Fuminari Komatsu

Endoscopic approaches to the trigeminal nerve and clinical consideration for trigeminal schwannomas: a cadaveric study.

OBJECT The course of the trigeminal nerve straddles multiple fossae and is known to be very complex. Comprehensive anatomical knowledge and skull base techniques are required for surgical management of trigeminal schwannomas. The aims of this study were to become familiar with the endoscopic anatomy of the trigeminal nerve and to develop a minimally invasive surgical strategy for the treatment of trigeminal schwannomas. METHODS Ten fresh cadavers were studied using 5 endoscopic approaches with the aid of 4-mm 0° and 30° endoscopes to identify surgical landmarks associated with the trigeminal nerve. The endoscopic approaches included 3 transcranial keyhole approaches (the extradural supraorbital, extradural subtemporal, and retrosigmoid approaches), and 2 endonasal approaches (the transpterygoid and the transmaxillary transpterygoid approaches). RESULTS The trajectories of the extradural supraorbital, transpterygoid, and extradural subtemporal approaches corresponded with the course of the first, second, and third divisions of the trigeminal nerve, respectively. The 3 approaches demonstrated each division in intra- and extracranial spaces, as well as the Meckel cave in the middle cranial fossa. The interdural space at the lateral wall of the cavernous sinus was exposed by the extradural supraorbital and subtemporal approaches. The extradural subtemporal approach with anterior petrosectomy and the retrosigmoid approach visualized the trigeminal sensory root and its neighboring neurovascular structures in the posterior cranial fossa. The transmaxillary transpterygoid approach revealed the course of the third division in the infratemporal fossa. CONCLUSIONS The 5 endoscopic approaches effectively followed the course of the trigeminal nerve with minimal invasiveness. These approaches could provide alternative options for the management of trigeminal schwannoma.

Endoscopic supraorbital extradural approach to the cavernous sinus: a cadaver study

OBJECT The cavernous sinus is a small complex structure located at the central base of the skull. Recent extensive use of endoscopy has provided less invasive approaches to the cavernous sinus via endonasal routes, although transcranial routes play an important role in the approach to the cavernous sinus. The aims of this study were to evaluate the feasibility of the purely endoscopic transcranial approach to the cavernous sinus through the supraorbital keyhole and to better understand the distorted anatomy of the cavernous sinus via endoscopy. METHODS Eight fresh cadavers were studied using 4-mm 0° and 30° endoscopes to develop a surgical approach and to identify surgical landmarks. RESULTS The endoscopic supraorbital extradural approach was divided into 4 stages: entry into the extradural anterior cranial fossa, exposure of the middle cranial fossa and the periorbita, exposure of the superior cavernous sinus, and exposure of the lateral cavernous sinus. This approach provided superb views of the cavernous sinus structures, especially through the clinoidal (Dolenc) triangle. The lateral wall of the cavernous sinus, including the infratrochlear (Parkinson) triangle and anteromedial (Mullan) triangle, was also clearly demonstrated. CONCLUSIONS An endoscopic supraorbital extradural approach offers excellent exposure of the superior and lateral walls of the cavernous sinus with minimal invasiveness via the transcranial route. This approach could be an alternative to the conventional transcranial approach.

Endoscopic extradural anterior clinoidectomy via supraorbital keyhole: a cadaveric study.

BACKGROUND: Anterior clinoidectomy is an essential preliminary step for parasellar and pericavernous sinus surgery. Endoscopy is a widely accepted modality for neurosurgical strategies and is becoming more important in treating conditions involving the cranial base. OBJECTIVE: To determine the feasibility of endoscopic extradural anterior clinoidectomy via the supraorbital keyhole. METHODS: Eight fresh cadaver heads were studied using 4-mm, 0- and 30-degree rigid endoscopes to perform endoscopic extradural anterior clinoidectomy. We also evaluated a bony landmark for this technique in 36 dry craniums. RESULTS: An endoscope was introduced into the extradural space created via a supraorbital keyhole craniotomy. The periorbita and the duplication of the dura extending to the temporal lobe dura and periorbita were exposed by drilling. Anterior clinoidectomy proceeded using a diamond drill under endoscopic visualization without a dural incision. A submerged view with continuous irrigation through an endoscopic sheath maintained clear visibility while drilling. A small bony eminence at the transition between the sphenoid ridge and the anterior clinoid process, which is an anatomic landmark for endoscopic extradural anterior clinoidectomy, was identified in 57.4% of 36 adult dry craniums. CONCLUSION: The endoscopic extradural procedure can accomplish reliable anterior clinoidectomy under superb endoscopic visualization. This method would be applicable to parasellar and cavernous sinus surgery combined with keyhole or conventional craniotomy.

