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Ken Matsushima and Michihiro Kohno

Surgical management of cerebellopontine angle meningiomas is challenging due to the intricate neurovascular structures within the limited operative field and the compression of eloquent structures including the brainstem. Surgery on tumors extending into the temporal bone is especially difficult and demands complicated approaches. However, modifications to the retrosigmoid approach utilizing intradural temporal bone drilling enable access to such tumoral extensions without any additional invasive approaches. This video demonstrates the case of a cerebellopontine angle meningioma extending into the internal acoustic meatus and jugular foramen that was surgically treated through the retrosigmoid transmeatal and suprajugular approaches under continuous vagus nerve monitoring.

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Ken Matsushima, Michihiro Kohno and Helmut Bertalanffy

Hemorrhagic brainstem cavernous malformations carry a high risk of progressive neurological deficits owing to recurrent hemorrhages and hence require complete surgical resection while minimizing damage to the dense concentration of nuclei and fibers inside the brainstem. To access lesions inside the lower pons, the senior author (H.B.) has preferred to approach the lesions via the “perifacial zone” through the pontomedullary sulcus from the inferior surface of the pontine bulge for more than 20 years.1,2 This video demonstrates a case of a cavernous malformation inside the lower pons, which was surgically treated via the pontomedullary junction through the retrosigmoid supracondylar approach in a half-sitting position. The lesion was completely removed in piecemeal fashion through a tiny incision on the sulcus, which did not cause any new neurological deficits. The modified Rankin Scale improved from 4 before the surgery to 1, and the patient had no recurrence during the 2 years of follow-up. The advantage of this access and the dissection techniques for this challenging lesion are introduced, based on our experience with more than 230 surgeries of brainstem cavernoma.

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Ken Matsushima, Kaan Yagmurlu, Michihiro Kohno and Albert L. Rhoton Jr.


Fissure dissection is routinely used in the supratentorial region to access deeply situated pathology while minimizing division of neural tissue. Use of fissure dissection is also practical in the posterior fossa. In this study, the microsurgical anatomy of the 3 cerebellar-brainstem fissures (cerebellomesencephalic, cerebellopontine, and cerebellomedullary) and the various procedures exposing these fissures in brainstem surgery were examined.


Seven cadaveric heads were examined with a microsurgical technique and 3 with fiber dissection to clarify the anatomy of the cerebellar-brainstem and adjacent cerebellar fissures, in which the major vessels and neural structures are located. Several approaches directed along the cerebellar surfaces and fissures, including the supracerebellar infratentorial, occipital transtentorial, retrosigmoid, and midline suboccipital approaches, were examined. The 3 heads examined using fiber dissection defined the anatomy of the cerebellar peduncles coursing in the depths of these fissures.


Dissections directed along the cerebellar-brainstem and cerebellar fissures provided access to the posterior and posterolateral midbrain and upper pons, lateral pons, floor and lateral wall of the fourth ventricle, and dorsal and lateral medulla.


Opening the cerebellar-brainstem and adjacent cerebellar fissures provided access to the brainstem surface hidden by the cerebellum, while minimizing division of neural tissue. Most of the major cerebellar arteries, veins, and vital neural structures are located in or near these fissures and can be accessed through them.

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Michihiro Kohno, Hiroshi Takahashi, Katsuhisa Ide, Buichi Ishijima, Katsuhiro Yamada and Shigeru Nemoto

✓ A 51-year-old man presenting with radiculopathy with a rare cervical dural arteriovenous fistula (AVF) is reported. Angiography revealed that the cervical dural AVF was fed mainly by the left C-3 and C-4 radicular arteries and drained into the internal vertebral venous plexus with no communication with intradural structures. The dural AVF was treated surgically after embolization therapy. Although the AVF showed mass effect on computerized tomography (CT) scanning, abnormal vessels, which were suspected to drain the AVF, were observed intraoperatively to compress the left C-4 and C-5 nerve root sleeves. After resection of these abnormal epidural vessels, monoparesis of the left proximal upper extremity was markedly improved. In this patient, dynamic CT scanning was useful in the initial diagnosis, and the preoperative embolization therapy was very effective.

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Michihiro Kohno, Hiroshi Takahashi, Katsuhisa Ide, Kenta Yamakawa, Tatsuya Saitoh and Kiyoharu Inoue

Object. Cervical flexion myelopathy is a rare condition that mainly affects adolescent boys. In recent years, avoidance of neck flexion has been advocated as the treatment for cervical flexion myelopathy, and treatment with a cervical collar and surgery in which fusion of the cervical spine is performed have been found to be effective. However, previously reported series contained only a limited number of patients. The authors report their experience with treating 10 male patients in whom surgery was performed to correct cervical flexion myelopathy, and they evaluate the patients' surgical outcome.

Methods. The authors performed anterior decompressive surgery and fusion in the cervical spine by using a long bone graft after resection of one or two vertebrae in seven patients. The other three patients underwent posterior fusion of four or five laminae.

After surgery, symptom progression was stopped in all patients, muscle strength improved in seven, and sensory disturbance was alleviated in another two. However, the muscular atrophy in the upper extremities, which was evident in nine patients preoperatively, improved in only two.

Conclusions. Because some neurological improvement was seen in nine of 10 patients, it is believed that surgical fusion of the cervical spine is an effective treatment for patients with cervical flexion myelopathy.

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Jiro Akimoto, Kenta Nagai, Daisuke Ogasawara, Yujiro Tanaka, Hitoshi Izawa, Michihiro Kohno, Keisuke Uchida and Yoshinobu Eishi

Sarcoidosis is a systemic granulomatous disease with unknown cause, which very rarely occurs exclusively in the central nervous system. The authors performed biopsy sampling of a mass that developed in the left tentorium cerebelli that appeared to be a malignant tumor. The mass was diagnosed as a sarcoid granuloma, which was confirmed with the onset of antibody reaction product against Propionibacterium acnes. Findings suggesting sarcoidosis to be an immune response to P. acnes infection have recently been reported, and they give insight for diagnosis and treatment of this disease. The authors report the possible first case that was confirmed with P. acnes infection in a meningeal lesion in solitary neurosarcoidosis.

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Ken Matsushima, Michihiro Kohno, Noritaka Komune, Koichi Miki, Toshio Matsushima and Albert L. Rhoton Jr.


Jugular foramen tumors often extend intra- and extracranially. The gross-total removal of tumors located both intracranially and intraforaminally is technically challenging and often requires a combined skull base approach. This study presents a suprajugular extension of the retrosigmoid approach directed through the osseous roof of the jugular foramen that allows the removal of tumors located in the cerebellopontine angle with extension into the upper part of the foramen, with demonstration of an illustrative case.


The cerebellopontine angles and jugular foramina were examined in dry skulls and cadaveric heads to clarify the microsurgical anatomy around the jugular foramen and to define the steps of the suprajugular exposure.


The area drilled in the suprajugular approach is inferior to the acoustic meatus, medial to the endolymphatic depression and surrounding the superior half of the glossopharyngeal dural fold. Opening this area exposed the upper part of the jugular foramen and extended the exposure along the glossopharyngeal nerve below the roof of the jugular foramen. In the illustrative case, a schwannoma originating from the glossopharyngeal nerve in the cerebellopontine angle and extending below the roof of the jugular foramen and above the jugular bulb was totally removed without any postoperative complications.


The suprajugular extension of the retrosigmoid approach will permit removal of tumors located predominantly in the cerebellopontine angle but also extending into the upper part of the jugular foramen without any additional skull base approaches.