Contralateral supracerebellar infratentorial approach

Contralateral supracerebellar infratentorial approach

Approaches to the pulvinar remain challenging because of the depth of the target, surrounding critical neural structures, and complicated arterial and venous relationships.

Four approaches for reaching the pulvinar without cortical transgression are the ipsilateral supracerebellar infratentorial (iSCIT), contralateral supracerebellar infratentorial approach (cSCIT), ipsilateral occipital transtentorial approach (iOCTT), and contralateral occipital transtentorial/falcine (cOCTF) approaches. A study quantitatively compared these approaches in terms of surgical exposure and maneuverability.

Each of the 4 approaches was performed in 4 cadaveric heads (8 specimens in total) and studied from authors in the Barrow Neurological Institute, Department of Neurosurgery, The First Affiliated Hospital of Soochow UniversitySuzhou, and Department of Neurosurgery, Irkutsk State Medical University.: A 6-sided anatomical polygonal region was configured over the cisternal pulvinar, defined by 6 reachable anatomical points in different vectors. Multiple polygons were subsequently formed to calculate the areas of exposure. The surgical freedom of each approach was calculated as the maximum allowable working area at the proximal end of a probe, with the distal end fixed at the posterior pole of the pulvinar. Areas of exposure, surgical freedom, and the working distance (surgical depth) of all approaches were compared.

No significant difference was found among the 4 different approaches with regard to the surgical depth, surgical freedom, or medial exposure area of the pulvinar. In the pairwise comparison, the cSCIT approach provided a significantly larger lateral exposure (39 ± 9.8 mm2) than iSCIT (19 ± 10.3 mm2, p < 0.01), iOCTT (19 ± 8.2 mm2, p < 0.01), and cOCTF (28 ± 7.3 mm2, p = 0.02) approaches. The total exposure area with a cSCIT approach (75 ± 23.1 mm2) was significantly larger than with iOCTT (43 ± 16.4 mm2, p < 0.01) and iSCIT (40 ± 20.2 mm2, p = 0.01) approaches (pairwise, p ≤ 0.01).

The cSCIT approach is preferable among the 4 compared approaches, demonstrating better exposure to the cisternal pulvinar than ipsilateral approaches and a larger lateral exposure than the cOCTF approach. Both contralateral approaches described (cSCIT and cOCTF) provided enhanced lateral exposure to the pulvinar, while the cOCTF provided a larger exposure to the lateral portion of the pulvinar than the iOCTT. Medial exposure and maneuverability did not differ among the approaches. A short tentorium may negatively impact an ipsilateral approach because the cingulate isthmus and parahippocampal gyrus tend to protrude, in which case they can obstruct access to the cisternal pulvinar ipsilaterally 1).


Cohen-Cohen et al. analyzed and compared the ipsilateral vs the contralateral version of the 2 main approaches to the cisternal pulvinar surface: paramedian supracerebellar infratentorial (PSCI) and interhemispheric occipital transtentorial (IOT).

The PSCI and IOT approaches were performed on 7 formalin-fixed adult cadaveric heads to evaluate qualitatively and quantitatively the microsurgical exposure of relevant anatomic structures. We quantitatively measured the corridor distance to our target with each approach.

The ipsilateral PSCI approach provided an easier access and a better exposure of the anteromedial portion of the cisternal pulvinar surface. The contralateral approach provided a wider and more accessible exposure of the posterolateral portion of the cisternal pulvinar surface. When protrusion of the posterior parahippocampal gyrus above the free edge of the tentorium was present, the contralateral PSCI approach provided an unobstructed view to both areas. The IOT approach provided a better view of the anteromedial portion of the cisternal pulvinar surface, especially with a contralateral approach.

Multiple approaches to the pulvinar have been described, modified, and improved. Based on this anatomic study we believe that although the corridor distance with a contralateral approach is longer, the surgical view and access can be better. We recommend the use of a PSCI contralateral approach especially when a significant protrusion of the posterior parahippocampal gyrus is present 2).


From 1997 to 2017, 75 patients underwent this approach for cerebrovascular/oncologic pathology by Lawton. Of these, 30 patients underwent the ipsilateral approach for CM resection, and 3 patients underwent the contralateral approach. Historical patient data, radiographic features, surgical technique, and postoperative neurological outcomes were evaluated in each patient.

All 3 patients presented with symptomatic CMs within the right posterior thalamus with radiographic evidence of hemorrhage. All surgeries were performed in the sitting position. There were no intraoperative complications. Neuroimaging demonstrated complete CM resection in all cases. There were no new or worsening neurological deficits or evidence of rebleeding/recurrence noted postoperatively.