The subdiaphragmatic cistern: historic and radioanatomic findings

BackgroundIn the past, sporadic demonstrations of the existence of a subarachnoid subdiaphragmatic cistern have been published. The aim of this study was to evaluate the anatomical characteristics of the subdiaphragmatic cistern of the pituitary gland.MethodsAfter a complete review of the literature published on the topic, we report anatomical observations of the subdiaphragmatic cistern and its relationship to the pituitary gland and to the chiasmatic cistern. Ten cadaveric heads were studied using different techniques and surgical methods (plastination, plastic casts of the subarachnoid spaces, microscopic and transsphenoidal endoscopic approaches). Moreover, 3-T magnetic resonance images of ten healthy volunteers were analyzed to investigate the presence and anatomical variability of the subdiaphragmatic cistern.ResultsBy means of our qualitative radioanatomic study, we found that the roof of the subdiaphragmatic cistern is formed by the diaphragma sellae, the floor by the superior face of the pituitary gland, the lateral walls by the arachnoidea extending laterally through the medial walls of the cavernous sinus, and the medial walls by the infundibular stem. The subdiaphragmatic cistern communicates by means of the ostium of the diaphragm with the chiasmatic cistern.ConclusionWe confirmed the existence of the subdiaphragmatic cistern. The overused term “suprasellar cistern” refers more to a complex of cisterns, formed by the subdiaphragmatic cistern, below the diaphragma sella, and by the chiasmatic cistern, above it, in direct communication with the lamina terminalis and carotid cisterns.

Endoscopic reconstruction of the middle cranial fossa through a subtemporal keyhole using a pedicled deep temporal fascial flap: a cadaveric study.

BACKGROUND: Reconstruction of the skull base is essential to prevent postoperative leakage of cerebrospinal fluid (CSF). However, a reliable method of reconstructing the middle cranial fossa via a subtemporal keyhole is not available. OBJECTIVE: To determine whether less invasive reconstruction of the middle cranial fossa under endoscopic guidance with a pedicled deep temporal fascia approach via a subtemporal keyhole is feasible and useful. METHODS: The middle cranial fossa in 4 fresh cadaver heads was reconstructed with a 4-mm 0° rigid endoscope. RESULTS: A subtemporal skin incision (subtemporal incision) was followed by 2 small skin incisions (temporal line incisions) made on the superior temporal line. The endoscope was inserted through the temporal line incisions, and then the deep temporal fascia was separated from the superficial temporal fascia and temporal muscle under endoscopic view. A pedicled flap was harvested from the subtemporal incision and applied to the middle cranial fossa after subtemporal keyhole craniotomy. The pedicled deep temporal fascial flap was flexible, long, and large enough to overlay skull base defects. CONCLUSION: This purely endoscopic technique using a pedicled deep temporal fascial flap provided reliable reconstruction of the middle cranial fossa through a subtemporal keyhole. This technique would also be applicable in preventing CSF leakage or treating traumatic, acquired nontraumatic, or congenital encephalocele in the middle cranial fossa.

A case of a heavily pigmented orbital melanocytoma

We present an extremely rare case of an orbital melanocytoma that occurred in a 51-year-old man. The patient suffered from diplopia and mild exophthalmos of the right eye for 2 months. Brain magnetic resonance imaging showed a well-demarcated round mass 3.5 cm in diameter in the right orbit. We performed total resection of this tumor. Histological findings revealed a proliferation of large polygonal cells with fine pigment granules in the cytoplasm and prominent nucleoli. Although these tumor cells revealed immunohistochemical reactivity in HMB-1, there was no S-100 or Melan A antibody reactivity. Also, there were no malignant findings of nuclear polymorphism, mitoses, or necrosis. The brown pigments were confirmed to be melanin by bleaching and the Fontana-Masson silver stain method. The MIB-1 labeling index was less than 1%. This tumor also consisted of 50% melanophages, which revealed immunohistochemical reactivity in CD68, CD163, and in (1-AT antibodies. These histological findings led us to diagnose an orbital melanocytoma with partial tumor regression.

