ORIGINAL ARTICLE - NEUROSURGERY GENERAL Brain biopsy in suspected non-neoplastic neurological disease Carolina Noronha 1,2 & Gonçalo Figueiredo 1 & Célia Pinheiro 1 & Ernesto Carvalho 1 & Alfredo Calheiros 1 & Manuel Melo Pires 3 & Ricardo Taipa 3 Received: 17 January 2019 /Accepted: 10 April 2019 # Springer-Verlag GmbH Austria, part of Springer Nature 2019 Abstract Brain biopsy has a well-established role in the diagnosis of CNS neoplasia. Nevertheless, despite being essential for the diagnosis of some benign neurological diseases, little consensus exists regarding its indications for disease diagnosis and patient orienta- tion. Our aim was to assess brain biopsy diagnostic yield in patients with neurological deterioration of unknown etiology, to identify the clinical characteristics associated with an increased likelihood of achieving a diagnostic biopsy as well as the characteristics linked to a particular diagnosis. Methods A retrospective analysis of 62 consecutive brain biopsies performed at a single tertiary care center between January 2004 and December 2015 for suspected non-neoplastic neurological disease was performed. The clinical presentation, imaging, and laboratory results were collected and compared between diagnostic groups. Results Sixty-eight percent of the biopsies led to a definitive diagnosis. The most common histological diagnosis was central nervous system lymphoma (eight cases), followed by astrocytoma, demyelinating disease, and progressive multifocal leukoencephalopathy (four cases each). No clinical characteristics were found to predict a diagnostic biopsy or to correlate with a specific diagnosis. Importantly, a distinct diagnosis from the initially suspected was achieved in 52% of cases and biopsy findings led to a change of therapeutic orientation in 78% of the cases. Conclusions Our results suggest that brain biopsies have a significant impact on patient management and should be considered early in selected cases in which less invasive testing was unable to reach a definitive diagnosis. Keywords Brain biopsy . Benign neurological disease Abbreviations ADC Apparent diffusion coefficient AIDS Acquired immunodeficiency syndrome CNS Central nervous system CSF Cerebral spinal fluid CT Computed tomography DWI Diffusion weighted imaging FLAIR Fluid-attenuated inversion recovery HBV Hepatitis virus B HCV Hepatitis C virus HAART Highly active anti-retroviral therapy HIV Human immunodeficiency virus MRI Magnetic resonance imaging PML Progressive multifocal leukoencephalopathy This article is part of the Topical Collection on Neurosurgery general Presented as a poster at the 2016 AANS Annual Scientific Meeting - Chicago, IL * Carolina Noronha noronhac44@gmail.com 1 Neurosurgery Department, Hospital Santo Antonio, Centro Hospitalar e Universitario do Porto, Largo Prof Abel Salazar, Porto 4099-001, Portugal 2 i3s Institute for Research and Innovation in Health, Universidade do Porto, Porto, Portugal 3 Neuropathology Unit, Hospital de Santo Antonio, Centro Hospitalar e Universitario do Porto, Porto, Portugal Acta Neurochirurgica https://doi.org/10.1007/s00701-019-03910-8