Skin landmarks to main cerebral structures: how to identify the main cerebral sulci? An anatomical study

Abstract

Purpose Neuronavigation is used in neurosurgical practice to locate the cortical structures. If this tool is unavailable, basic anatomical knowledge should be used. Craniometry has been rarely detailed in recent literature, systematically using bony landmarks. The aim of this study is to describe skin landmarks for neurosurgical practice. Methods Dissection of 10 hemispheres with insertion of radio-opaque markers within the limits of lateral sulcus, central and pre-central sulci, and preoccipital notch. Computed tomography was performed in all cases and multiplanar reconstructions were performed. Maximal intensity projection (MIP) fusion images were used for measurements between known skin landmarks and sulci of interests. ResultsThe Anterior Sylvian Point is measured 31.8 ± 2.8 mm behind the orbital wall, 36.9 ± 3 mm above the zygomatic arch. The horizontal part of the lateral sulcus is measured 59 ± 6 mm above the tragus. The Superior Rolandic Point is measured 190.7 ± 4.5 mm behind the nasion. The Pre-occipital Notch is measured 37.0 ± 6.9 mm above the tragus and 67.1 ± 6.4 mm behind. The Ideal Entry Points (IEP) for ventricular punctures are measured 120.2 ± 7 mm behind the nasion and 33.8 ± 3 mm laterally for the frontal IEP, and 61.3 mm ± 2.5 mm above and 64.7 ± 6.8 mm behind the tragus for the parieto-occipital IEP. ConclusionIn this study, we described simple skin landmarks for lateral sulcus, central sulcus, preoccipital notch, and an IEP for ventricular drainage. Precise knowledge of brain sulcal anatomy will guide patient's positioning, skin incision, and craniotomies; and permits checking of imaging data provided by neuronavigation systems.

Skin landmarks as ideal entry points for ventricular drainage, a radiological study

“…We found that the parietooccipital IEP was approximately 6 cm above the tragus in the coronal plane and 5.5 cm behind the tragus in the axial plane, which is comparable to recent descriptions by other authors. 3,14 The parieto-occipital approach we describe remains similar to Frazier's point. 9 Knowledge of these IEPs is mandatory for safe ventricular access and must be taught very early to neurosurgical trainees.…”