Inferior Fronto-Occipital fascicle anatomy in brain tumor surgeries: From anatomy lab to surgical theater.

The Inferior Fronto-Occipital fascicle (IFOF) is a multitasking white matter (WM) bundle bridging frontal, temporal, parietal and occipital lobe. Many papers describe its role in the physiology of language, attention and affective behavior but its anatomical components and cortical terminations remain unclear. We analyze the surgical anatomy of the IFOF in the light of our experience with awake surgery, anatomical dissection on 10 human adult hemispheres (Klingler method) and literature review. Dissecting the specimens from lateral to medial we can describe 3 segments: a vertical segment that runs along the frontal lobe; an horizontal segment that runs along frontal lobe; an horizontal segment that runs from the limen insulae, passes into to the temporal stem and arrives at the parietal and occipital lobes. We retrospectively analyzed also 23 awake surgeries. 2 responses were elicited at subcortical stimulation at the third segment of the IFOF; stimulation gave paraphasias on the first segment of the IFOF in one case. All IFOF responses were founded in the left hemisphere. Anatomical knowledge is the cornerstone of surgical orientation, it allows eloquent structures to be reached quickly and it is of primary importance in awake surgery to avoid patient fatigue with lack of concentration.