Retrosigmoid Approach: A Simple and Safe Way to Resect Intrinsic Pontomedullary Lesions

Abstract

Objectives The main objective of this article is to describe a simple and safe protocol for the microsurgical management of ventrally located intrinsic pontomedullary lesions based on the retrosigmoid approach, cortectomy performed utilizing safe entry zones of the pons and medulla, and a delicate microsurgical resection. The intraoperative protocol includes redundant procedures that provide security in decision-making during surgery.

Design A prospective series of 11 cases is presented. All patients were studied following the same clinical and imaging workup. A regular retrosigmoid craniotomy surgical approach was utilized. The peritrigeminal area in the pons and the olivary area in the medulla were considered as the safe entry zones. Neuronavigation of the white fiber tracts and electrophysiological monitoring were used as intraoperative aids to locate the lesions, the safe entry zones, and the placement of the cortectomy.

Results Six lesions were pontine, two medullary, and the remaining six pontomedullary. Eight lesions were cavernomas, while the remaining three tumors. Overall, we obtained a postoperative functional improvement in the affected cranial nerves in 90.1% of the patients and a total or partial recovery of long ascending or descending pathway symptoms in 72.3% of the patients. All the patients were satisfied with the procedure and the results.

Conclusions Radical resection of ventral intrinsic pontomedullary lesions displays a high degree of intraoperative reliability, and a good clinical result is possible using simple surgical procedures. The anatomical references are the first element in the decision-making process during surgery.

Keywords

intrinsic pontomedullary cavernoma - intrinsic pontomedullary ventral lesion - retrosigmoid approach - safe entry zones

