Feasibility and Safety of Single-Probe Cryoablation with Liquid Nitrogen: An Initial Experience in 24 Various Tumor Lesions

Simple Summary

Percutaneous cryoablation was developed to minimally perform multi-organ tumor ablations. The most widely known cryotherapy systems use argon gas (high-pressure) and multiple needles to achieve sufficient ablations. The aim of our retrospective study was to assess the feasibility of a new cryotherapy system using single-probe liquid nitrogen for tumor lesions of various sizes and locations, and to evaluate the safety of cryoablation with this technique. Correlations between ice ball sizes and ablation zone sizes with two needle sizes (10G or 13G) and with the freezing duration were evaluated, as well as the sphericity of the ice ball and ablation zones. We showed that this technique is safe in all organs tested. We showed a correlation between the freezing duration and the ice ball size, but not with the ablation zone, which is useful for planning the procedure and treatment conducted by the oncology team.

Abstract

Background: Percutaneous cryoablation with liquid nitrogen is a new technique being used in the treatment of some malignant tumors. Our objective was to assess its feasibility in the ablation of tumor lesions of various sizes and locations. Methods: This retrospective, monocentric study included all consecutive patients who underwent percutaneous cryoablation with liquid nitrogen between December 2019 and March 2021. Cryoablation was performed using 10G or 13G cryoprobes. The ablation volume was measured on post-treatment CT or MRI. Results: 22 patients (24 lesions) were included, 16 of whom were men (73%), while median age was 66 years. The lesions were located in the bone (42%), kidney (29%), soft tissue (17%), lung (8%), or liver (4%). It was feasible in all tumor locations and produced median ablation zones 25 mm in width and 35 mm in length, with a 23 min median freezing time. Freezing duration was correlated with the ice volume (p Spearman = 0.02), but not with the ablation volume (p = 0.11). The average difference between the ablation zone and ice ball sizes were −6.4 mm in width and −7.7 mm in length. Both ice and ablation volumes were larger when using the 10G probe as compared to when the 13G was used. No complications were reported. Discussion: We showed that this technique was safe and feasible in all organs tested. The freezing duration was correlated with the ice ball size, but not with the ablation zone.

Antidepressant treatment in helpless rats: effect on the electrophysiological activity of raphe dorsalis serotonergic neurons

Chronic treatment with antidepressants renders serotonergic neuronal firing less sensitive to the inhibitory effect of serotonin (5-HT) reuptake blockers in the rat, and this has been considered as a major correlate of the therapeutic action of these drugs. We investigated whether the same mechanisms could be evidenced in an experimental model of depression, the learned helplessness paradigm. Rats rendered helpless by a single session of inescapable electrical footshocks exhibit, for several days, depression-like behavioural deficits which can be reversed by sub-chronic, but not acute, treatment with antidepressants. Recording of serotonergic neurons in the dorsal raphe nucleus revealed that, under baseline conditions, the spontaneous firing was similar in helpless rats and in non-helpless controls. However, neurons in the former group exhibited an enhanced sensitivity to the inhibitory action of the 5-HT reuptake blocker, citalopram (ED50 = 0.18 +/- 0.02 mg/kg IV in helpless rats versus 0.27 +/- 0.03 mg/kg IV in controls, P < 0.05). Treatment with zimeldine during 3 consecutive days induced in both helpless and control rats, a decrease in the inhibitory response of serotonergic neurons to the citalopram challenge, which resulted in a normalization of the neuronal reactivity in the helpless group (ED50 = 0.31 +/- 0.03 mg/kg IV). Since this adaptive phenomenon parallels the behavioural improvement induced by the repeated administration of zimeldine and other antidepressants in helpless rats, it might be considered as a crucial event in the mechanism of therapeutic action of these drugs.

Sleep deprivation reduces the citalopram-induced inhibition of serotoninergic neuronal firing in the nucleus raphe dorsalis of the rat

Sleep deprivation (SD) for one night induces mood improvement in depressed patients. However, relapse often occurs on the day after deprivation subsequently to a sleep episode. In light of the possible involvement of central serotonin (5-hydroxytryptamine, 5-HT) neurotransmission in both depression and sleep mechanisms, we presently investigated, in the rat, the effects of SD and recovery sleep on the electrophysiological response of 5-HT neurons in the nucleus raphe dorsalis (NRD) to an acute challenge with the 5-HT reuptake blocker citalopram. In all rats, citalopram induced a dose-dependent inhibition of the firing of NRD neurons recorded under chloral hydrate anaesthesia. After SD, achieved by placing rats in a slowly rotating cylinder for 24 h, the inhibitory action of citalopram was significantly reduced (with a concomitant 53% increase in its ED50 value). After a recovery period of 4 h, a normal susceptibility of the firing to citalopram was restored. The decreased sensitivity of 5-HT neuronal firing to the inhibitory effect of citalopram after SD probably results in an enhancement of 5-HT neurotransmission. Such an adaptive phenomenon (similar to that reported after chronic antidepressant treatment), and its normalization after recovery sleep, parallel the mood improvement effect of SD and the subsequent relapse observed in depressed patients. These data suggest that the associated changes in 5-HT autocontrol of the firing of NRD serotoninergic neurons are relevant to the antidepressant action of SD.