Congenital Medulloblastoma with Atypical MRI Appearance

A 13-day-old female infant was admitted with hydrocephalus that had been diagnosed on prenatal ultrasound at 33 weeks’ gestation. She was delivered by Caesarean section at 34 weeks with an Apgar score of 10. On admission, she weighed 2,103 g. The head circumference was 32.3 cm, and the fontanelle was tense. T1- and T2-weighted MR images revealed an isointense mass occupying the fourth ventricle with multiple cysts in the vermis. The mass was not enhanced after gadolinium administration. CT showed no definite calcification in the lesion. Preoperatively, vermian tumors, including medulloblastoma, ependymoma, astrocytoma, and hamartomas, were considered in the differential diagnosis. Hamartoma was strongly suspected due to the lack of enhancement on MRI. After a suboccipital midline craniotomy, subtotal resection of a soft grayish tumor with areas of hematoma was carried out. The pathological diagnosis was medulloblastoma. Despite chemotherapy, CSF dissemination resulted in death at 11 months. We report this case of congenital medulloblastoma with atypical MRI findings and discuss the clinical characteristics of this lesion.

Potential neural progenitor cells in fetal liver and regenerating liver

From unfractionated embryonic mice liver cells, appreciable amount of spherical bodies containing nestin-positive cells were generated in the presence of neuronal growth factors. Following cultivation on poly-d-lysine/laminin-coated slips, approximately 70% of the cells expressed neuronal markers, and 16% had long processes. Functional analysis of these long-process-bearing cells with the whole-cell patch clamp method showed an inward current in response to glutamate, GABA, and serotonin as the neuronal characteristics. Furthermore, regenerating liver in adult mice also contained nestin-positive cells to the same extent as fetal liver. Regenerating liver could have potential as a source of neural cells for autologous transplantation.

Retrospective review of previous minor leak before major subarachnoid hemorrhage diagnosed by MRI as a predictor of occurrence of symptomatic delayed cerebral ischemia

OBJECTIVE This study attempted to determine whether a previous minor leak correlated with the occurrence of symptomatic delayed cerebral ischemia (sDCI). METHODS The authors retrospectively evaluated sDCI-related clinical features and findings from MRI, including T1-weighted imaging (T1WI)-FLAIR mismatch at the time of admission, in 151 patients admitted with subarachnoid hemorrhage (SAH) within 48 hours of ictus. RESULTS The overall incidence of sDCI was 23% (35 of 151 patients). In all subjects, multivariate analysis revealed that World Federation of Neurosurgical Societies Grades II-V, age 70 years or older, presence of rebleeding after admission, a previous minor leak before the major SAH attack as diagnosed by T1WI-FLAIR mismatch, acute infarction on diffusion-weighted imaging, and CT SAH score were significantly associated with occurrence of sDCI. In patients with no previous minor leak before major SAH as diagnosed by T1WI-FLAIR mismatch, the incidence of sDCI was only 7% (7 of 97 patients). CONCLUSIONS A previous minor leak before major SAH as diagnosed by T1WI-FLAIR mismatch represents an important sDCI-related factor. When the analysis was restricted to patients with true acute SAH without a previous minor leak diagnosed by T1WI-FLAIR mismatch, the incidence of sDCI was extremely low.

Pilomyxoid Astrocytomas: Chemotherapy

Pilomyxoid astrocytoma (PMA) is a variant of pilocytic astrocytoma (PA). However, PMA shows a higher rate of recurrence and dissemination in cerebrospinal fluid (CSF) than does pilocytic astrocytoma (PA). PMA occurs predominantly in the hypothalamic/chiasmic region, and thus it is usually treated with chemotherapy following surgical biopsy. We discuss the treatment of PMA. Materials and Methods: Between 1992 and 2009, the authors treated 5 patients, 2 males and 3 females, ranging in age from 3 months to 11 years. Results: Three patients showed CSF dissemination on the initial radiographic examination. All patients received chemotherapy; the most commonly used drug combination was that of cisplatin (CDDP)/carboplatin (CBDCA) and etoposide. If these drugs were unsuccessful, they were changed, or other drugs were added to the combination. After chemotherapy, four patients showed remarkable tumor regression. Nevertheless, one patient died due to tumor progression 22 months after initial diagnosis. Conclusion: Although our series comprised a small number of patients, treatment of PMA with chemotherapy appeared to be of value. Even if initial chemotherapy is ineffective, we recommend continued CDDP/CBDCA-based chemotherapy with new drug combinations.