Supracerebellar Infratentorial Variant Approaches to the Intercollicular Safe Entry Zone

OBJECTIVEThe lateral recess is a unique structure communicating between the ventricle and cistern, which is exposed when treating lesions involving the fourth ventricle and the brainstem with surgical approaches such as the transcerebellomedullary fissure approach. In this study, the authors examined the microsurgical anatomy around the lateral recess, including the fiber tracts, and analyzed their findings with respect to surgical exposure of the lateral recess and entry into the lower pons.METHODSTen cadaveric heads were examined with microsurgical techniques, and 2 heads were examined with fiber dissection to clarify the anatomy between the lateral recess and adjacent structures. The lateral and medial routes directed to the lateral recess in the transcerebellomedullary fissure approach were demonstrated. A morphometric study was conducted in the 10 cadaveric heads (20 sides).RESULTSThe lateral recess was classified into medullary and cisternal segments. The medial and lateral routes in the transcerebellomedullary fissure approach provided access to approximately 140º–150º of the posteroinferior circumference of the lateral recess. The floccular peduncle ran rostral to the lateral recess, and this region was considered to be a potential safe entry zone to the lower pons. By appropriately selecting either route, medial-to-lateral or lateral-to-medial entry axis is possible, and combining both routes provided wide exposure of the lower pons around the lateral recess.CONCLUSIONSThe medial and lateral routes of the transcerebellomedullary fissure approach provided wide exposure of the lateral recess, and incision around the floccular peduncle is a potential new safe entry zone to the lower pons.

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Surgical Removal of Ventral Lower Pontine Cavernous Angiomas: Surgical Approach and Safe Entry Zone to the Brain Stem

Surgery for Cerebral Stroke ◽

10.2335/scs.36.112 ◽

2008 ◽

Vol 36 (2) ◽

pp. 112-117 ◽

Cited By ~ 1

Author(s):

Takehiko SASAKI ◽

Kazuyuki HAYASE ◽

Ken-ichi SATOH ◽

Toshi-ichi WATANABE ◽

Yoshinobu SEO ◽

...

Keyword(s):

Brain Stem ◽

Surgical Approach ◽

Surgical Removal ◽

Entry Zone ◽

Cavernous Angiomas ◽

The Brain ◽

Safe Entry Zone

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Endoscopic Transoral-Transclival Approach to the Brainstem and Surrounding Cisternal Space: Anatomic Study

Neurosurgery ◽

10.1227/01.neu.0000097271.55741.60 ◽

2004 ◽

Vol 54 (1) ◽

pp. 125-130 ◽

Cited By ~ 55

Author(s):

Oreste de Divitiis ◽

Alfredo Conti ◽

Filippo Flavio Angileri ◽

Salvatore Cardali ◽

Domenico La Torre ◽

...

Keyword(s):

Postoperative Complications ◽

Cranial Base ◽

Transoral Approach ◽

Anatomic Study ◽

Entry Zone ◽

Adult Human ◽

Exposure Potential ◽

Dural Opening ◽

Formalin Fixed ◽

Safe Entry Zone

Abstract OBJECTIVE The purpose of this study was to review the endoscopic anatomic features of the anterior brainstem and surrounding cisternal spaces via a transoral-transclival approach. METHODS Fifteen adult human cadaveric heads, obtained from 10 fresh cadavers and 5 formalin-fixed cadavers, were used to demonstrate both the feasibility of an endoscopic transoral-transclival intradural approach and its exposure potential. To analyze the exact extension of a safe entry zone through the clivus, 20 skull bases were used to obtain anatomic measurements. RESULTS The transoral approach was performed without maxillotomy or mandibulotomy and with a clival opening of 20 by 15 mm. Such a limited clival and dural opening allowed the insertion of the endoscope and instruments, full visualization of the anterolateral brainstem and cisternal spaces around it, and reconstruction of all anatomic layers by means of a paraendoscopic technique. CONCLUSION The endoscopic transoral-transclival approach enables full access to the anterolateral brainstem and to the cisternal space around it. The use of the endoscope has the potential to reduce the need for a wider cranial base opening and the danger of postoperative complications.

