Key points
- Florey-led international research shows that structural changes following neurosurgery extend beyond the operation site, also leading to changes in distant brain regions.
- The researchers used sophisticated MRI acquisition and image analysis software to demonstrate that these brain changes occur at the endpoints of surgically disrupted pathways and onwards throughout the brain network.
- Their findings challenge the traditional view on how neurosurgery affects the human brain, potentially further enhancing the safety and effectiveness of life-changing treatment.
Neurosurgeons use resective surgery to remove a clearly defined section of the brain to treat a range of neurological conditions - from tumours through to epilepsy.
These highly specialised procedures require careful planning and compromise: removing enough tissue to treat the underlying condition, while preserving critical brain function, where possible.
New research published in the renowned journal Brain now shows that the structural effects of surgery can extend further than previously thought, challenging the traditional view on how surgery affects the human brain.
Researchers from The Florey Institute of Neuroscience and Mental Health found that even brain regions not directly implicated during surgery can change after the intervention.
Dr Philip Pruckner, lead author and Florey PhD student, explained that by using advanced MRI techniques, the team discovered that these changes are not random.
"Instead, they specifically occur at the endpoints of surgically disrupted brain pathways, as well as the pathways emanating from those endpoints," Dr Pruckner said.
"The surgical disruption of brain connections can lead to degeneration of cells at the endpoints of these connections, which then in return can cascade to other connected parts of the brain.
"Our research findings raise the exciting prospect of using advanced imaging methods to predict the effect of a surgical intervention, which could help guide more precise and individualised surgical planning in the future."
The work was conducted in collaboration with researchers at the Medical University of Vienna, where the patients included in this study were operated on to treat drug-resistant epilepsy.
Dr Pruckner this month was awarded the prestigious Austrian Ernst Niedermeyer Prize for Epileptology for the research.
Advanced diffusion MRI
To demonstrate that the surgery can affect interconnected anatomical networks of the brain, the researchers had to compare brain connections reconstructed from diffusion MRI before and after surgery. Unlike standard MRI, which shows only what the gross brain anatomy looks like, diffusion MRI enables the digital reconstruction of how different parts of the brain are connected.
For mapping these brain networks, the researchers relied on the widely used MRtrix3 software package, which was pioneered at The Florey.
During their analyses, however, they found that their existing state-of-the-art tools were not precise enough for the study's intended purpose, prompting them to develop more robust methods specifically tailored to look for changes in the brain's wiring over time.
"This research and the novel methods that facilitated it give us a clearer understanding of what surgery does to the brain's wiring as a whole," said Dr Robert Smith, senior author of the study and one of the lead developers of MRtrix3.
"It is really a unique opportunity to work in an environment that combines such strong clinical and technical expertise, allowing us to directly address challenges in clinical research as they arise," Dr Pruckner added.
The innovations that facilitated this study have now been integrated into the software, making them openly available for other researchers to use.
The researchers stressed that neurosurgery remains a very safe and effective treatment and advanced imaging could improve neurological interventions even further.
"By better tailoring neurological interventions to individual patients, surgeons can not only preserve brain tissues that does not need to be removed, but also potentially minimise network disruptions."
