Shigeyuki Osawa

The front door to meckel's cave: an anteromedial corridor via expanded endoscopic endonasal approach- technical considerations and clinical series.

OBJECTIVE Tumors within Meckels cave are challenging and often require complex approaches. In this report, an expanded endoscopic endonasal approach is reported as a substitute for or complement to other surgical options for the treatment of various tumors within this region. METHODS A database of more than 900 patients who underwent the expanded endoscopic endonasal approach at the University of Pittsburgh Medical Center from 1998 to March of 2008 were reviewed. From these, only patients who had an endoscopic endonasal approach to Meckels cave were considered. The technique uses the maxillary sinus and the pterygopalatine fossa as part of the working corridor. Infraorbital/V2 and the vidian neurovascular bundles are used as surgical landmarks. The quadrangular space is opened, which is bound by the internal carotid artery medially and inferiorly, V2 laterally, and the abducens nerve superiorly. This offers direct access to the anteroinferomedial segment of Meckels cave, which can be extended through the petrous bone to reach the cerebellopontine angle. RESULTS Forty patients underwent an endoscopic endonasal approach to Meckels cave. The most frequent abnormalities encountered were adenoid cystic carcinoma, meningioma, and schwannomas. Meckels cave and surrounding structures were accessed adequately in all patients. Five patients developed a new facial numbness in at least 1 segment of the trigeminal nerve, but the deficit was permanent in only 2. Two patients had a transient VIth cranial nerve palsy. Nine patients (30%) showed improvement of preoperative deficits on Cranial Nerves III to VI. CONCLUSION In selected patients, the expanded endoscopic endonasal approach to the quadrangular space provides adequate exposure of Meckels cave and its vicinity, with low morbidity.

Anatomic dissection and classic three-dimensional documentation: a unit of education for neurosurgical anatomy revisited.

OBJECTIVE AND IMPORTANCE:Despite development of computer-assisted neurosurgical navigation, learning by dissecting anatomic specimens is still important. CLINICAL PRESENTATION:We describe the processes from preparation of specimens for cranial dissection to documentation of three-dimensional (3-D) stereoscopic pictures, particularly focusing on the latter, which has been initiated in the Microneuroanatomy Laboratory, Department of Neurological Surgery, University of Florida. INTERVENTION:Preparation consists of irrigation of the major vessels and injection of colored silicone. The 3-D documentation, obtaining two pictures corresponding to each eyes view, is obtained by the shoot-shift-shoot method using a single camera mounted on a slide bar. The key of this method is correct shifting of the camera without alignment error to get exact 3-D effects. Observation of 3-D image can be made with free viewing, a 3-D viewer, or projection. Tips concerning all of the processes involved are described. CONCLUSION:The presented method of dissection and obtaining 3-D images is beneficial for accomplishing studies of anatomy and for providing teaching method.

Can proximity of the occipital artery to the greater occipital nerve act as a cause of idiopathic greater occipital neuralgia? An anatomical and histological evaluation of the artery-nerve relationship.

Background: The purpose of this study was to clarify whether proximity of the occipital artery to the greater occipital nerve can act as a cause of occipital neuralgia, analogous to the contribution of intracranial vessels due to compression in cranial nerve neuralgias, represented by trigeminal neuralgias due to compression of the trigeminal nerve root by adjacent arterial loops. Methods: Twenty-four suboccipital areas in cadaver heads were studied for anatomical relationships between the occipital artery and the greater occipital nerve, with histopathological assessment of the greater occipital nerve for signs of mechanical damage. Results: The occipital artery and greater occipital nerve were found to cross each other in the nuchal subcutaneous layer, and the latter was constantly situated superficial to the former at the cross point. An indentation of the greater occipital nerve due to the occipital artery was observed at the cross point in all specimens. However, histopathological examination did not reveal any findings of damage to nerves, even in specimens with atherosclerosis of the occipital artery. Conclusions: Although the present study did not provide direct evidence that the occipital artery contributes to occipital neuralgia at the point of contact with the greater occipital nerve, the possibility still cannot be precluded, because the occipital artery may be palpable in areas corresponding to tenderness of the greater occipital nerve. Further studies, including clinical cases, are needed to clarify this issue.

Primary central nervous system lymphoma in acquired immune deficiency syndrome mimicking toxoplasmosis

A 37-year-old man, a hepatitis B virus carrier due to mother-to-child transmission, had a medical examination in September 2008 in nearby hospitals due to anorexia and weight loss. He was transported to our hospital because computed tomography (CT) detected intracranial lesions, and he had a positive human immunodeficiency virus (HIV) antibody test. Head computed tomography (CT) revealed multiple hemorrhagic lesions and enhancement effect, suggesting a thin wall. Also, an enhancement effect was present in the ventricle walls and the subarachnoid space. No accumulation was found in the thallium-201 scintigraphy. The enhancement effect of the ventricle walls and the subarachnoid space disappeared after oral administration of pyrimethamine, sulfadiazine, and calcium folinate, contributing to the diagnosis of an abscess and meningitis due to toxoplasma. However, mass lesions did not reduce. A biopsy was performed on 30 October, and the pathological diagnosis was malignant lymphoma. He died from respiratory function deterioration on 8 November. Lymphoma cells were found in ventricle wall tissue and the subarachnoid space at the autopsy. Toxoplasmosis will typically occur as a brain lesion most commonly in acquired immune deficiency syndrome (AIDS), whereas malignant lymphoma commonly manifests as a brain neoplastic lesion. However, differentiating between images of these lesions is difficult, so diagnosis by early biopsy is recommended.