This study establishes the surgical feasibility of a contralateral SCIT approach in resection of symptomatic thalamic CMs It demonstrates the application for this procedure in extending the surgical trajectory superiorly and laterally and maximizing safe resectability of these deep CMs with gravity-assisted brain retraction 3).

Videos

A 19-year-old woman who presented with a long-standing history of right hemiparesis with recent deterioration. MRI revealed a large CVM located in the left thalamus, with signs of recent hemorrhage extending to the left cerebral peduncle. Resection was achieved with a paramedian contralateral supracerebellar infratentorial approach in a semisitting position, with an uneventful postoperative course.

 4)

References

1)

Sun Q, Zhao X, Gandhi S, Tayebi Meybodi A, Belykh E, Valli D, Cavallo C, Borba Moreira L, Nakaji P, Lawton MT, Preul MC. Quantitative analysis of ipsilateral and contralateral supracerebellar infratentorial and occipital transtentorial approaches to the cisternal pulvinar: laboratory anatomical investigation. J Neurosurg. 2019 Aug 2:1-10. doi: 10.3171/2019.4.JNS19351. [Epub ahead of print] PubMed PMID: 31374551.
2)

Cohen-Cohen S, Cohen-Gadol AA, Gomez-Amador JL, Alves-Belo JT, Shah KJ, Fernandez-Miranda JC. Supracerebellar Infratentorial and Occipital Transtentorial Approaches to the Pulvinar: Ipsilateral Versus Contralateral Corridors. Oper Neurosurg (Hagerstown). 2019 Mar 1;16(3):351-359. doi: 10.1093/ons/opy173. PubMed PMID: 30010967.
3)

Mascitelli J, Burkhardt JK, Gandhi S, Lawton MT. Contralateral Supracerebellar-Infratentorial Approach for Resection of Thalamic Cavernous Malformations. Oper Neurosurg (Hagerstown). 2018 Oct 1;15(4):404-411. doi: 10.1093/ons/opy004. PubMed PMID: 29490051.

Extreme lateral supracerebellar infratentorial approach

Extreme lateral supracerebellar infratentorial approach

Since the first report of application of the extreme lateral supracerebellar infratentorial (ELSI) approach in resecting the posterolateral pontomesencephalic junction (PMJ) region lesions in 2000, few articles concerning the ELSI approach have been published. A review of Chen et al., provided an intimate introduction of the ELSI approach, and evaluated it in facets of patient position, skin incision, craniectomy, draining veins, retraction against the cerebellum, exposure limits, patient healing, as well as advantages and limitations compared with other approaches. The ELSI approach is proposed to be a very young and promising approach to access the lesions of posterolateral PMJ region and the posterolateral tentorial gap. Besides, it has several advantages such as having a shorter surgical pathway, causing less surgical complications, labor-saving, etc. 1).

The extreme lateral supracerebellar infratentorial approach differs from the midline and paramedian supracerebellar infratentorial variants in the area of exposure, patient positioning, and location of the craniotomy. The technique is effective for approaching the posterolateral mesencephalon2).

The extreme-lateral corridor widens the exposure of the paramedian approach to include the anterolateral brainstem surface, offering a complete view of the cisternal space surrounding the middle incisural space 3). It provided visualization of the ambient and tentorial segments of the trochlear nerve 4).

It was initially proposed to treat lesions of the posterolateral surface of the pons principally cavernomas. The versatility of the approach allowed its use for other pathologies like gliomas, aneurysms, epidermoids, and meningiomas 5).

All the extreme-lateral supracerebellar infratentorial (SCIT) approaches warrant a safe route to the quadrigeminal plate. Among the different variants, the median approach had the smallest median surgical area exposure but presented superior results to access the intercollicular safe entry zone 6).

Lesions located at the lateral midbrain surface are better approached through the lateral mesencephalic sulcus (LMS). The goal of a study was to compare the surgical exposure to the LMS provided by the subtemporal approach and the paramedian and extreme-lateral variants of the supracerebellar infratentorial approach.

These 3 approaches were used in 10 cadaveric heads.

Cavalcanti et al., performed measurements of predetermined points by using a neuronavigation system. Areas of microsurgical exposure and angles of the approaches were determined. Statistical analysis was performed to identify significant differences in the respective exposures.

The surgical exposure was similar for the different approaches-369.8 ± 70.1 mm2 for the ST; 341.2 ± 71.2 mm2 for the SCIT paramedian variant; and 312.0 ± 79.3 mm2 for the SCIT extreme-lateral variant (p = 0.13). However, the vertical angular exposure was 16.3° ± 3.6° for the ST, 19.4° ± 3.4° for the SCIT paramedian variant, and 25.1° ± 3.3° for the SCIT extreme-lateral variant craniotomy (p < 0.001). The horizontal angular exposure was 45.2° ± 6.3° for the ST, 35.6° ± 2.9° for the SCIT paramedian variant, and 45.5° ± 6.6° for the SCIT extreme-lateral variant opening, presenting no difference between the ST and extreme-lateral variant (p = 0.92), but both were superior to the paramedian variant (p < 0.001). Data are expressed as the mean ± SD.

