Tomomi Okamura

Surgical strategy for cavernous angioma in hypothalamus

A very rare case of cavernous angioma in the hypothalamus is presented. The patient was successfully treated by total excision of the haematoma and angioma, and there was no regrowth of the lesion on follow-up MRI. Complete excision of the angioma is the recommended surgical strategy even for patients with deep-seated lesions.

Direct surgery for giant aneurysm exhibiting progressive enlargement after intraaneurysmal balloon embolization

A case of giant intracranial carotid artery aneurysm exhibiting progressive enlargement after incomplete intraaneurysmal balloon embolization is presented. The patient was successfully treated by the trapping and decompression of the aneurysm with a superficial temporal artery-middle cerebral artery anastomosis. The thrombus surrounding the intraluminal balloons was very soft and poorly organized. Either direct surgery with extracranial-intracranial arterial bypass or complete intravascular surgery should be performed for giant aneurysms when direct clipping is impossible.

Transcerebellar thrombectomy for the successful clipping of thrombosed giant vertebral artery-posterior inferior cerebellar artery aneurysm: Case report

The operative technique used for a thrombosed vertebral artery-posterior inferior cerebellar artery aneurysm that was treated by combined transcerebellar (petrosal surface) thrombectomy and neck clipping is presented. Transcerebellar thrombectomy permitted the successful clipping of this thrombosed vertebral artery-posterior inferior cerebellar artery aneurysm via the cerebello-medullary cistern.

A surgical strategy using a fusion image constructed from 11C-methionine PET, 18F-FDG-PET and MRI for glioma with no or minimum contrast enhancement

The objective of this study was to investigate the distribution of 11C-methionine (MET) and F-18 fluorodeoxyglucose (FDG) uptake in positron emission tomography (PET) imaging and the hyperintense area in T2 weighted imaging (T2WI) in glioma with no or poor gadolinium enhancement in magnetic resonance imaging (GdMRI). Cases were also analyzed pathologically. We prospectively investigated 16 patients with non- or minimally enhancing (< 10% volume) glioma. All patients underwent MET-PET and FDG-PET scans preoperatively. After delineating the tumor based on MET uptake, integrated 3D images from FDG-PET and MRI (GdMRI, T2WI or FLAIR) were generated and the final resection plane was planned. This resection plane was determined intraoperatively using the navigation-guided fencepost method. The delineation obtained by MET-PET imaging was larger than that with GdMRI in all cases with an enhanced effect. In contrast, the T2WI-abnormal signal area (T2WI+) tended to be larger than the MET uptake area (MET+). Tumor resection was > 95% in the non-eloquent area in 4/5 cases (80%), whereas 10 of 11 cases (90.9%) had partial resection in the eloquent area. In a case including the language area, 92% resection was achieved based on the MET-uptake area, in contrast to T2WI-based partial resection (65%), because the T2WI+/MET− area defined the language area. Pathological findings showed that the T2WI+/MET+ area is glioma, whereas 6 of 9 T2WI+/MET− lesions included normal tissues. Tissue from T2W1+/MET+/FDG+/GdMRI+ lesions gave an accurate diagnosis of grade in six cases. Non- or minimally enhancing gliomas were classified as having a MET uptake area that totally or partially overlapped with the T2WI hyperintense area. Resection planning with or without a metabolically active area in non- or minimally enhancing gliomas may be useful for accurate diagnosis, malignancy grading, and particularly for eloquent area although further study is needed to analyze the T2WI+/MET− area.

Indication and Timing of Surgery for Cochleovestibular Neurovascular Compression Syndrome