Intraoperative Ultrasonography during Drainage for Chronic Subdural Hematomas: A Technique to Release Isolated Deep-seated Hematomas—Technical Note

After the drainage of chronic subdural hematomas (CSDHs), residual isolated deep-seated hematomas (IDHs) may recur. We introduce intraoperative ultrasonography to detect and remove such IDHs. Intra-operative ultrasonography is performed with fine transducers introduced via burr holes. Images obtained before dural opening show the CSDHs, hyper- and/or hypoechoic content, and mono- or multilayers. Images are also acquired after irrigation of the hematoma under the dura. Floating hyperechoic spots (cavitations) on the brain cortex created by irrigation confirm the release of all hematoma layers; areas without spots represent IDHs. Their overlying thin membranes are fenestrated with a dural hook for irrigation. Ultrasonographs were evaluated in 43 CSDHs (37 patients); 9 (21%) required IDH fenestration. On computed tomography scans, 17 were homogeneous-, 6 were laminar-, 16 were separated-, and 4 were trabecular type lesions. Of these, 2 (11.8%), 3 (50%), 4 (25%), and 0, respectively, manifested IDHs requiring fenestration. There were no technique-related complications. Patients subjected to IDH fenestration had lower recurrence rates (11.1% vs. 50%, p = 0.095) and required significantly less time for brain re-expansion (mean 3.78 ± 1.62 vs. 18 ± 5.54 weeks, p = 0.0009) than did 6 patients whose IDHs remained after 48 conventional irrigation and drainage procedures. Intraoperative ultrasonography in patients with CSDHs facilitates the safe release of hidden IDHs. It can be expected to reduce the risk of postoperative hematoma recurrence and to shorten the brain re-expansion time.

An Operation in the Park Bench Position Complicated by Massive Tongue Swelling

This paper presents a case of massive tongue swelling as a complication after an operation in the park bench position. A 43-year-old male who had undergone a resection of a mass in the petrous bone of the clivus showed massive tongue swelling after the surgery in the left park bench position. A direct compression of the bite block caused the swelling of tongue. Tongue swelling may become fatal if it progresses to an airway obstruction; therefore the intraoperative and postoperative management is important.

Postoperative reversible deterioration in a spinal dural arteriovenous fistula

This 61-year-old man presented with weakness and sensory disturbance in the legs. There was a spinal dural arteriovenous fistula (SDAVF) fed by the left sixth intercostal artery with dorsal perimedullary drainage. Surgical division of the perimedullary drainage led to rapid neurological improvement. However, on the second postoperative day he experienced transient deterioration of second neuron function in the left upper lumbar segment resulting in motor weakness of the proximal leg muscles, absence of the patellar deep tendon reflex and thigh pain. No radiological findings explaining this deterioration were obtained. He was treated conservatively and all segmental symptoms and signs subsided by the fifth postoperative day. Although the precise mechanisms underlying the dramatic but often reversible deterioration after radical SDAVF treatment remain to be determined, we postulate that this was attributable to postoperative segmental venous hemodynamic changes based on the neurological changes.

Modified One-piece Supraorbital Approach for Orbital Tumors: Widely Preserved Orbital Roof in a Self-fitting Flap.

Objectives The one-piece supraorbital approach is a rational approach for the removal of orbital tumors. However, cutting the roof through the orbit is often difficult. We modified the technique to facilitate the osteotomy and improve the cosmetic effect. Design Three burr holes are made: the first, the MacCarty keyhole (burr hole 1), exposes the anterior cranial fossa and orbit; the second is placed above the supraorbital nerve (burr hole 2); and the third on the superior temporal line. Through burr hole 2, a small hole is created on the roof, 10 mm in depth. Next the roof is rongeured through burr hole 1 toward the preexisting small hole. Seamless osteotomies using a diamond-coated threadwire saw and the preexisting four holes are performed. Lastly the flap is removed. On closure, sutures are passed through holes in the cuts made with the threadwire saw, and tied. Results We applied our technique to address orbital tumors in two adult patients. The osteotomies in the roof were easy, and most parts of the roof were repositioned. Conclusions Our modification results in orbital osteotomies with greater preservation of the roof. Because the self-fitting flap does not require the use of fixation devices, the reconstruction is cosmetically satisfactory.