Anatomy of the human subthalamic nucleus: a combined morphometric study

Abstract

Purpose. Our purpose was to provide a combined clinically oriented study focused on the detailed anatomy of the human STN, with great respect to its targeting. Methods. For our imaging study, we used cerebral magnetic resonance images (MRIs) from 26 neurosurgical patients and for our anatomic study 32 cerebral hemispheres from 18 normal brains from cadaver donors. We measured and analyzed the STN dimensions (based on its stereotactic coordinates). Results. At stereotactic level Z = -4, the STN length was 7.7 mm on MRIs and 8.1 mm in anatomic specimens. Its width was 6 mm on MRIs and 6.3 mm in anatomic specimens. The STN was averagely visible in 3.2 transverse MRI slices and its maximum dimension was 8.5 mm. The intercommissural distance was 26.3 mm on MRIs and 27.3 mm in anatomic specimens. We found statistically significant difference of the STN width and length between individuals <60 and ≥60 years old. Conclusion. The identification of the STN limits was easier in anatomic specimens than on MRIs and easier on T2 compared to T1-weighted MRIs sections. STN dimensions appear slightly smaller on MRIs. Younger people have wider and longer STN.

Figure 1

Transverse cerebral MRI section (T2-weighted, 1.5 Tesla) at level Z = −4 (zoom on mesencephalon), from a 37-year-old male, showing the STN location and surface area. 1: STN, 2: red nucleus, 3: aqueduct (of Sylvius), A: anterior, P: posterior and, R: right, L left.

Figure 2

Transverse cerebral MRI section (T2-weighted, 1.5 Tesla) at level Z = 0, from a 51-year-old male, showing measurement of the AC-PC length. 1: AC-PC length, 2: AC, 3: third ventricle, 4: temporal lobe, 5: frontal lobe, 6: insula, 7: Sylvian fissure, A: anterior, P: posterior and, R: right, L left.

Figure 3

Formalin-fixated human brain from a middle-aged male, right cerebral hemisphere, transverse section at Z = −4 showing measurement of the STN coordinates. 1: STN, 2: red nucleus, 3: cerebral peduncle, 4: coronal level (perpendicular to the AC-PC plane) containing the MCP, 5: midline, 6: temporal lobe, 7: occipital lobe, X, X′, Y, Y′, Z stereotactic coordinates of the STN.