moderate- severe WMH [9] (Fig1 D). Lacunar infarction usually shows marginal high signal intensity on T2WI sequence with a diameter of ≥ 3 mm.
Cognitive assessment
All subjects were evaluated by the same physician trained by the formal unified neuropsychological scale in the same environment. The test scale includes overall cognitive function, memory, information processing speed, executive function and verbal fluency function. Convert the each test scores into standardized Z-score (individual test score - mean test score) / standard deviation [10]. Finally, the test Z-score of each cognitive domain is averaged, and the compound Z-score of the cognitive domain is obtained. The higher the Z-score, the better the performance.
The test scale includes: (1) Overall cognitive function: Montreal cognitive assessment (MoCA) has been widely used in vascular cognitive impairment and Mild cognitive impairment screening. Compared with mini-mental state examination (MMSE), it has higher sensitivity and specificity [11]. (2) Memory Z-score: Auditory word learning test (AVLT), Digit span test (DS)forward, Z = (Z/ AVLT immediate recall + Z/ AVLT delayed recall + Z/ AVLT recognition + Z/ DS forward) / 4. (3) Information processing speed Z-score: Symbol digit modalities test (SDMT), Trail making test-A(TMT-A), Stroop color-word test-A(SCWT-A), Stroop color-word test-B(SCWT-B), Z= (Z/SDMT+Z/TMT-A+ average Z/ SCWT-A + SCWT-B completion time) / 3. (4) Executive function Z-score: SCWT interference score = SCWT completion time (SCWT-A+ SCWT-B) average completion time, TMT interference times=TMT-B-TMT-A, DS backward, Z= (Z/ SCWT interference score +Z/ TMT interference times + Z/ DS backward) / 3. (5) Verbal fluency Z-score: Semantic verbal fluency, Phonemic verbal fluency, Z= (Z/ Semantic verbal fluency +Z/ Phonemic verbal fluency) / 2 [12].
P300 ERP data acquisition
The P300 wave was generated from the keypoint EMG evoked potential instrument produced by Dandy Company. The reference electrode was placed in the posterior mastoid of both ears, the recording electrode was placed at the Cz point, and the ground electrode was placed in the center of the forehead. It was suitable for scrub to reduce the resistance of each electrode to less than 5K Ω, and the sensitivity was 5μV. Auditory Oddball mode was selected, which consists of two different frequencies of sound. One was target stimulus, also known as treble stimulus, the occurrence rate was 20%. The other was non-target stimulus, also known as bass stimulus, the occurrence rate was 80%. The two stimuli occur irregularly alternately, the interval of sound stimulation was 1.5s, superimposed 200 times. Keystroke responses to Target stimuli is monitored when the patients stays quiet and with closed eyes. The reaction time and hit rate of the subjects were recorded, the test was repeated twice, and the average value was taken.
In this study, basic waveform on the Cz points were recorded, the P300 latency (the straightline distance from the start of stimulation to the peak of the maximum P300 amplitude) and amplitude (the vertical distance from the baseline to the peak of P300) were analyzed in both groups.
Statistical analysis
H-EPVS was classified as extensive H-EPVS and non-extensive H-EPVS according to H-EPVS counts (≥ 7H-EPVS). To study the risk factors associated with H-EPVS classification (non-extensive and extensive H-EPVS), we first conducted a univariate analysis to associate H-EPVS classification with demographic information, VRF, P300 ERP, neuropsychological scale evaluation and other cerebral small vascular disease (CSVD) markers. Pearson’s χ2 was used for the comparison of categorical variables, and Mann-Whitney U test or t test was used for continuous variables (Table 1). Second, Spearman correlation analysis was used to analyze the correlation between information processing speed Z-score, speech fluency Z-score, P300 latency and H-EPVS counts (Fig 2). After adjusting the covariates of age, sex and education years, further analysis the relationship between H-EPVS count and P300 latency. The results were expressed in terms of β and 95% confidence interval (Table 2). Finally, receiver operating characteristic (ROC) curves was generated, and analyze the specificity and sensitivity of P300 latency in predicting cognitive impairment with extensive H-EPVS in patients with acute lacunar stroke.