Impact of biologically effective dose on tremor decrease after stereotactic radiosurgical thalamotomy for essential tremor: a retrospective longitudinal analysis

AbstractStereotactic radiosurgery (SRS) is one of the surgical alternatives for drug-resistant essential tremor (ET). Here, we aimed at evaluating whether biologically effective dose (BEDGy2.47) is relevant for tremor improvement after stereotactic radiosurgical thalamotomy in a population of patients treated with one (unplugged) isocenter and a uniform dose of 130  Gy. This is a retrospective longitudinal single center study. Seventy-eight consecutive patients were clinically analyzed. Mean age was 69.1 years (median 71, range 36–88). Mean follow-up period was 14 months (median 12, 3–36). Tremor improvement was assessed at 12 months after SRS using th e ET rating assessment scale (TETRAS, continuous outcome) and binary (binary outcome). BED was defined for an alpha/beta of 2.47, based upon previous studies considering such a value for the normal brain. Mean BED was 4573.1 Gy2.47 (median 4612, 4022.1 –4944.7). Mean beam-on time was 64.7 min (median 61.4; 46.8–98.5). There was a statically significant correlation between delta (follow-up minus baseline) in TETRAS (total) with BED (p = 0.04; beta coefficient − 0.029) and beam-on time (p = 0.03; beta coefficient 0.57) but also between TETRAS (ADL) with BED (p = 0.02; beta coefficient 0.038) and beam-on time (p = 0.01; beta coefficient 0.71). Fractional polynomial multivariate regression suggested that a BED >  4600 Gy2.47 and a beam-on time  >  70 min did not further increase cli...
Source: Neurosurgical Review - Category: Neurosurgery Source Type: research