The Challenge of Access to the Pontomesencephalic Junction: An Anatomical Study of Lateral Approach and Exposure

ABSTRACT

We quantitatively compared relative merits of lateral approaches to the pontomesencephalic junction (PMJ): anterior petrosectomy, subtemporal transtentorial, posterior petrosectomy, and retrosigmoid transtentorial. In dissected cadaveric heads, lengths of exposure were measured anteriorly from CN V along the pontomesencephalic sulcus (PMS); posterosuperiorly along the lateral mesencephalic sulcus (LMS); and posteroinferiorly along the interpeduncular sulcus (IPS). Subtemporal transtentorial approach provided best anterior exposure along the PMS (23.8 ± 4.5 mm). Posterosuperior exposures were comparable for all approaches except anterior petrosectomy (limited). Posteroinferior exposure was most with subtemporal transtentorial approach (13.2 ± 2.8 mm). CN V entry/exit point was identified through all approaches, except for subtemporal transtentorial; shortest surgical depth with posterior petrosectomy was 43.7 ± 5.5 mm. PMS-LMS-IPS convergence point: reached through all approaches, except for anterior petrosectomy (limited); shortest surgical depth with posterior petrosectomy was 40.3 ± 4.3 mm. Anterior petrosectomy provides direct anterolateral views of the pons not afforded by subtemporal approach. Subtemporal transtentorial approach provides optimal posterolateral view to the PMJ and cerebellar peduncles. Retrosigmoid transtentorial approach offers wide exposure of the lateral surface, limited on the posteroinferior PMJ by the cerebellum. The small opening of posterior petrosectomy creates an awkward corridor to anterior PMJ targets but provides a direct and shortest route to the cerebellar peduncles.

KEYWORDS

Petrosal approach - pontomesencephalic junction - retrosigmoid approach - subtemporal approach - surgical-anatomical study

