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High-resolution diffusion tensor magnetic resonance imaging of the brainstem safe entry zones


Operative management of intrinsic brainstem lesions remains challenging despite advances in electrophysiological monitoring, neuroimaging, and neuroanatomical knowledge. Surgical intervention in this region requires detailed knowledge of adjacent critical white matter tracts, brainstem nuclei, brainstem vessels, and risks associated with each surgical approach. Our aim was to systematically verify internal anatomy associated with each brainstem safety entry zone (BSEZ) via neuroimaging modalities commonly used in pre-operative planning, namely high-resolution magnetic resonance imaging (MRI) and diffusion tensor tractography (DTT). Twelve BSEZs were simulated in eight, formalin-fixed, cadaveric brains. Specimens then underwent radiological investigation including T2-weighted imaging and DTT using 4.7 T MRI to verify internal anatomic relationships between simulated BSEZs and adjacent critical white matter tracts and nuclei. The distance between simulated BSEZs and pre-defined, adjacent critical structures was systemically recorded. Entry points and anatomic limits on the surface of the brainstem are described for each BSEZ, along with description of potential neurological sequelae if such limits are violated. With high-resolution imaging, we verified a maximal depth for each BSEZ. The relationship between proposed safe entry corridors and adjacent critical structures within the brainstem is quantified. In combination with tissue dissection, high-resolution MR diffusion tensor imaging allows the surgeon to develop a better understanding of the internal architecture of the brainstem, particularly as related to BSEZs, prior to surgical intervention. Through a careful study of such imaging and use of optimal surgical corridors, a more accurate and safe surgery of brainstem lesions may be achieved.

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Debraj Mukherjee, MD, MPH is partially supported by The Robert Wood Johnson Foundation, The Beckwith Institute, and an American Medical Association Foundation Seed Grant. None of these grants were used in this study.

Author information

Correspondence to Mustafa K. Başkaya.

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The authors declare that they have no conflict of interest.

Ethical approval

The complete study was performed on the cadaveric specimens of the Department of Neurosurgery, University of Wisconsin, Madison, USA. According to the Institutional Rules, the use of these cadaveric specimens for anatomical dissections does not require specific approval from ethics committee.

This article does not contain any studies with human participants or animals performed by any of the authors. For this type of study, formal consent is not required.

Additional information

This manuscript has been partially reported as an oral presentation at the Congress of Neurological Surgeons Annual Meeting in September 2016 in San Diego, USA.

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Mukherjee, D., Antar, V., Soylemez, B. et al. High-resolution diffusion tensor magnetic resonance imaging of the brainstem safe entry zones. Neurosurg Rev 43, 153–167 (2020). https://doi.org/10.1007/s10143-018-1023-4

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  • Brainstem
  • Diffusion tensor imaging
  • Magnetic resonance imaging
  • Microsurgical anatomy
  • Safe entry zone
  • Surgical approaches