Jun Masuoka

Transcondylar Fossa (Supracondylar Transjugular Tubercle) Approach: Anatomic Basis for the Approach, Surgical Procedures, and Surgical Experience

The authors clarify the anatomic basis and the usefulness of the transcondylar fossa approach (T-C-F A), in which the posterior portion of the jugular tubercle is removed extradurally through the condylar fossa with the atlanto-occipital joint intact. The authors first performed an anatomic study to identify the area to be removed using cadaveric specimens and then applied the T-C-F A to foramen magnum surgeries. The surgeries included clipping a vertebral artery-posterior inferior cerebellar artery aneurysm in 11 cases, microvascular decompression for glossopharyngeal neuralgia in 15 cases, and removing intradural foramen magnum tumors in 17 cases. Only the condylar fossa was removed, but the approach offered very good visualization of the lateral part of the foramen magnum and sufficient working space. These surgeries were performed safely without major complications. This skull base approach is minimally invasive and is not difficult. Therefore, it can be a standard approach for accessing intradural lesions of the foramen magnum. It can be combined with the transcerebellomedullary fissure approach from the lateral side and can also be easily changed to the transcondylar approach, if necessary.

Fas ligand expression and depletion of T-cell infiltration in astrocytic tumors

Fas (APO-1/CD95) ligand (FasL) and its receptor, Fas, play a key role in the regulation of apoptosis in the immune system. FasL acts as a cytotoxic effector molecule to Fas-expressing malignant tumor cells; however, it has recently been suggested that FasL also acts as a possible mediator of tumor immune privilege. We studied FasL expression in glioblastoma cell lines and a series of human glioma specimens by Western blotting and immunohistochemistry. In addition, quantitative analysis of T-cell infiltration in these tumors was performed. FasL expression was seen in all cell lines and in 9 of 14 specimens by Western blotting and immunohistochemistry. The distribution of FasL was recognized in the cytoplasm of tumor cells (5 of 9) and in the vascular endothelium (4 of 9). Both types of FasL expression were associated with a significant reduction (p<0.05) in T-cell infiltration when compared with FasL-negative areas within the same tumor or FasL-negative specimens. Since T-cell apoptosis could be induced by FasL-expressing tumor cells, the present findings suggest that apoptosis induction by FasL expressed on tumor cells and/or vascular endothelium might be one mechanism for T-cell depletion in astrocytic tumor tissues.

Induction of apoptosis in glioma cells by recombinant human Fas ligand.

OBJECTIVE Fas ligand (FasL) belongs to the tumor necrosis factor family and has the ability to induce apoptosis in susceptible target cells by binding to its receptor, Fas. It has been demonstrated recently that the FasL/Fas system plays a pivotal role in the cytocidal activity of T lymphocytes in the immune system. FasL may act as a cytotoxic effector molecule to Fas-expressing malignant tumor cells. We reported previously that Fas is commonly expressed in human brain tumor cells. In this study, we examine the possible application of FasL to therapy for malignant brain tumors. METHODS To develop an expression system yielding large amounts of FasL, we constructed a baculovirus vector containing complementary deoxyribonucleic acid of human FasL under the control of a polyhedrin promoter. We produced human FasL in Spodoptera frugiperda (Sf9) insect cells infected by the recombinant baculovirus carrying FasL complementary deoxyribonucleic acid and studied the cytocidal activity of FasL against the T98G human glioblastoma cell line. RESULTS FasL expression in Sf9 cells was confirmed immunocytochemically with rabbit antibody raised against the cytoplasmic domain of human FasL. The FasL released into the supernatant of cultured Sf9 cells was also verified by Western blotting, and it specifically induced apoptosis in T98G cells. The induced apoptosis by recombinant human FasL was confirmed by annexin V-fluorescein isothiocyanate staining. CONCLUSION The present results suggest that the induction of apoptosis by the Fas/FasL system could be a new strategy for the treatment of malignant brain tumors, which are resistant to conventional therapies.

Adhesion of rhomboid lip to lower cranial nerves as special consideration in microvascular decompression for hemifacial spasm: Report of two cases.

