Our present study demonstrates the feasibility of the NaMIPSI-A without rerouting of the facial nerve in patients with various tumors of the jugular foramen avoiding postoperative morbidity, in particular lower cranial nerve deficits. In our previous morphometric anatomical study, we have shown that this approach provided adequate access for tumor removal of Fisch grade C1, De1, De2, Di1 and Di2 JFTs.  Here we demonstrate that it allowed GTR in three patients, and NTR in two with marked tumor adherence to the lower cranial nerves after previous radiation therapy. While neurological deterioration did not occur in any patient, neurological improvement was noted in 4 instances. Avoiding the sacrifice of important anatomical structures, sufficient access could be achieved in all selected tumors as determined by our previous study on surgical anatomy.
JFTs may originate from the jugular foramen itself or they may extend from adjacent structures into the jugular foramen. Through the aperture of the jugular foramen the tumors may grow in different directions. Thus, JFTs can have an intradural, intraforaminal-intradural, extradural, intraforaminal-extradural, or both extra-intradural location. [6,7,25,41] The choice of the appropriate surgical approach to JFTs should provide adequate access, minimal brain manipulation, minimal risk of approach-related morbidity and safe gross total resection in a single-stage. For achieving the goal of successful gross total resection with minimal risk of approach-related morbidity, it is important to expose only the necessary surrounding structures depending on the extension of the JFT. Additionally, technical advancements in microneurosurgery, neuroimaging, intraoperative monitoring and the introduction of image-guided skull base surgery permit safer GTR of JFTs with considerable reduction of morbidity and mortality. [30,48] Depending on the location and extension of JFTs, several approaches have been described to gain sufficient access for radical tumor resection. [4,24,26,39] Related to the external auditory canal, all these approaches are grouped as posterior, lateral or anterior approaches. [8,16,24] Also, several combinations of surgical routes have been described. [3,16,28,37]
The suboccipital retrosigmoidal approach represents the most important and well known standard posterior approach. The suboccipital retrosigmoidal approach is particularly suited for JFTs located intradurally. Access to intraforaminal and extradural parts of JFTs, however, is not possible like with the NaMIPSI-A. [16,24–26,31,41] In an anatomical study, Matsushima et al. described a suprajugular extension of the subocciptal retrosigmoidal approach to JFTs.  They noted that suprajugular drilling of the area between internal acoustic meatus, roof of the jugular foramen and anteromedial part of the endolymphatic depression permits removal of some JFTs located mainly in the cerebellopontine angle with intraforaminal extension and into the upper part of the jugular foramen. However, they emphasized that the retrosigmoidal suprajugular approach gains no access to the extradural part of JFTs. Samii et al. reported GTR of JFTs in 7 patients treated with an endoscopically assisted retrosigmoidal suprajugular approach.  They stressed the usefulness of this approach for tumors in the cerebellopontine angle with small extension into the jugular foramen. In a recent retrospective clinical study, Matsushima et al. reported 19 patients with JFTs mainly located intradurally with partial extension into the upper jugular foramen treated via a retrosigmoid suprajugular approach.  In 18 instances GTR was possible without recurrence during the follow-up period. They indicated that JFTs located predominantly in the cerebellopontine angle extending into the upper part of the jugular foramen without invading the sigmoid-jugular venous system would be appropriate for removal via the retrosigmoidal suprabulbar approach. For JFTs extending more inferiorly or extending intra- and extracranially with intraforaminal invasion, they suggested not to use the retrosigmoidal suprajugular approach alone. Recently, Constanzo et al. also outlined the advantages, disadvantages and indications of the retrosigmoidal suprajugular approach.  They advocated resection of JFTs mainly located intradurally with extension up to 10 mm into the jugular foramen via the retrosigmoidal suprajugular approach, while JFTs with extension to the anterior half of the jugular foramen were deemed as not suitable. Furthermore, they considered that drilling of the small suprajugular area, right above the lower cranial nerves and the sigmoid sinus increases the risk of injuring the jugular bulb and the lower cranial nerves. We may suggest that in such cases the retrosigmoidal approach could also be combined with the NaMIPSI-A in order to gain access for both JFTs.