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The suboccipital, telovelar, transsuperior fovea approach to dorsal pontine lesions

Neurosurgical Focus: Video ◽

10.3171/2019.7.focusvid.1927 ◽

2019 ◽

Vol 1 (1) ◽

pp. V19

Author(s):

M. Yashar S. Kalani ◽

Kaan Yağmurlu ◽

Nikolay L. Martirosyan ◽

Robert F. Spetzler

Keyword(s):

Fourth Ventricle ◽

Cavernous Malformation ◽

Venous Anomaly ◽

Entry Zone ◽

Lateral Entry ◽

Link Type ◽

Safe Entry Zone

Dorsal pons lesions at the facial colliculus level can be accessed with a suboccipital telovelar (SOTV) approach using the superior fovea safe entry zone. Opening the telovelar junction allows visualization of the dorsal pons and lateral entry at the level of the fourth ventricle floor. Typically, a lateral entry into the floor of the fourth ventricle is better tolerated than a midline opening. This video demonstrates the use of the SOTV approach to remove a cavernous malformation at the level of the facial colliculus. This case is particularly interesting because of a large venous anomaly and several telangiectasias in the pons. Dissections in the video are reproduced with permission from the Rhoton Collection (http://rhoton.ineurodb.org).The video can be found here: https://youtu.be/LqzCfN2J3lY.

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Location of the obturator artery as it traverses the obturator foramen in relation to the transobturator sling's safe entry zone: Clinical implications

The Journal of the American Association of Gynecologic Laparoscopists ◽

10.1016/s1074-3804(04)80267-6 ◽

2004 ◽

Vol 11 (3) ◽

pp. S4 ◽

Cited By ~ 1

Author(s):

MA Pelosi

Keyword(s):

Clinical Implications ◽

Obturator Foramen ◽

Obturator Artery ◽

Entry Zone ◽

Safe Entry Zone

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Using the Lateral Pontine Safe Entry Zone for Resection of Deep-Seated Cavernous Malformations in the Lateral Pons: 2-Dimensional Operative Video

Operative Neurosurgery ◽

10.1093/ons/opaa142 ◽

2020 ◽

Vol 19 (5) ◽

pp. E518-E519

Author(s):

Daniel D Cavalcanti ◽

Joshua S Catapano ◽

Paulo Niemeyer Filho

Keyword(s):

Trigeminal Nerve ◽

Cranial Nerve ◽

Cavernous Malformation ◽

Vascular Malformations ◽

Cranial Nerves ◽

Cavernous Malformations ◽

Entry Zone ◽

History Of ◽

Tumor Biopsies ◽

Safe Entry Zone

Abstract The retrosigmoid approach is one of the main approaches used in the surgical management of pontine cavernous malformations. It definitely provides a lateral route to large central lesions but also makes possible resection of some ventral lesions as an alternative to the petrosal approaches. However, when these vascular malformations do not emerge on surface, one of the safe corridors delimited by the origin of the trigeminal nerve and the seventh-eight cranial nerve complex can be used.1-5 Baghai et al2 described the lateral pontine safe entry zone in 1982, as an alternative to approaches through the floor of the fourth ventricle when performing tumor biopsies. They advocated a small neurotomy performed right between the emergence of the trigeminal nerve and the facial-vestibulocochlear cranial nerves complex. Accurate image guidance, intraoperative cranial nerve monitoring, and comprehensive anatomical knowledge are critical for this approach.4,5 Knowing the natural history of a brainstem cavernous malformation after bleeding,6 we sought to demonstrate in this video: (1) the use of the retrosigmoid craniotomy in lateral decubitus for resection of deep-seated pontine cavernous malformations; (2) the wide opening of arachnoid membranes and dissection of the superior petrosal vein complex to improve surgical freedom and prevent use of fixed cerebellar retraction; and (3) the opening of the petrosal fissure and exposure of the lateral pontine zone for gross total resection of a cavernous malformation in a 19-yr-old female with a classical crossed brainstem syndrome. She had full neurological recovery after 3 mo of follow-up. The patient consented in full to the surgical procedure and publication of the video and manuscript.

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Subtemporal approach for the resection of a midbrain cavernous malformation: evaluation of safe surgical corridors

Neurosurgical Focus: Video ◽

10.3171/2019.7.focusvid.19135 ◽

2019 ◽

Vol 1 (1) ◽

pp. V1 ◽

Cited By ~ 1

Author(s):

Thalia Estefania Sanchez Correa ◽

David Gallardo Ceja ◽

Diego Mendez-Rosito

Keyword(s):