REFERENCES

• 1 Bricolo A. Surgical management of intrinsic brain stem gliomas.  Operative Techniques in Neurosurgery. 2000;  3 137-154
• 2 Porter R W, Detwiler P W, Spetzler R F et al.. Cavernous malformations of the brainstem: experience with 100 patients.  J Neurosurg. 1999;  90 50-58
• 3 Samii M, Eghbal R, Carvalho G A, Matthies C. Surgical management of brainstem cavernomas.  J Neurosurg. 2001;  95 825-832
• 4 Smith E R, Chapman P H, Ogilvy C S. Far posterior subtemporal approach to the dorsolateral brainstem and tentorial ring: technique and clinical experience.  Neurosurgery. 2003;  52 364-368, discussion 368–369
• 5 Ammirati M, Bernardo A, Musumeci A, Bricolo A. Comparison of different infratentorial-supracerebellar approaches to the posterior and middle incisural space: a cadaveric study.  J Neurosurg. 2002;  97 922-928
• 6 Yonekawa Y, Imhof H G, Taub E et al.. Supracerebellar transtentorial approach to posterior temporomedial structures.  J Neurosurg. 2001;  94 339-345
• 7 Abdel Aziz K M, Sanan A, van Loveren H R, Tew Jr J M, Keller J T, Pensak M L. Petroclival meningiomas: predictive parameters for transpetrosal approaches.  Neurosurgery. 2000;  47 139-150, discussion 150–152
• 8 Kawase T, Toya S, Shiobara R, Mine T. Transpetrosal approach for aneurysms of the lower basilar artery.  J Neurosurg. 1985;  63 857-861
• 9 Miller C G, van Loveren H R, Keller J T, Pensak M, el-Kalliny M, Tew Jr J M. Transpetrosal approach: surgical anatomy and technique.  Neurosurgery. 1993;  33 461-469, discussion 469
• 10 Vrionis F D, Gardner G, Robertson J H, Brodkey J A. Transtemporal approaches to the posterior cranial fossa. In: Schmidek HH, Roberts DW Schmidek and Sweet's Operative Neurosurgical Techniques: Indicators, Methods, and Results. Philadelphia; W.B. Saunders 2005: pp. 275-89
• 11 Youssef S, Kim E Y, Aziz K M, Hemida S, Keller J T, van Loveren H R. The subtemporal interdural approach to dumbbell-shaped trigeminal schwannomas: cadaveric prosection.  Neurosurgery. 2006;  59(4, Suppl 2) ONS270-ONS277 discussion ONS277-ONS278
• 12 Jittapiromsak P, Deshmukh P, Nakaji P et al.. Comparative analysis of retrosigmoid approach and lateral supracerebellar infratentorial approaches along the lateral surface of ponto-mesencephalic junction: a different perspective.  Neurosurgery. 2008; 
• 13 Yasargil M C. Infratentorial approaches. Microneurosurgery of CNS Tumors. New York; Thieme 1996: 58-60
• 14 Spetzler R F, Daspit C P, Pappas C T. The combined supra- and infratentorial approach for lesions of the petrous and clival regions: experience with 46 cases.  J Neurosurg. 1992;  76 588-599
• 15 Vishteh A G, David C A, Marciano F F, Coscarella E, Spetzler R F. Extreme lateral supracerebellar infratentorial approach to the posterolateral mesencephalon: technique and clinical experience.  Neurosurgery. 2000;  46 384-388, discussion 388–389
• 16 Ulm A J, Tanriover N, Kawashima M, Campero A, Bova F J, Rhoton Jr A. Microsurgical approaches to the perimesencephalic cisterns and related segments of the posterior cerebral artery: comparison using a novel application of image guidance.  Neurosurgery. 2004;  54 1313-1327 discussion 1327-1328
• 17 Rhoton Jr A L. The cerebellar arteries.  Neurosurgery. 2000;  47(3, Suppl) S29-S68
• 18 MacDonald J D, Antonelli P, Day A L. The anterior subtemporal, medial transpetrosal approach to the upper basilar artery and ponto-mesencephalic junction.  Neurosurgery. 1998;  43 84-89
• 19 Figueiredo E G, Zabramski J M, Deshmukh P, Crawford N R, Spetzler R F, Preul M C. Comparative analysis of anterior petrosectomy and transcavernous approaches to retrosellar and upper clival basilar artery aneurysms.  Neurosurgery. 2006;  58(1, Suppl) ONS13-ONS21 discussion ONS13-ONS21
• 20 Terasaka S, Sawamura Y, Kamiyama H, Fukushima T. Surgical approaches for the treatment of aneurysms on the P2 segment of the posterior cerebral artery.  Neurosurgery. 2000;  47 359-364 discussion 364-366
• 21 Ammerman J M, Lonser R R, Oldfield E H. Posterior subtemporal transtentorial approach to intraparenchymal lesions of the anteromedial region of the superior cerebellum.  J Neurosurg. 2005;  103 783-788
• 22 Khosla V K, Hakuba A, Takagi H. Measurements of the skull base for transpetrosal surgery.  Surg Neurol. 1994;  41 502-506
• 23 Sarmiento P B, Eslait F G. Surgical classification of variations in the anatomy of the sigmoid sinus.  Otolaryngol Head Neck Surg. 2004;  131 192-199
• 24 Horgan M A, Anderson G J, Kellogg J X et al.. Classification and quantification of the petrosal approach to the petroclival region.  J Neurosurg. 2000;  93 108-112
• 25 Siwanuwatn R, Deshmukh P, Figueiredo E G, Crawford N R, Spetzler R F, Preul M C. Quantitative analysis of the working area and angle of attack for the retrosigmoid, combined petrosal, and transcochlear approaches to the petroclival region.  J Neurosurg. 2006;  104 137-142
• 26 Samii M, Tatagiba M, Carvalho G A. Retrosigmoid intradural suprameatal approach to Meckel's cave and the middle fossa: surgical technique and outcome.  J Neurosurg. 2000;  92 235-241
• 27 Seoane E, Rhoton Jr A L. Suprameatal extension of the retrosigmoid approach: microsurgical anatomy.  Neurosurgery. 1999;  44 553-560
• 28 Chanda A, Nanda A. Retrosigmoid intradural suprameatal approach: advantages and disadvantages from an anatomical perspective.  Neurosurgery. 2006;  59(1, Suppl 1) ONS1-ONS6 discussion ONS1-ONS6
• 29 Goel A. Tentorial dural flap for transtentorial surgery.  Br J Neurosurg. 1995;  9 785-786
• 30 Day J D, Fukushima T, Giannotta S L. Cranial base approaches to posterior circulation aneurysms.  J Neurosurg. 1997;  87 544-554
• 31 Samii M, Carvalho G A, Tatagiba M, Matthies C, Vorkapic P. Meningiomas of the tentorial notch: surgical anatomy and management.  J Neurosurg. 1996;  84 375-381
• 32 Lustig L R, Jackler R K. The vulnerability of the vein of labbé during combined craniotomies of the middle and posterior fossae.  Skull Base Surg. 1998;  8 1-9
• 33 Sakata K, Al-Mefty O, Yamamoto I. Venous consideration in petrosal approach: microsurgical anatomy of the temporal bridging vein.  Neurosurgery. 2000;  47 153-160 discussion 160-161
• 34 Rhoton Jr A L. The posterior fossa veins.  Neurosurgery. 2000;  47(3, Suppl) S69-S92
• 35 Tanriover N, Abe H, Rhoton Jr A L, Kawashima M, Sanus G Z, Akar Z. Microsurgical anatomy of the superior petrosal venous complex: new classifications and implications for subtemporal transtentorial and retrosigmoid suprameatal approaches.  J Neurosurg. 2007;  106 1041-1050
• 36 Safavi-Abbasi S, Zabramski J M, Deshmukh P et al.. Moving toward the petroclival region: a model for quantitative and anatomical analysis of tumor shift.  J Neurosurg. 2007;  107 797-804