Medial Gamma-Thalamotomy for Intractable Pain.

Objective: Ablative procedures are still useful in the treatment of intractable pain despite the proliferation of neuromodulation techniques. Here we present the results of gamma knife thalamotomy (GT) in various pain syndromes. Methods and Patients: Between 1996 and 2015, we performed unilateral GT in 18 patients (F:M = 12:6; age range 53-89, mean 80 yrs) suffering from various severe pain syndromes (3 thalamic pain, 5 postherpetic trigeminal neuralgia [TN], 4 resistant classic TN, 3 secondary TN, 2 TN with multiple sclerosis, 1 phantom pain), in whom conservative treatment had failed. The median follow up was 22 months (range 12-78 months). Invasive procedures for pain release preceded in 13 patients: gamma knife irradiation of the trigeminal nerve, balloon compression or glycerolysis in the cavum Meckeli. The Leksell Sterotactic Frame, Gamma- Plan Software (Elekta) and T1- and T2-weighted sequences acquired at 1.5 T (Siemens Avanto) were used for localization of the targeted medial thalamus - centrum medianum (CM). The CM was localized 4-6 mm lateral to the wall of the 3rd ventricle, 8 mm posterior to the mid-point and 3 mm superior to the intercommissural line. GT was performed by Leksell Gamma Knife with an applied dose ranging from 140 to 155 Gy; single shot, 4 mm collimator. Pain relief after radiation was evaluated. Decreased pain intensity to less than 50% of the previous level was considered as successful. Results: Initial successful results were achieved in 8 (44.4%) of the patients, with complete pain relief in 1 these patients. Relief was achieved after a median latency of 5 months (range 2-36 months). Pain recurred in 4 (50%) of patients after a median latent interval of 24 months (22-30 months). No neurological deficits were observed. Conclusions: Our results suggest that GT in patients suffering from severe pain syndromes is a relatively successful and safe method that can be used even in severely affected patients. The only risk of GT for our patients was failure of treatment, as we did not observe any clinical side effects. Supported by MH CZ - DRO (Nemocnice Na Homolce -NNH, 00023884), IG151201. [ABSTRACT FROM AUTHOR]