The extreme-lateral SCIT approach had the smaller area of surgical exposure; however, these differences were not statistically significant. The extreme-lateral SCIT approach presented a wider vertical and horizontal angle to the LMS compared to the other craniotomies. Also, it provides a 90° trajectory to the sulcus that facilitates the intraoperative microsurgical technique 7).


Five cavernous malformations, two juvenile pilocytic astrocytomas, and one peripheral superior cerebellar artery aneurysm located in this region were approached in eight patients. In this extreme lateral approach, the sigmoid sinus is unroofed more superiorly and the bone flap includes not only a posterior fossa craniotomy but also a portion that extends just above the transverse sinus. The dural opening is based along the transverse and sigmoid sinuses. After the cerebrospinal fluid has been drained, the lateral aspect of the brainstem is approached via the cerebellar surface. A proximal tentorial incision offers additional rostral exposure where needed.

Seven patients in this series underwent successful resection of their lesion. The remaining patient’s aneurysm was clipped successfully with no major complications.

The extreme lateral supracerebellar infratentorial approach differs from the midline and paramedian supracerebellar infratentorial variants in the area of exposure, patient positioning, and location of the craniotomy. The technique is effective for approaching the posterolateral mesencephalon8).


The extreme lateral infratentorial supracerebellar approach to treat pathologies located in the ambient cistern and posterior incisural space is a technically feasible route in selected cases. In this cadaveric study, we demonstrate the benefits of endoscope-assisted microsurgical maneuvers using the extreme lateral supracerebellar infratentorial approach.

An endoscope-assisted infratentorial supracerebellar approach was performed in six formalin-fixed cadaveric heads using standard microneurosurgical methods. Dissections were performed in a stepwise fashion, comparing the exposure afforded by the microsurgical route alone to the endoscope-assisted route, using 0- and 30-degree angled lenses. Relationships among the target and the surroundings neurovascular structures were described.

Endoscope-assisted maneuvers for the extreme lateral supracerebellar approach provide an improved operative view and have the potential to reduce parenchymal trauma and neurovascular injuries. The endoscopic techniques bring the surgeon to the anatomy, enhancing illumination and surgical visualization.

Direct visualization of the posterior and posterolateral incisural space avoids retraction of the occipital lobe and damage to the deep venous complex. The extreme lateral infratentorial supracerebellar corridor is effective for approaching the posterolateral mesencephalic junction and the posterior incisural space in selected cases. Endoscope-assisted microsurgery can improve visualization and minimize parenchymal retraction, which should enhance surgical control 9).


For endoscopic-controlled approaches, the extreme lateral approach provides the largest surgical freedom when accessing the ipsilateral superior colliculus (P < 0.0001), the lateral approach provides the largest surgical freedom to the pineal gland (P < 0.0001), and the paramedian craniotomy provides the largest surgical freedom when accessing the splenium (P < 0.0001). The extreme lateral approach to the pineal gland provided the largest horizontal angle of attack (P < 0.0001), and the extreme lateral approach to the ipsilateral superior colliculus provided the largest vertical angle of attack (P < 0.001). The microscope provides marginally increased surgical freedom and a better angle of attack to specific anatomical targets in the paramedian and extreme lateral approach compared with those provided by the endoscope, but these differences are negligible during intraoperative application.

Presurgical planning and a detailed understanding of the important neurovascular structures in the pineal region are paramount to safe and successful surgical execution. Our current cadaveric study indicates that the medial-to-lateral location of craniotomy can maximize access to pineal region targets. Furthermore, the endoscope is a viable alternative to the microscope for identifying pathology of the posterior incisura. These differences in surgical freedom and angle of attack to the pineal region may be useful to consider when planning minimal-access approaches 10).

Videos

A video illustrates the case of a 52-year-old man with a history of multiple bleeds from a lateral midbrain cerebral cavernous malformation, who presented with sudden-onset headache, gait instability, and left-sided motor and sensory disturbances. This lesion was eccentric to the right side and was located in the dorsolateral brainstem. Therefore, the lesion was approached via a right-sided extreme lateral supracerebellar infratentorial (exSCIT) craniotomy with monitoring of the cranial nerves. This video demonstrates the utility of the exSCIT for resection of dorsolateral brainstem lesions and how this approach gives the surgeon ready access to the supracerebellar space, and cerebellopontine angle cistern. The lateral mesencephalic safe entry zone can be accessed from this approach; it is identified by the intersection of branches of the superior cerebellar artery and the fourth cranial nerve with the vein of the lateral mesencephalic sulcus. The technique of piecemeal resection of the lesion from the brainstem is presented. Careful patient selection and respect for normal anatomy are of paramount importance in obtaining excellent outcomes in operations within or adjacent to the brainstem. The link to the video can be found at: https://youtu.be/aIw-O2Ryleg 11).

