The human locus coeruleus 3-D stereotactic anatomy

Abstract

The main goal of this work was to study the stereotactic anatomy of the human locus coeruleus (LC), important relay of adrenergic and dopaminergic human brainstem (HB) circuitry, to allow its easy localization on MRI and in microsurgical procedures. Forty LC were studied from 20 adult HB of both sexes. The melanin pigmentation of its cells was used to identify and localize them and so to define the 2-D and 3-D LC contours. These HB were cut on a cryomicrotome with 3-D referenciation. The slices were coloured with haematoxyline-eosin. On the slices, digitized images of the cells were referenced to the midline, the fourth ventricle floor plane and the pontomedullary junction plane with an appropriate computer program. The LC revealed to be a symmetric, thin and elongated nucleus, divergent caudally except in its superior part, with a sub-ependymal location on the superior dorsal lateral pons. The main LC dimensions are: length 12.0-17.0mm (m 14.5); width 2.5mm; height 2.0mm. The 3-D references of the LC center are: 3.2±0.3mm to the midline; 1.1±0.2mm to the IV ventricle floor and 18.5±1.5mm to the ponto-medullary junction. The human LC is a nucleus thinner and longer than previously described (in average 14.5mm long and 2-2.5mm thick), localized 1mm under the IV ventricle, 3mm apart from the midline and centered 14-21mm above de ponto-medullary junction. No correlation was found between LC and pons dimensions, the gender or the age.