ESTRO 2021 Abstract Book

S637

ESTRO 2021

Conclusion Delivering SFRT in five fractions for vestibular schwannoma appears safe, and efficient combining both, efficiency and short treatment time while optimizing neurological function preservation

PD-0804 Therapeutic use of Linac-based SRS in the treatment of malignant spasticity L. Nicosia 1 , P. Romanelli 2 , F. Ferrari 3 , F. Marchioretto 4 , M. Zamperini 5 , A. De Simone 1 , R. Ruggieri 1 , F. Alongi 1,6 , R. Avesani 3 1 IRCSS Sacro Cuore Don Calabria Hospital, via Don A. Sempreboni 5, 37024, Advanced Radiation Oncology Department, Negrar, Italy; 2 Centro Diagnostico Italiano, Neurosurgery, Cyberknife Center, Milan, Italy; 3 IRCSS Sacro Cuore Don Calabria Hospital, via Don A. Sempreboni 5, 37024, Department of Rehabilitation, Negrar, Italy; 4 IRCSS Sacro Cuore Don Calabria Hospital, via Don A. Sempreboni 5, 37024, Neurological Unit, Negrar, Italy; 5 IRCSS Sacro Cuore Don Calabria Hospital, via Don A. Sempreboni 5, 37024, Department of Anesthesia, Intensive Care and Pain Therapy, Negrar, Italy; 6 University of Brescia, -, Brescia, Italy Purpose or Objective spasticity is a clinical event characterized by increased muscle contraction, sometimes painful, secondary to central nervous system damage. This can be evoked both by an active and passive muscle movement. It has several social and rehabilitation consequences with a high rate of nursing procedures, hospital admissions, and costs. The quality of life of these patients can be severely impaired with problems in sleeping, breathing, and speaking. In the case of systemic spasticity, the standard treatment option is represented by oral or intrathecal baclofen. In the case of focal spasticity, the most frequent treatment options are intramuscular botulinum toxin, alcoholic or surgical neurolysis or, less commonly, selective neurotomies or rhizotomies. However, these procedures requires a surgical intervention with infective, anesthetic and surgical complications. Surgical interventions are characterized by prolonged surgical sessions, infective, anesthetic, and surgical complications. It requires an experienced team, the costs are relatively high, and the learning curve is slow. The aim of the present study is to evaluate the therapeutical effectiveness of linac-based stereotactic radiosurgery (SRS) in the treatment of malignant spasticity. Materials and Methods patients with spasticity to the lower limbs unresponsive to systemic therapies were treated with linac-based SRS to the spinal nerves responsible for the spasms within a prospective observational trial (n° 51262). Treatment dose was 45 Gy in a single fraction delivered with VMAT technique. The primary end-point was the reduction of the muscular resistance to passive movement measured with the Modified Ashworth Scale (MAS). Secondary end-points were toxicity, quality of life, and spinal nerves radiological features (fractional anisotropy, diffusivity, tractography). Results in December 2020, the first 2 patients were treated at our Institution. The first patient was treated at the bilateral spinal nerves L4-S1 and had a complete resolution of the spasms the day after SRS administration. The second patient was treated at the bilateral levels L3-L5 and had a progressive reduction up to 20% of the