THE OCCIPITAL TRANS-TENTORIAL APPROACH TO PINEAL REGION TUMORS

BACKGROUND The Occipital Trans-Tentorial approach (OTT) to pineal region was popularized by Poppen in 1966. The 'so-called' Poppen's approach offers some unquestionable advantages in the treatment of those pineal tumors extending superioriorly above the tentorial edge, inferioriorly into the cerebellomesencephalic fissure and/or laterally beyond the medial borders of the tentorium. The authors report a step-by-step description of the OTT approach also highlighting the tips and the triks of this approach and the advantages related to a supratentorial surgical perspective to pineal area and posterior fossa. MATERIALS AND METHODS A stepwise description of the OTT approach has been reported. Some surgical cases from a personal series of 20 pineal tumors treated in a range period of 10 years (2004-2014) have been furthermore reviewed and discussed. RESULTS OTT approach involves a midline or L-shaped skin incision extending more above than below the inion to skeletonize the occipital squama and the external occipital protuberance. The inion serves as an important landmark to identify the torcular. A burr hole has to be placed on the external occipital protuberance and along the superior sagittal and ipsilateral transverse sinuses to perform a paramedian supratentorial occipital craniotomy. Extremely care should be taken to avoid injuries to the sinuses. Opening of the dura above the tranverse sinus and immediately lateral to the superior sagital sinus allows for a posterior inter emispheric exposure of the ipsilateral tentorium. The trans-tentorial access to the pineal region and the posterior third ventricle involves the caoagulation, cutting and reflection of the tentorium. This allows for a sub-occipital trans-tentorial perspective of the pineal region. In the personal series the OTT approach has been employed alone or in a combination with the infratentorial supracerebellar approach (ITSC) to treat different kind of lesions involving the pineal region. Compared with the ITSC, OTT approach has resulted more suitable and advantageous exspecially in those lesions with a para median or more cephalad extension. CONCLUSIONS The OTT approach is very useful to treat those pineal tumors caraharacterized by a para-mediam extension and/or involving the posterior third ventricle. The reflection of the tentorium provides an excellent and wide view of the pineal region both from above and from below. A detailed knowledge of the anatomy of this region, as well as the different steps of the approach are both of utmost importance to execute safely the approach.