Case series

Five cavernous malformations, two juvenile pilocytic astrocytomas, and one peripheral superior cerebellar artery aneurysm located in this region were approached in eight patients. In this extreme lateral approach, the sigmoid sinus is unroofed more superiorly and the bone flap includes not only a posterior fossa craniotomy but also a portion that extends just above the transverse sinus. The dural opening is based along the transverse and sigmoid sinuses. After the cerebrospinal fluid has been drained, the lateral aspect of the brainstem is approached via the cerebellar surface. A proximal tentorial incision offers additional rostral exposure where needed.

Seven patients in this series underwent successful resection of their lesion. The remaining patient’s aneurysm was clipped successfully with no major complications 12).

References

1)

Chen X, Feng YG, Tang WZ, Li HT, Li ZJ. A young and booming approach: the extreme lateral supracerebellar infratentorial approach. Neurosci Bull. 2010 Dec;26(6):479-85. doi: 10.1007/s12264-010-1036-7. Review. PubMed PMID: 21113199; PubMed Central PMCID: PMC5560335.
2) , 8)

Vishteh AG, David CA, Marciano FF, Coscarella E, Spetzler RF. Extreme lateral supracerebellar infratentorial approach to the posterolateral mesencephalon: technique and clinical experience. Neurosurgery. 2000 Feb;46(2):384-8; discussion 388-9. PubMed PMID: 10690727.
3)

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 Oct;97(4):922-8. PubMed PMID: 12405382.
4)

Ammirati M, Musumeci A, Bernardo A, Bricolo A. The microsurgical anatomy of the cisternal segment of the trochlear nerve, as seen through different neurosurgical operative windows. Acta Neurochir (Wien). 2002 Dec;144(12):1323-7. PubMed PMID: 12478346.
5)

Giammattei L, Borsotti F, Daniel RT. Extreme lateral supracerebellar infratentorial approach: how I do it. Acta Neurochir (Wien). 2019 Apr 1. doi: 10.1007/s00701-019-03886-5. [Epub ahead of print] PubMed PMID: 30937609.
6)

Cavalcanti DD, Morais BA, Figueiredo EG, Spetzler RF, Preul MC. Supracerebellar Infratentorial Variant Approaches to the Intercollicular Safe Entry Zone. World Neurosurg. 2019 Feb;122:e1285-e1290. doi: 10.1016/j.wneu.2018.11.033. Epub 2018 Nov 14. PubMed PMID: 30447444.
7)

Cavalcanti DD, Morais BA, Figueiredo EG, Spetzler RF, Preul MC. Surgical approaches for the lateral mesencephalic sulcus. J Neurosurg. 2019 Apr 12:1-6. doi: 10.3171/2019.1.JNS182036. [Epub ahead of print] PubMed PMID: 30978690.
9)

Rehder R, Luiz da Costa MP, Al-Mefty O, Cohen AR. Endoscope-Assisted Microsurgical Approach to the Posterior and Posterolateral Incisural Space. World Neurosurg. 2016 Jul;91:210-7. doi: 10.1016/j.wneu.2016.04.017. Epub 2016 Apr 16. PubMed PMID: 27090972.
10)

Zaidi HA, Elhadi AM, Lei T, Preul MC, Little AS, Nakaji P. Minimally Invasive Endoscopic Supracerebellar-Infratentorial Surgery of the Pineal Region: Anatomical Comparison of Four Variant Approaches. World Neurosurg. 2015 Aug;84(2):257-66. doi: 10.1016/j.wneu.2015.03.009. Epub 2015 Mar 28. PubMed PMID: 25827042.
11)

Kalani MYS, Couldwell WT. Extreme Lateral Supracerebellar Infratentorial Approach to the Lateral Midbrain. J Neurol Surg B Skull Base. 2018 Dec;79(Suppl 5):S415-S417. doi: 10.1055/s-0038-1669981. Epub 2018 Sep 25. PubMed PMID: 30456047; PubMed Central PMCID: PMC6240419.
12)

Vishteh AG, David CA, Marciano FF, Coscarella E, Spetzler RF. Extreme lateral supracerebellar infratentorial approach to the posterolateral mesencephalon: technique and clinical experience. Neurosurgery. 2000 Feb;46(2):384-8; discussion 388-9. PubMed PMID: 10690727.
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