Objective: To describe the experience of a single Spanish center in gamma knife thalamotomy (GKT) as treatment of refractory tremor in patients with Essential Tremor (ET) and Parkinson´s Disease (PD).

Background: GKT is a minimally invasive stereotactic surgical option to treat medically refractory tremor in patients with ET and PD, particularly indicated for elderly and fragile patients. Recent studies have shown good results in terms of safety and efficacy (1,2). However, long-term evidence is limited, especially for PD tremor.

Methods: During a 5-year period (2013-2017), 12 patients underwent unilateral GKT and were followed-up for at least 12 months with motor and neuropsychiatric evaluations. Five patients had asymmetric tremor predominant PD, 4 cases had intractable ET and 3 patients had ET-PD. Mean age was 78.8±6.8 years old (6 patients >75 years old). 2 patients were on anticoagulants. Leksell Gamma Knife was used to target the ventral intermediate nucleus with a radiation dose of 130 Gy. Efficacy was scored based on subscales of the Fahn-Tolosa-Marin (FTM) tremor rating scale, target-side tremor subscales of the motor part of the Unified Parkinson´s Disease Rating Scale (UPDRS), and EuroQoL-5D to assess quality of life.

Results: Median follow-up duration was 22 months (12-54 months). After GKT, 11 patients (91.7%) improved their tremor scores. 6 patients (50%), 3 PD, 2 ET and 1 ET+PD reported tremor erradication or minimal symptoms. Tremor improvement was sustained at the end of follow-up in 10 out of 11 patients (90.9%). Mean FTM scores improved significantly: for hand postural tremor, from 2.86 pre to 1.14 (p=0.006); for kinetic tremor, from 3.14 to 1.29 (p=0.007); for handwriting, from 2.57 to 1.29 (p=0.016); and for drinking, from 3.14 to 1.71 (p=0.015). Mean motor UPDRS scores significantly decreased: for rest tremor in the targeted upper limb, from 3.00 to 0.71 (p=0.001); and for overall tremor in the target-side, from 10.29 to 2.14 (p=0.002). EuroQoL-5D ameliorated from 8.89 to 6.56 (p=0.027). No severe adverse events occurred. Three patients reported transient hand paresthesias, cognitive disturbances without changes in neurophysicological tests and depression, respectively.

Conclusions: This study suggests that GKT is a safe and long-term efficacious treatment option for medically refractory ET, and may be considered for asymmetric tremor predominant PD, especially in patients who are elderly, on anticoagulants or have high surgical risk that contraindicates DBS.

References: 1. Martínez-Moreno NE, Sahgal A, De Salles A, Hayashi M, Levivier M, Ma L, Paddick I, Régis J, Ryu S, Slotman J, Martínez-Álvarez R. Stereotactic radiosurgery for tremor: systematic review. J Neurosurg. 2018 Feb 23:1-12. 2. Niranjan A, Raju SS, Kooshkabadi A, Monaco E, Flickinger JC, Lunsford LD. Stereotactic radiosurgery for essential tremor: Retrospective analysis of a 19-year experience. Mov Disord. 2017;32(5):769-777.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/gamma-knife-radiosurgery-for-essential-and-parkinsonian-tremor-long-term-experience-in-a-spanish-center/