Feasibility and safety of a non-operative clinical strategy for radiologically diagnosed low grade anterior mesial temporal tumours in the absence of a histological diagnosis.

Abstract

Background: Although resection of mesial temporal lobe lesions can be achieved with relatively low morbidity, resective surgery is not without risk. Whilst many lesions found in the anterior mesiotemporal lobe are low-grade entities, transforming and high-grade lesions have also been demonstrated. We investigate the feasibility of utilising serial quantitative volumetric imaging, to determine if a strategy of imaging surveillance can be safely employed for the management of radiologically diagnosed anterior mesial temporal low-grade tumours without a confirmed histological diagnosis.

Methods: A retrospective case-note and radiology review design were utilised. The primary presenting symptomatology was recorded together with the efficacy of symptomatic control. Volumetric analysis of MRI images was performed using Brainlab software. Pre- and post-operative neuropsychological data were analysed.

Results: 35 patients were identified with a radiological diagnosis of a low-grade anterior mesial temporal lobe tumour. Of these, 29% (n = 10) underwent surgical resection. For the whole cohort, the mean tumour volume at diagnosis was 6.5cm³, with a mean volumetric expansion of 1.4% per month. A significant difference was found between the volumetric expansion rate of those that underwent surgical treatment and those that did not (4.9% per month vs 0.06% per month, p < .01). Of those cases that did not undergo surgical resection, no significant difference was seen between the initial diagnostic volume and the volume at the time of their most recent interval surveillance scan (p = .97). New onset epilepsy was significantly associated with a requirement for eventual surgical tumour resection; relative risk = 6.25, 95% CI = 1.5-25.9, p = .0114.

Conclusion: Where medical seizure control is adequate, we suggest that conservative management is feasible even in the absence of a confirmed histological diagnosis. However, in patients aged over 50 years with new onset epilepsy, a lower threshold for intervention should be considered.