The safest electrode trajectory for deep brain stimulation of the human nucleus accumbens: a stereotactic anatomic study.

Background: The primary purpose of our stereotactic anatomic study was to determine the safest electrode trajectory for deep brain stimulation (DBS) of the human nucleus accumbens (NA). Considering NA DBS together with the complications related to surgical implantation and based on methods for assessing the electrode trajectory we tried to reveal the secret of a trajectory for targeting the NA with the highest possible level of safety.

Material and methods: Our material consisted of 30 cerebral hemispheres we have in our Department from cadaver donors for students' education. We identified the electrode's target point in coronal sections. As safe we considered a trajectory from the cerebral cortex to the NA, which traverses the anterior limb of the internal capsule (AIC) without passing through either the caudate nucleus or putamen. We measured the minimum, maximum and safest coronal angles of the electrode trajectory (between the trajectory and the midline), as well as the AIC angle and width of the trajectory angle. We also measured trajectory projection length from the cerebral surface to the superior (d1) and inferior (d2) margins of the NA.

Results: The safest trajectory angle for NA DBS was found to have a mean value of 29.10 degrees, ranging from 23.80 to 35.40 degrees. The mean AIC angle was 33.78 degrees. We found no statistically significant difference between right and left hemispheres and a strong statistical relation between the safest electrode trajectory and AIC angle. Mean values of d1 and d2 were found to be 53.57 mm and 60.86 mm respectively. The mean value of the length of the electrode trajectory in coronal projection within the NA (d2-d1) was found to be 7.29 mm.

Conclusion: The new knowledge that our stereotactic anatomic study offers is a definition of the safest electrode trajectory for NA DBS, its coronal angle width, as well as an estimation of its length.