Trends in Reconstructive Neurosurgery by Massimiliano Visocchi H. Maximilian Mehdorn Yoichi Katayama & Klaus R. H. von Wild

Author:Massimiliano Visocchi, H. Maximilian Mehdorn, Yoichi Katayama & Klaus R. H. von Wild
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Complications: Middle Versus Inferior Temporal Gyrus

With growing interest in transcortical approaches to MTL tumors, an important consideration is the gyrus through which surgery proceeds. In their white matter fiber dissection analysis of the optic radiations, Sincoff et al. propose that corticectomies limited to areas inferior to the inferior temporal sulcus could avoid Meyer’s loop as it passes lateral to the temporal horn deep to the superior and middle temporal gyri [24]. Several groups have reported small case series in which the approach through the MTL is primarily the inferior temporal sulcus for MTL epilepsy; with well-documented Humphrey visual field examination, visual field defects were not noted postoperatively [8, 14, 15].

In our series of patients, all patients with new postoperative visual field complications underwent resection via a middle temporal gyrus approach where the ventricle was entered. While the corticectomy site (middle versus inferior temporal gyrus) was based on surgeon preference, no other variable (i.e., tumor size, Schramm classification) was found to be associated with complication occurrence. Due to the above anatomic considerations, it is probable that an approach through the middle temporal gyrus is much more likely to injure these visual fibers as they pass around the ventricle to the occipital lobe. However, statistical analysis did not reveal any significant difference in outcomes between inferior temporal gyrus and middle temporal gyrus entry in our limited series.

Conclusion

High-grade astrocytomas represent a cohort of less commonly encountered tumors in the mesial temporal lobe. From the oncologic standpoint, they represent a unique surgical challenge in comparison to the low-grade well-circumscribed lesions that typically are encountered in this region; there is a need to obtain gross total resection in order to obtain survival benefit. This need for an oncologic resection is compounded by the anatomic complexity of this region with surrounding white fiber tracts and neurovascular structures. Several approaches to a variety of lesions in the MTL have been described – including the trans-sylvian, subtemporal, and transcortical approaches; yet outcomes have not been discussed in the context of high-grade astrocytomas. Our experience indicates that the transcortical approach can be safely employed to obtain satisfactory resection of infiltrative lesions in this area; it further appears that there is no statistically significant difference in outcomes between inferior temporal gyrus as opposed to middle temporal gyrus entry. A larger study is necessary to confirm these findings.

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