• Ivair Matias, Daoud Hibrahim Elias-Filho, Camila Araújo Bernardino Garcia, Guilherme Henrique Silva, Jorge Mejia, Francisco Romero Cabral, Ana Cláudia Camargo Miranda, Gomes da SilvaSérgioS3Hospital Israelita Albert Einstein; and.5Núcleo de Pesquisas Tecnológicas (NPT), Universidade de Mogi das Cruzes, São Paulo, Brazil., Luíza da Silva Lopes, Norberto Cysne Coimbra, and Hélio Rubens Machado.
• 1Laboratory of Pediatric Neurosurgery and Developmental Neuropathology, Department of Surgery and Anatomy.
• J. Neurosurg. 2019 Apr 1; 130 (4): 121012231210-1223.

ObjectiveThe objective of this study was to describe a new experimental model of hemispherotomy performed on laboratory animals.MethodsTwenty-six male young adult Wistar rats were distributed into two groups (surgery and control). The nonfluorescent anterograde neurotracer biotinylated dextran amine (BDA; 10,000 MW) was microinjected into the motor cortex area (M1) according to The Rat Brain in Stereotaxic Coordinates atlas to identify pathways and fibers disconnected after the experimental hemispherectomy. SPECT tomographic images of 99mTc hexamethylpropyleneamine oxime were obtained to verify perfusion in functioning areas of the disconnected and intact brain. A reproducible and validated surgical procedure is described in detail, including exact measurements and anatomical relationships. An additional 30 rodents (n = 10 rats per group) were divided into naïve, sham, and hemispherotomy groups and underwent the rotarod test.ResultsCortico-cortical neural pathways were identified crossing the midline and contacting neuronal perikarya in the contralateral brain hemisphere in controls, but not in animals undergoing hemispherotomy. There was an absence of perfusion in the left side of the brain of the animals undergoing hemispherotomy. Motor performance was significantly affected by brain injuries, increasing the number of attempts to maintain balance on the moving cylinder in the rotarod test at 10 and 30 days after the hemispherotomy, with a tendency to minimize the motor performance deficit over time.ConclusionsThe present findings show that the technique reproduced neural disconnection with minimal resection of brain parenchyma in young adult rats, thereby duplicating the hemispherotomy procedures in human patients.

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