• References

• 1 Recalde RJ, Figueiredo EG, de Oliveira E. Microsurgical anatomy of the safe entry zones on the anterolateral brainstem related to surgical approaches to cavernous malformations. Neurosurgery 2008; 62 (03) (Suppl. 01) 9-15 , discussion 15–17
• 2 Strauss C, Lütjen-Drecoll E, Fahlbusch R. Pericollicular surgical approaches to the rhomboid fossa. Part I. Anatomical basis. J Neurosurg 1997; 87 (06) 893-899
• 3 Strauss C, Romstöck J, Nimsky C, Fahlbusch R. Intraoperative identification of motor areas of the rhomboid fossa using direct stimulation. J Neurosurg 1993; 79 (03) 393-399
• 4 Abla AA, Turner JD, Mitha AP, Lekovic G, Spetzler RF. Surgical approaches to brainstem cavernous malformations. Neurosurg Focus 2010; 29 (03) E8
• 5 Cavalcanti DD, Preul MC, Kalani MY, Spetzler RF. Microsurgical anatomy of safe entry zones to the brainstem. J Neurosurg 2015; 9: 1-18
• 6 Cavalheiro S, Yagmurlu K, da Costa MD. , et al. Surgical approaches for brainstem tumors in pediatric patients. Childs Nerv Syst 2015; 31 (10) 1815-1840
• 7 Yagmurlu K, Rhoton Jr AL, Tanriover N, Bennett JA. Three-dimensional microsurgical anatomy and the safe entry zones of the brainstem. Neurosurgery 2014; 10 (Suppl. 04) 602-619 , discussion 619–620
• 8 Ferroli P, Schiariti M, Cordella R. , et al. The lateral infratrigeminal transpontine window to deep pontine lesions. J Neurosurg 2015; 123 (03) 699-710
• 9 Gross BA, Dunn IF, Du R, Al-Mefty O. Petrosal approaches to brainstem cavernous malformations. Neurosurg Focus 2012; 33 (02) E10
• 10 Mai JC, Ramanathan D, Kim LJ, Sekhar LN. Surgical resection of cavernous malformations of the brainstem: evolution of a minimally invasive technique. World Neurosurg 2013; 79 (5-6): 691-703
• 11 Maurer AJ, Bonney PA, Strickland AE, Safavi-Abbasi S, Sughrue ME. Brainstem cavernous malformations resected via miniature craniotomies: technique and approach selection. J Clin Neurosci 2015; 22 (05) 865-871
• 12 Linsler S, Oertel J. Endoscopic endonasal transclival resection of a brainstem cavernoma: a detailed account of our technique and comparison with the literature. World Neurosurg 2015; 84 (06) 2064-2071
• 13 Ohue S, Fukushima T, Friedman AH, Kumon Y, Ohnishi T. Retrosigmoid suprafloccular transhorizontal fissure approach for resection of brainstem cavernous malformation. Neurosurgery 2010; 66 (6 Suppl Operative): 306-312
• 14 Hauck EF, Barnett SL, White JA, Samson D. The presigmoid approach to anterolateral pontine cavernomas. Clinical article. J Neurosurg 2010; 113 (04) 701-708
• 15 Oiwa Y, Nakai K, Masaki Y. , et al. Presigmoid approach for cavernous angioma in the pons--technical note. Neurol Med Chir (Tokyo) 2002; 42 (02) 91-96 , discussion 97–98
• 16 Flores BC, Whittemore AR, Samson DS, Barnett SL. The utility of preoperative diffusion tensor imaging in the surgical management of brainstem cavernous malformations. J Neurosurg 2015; 122 (03) 653-662
• 17 Prats-Galino A, Soria G, de Notaris M, Puig J, Pedraza S. Functional anatomy of subcortical circuits issuing from or integrating at the human brainstem. Clin Neurophysiol 2012; 123 (01) 4-12
• 18 Ulrich NH, Ahmadli U, Woernle CM, Alzarhani YA, Bertalanffy H, Kollias SS. Diffusion tensor imaging for anatomical localization of cranial nerves and cranial nerve nuclei in pontine lesions: initial experiences with 3T-MRI. J Clin Neurosci 2014; 21 (11) 1924-1927
• 19 Ulrich NH, Kockro RA, Bellut D. , et al. Brainstem cavernoma surgery with the support of pre- and postoperative diffusion tensor imaging: initial experiences and clinical course of 23 patients. Neurosurg Rev 2014; 37 (03) 481-491 , discussion 492
• 20 Yao Y, Ulrich NH, Guggenberger R, Alzarhani YA, Bertalanffy H, Kollias SS. Quantification of corticospinal tracts with diffusion tensor imaging in brainstem surgery: prognostic value in 14 consecutive cases at 3T magnetic resonance imaging. World Neurosurg 2015; 83 (06) 1006-1014
• 21 Sarnthein J, Bozinov O, Melone AG, Bertalanffy H. Motor-evoked potentials (MEP) during brainstem surgery to preserve corticospinal function. Acta Neurochir (Wien) 2011; 153 (09) 1753-1759
• 22 Shiban E, Zerr M, Huber T. , et al. Poor diagnostic accuracy of transcranial motor and somatosensory evoked potential monitoring during brainstem cavernoma resection. Acta Neurochir (Wien) 2015; 157 (11) 1963-1969 , discussion 1969
• 23 Abla AA, Lekovic GP, Turner JD, de Oliveira JG, Porter R, Spetzler RF. Advances in the treatment and outcome of brainstem cavernous malformation surgery: a single-center case series of 300 surgically treated patients. Neurosurgery 2011; 68 (02) 403-414 , discussion 414–415
• 24 Bradac O, Majovsky M, de Lacy P, Benes V. Surgery of brainstem cavernous malformations. Acta Neurochir (Wien) 2013; 155 (11) 2079-2083
• 25 Dukatz T, Sarnthein J, Sitter H. , et al. Quality of life after brainstem cavernoma surgery in 71 patients. Neurosurgery 2011; 69 (03) 689-695
• 26 Garcia RM, Ivan ME, Lawton MT. Brainstem cavernous malformations: surgical results in 104 patients and a proposed grading system to predict neurological outcomes. Neurosurgery 2015; 76 (03) 265-277 , discussion 277–278
• 27 Schwartz C, Grillhösl A, Schichor C. , et al. Symptomatic cavernous malformations of the brainstem: functional outcome after microsurgical resection. J Neurol 2013; 260 (11) 2815-2822