Background Although the rhomboid lip is a well-known structure constructing the foramen of Luschka, less attention has been directed to the structure for posterior fossa microsurgeries. The authors report two cases of the hemifacial spasm (HFS) with a large rhomboid lip, focusing on the importance of the structure during microvascular decompression. Case Description A 59-year-old female presenting with left HFS was admitted to our hospital. A preoperative magnetic resonance image demonstrated an offending artery at the root exit zone of the VII nerve. The patient underwent microvascular decompression through the lateral suboccipital approach. The intraoperative findings showed that a large rhomboid lip adhered to the IX and X cranial nerves and prevented the exposure of the root exit zone of the VII cranial nerve. The rhomboid lip was meticulously separated from the cranial nerves so that the choroid plexus of the foramen of Luschka and the rhomboid lip could be safely lifted with a spatula, and the offending artery was successfully detached from the root exit zone. In another case of a 60-year-old male, the rhomboid lip was so large that it needed to be incised before separating it from the lower cranial nerves. In each case, the HFS was resolved following surgery without any new deficits. Conclusion The large rhomboid lip adhering to the cranial nerves should be given more attention in the posterior fossa surgeries and should be managed based on the microsurgical anatomy for preventing unexpected lower cranial nerve deficit.

Importance of awareness of the rhomboid lip in microvascular decompression surgery for hemifacial spasm

OBJECT The authors adopted the infrafloccular approach for microvascular decompression (MVD) surgery to treat hemifacial spasm (HFS). The inferior portion of the flocculus is retracted to observe the root exit zone of cranial nerve (CN) VII between CN IX and the flocculus. During the procedure, the rhomboid lip, a sheetlike layer of neural tissue forming the lateral recess of the fourth ventricle, is sometimes encountered. The existence of the rhomboid lip in cases of HFS was reviewed to determine the importance of the structure during MVD surgery. METHODS Preoperative imaging and intraoperative observations in 34 consecutive cases of HFS treated in the period from October 2008 through September 2011 were used to assess the frequency of encountering the rhomboid lip. RESULTS The rhomboid lip was observed during MVD surgery in 9 (26.5%) of the 34 cases but had been demonstrated on preoperative MR images in only 3 cases (8.8%). On T2-weighted images, it appeared as a high-intensity nonstructural area on the ventral side of the flocculus and continued into the fourth ventricle via the foramen of Luschka. CONCLUSIONS A large rhomboid lip presents an impediment to MVD surgery in a significant minority of patients with HFS. It is seldom observed on preoperative MR images. Proper dissection of the rhomboid lip away from the arachnoid membrane and/or the lower CNs during MVD surgery provides good visualization of the root exit zone of CN VII and reduces injury of CNs IX and X, avoiding postoperative deficits like dysphagia.

Expression of ICAD-L and ICAD-S in human brain tumor and its cleavage upon activation of apoptosis by anti-Fas antibody

ICAD/DFF is a downstream molecule of caspases, participating in nuclear DNA fragmentation during apoptosis. ICAD/DFF binds CAD/DFF40 and inhibits its DNase activity. ICAD/DFF has two alternative isoforms, long isoform (ICAD‐L/DFF45) and short isoform (ICAD‐S/DFF35). We have studied the presence and functional status of ICAD/DFF in human glioma cell lines. All cell lines tested expressed both ICAD‐L and ICAD‐S. When the cultured glioma cells were exposed to anti‐Fas antibody, these isoforms were degraded prior to the fragmentation of the nuclear DNA, indicating that the ICAD/DFF expressed in cultured glioma cells was potentially functional. In primary brain tumors and normal brain tissues, there was a difference in the expression level between ICAD‐L and ICAD‐S. In glioblastomas, ICAD‐S was more abundant than ICAD‐L. In contrast, ICAD‐L was more abundant than ICAD‐S in medulloblastomas. The present findings suggest that primary brain tumors and normal brain constitutively express ICAD/DFF, and that there is a difference between the expression levels of ICAD‐L and ICAD‐S.

