Table 1. Overview of patient characteristics.
Continuous variables are expressed as mean (standard deviation).
Continuous variables were compared using the Mann–Whitney U test. Fisher’s exact test or the chi-square test was used for comparing categorical variables. Statistical significance was set at p-values <0.05. For statistical analysis methods that do not use test statistics (e.g., Fisher’s exact test), this field was marked as not applicable.
N/A: not applicable; MEP: motor evoked potential
| Characteristic | Postoperative motor function | Test statistics | P-value | |
| Stable (n = 117) | Decline (n = 8) | |||
| Age, years | 57.6 (18.7) | 59.75 (11.1) | U = 448.0 | 0.844 |
| Sex | χ2 = 2.811 | 0.094 | ||
| Male | 52 | 6 | ||
| Female | 65 | 2 | ||
| Body mass index, kg/m2 | 22.7 (3.7) | 21.7 (2.3) | U = 404 | 0.594 |
| Preoperative motor weakness | N/A | 0.039 | ||
| Positive | 30 | 3 | ||
| Negative | 87 | 5 | ||
| Pathological diagnosis | χ2 = 3.942 | 0.268 | ||
| Meningioma | 54 | 2 | ||
| Glioblastoma | 25 | 4 | ||
| Schwannoma | 8 | 0 | ||
| Others | 30 | 2 | ||
| Side of lesion | χ2 = 2.439 | 0.295 | ||
| Left | 49 | 3 | ||
| Right | 51 | 6 | ||
| Others | 17 | 0 | ||
| Tumor location | χ2 = 5.504 | 0.239 | ||
| Frontal lobe | 19 | 1 | ||
| Temporal lobe | 14 | 3 | ||
| Falx | 9 | 0 | ||
| Convexity | 18 | 0 | ||
| Others | 57 | 4 | ||
| Operative time, min | 553.7 (205.9) | 583.1 (252.7) | U = 448.5 | 0.879 |
| Methods of stimulation | N/A | 0.147 | ||
| Transcranial | 64 | 2 | ||
| Direct cortical | 53 | 6 | ||
| Muscle monitored by MEP | χ2 = 0.250 | 0.732 | ||
| Abductor pollicis brevis | 73 | 5 | ||
| Abductor digiti minimi | 24 | 2 | ||
| Tibialis anterior | 2 | 0 | ||
| Abductor hallucis | 18 | 1 | ||
| Amplitude of baseline MEP, μV | 919.8 (1085.9) | 394.9 (620.5) | U = 275.0 | 0.052 |
| Changes in intraoperative MEP response (vs. baseline amplitude) | N/A | 0.039 | ||
| MEP decline >50% | 30 | 5 | ||
| MEP decline ≤50% | 87 | 3 | ||
| Amplitude of last measured MEP, μV | 976.8 (1079.5) | 52.7 (92.0) | U = 55.5 | <0.001 |
| Amplitude ratio: last measured/baseline, % | 149.4 (126.7) | 55.7 (63.9) | U = 203.0 | 0.008 |