Diffusion changes in minimally invasive parafascicular approach for deep-seated tumours: impact on clinical outcomes

Minimally invasive parafascicular surgery (MIPS) with the use of tubular retractors achieve a safe resection in deep seated tumours. Diffusion changes noted on postoperative imaging; the significance and clinical correlation of this remains poorly understood. Single centre retrospective cohort study of neuro-oncology patients undergoing MIPS. The impact of surgical approach-transsulcal (TS) versus transgyral (TG) - and respective entry points in clinical and imaging outcomes was assessed. 82 patients (35 male; 47 female, average age 43.94 +/- 22.85 years) were included. 84% presented with neurological deficit and glioblastoma was the commonest diagnosis (38.24%). Surgical approach was not relevant for the number of patients that showed postoperative peritubular injury (TS: 20 (37.74%) versus TG: 8 (27.59%), p = 0.354) or its volume (TS: 0.95 +/- 1.82 cc versus TG: 0.43 +/- 1.32 cc, p = 0.1435). When adjusted for preoperative volume and depth of tumour, TS approach was associated with less diffusion restriction (p = 0.030). Temporal lobe access points had the highest volume of diffusion restriction (temporal lobe-2.50 +/- 3.54 cc versus frontal lobe - 1.15 +/- 1.53 versus parietal lobe-0.51 +/- 0.91 cc, p = 0.0096), particularly in the TS approach (p = 0.0152). Superior motor outcomes were demonstrated in the TS versus the TG approach (postoperative improvement: TS: 14.63% versus TG: 6.9%, p = 0.015), especially for parietal approaches (p = 0.039). TS approach was related with a significantly decreased length of stay (TS-11.67 +/- 14.19 days versus TG - 23.97 +/- 18.01 days, p = 0.001). Transsulcal approach demonstrated a better motor outcome profile, particularly in parietal lobe, and shorter length of stay. The superior temporal sulcus was more susceptible to ischaemic changes. Therefore, transgyral route can be considered in temporal lobe MIPS.