Intracranial pial single-channel arteriovenous fistula presenting with significant brain edema

The authors report a rare case of pial single-channel arteriovenous fistula presenting with significant brain edema. A 51-year-old woman was admitted with a 5-day history of headache and nausea, followed by consciousness disturbance. Computed tomography showed cerebellar swelling with obstructive hydrocephalus. Magnetic resonance imaging revealed extensive vasogenic edema in the cerebellum bilaterally. Angiography demonstrated 2 different arteriovenous shunts (AVSs) at peripheral branches of the right anterior inferior cerebellar artery. One was located on the suboccipital surface. It drained through a dilated inferior vermian vein and emptied retrogradely into the contralateral cerebellar veins with marked stagnation. Focal stenosis of the dilated draining vein was present. The other AVS was located on the petrosal surface, which had a slow flow with no angiographic evidence of venous congestion. Given that the latter was believed to be asymptomatic, the former AVS was excised, and histological examination revealed that the lesion consisted of a direct communication of multiple arterial feeding vessels with a single vein, consistent with a diagnosis of pial single-channel arteriovenous fistula. The restriction of venous drainage presumably caused venous hypertension, leading to the brain edema and neurological symptoms.

Technical Strategies for En Bloc Resection and Immediate Reconstruction in Hemangioma of the Frontal Bone

Hemangioma of the skull is a benign solitary tumor, often found in the frontal or parietal area. A hemangioma lesion typically involves the outer table rather than the inner, but its complete removal at the diploe level is difficult. Full-thickness resection at the calvaria is often needed to ensure a free margin, but it will leave a bony defect that requires reconstruction. Although curettage and covering of the lesion with alloplastic material are a simple treatment option for hemangioma of the skull, it does not always prevent recurrence. Hence, complete resection is needed. As our technical strategies for reconstruction, we organize a split calvarial bone graft if a defect is near the frontal sinus and calcium phosphate cement if it is somewhat far from the sinus.

Carotid artery stenosis with a high-intensity signal plaque on time-of-flight magnetic resonance angiography and association with evidence of intraplaque hypoxia

OBJECTIVE Hypoxia induces angiogenesis and plays a major role in the progression of carotid plaques. During carotid intervention, plaques with high-intensity signals on time-of-flight (TOF) magnetic resonance angiography (MRA) often cause ischemic stroke and embolic complications. However, the role of intraplaque hypoxia before carotid endarterectomy (CEA) and carotid artery stenting is not presently understood. In this study the authors aimed to investigate the relationship between intraplaque hypoxia and MRA findings. METHODS Nineteen consecutive patients with 20 carotid artery stenoses who underwent CEA at Saga University Hospital between August 2008 and December 2014 were enrolled in the study. The expressions of hypoxia-inducible transcription factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) were analyzed by immunohistochemical analysis. In addition, the relationship between the findings on TOF MRA and pathology for the carotid plaques was analyzed. RESULTS High-intensity plaques on TOF MRA showed higher expression levels of HIF-1α (p = 0.015) and VEGF (p = 0.007) compared with isointensity plaques. The rate of intraplaque hemorrhage (IPH) on TOF MRA was also significantly higher in the high-intensity plaques than in the isointensity plaques (p = 0.024). Finally, the mean number of neovessels was significantly higher in those without plaque hemorrhage than in those with plaque hemorrhage (p = 0.010). CONCLUSIONS Plaques with high-intensity signals on TOF MRA were associated with IPH and evidence of intraplaque hypoxia. This fact may represent an opportunity to establish novel therapeutic agents targeting intraplaque hypoxia.

Cushing’s Syndrome and Psychosis: A Case Report and Literature Review

Psychiatric complications of Cushings syndrome include irritability, anxiety, depressed mood, and cognitive impairment. Psychosis is a rare manifestation of Cushings syndrome; therefore, the literature on the subject is limited and consists mainly of clinical case reports. We report a case of Cushings syndrome misdiagnosed as schizophrenia-like psychosis for more than 10 years. Transsphenoidal adenomectomy resulted in amelioration of psychiatric symptoms as well as improvement of cognitive ability. Clinicians should consider the presence of psychiatric symptoms predating the diagnosis of Cushings syndrome, especially when these symptoms are persistent and treatment-resistant, as seen in the present case.