Female Patient ◽

Deleterious Effect ◽

Cavernous Malformation ◽

Clinical Analysis ◽

Anatomical Landmarks ◽

Entry Zone ◽

Subtemporal Approach ◽

Critical Location ◽

Brainstem Cavernous Malformation ◽

Safe Entry Zone

Brainstem cavernous malformation management is complex due to its critical location and deleterious effect when bleeding. Therefore, every case should be thoroughly analyzed preoperatively. We present the case of a female patient with a midbrain cavernous malformation. A comprehensive anatomical and clinical analysis of the surgical corridors is done to decide the safest route. A subtemporal approach was done and the lateral mesencephalic sulcus and vein were important anatomical landmarks to guide the safe entry zone. Nuances of technique and surgical pearls related to the safe entry zones of the midbrain are discussed and illustrated in this operative video.The video can be found here: https://youtu.be/vYA-IgiT2lU.

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The Role of Intraoperative Monitoring of Oculomotor and Trochlear Nuclei -Safe Entry Zone to Tegmental Lesions

min - Minimally Invasive Neurosurgery ◽

10.1055/s-2006-944239 ◽

2006 ◽

Vol 49 (3) ◽

pp. 168-172 ◽

Cited By ~ 18

Author(s):

H. Ishihara ◽

M. Bjeljac ◽

D. Straumann ◽

Y. Kaku ◽

P. Roth ◽

...

Keyword(s):

Intraoperative Monitoring ◽

Entry Zone ◽

Safe Entry Zone

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Posterior petrosectomy for resection of pontine cavernous malformation

Neurosurgical Focus: Video ◽

10.3171/2019.10.focusvid.19389 ◽

2019 ◽

Vol 1 (2) ◽

pp. V18

Author(s):

Avital Perry ◽

Thomas J. Sorenson ◽

Christopher S. Graffeo ◽

Colin L. Driscoll ◽

Michael J. Link

Keyword(s):

Real Time ◽

Surgical Resection ◽

Cavernous Malformation ◽

Low Pressure ◽

Vascular Lesions ◽

Cavernous Malformations ◽

Entry Zone ◽

Microsurgical Techniques ◽

Safe Entry Zone ◽

Ultrasound Probes

Cavernous malformations (CMs) are low-pressure, focal, vascular lesions that may occur within the brainstem and require treatment, which can be a substantial challenge. Herein, we demonstrate the surgical resection of a hemorrhaged brainstem CM through a posterior petrosectomy approach. After dissection of the overlying vascular and meningeal structures, a safe entry zone into the brainstem is identified based on local anatomy and intraoperative neuronavigation. Small ultrasound probes can also be useful for obtaining real-time intraoperative feedback. The CM is internally debulked and resected in a piecemeal fashion through an opening smaller than the CM itself. As brainstem CMs are challenging lesions, knowledge of several surgical nuances and adoption of careful microsurgical techniques are requisite for success.The video can be found here: https://youtu.be/szB6YpzkuCo.

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The interpeduncular fossa approach for resection of ventromedial midbrain lesions

Journal of Neurosurgery ◽

10.3171/2016.9.jns161680 ◽

2018 ◽

Vol 128 (3) ◽

pp. 834-839 ◽

Cited By ~ 6

Author(s):

M. Yashar S. Kalani ◽

Kaan Yağmurlu ◽

Robert F. Spetzler

Keyword(s):

Oculomotor Nerve ◽

Cavernous Malformations ◽

Entry Zone ◽

Mammillary Bodies ◽

Adult Human ◽

Fiber Dissection ◽

Dissection Technique ◽

Anatomical Information ◽

Gain Access ◽

Safe Entry Zone

The authors describe the interpeduncular fossa safe entry zone as a route for resection of ventromedial midbrain lesions. To illustrate the utility of this novel safe entry zone, the authors provide clinical data from 2 patients who underwent contralateral orbitozygomatic transinterpeduncular fossa approaches to deep cavernous malformations located medial to the oculomotor nerve (cranial nerve [CN] III). These cases are supplemented by anatomical information from 6 formalin-fixed adult human brainstems and 4 silicone-injected adult human cadaveric heads on which the fiber dissection technique was used.The interpeduncular fossa may be incised to resect anteriorly located lesions that are medial to the oculomotor nerve and can serve as an alternative to the anterior mesencephalic safe entry zone (i.e., perioculomotor safe entry zone) for resection of ventromedial midbrain lesions. The interpeduncular fossa safe entry zone is best approached using a modified orbitozygomatic craniotomy and uses the space between the mammillary bodies and the top of the basilar artery to gain access to ventromedial lesions located in the ventral mesencephalon and medial to the oculomotor nerve.

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