Objective: Optimal surgical indications for cochleovestibular neurovascular compression syndrome (CNVC) remain controversial. We examined the surgical indications and timing of surgery for CNVC. Methods: The surgical outcomes of 30 patients (32 sides) with vertigo, tinnitus and hearing loss were evaluated. CNVC was diagnosed according to five items for clinical features with a scoring system of 1 or 0 based on the following features: a history, neurological and otological findings, an ABR evaluation, and vascular contact with the eighth cranial nerve on MR or air CT imaging. Patients with scores of 4-5 were diagnosed with CNVC. In addition, three modulation types of tinnitus using median nerve stimulation were evaluated in CNVC (28 sides) and other diseases (12 sides), and classified as suppression (S-type), no change (N-type), and excitation (E-type). Results: At early time, results of 16 sides evaluated using the modulation test before surgery for CNVC, the relationship between modulation of tinnitus and surgical results was evaluated. The ratio of the tinnitus intensity early after the surgery to that before the surgery was significantly lower for the S-type than for the other two types (P<0.01). At one year follow-up, the results of 32 sides were excellent in 8 sides, good in 19 sides, fair in 2 sides and poor in 3 sides. The duration of preoperative symptoms in the excellent group (1.9 ± 6.7 years) was shorter than that in the good group (5.8 ± 5.8 years). Results of CNVC with a chief complaint of vertigo and the duration of symptoms over 15 years and CNVC with a chief complaint of tinnitus and the duration of symptoms over 3 years was not always satisfactory. Conclusion: Indications for good outcomes are limited and need to consider not only the duration of symptoms, but also the modulation of tinnitus. Our findings suggest that the timing of surgery for CNVC with a complaint of vertigo should be within about 15 years, but that for CNVC with tinnitus should be within 3 years of onset of symptoms. Furthermore, some patients with S-type of less than 6 years are good candidates for surgery.

Cerebellopontine angle facial schwannoma relapsing towards middle cranial fossa

Facial nerve schwannomas involving posterior and middle fossas are quite rare. Here, we report an unusual case of cerebellopontine angle facial schwannoma that involved the middle cranial fossa, two years after the first operation. A 53-year-old woman presented with a 3-year history of a progressive left side hearing loss and 6-month history of a left facial spasm and palsy. Magnetic resonance imaging (MRI) revealed 4.5 cm diameter of left cerebellopontine angle and small middle fossa tumor. The tumor was subtotally removed via a suboccipital retrosigmoid approach. The tumor relapsed towards middle cranial fossa within a two-year period. By subtemporal approach with zygomatic arch osteotomy, the tumor was subtotally removed except that in the petrous bone involving the facial nerve. In both surgical procedures, intraoperative monitoring identified the facial nerve, resulting in preserved facial function. The tumor in the present case arose from broad segment of facial nerve encompassing cerebellopontine angle, meatus, geniculate/labyrinthine and possibly great petrosal nerve, in view of variable symptoms. Preservation of anatomic continuity of the facial nerve should be attempted, and the staged operation via retrosigmoid and middle fossa approaches using intraoperative facial monitoring, may result in preservation of the facial nerve.

Zygomatic Approach to Vascular Lesions in the Skull Base

Lesions located in the middle fossa, prepontine and interpeduncular cisterns are some of the most difficult to approach in case of radical surgery, even with the aid of an operating microscope. To minimize the retraction of the temporal lobe and achieve wide exposure, many operative modalities have been reported. We describe a zygomatic approach without removal of the lateral orbital rim, which we developed based on a modification of Fujitsus approach. This approach has been used in 8 patients: 2 with aneurysms in the territory of the basilar artery, 3 with brain stem ischemia, 1 with a hypothalamic hematoma, and 1 with a cavernous angioma in the midbrain. The last patient had an anterior communicating artery aneurysm and a concomitant temporal convexity meningioma. Complete clip ligation was performed for all 3 aneurysms and gross total removal was achieved in hypothalamic hematoma case and cavernous angioma case. Also, the anastomosis of the superficial temporal artery to superior cerebellar artery was performed for 3 patients with brain stem ischemia. One patient with a large basilar tip aneurysm died due to initial damage of the brain on attack. Another with cavernous angioma developed left hemiparesis and oculomotor palsy but these symptoms markedly improved 6 months after the operation. The complications we observed in this series, consisted of 2 types. The first comprised temporary third nerve paresis in 2 cases and the second was temporal muscle atrophy. Based on our experience and the operative results obtained, we concluded that this procedure allows a wide operative field and easy access to the interpeduncular fossa with minimal brain retraction.

Usefulness of the Initial Clipping on Surgery of the Cerebral Aneurysm

The prognosis of patients with subarachnoid hemorrhage due to a ruptured cerebral aneurysm is chiefly influenced by initial damage of the brain on insult, the operation and the occurrence of vasospasm. However, the operation may play the most important part of these three factors. The authors think that the results of an operation for cerebral aneurysms will depend on the occurrence of premature rupture during the dissection of an aneurysm from the surrounding tissue. In order to prevent premature rupture of a cerebral aneurysm and to shorten the time of temporary clipping of the parent arteries during dissection, the authors use the technique of initial clipping with good results. So, the authors explain the technique of initial clipping in our representative cases. Finally, based our experiences, the authors state the merits of this technique and discuss its usefulness in surgery.