3D Microsurgical Anatomy Advances the Search for Safe Entry Zones of the Brain-Stem

 Neuroscience  

A new study using intricate fiber dissection techniques provides new insights into the deep anatomy of the human brain-stem.  This work helps to define 'safe entry zones' for neurosurgeons performing brain-stem surgery.

A study using intricate fiber dissection techniques provides new insights into the deep anatomy of the human brain-stem—and helps to define "safe entry zones" for neurosurgeons performing brain-stem surgery, according to a special article published in Operative Neurosurgery, a quarterly supplement to Neurosurgery, official journal of the Congress of Neurological Surgeons.

Neurosurgeons Dr. Kaan Yagmurlu and Dr. Albert L. Rhoton, Jr, of University of Florida, Gainesville, and colleagues performed fiber tract dissections, along with three-dimensional photography, to explore and document the complex anatomy of the brain-stem. "We hope that the use of this knowledge will make surgical entry into the brainstem more accurate and safe," Dr. Rhoton and coauthors write.

"We hope that the use of this knowledge will make surgical entry into the brainstem more accurate and safe."

Working under the operating microscope, the researchers performed meticulous dissections of human brain-stem specimens. They used a technique called fiber tract dissection, which traces the complex course of the nerve fibers that make up the brain-stem. At each step of the dissection, 3D photographs were obtained. In some areas, a magnetic resonance imaging technique called diffusion tensor imaging was used to help in visualizing the nerve fiber tracts.

The lowermost portion of the brain is directly connected to the spinal cord. The brain-stem is involved in regulating some of the body's most basic functions. In addition to mapping and illustrating the inner anatomy of the brain-stem, the researchers sought to identify the best surgical approaches to specific brain-stem areas.

In their article, Drs. Yagmurlu and Rhoton and colleagues present richly detailed descriptions and 3D images of the fiber tract anatomy of the brain-stem. They also propose a short list of "safe entry zones" for each of the three major portions of the brain-stem: the midbrain, pons, and medulla.

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For each area, the suggested routes include key anatomical landmarks for the neurosurgeon to follow. The fundamental principle is to pass through as little normal tissue as possible, while avoiding critical areas and tracts.

"The safest approach for lesions located below the surface is usually the shorter and most direct route," the researchers write. However, for some parts of the brain-stem, a more circuitous approach is needed to reach the target while protecting essential functional areas.

Although previous studies have used fiber dissection techniques to examine safe entry zones to the brain-stem, most have focused on the surface anatomy. The new study is the first to use these techniques to define and document the "complex internal architecture" of the brain-stem.

Drs. Yagmurlu and Rhoton and coauthors note that their dissection study cannot account for the infinite variations in anatomy of the human brain-stem—the use of neurophysiological monitoring and mapping remains crucial during surgery. However, by providing unprecedented descriptions and 3D images of the inner anatomy of the brain-stem, the researchers hope their work will help neurosurgeons in planning the best approach to microsurgical procedures for gliomas (brain cancers) and blood vessel malformations in each area of the brain-stem.


SOURCE  Medical Xpress

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