Telovelar/Transcerebellomedullary Fissure Approach: Giant Distal Posterior Inferior Cerebellar Artery Aneurysm, Epidermoid Cyst, and Brainstem Cavernoma: 2-Dimensional Operative Video
Authors: Matsushima Ken , Matsushima Toshio 
Published: June 2023

INDICATIONS: CORRIDOR AND LIMITS OF EXPOSURE
The telovelar or transcerebellomedullary fissure approach can provide wide exposure of the cerebellomedullary fissure and fourth ventricle by separating the natural plane between the medulla and cerebellum.
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ANATOMIC ESSENTIALS: NEED FOR PREOPERATIVE PLANNING AND ASSESSMENT
The cerebellar tonsil is attached to the adjacent cerebellum only by the tonsillar peduncle at its superolateral edge.
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The posterior inferior cerebellar artery (PICA) runs in the cerebellomedullary fissure, usually making its caudal and cranial loops.
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ESSENTIALS STEPS OF THE PROCEDURE
After widely opening the foramen magnum, the tonsil is gently elevated by shearing the tela choroidea up to the lateral recess from the taenia, where the vein of the inferior cerebellar peduncle courses.
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PITFALLS/AVOIDANCE OF COMPLICATIONS
The developed occipital sinus, posterior condylar vein, and anomalies of the vertebral artery and PICA origin can obstruct the exposure. Detailed neuromonitoring is essential for accomplishing the procedure safely.
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VARIANTS AND INDICATIONS FOR THEIR USE
This exposure can be extended to the lower cerebellopontine angle and can also be applied to the dorsal brainstem surgery.
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The patients consented to the procedure and to the publication of their images.
Image Credits: Department of Neurosurgery, Tokyo Medical University logo used by permission. Image at 0:10, 1:02, 2:46, 6:22, and 7:10 from Matsushima and Kohno,
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used by permission from Medical View Co., Ltd.
Right image at 0:14 and also upper image at 0:46, image at 1:26, and for left and lower right images at 1:54 from Matsushima et al,
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by permission from Journal of Neurosurgery Publishing Group (JNSPG). Left image at 0:14, from Matsushima et al,
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used by permission from the Congress of Neurological Surgeons. Lower image at 0:46 reprinted from Matsushima et al,
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by permission from Elsevier. Left image at 1:06 from Matsushima et al,
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used by permission from the Congress of Neurological Surgeons.
Image at top right at 1:54 from Lister et al,
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used by permission from the Congress of Neurological Surgeons. Image in center at 6:56 from Matsushima et al,
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used by permission from Springer Nature. Image at right at 6:56 from Matsushima et al,
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used by permission from JNSPG. Images at 9:48, by year: 1982 article screenshot and figure from Matsushima et al,
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by permission from the Congress of Neurological Surgeons; 1992: article title screenshot from Matsushima et al,
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by permission from the Congress of Neurological Surgeons; 1996: used with permission of McGraw-Hill Health Professions Division, from Microsurgical Anatomy of the Fourth Ventrical, Matshushiam T and Rhoton AL Jr, in Neurosurgery, eds Wilkins and Rengachary, vol 1, 1996, permission conveyed through Copyright Clearance Center, Inc.; 2000: article title screenshot from Mussi et al,
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reused with permission from JNSPG; 2001: article title screenshot from Matsushima, Transcerebellomedullary fissure approach with special reference to methods of dissecting the fissure, J Neurosurg, vol 91, 2001, p. 257-264, by permission from JNSPG; 2021: article title screenshot from Matsushima et al,
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by permission from Springer Nature. Images at 11:05 from Inoue T et al, “Surgical approach to the mesencephalic vascular malformation” [in Japanese], Surg Cereb Stroke, vol 26, 1998, p 288-289, by permission from the Japanese Society on Surgery for Cerebral Stroke. Cadaveric image at 11:56 from Matsushima T et al, “Exposure of the wide interior of the fourth ventricle without splitting the vermis: importance of cutting procedures for the tela choroidea” Neurosurg Rev, vol 35, 2012, p 563-571, used with permission from Springer Nature.