Suprajugular extension of the retrosigmoid approach: microsurgical anatomy

Abstract

Object Jugular foramen tumors often extend intra- and extracranially. The gross-total removal of tumors located both intracranially and intraforaminally is technically challenging and often requires a combined skull base approach. This study presents a suprajugular extension of the retrosigmoid approach directed through the osseous roof of the jugular foramen that allows the removal of tumors located in the cerebellopontine angle with extension into the upper part of the foramen, with demonstration of an illustrative case. Methods The cerebellopontine angles and jugular foramina were examined in dry skulls and cadaveric heads to clarify the microsurgical anatomy around the jugular foramen and to define the steps of the suprajugular exposure. Results The area drilled in the suprajugular approach is inferior to the acoustic meatus, medial to the endolymphatic depression and surrounding the superior half of the glossopharyngeal dural fold. Opening this area exposed the upper part of the jugular foramen and extended the exposure along the glossopharyngeal nerve below the roof of the jugular foramen. In the illustrative case, a schwannoma originating from the glossopharyngeal nerve in the cerebellopontine angle and extending below the roof of the jugular foramen and above the jugular bulb was totally removed without any postoperative complications. Conclusions The suprajugular extension of the retrosigmoid approach will permit removal of tumors located predominantly in the cerebellopontine angle but also extending into the upper part of the jugular foramen without any additional skull base approaches.

Endoscope-assisted retrosigmoid infralabyrinthine approach to jugular foramen tumors

“…14 Matsushima et al described the anatomical steps of this suprajugular approach in detail in a recent cadaveric study. 11 He has been using the endoscope-assisted retrosigmoid infralabyrinthine approach to JF lesions since 2005. In this study we described our experience with this approach, in terms of access to the intraforaminal tumor extension, safety of tumor removal, and approach-related morbidity.…”

“…20 The JF is not a true foramen; it is rather a canal with endocranial and exocranial openings and courses inferiorly and anterolateraly under the petrous bone. 11,18,20 This canal is triangular-shaped and bounded by the petrous part of the temporal bone anterolaterally and the basioccipital bone posteromedially. [18][19][20] The features of anterolateral margin of the JF formed by the petrous bone are named (from posterior to anterior) the jugular notch, the intrajugular process, and the pyramidal fossa and sulcus for the inferior petrosal sinus (IPS).…”

“…1 right) from the vagal meatus that contains the vagus and accessory nerves. 1,11,17,19 Inside the canal of the JF the lower CNs are tightly enveloped in a common sheath of periosteal dura that gradually transforms into epineurium. 17 …”

“…It covers the intrajugular process, the glossopharyngeal recess, and the CN meatus. 11,17,19 The dural covering of the JF has a defect called the jugular pocket, through which the lower CNs exit the cranium. 11,17 The glossopharyngeal meatus is located anterosuperomedially and is separated by a dural septum ( Fig.…”

“…For surgical purposes we agree with the classification of Katsuta et al who divided the JF into the petrosal part, the intrajugular part, and the sigmoid part. 1,[9][10][11]13,16,18 The intrajugular part is located between the two venous parts and contains the meatuses of all the 3 lower CNs in the JF.…”