Inverted positioning of Leksell Frame G for very low posterior fossa and brain stem lesions biopsies.

BACKGROUND: The specificity of imaging alone in diagnosing posterior fossa lesions is insufficient, hence the importance of biopsy for diagnostic, therapeutic and prognostic purposes. Concerning the operative technique, many studies have demonstrated the superior safety of stereotactic biopsy over craniotomy and superior accuracy of frame-based systems over frameless ones as far as the posterior fossa is concerned; however versatile, frame-based instruments bear some intrinsic limitations in the positioning of frame in lower lesions mainly in short neck and kyphotic patients. For all these reasons, a more proficient technical bioptic approach to the posterior fossa and lower brainstem is sometimes required.

METHODS: In order to obtain a specimen a Leksell System (Elekta®) constituted by the Leksell Coordinate G Frame (Article No: 014611), 4 adjustable posts (Article No: 1006476), 4 reusable screws (Article No: 1006581), an open indicator box (Article No: 1006559), a Leksell Multi-purpose Stereotactic Arc (Article No: 1008174) and a Sedan Needle (Article No: A2430-01) are required.

RESULTS: This is a simple and reliable technique to obtain a brainstem/cerebellar specimen maintaining unchanged the know risks of the procedure, as well the morbidity and mortality. We otherwise recommend this procedure to be performed by a team of neurosurgeons trained in stereotaxy.

CONCLUSIONS: If meticulously planned, our modified procedure provide a direct and precise access to deep seated areas of the posterior fossa and brainstem and is particularly helpful in those patients with short neck and kyphosis in which is crucial obtain an istopathologic diagnosis in lower posterior fossa.