Impact of Parameters of Radiofrequency Coagulation on Volume of Stereotactic Lesion in Pallidotomy and Thalamotomy

Abstract

Background: One of the many reasons why lesional surgery for movement disorders has been more or less abandoned may have been the difficulty in predicting the shape and size of the stereotactic radiofrequency (RF) lesion. Objectives: To analyse the contribution of various RF coagulation parameters towards the volume of pallidotomies and thalamotomies. Methods: The relationship between temperature of coagulation, length of coagulated area and duration of coagulation on the one hand, and lesion volume on the other was retrospectively evaluated. Lesion diameters were measured on stereotactic thin-slice CT and MRI scans, and volumes of lesions were calculated concerning 36 pallidotomies and 14 thalamotomies in 46 patients who were operated using the same RF generator and same RF electrode. Results: The coagulation temperature, length of coagulated area and duration of coagulation were all correlated to the lesion volume. However, for a given length of coagulated area, the lesion´s size was most strongly influenced by the temperature. Despite this clear correlation, and the relatively homogenous coagulation parameters, the lesions’ volumes were markedly scattered. Conclusions: The volume of the stereotactic RF lesions could be correlated with the coagulation parameters, especially the temperature, at a group level, but could not be predicted in individual patients based solely on the RF coagulation parameters.

Deep Brain Stimulation of the Ventroposteromedial (VPM) Thalamus 10 Years after VPM Thalamotomy to Treat a Recurrent Facial Pain

“…According to the literature, the size of a thalamotomy lesion differs from one individual to other and is unpredictable, even when performed under constant thermocoagulation parameters [15]. It ranges from no lesion [16] to a 177-mm 3 lesion, with mean values varying from 26 to 74.5 mm 3 [15,16,17].…”

“…It ranges from no lesion [16] to a 177-mm 3 lesion, with mean values varying from 26 to 74.5 mm 3 [15,16,17]. The volume of the thalamotomy lesion, measured in our patient with a fine-cut CT scan and MRI 10 years after the thalamotomy procedure, was about 269.6 mm 3 (4.65 mm in length, 5.73 mm in width, 10.12 mm in height), which is larger than the maximal estimated anatomical volume of the VPM nucleus.…”

Volumetric analysis of magnetic resonance–guided focused ultrasound thalamotomy lesions

“…1,4,6,21 Literature on radiofrequency thalamotomy has suggested that while treatment parameters correlate with some of the lesion characteristics, these alone could not predict lesion volume, likely due to individual variation. 12 Sonication parameters needed to achieve goal temperatures and clinical effects vary between patients due to individual variation in factors, such as skull characteristics. 2 In this series, to achieve the desired clinical effect, patients had anywhere between 2 and 7 suprathreshold sonications (10 seconds each) and a total of 15-28 sonications (including subthreshold).…”

Optical Monitoring Techniques for Navigation during Stereotactic Neurosurgery

“…(17) Another area where optical techniques have been introduced as intraoperative guidance tools is during stereotactic and functional neurosurgery. In functional neurosurgery, a small area of the brain is altered either by radiofrequency (RF) lesioning, i.e., thermal coagulation, (18,19) deep brain stimulation (DBS), (20,21) or cell-line implantation. (22,23) Of these named methods, DBS is the method most commonly used today, with more than 120000 lead implantations worldwide.…”

“…(29) During stereotactic neurosurgery, impedance measurements are often performed in relation to RF lesioning, i.e., coagulation of a small brain region in the pallidum or thalamus to alleviate movement disorders. (19) The principle is similar to DBS, i.e., that the cluster of nerves creating the symptoms are affected. However, due to the irreversible effect of the RF technology, many clinical centers prefer to use DBS instead.…”