Lateral approaches are favored usually by ENT surgeons. The most familiar lateral approaches are the infratemporal approach type A, the translabyrinthine-transcochlear approach, the petro-occipital approach and the juxtacondylar approach. Commonly, lateral approaches gain access for resection of extradurally located JFTs. Resection of intradurally located JFTs with lateral approaches is limited. The infratemporal approach type A is one of the most familiar lateral approaches providing access to large extradurally located JFTs. [12,22] However, blind sack closure of the external auditory canal with removal of the middle ear causes hearing loss and transposition of the facial nerve is associated with a risk of permanent peripheral facial nerve palsy. [12,13,43] The translabyrinthine-transcochlear approach allows only resection of extradural JFTs. Sacrificing the labyrinthine block, sacrificing the cochlea and transposition of the facial nerve may result in vertigo, hearing loss, and persistent facial nerve palsy. [1,19,20] The petro-occipital approach is a combination of the retrolabyrinthine and retrosigmoidal approach. It is suitable for intradurally and extradurally located JFTs. While the petro-occipital approach allows preserving the external auditory canal, the middle ear, and the facial nerve, the sigmoid sinus is ligated. Ligation of the sigmoid sinus, however, may increase the risk of venous congestion. [32,42] The more recently described juxtacondylar approach gains a wide postero-inferior access to the extradural part of the jugular foramen. [5,15] The risk of facial nerve palsy and the risk of hearing loss is avoided by saving the labyrinthine block and the fallopian canal. However, removal of the occipital condyle represents a potential risk for craniocervical junction instability. [5,9,15,46]
Anterior approaches alone are not preferred for JFTs as they allow access only to small ventrally located JFTs. The subtemporal-infratemporal approach represents the major variant of the anterior approaches. Frequently, the subtemporal-infratemporal approach is combined with lateral approaches for JFTs with extradural ventral extension. [17,37] Due to the permanent anterior transposition of the facial nerve, resection of the mandibular condyle, and resection of the tympanic part of the temporal bone, the subtemporal-infratemporal approach is often associated with hearing loss, facial palsy, and jaw malocclusion.
In JFTs extending mainly into the petrous bone without destruction of the important neurovascular and osseous anatomical structures, preserving important anatomical structures might reduce the approach-related morbidity. In such cases, the NaMIPSI-A may present a favorable alternative to the classical lateral approaches. If there is osseous destruction by the tumor in the infralabyrinthine space, the infralabyrinthine approach can be widened accordingly.
With regard to the technical progress in radiosurgery, some have recommended subtotal resection with minimal dissection of neurovascular structures in the jugular foramen to improve neurological outcome followed by radiation therapy of the tumor remnants to decrease the rate of recurrence. [6,14,21,27,36] Radiation therapy, however, may result in tumor adherence to neurovascular structures around the jugular foramen making repeat surgeries more difficult. [44,49] Repeat surgeries, in general increase the risk of lower cranial nerve injuries due to scarring. In such cases only NTR may be possible, as also seen in two patients of the present study.
There is no consensus on the selection of the optimal surgical approach for JFTs. The choice of the approach depends mainly on the personal experience and preference of the surgeon. Appropriate patient selection and careful consideration of surgical anatomy is pivotal for applying the approach presented here. JFTs with limited intraforaminal and intradural extension without destruction of important neurovascular and osseous anatomical structures are considered to be suited best. If JFTs extend more inferiorly through the jugular foramen, are or located predominantly within the posterior fossa or occupy both intra- and extracranial spaces with intraforaminal invasion, this approach should not be selected for GTR. In such cases, the infralabyrinthine approach, however, may be combined with other approaches.