Hisayuki Murai

Nationwide investigation of the current status of therapeutic neuroendoscopy for ventricular and paraventricular tumors in Japan: Clinical article

OBJECT The authors report their investigation on the current status of neuroendoscopic biopsy for ventricular and paraventricular tumors as well as treatment for associated hydrocephalus in Japan. METHODS Patients who had undergone therapeutic neuroendoscopy between 2005 and 2009 were included in this study. The main items examined were age; sex; localization of tumor; pathological diagnosis using biopsy; the presence, treatment, and efficacy of treatment of associated hydrocephalus; perioperative complications; activities of daily living (ADL) before and after therapeutic neuroendoscopy; and the presence of dissemination during the postoperative course. RESULTS Seven hundred fourteen patients from 123 sites (462 male and 252 female patients, mean age 33.3 years) were enrolled. Localization of the tumor was mainly classified into the lateral ventricle in 91 patients, the third ventricle in 339, the fourth ventricle in 18, the suprasellar region in 75, and other paraventricular areas in 191 patients. The most commonly observed tumors were germ cell tumors in the third ventricle (177 cases [39%]), cystic lesions in the suprasellar region (56 cases [75%]), and astrocytic tumors in the thalamus-basal ganglia (71 cases [38%]). Although 641 (92.8%) of 691 patients could receive neuroendoscopic diagnosis using biopsy, the diagnosis obtained with endoscopic biopsy differed from the final diagnosis based on subsequent craniotomy in 18 patients and clinical course in 3 patients. Of these 21 patients, 7 had astrocytic tumors, 4 had pineal tumors, 6 had germ cell tumors, and 4 had other tumors. The final diagnostic accuracy rate was 89.7%. Associated hydrocephalus was observed in 517 patients (72.4%), of whom 316 and 39 underwent third ventriculostomy and fenestration of the septum, respectively. The response rates were 96.2% and 89.7%, respectively. Third ventriculostomy was required for recurrence of hydrocephalus in 41 patients (13.0%), and the long-term response rate was therefore 83.2% (263 of 316 patients). Perioperative complications other than fever, such as new onset of or progressive hydrocephalus, infection due to CSF leakage, and bleeding in the ventricle or tumor, were found in 81 patients (11.3%). The median Karnofsky Performance Scale score before endoscopic surgery was 80, but it increased to 90 after surgery. The score was thus significantly increased after surgery (p < 0.0001, Mann-Whitney U-test). Activities of daily living after surgery decreased due to perioperative complications in 15 patients (2.1%). The incidence of new dissemination after endoscopic biopsy was 6.8% and not high compared with routine surgical treatment. CONCLUSIONS The authors concluded that neuroendoscopic diagnosis using biopsy for ventricular and paraventricular tumors is adequately accurate and safe. It was demonstrated that endoscopic procedures play important roles not only in the treatment of hydrocephalus associated with intra- and paraventricular tumors but also in significantly improving ADL. Furthermore, the long-term outcome of endoscopic third ventriculostomy was clearly favorable.

Endoscopic endonasal skull base reconstruction using a nasal septal flap: surgical results and comparison with previous reconstructions

The objective of this study is to evaluate the usefulness and reliability of endoscopic endonasal skull base reconstructions using a nasal septal flap. This study is designed as a retrospective review. Between April 2005 and November 2009, we performed 32 endoscopic endonasal skull base reconstructions for closure of large dural defects. Eleven patients underwent reconstructions using fat grafts or the fascia lata (non-flap group). Twenty one patients underwent reconstructions using a nasal septal flap with a balloon catheter (flap group). Incidence of postoperative cerebrospinal fluid (CSF) leaks and perioperative insertion rate of external lumbar drain (ELD) were compared between the two groups. Postoperative CSF leaks occurred in two patients (9.5%) in the flap group. Three patients (27.3%) presented CSF leaks in the non-flap group. The rate of insertion of ELD was 81.8% in the non-flap group. In the flap group, one patient (4.8%) should be placed with ELD postoperatively. The incidence of postoperative CSF leaks in the flap group was lower than in the non-flap group, whereas the rate of insertion of ELD in the non-flap group was higher than in the flap group. Endoscopic endonasal skull base reconstruction using a nasal septal flap without ELD seems to be useful and reliable for ventral skull base defects after endoscopic endonasal approaches as compared with our previous single-layer reconstructions using free fat grafts or fascia lata. The long-term effectiveness of nasal septal flaps to prevent intracranial complications should be confirmed.

Involvement of highly polysialylated neural cell adhesion molecule (PSA-NCAM)-positive granule cells in the amygdaloid-kindling-induced sprouting of a hippocampal mossy fiber trajectory.

The mossy fiber system in the hippocampus of amygdaloid-kindled rats was examined by using highly polysialylated neural cell adhesion molecule (PSA-NCAM) as a marker for immunohistochemical detection of immature dentate granule cells and mossy fibers in combination with bromodeoxyuridine (BrdU) labeling of newly generated granule cells. Statistically significant increases in BrdU-labeled cells and PSA-NCAM-positive cells occurred in the dentate gyrus following kindling. The increase in PSA-NCAM-immunoreactive neurites was confined to the entire stratum lucidum of CA3. Immunoelectron-microscopic examination also revealed that PSA-NCAM-positive immature synaptic terminals of the sprouting mossy fibers increased in the stratum lucidum of CA3 in the kindled rats. The increase in the numbers of PSA-NCAM-positive granule cells correlated well with the increase in the immunopositive neurites and synaptic terminals on the mossy fiber trajectory. The increase in these PSA-NCAM-immunopositive structures is thought to reflect the enhancement of sprouting and synaptogenesis of mossy fibers by a subset of granule cells newly generated during amygdaloid-kindling and suggests that the reorganization of the mossy fiber system on the normal trajectory at least in part contributes to the acquisition and maintenance of an epileptogenic state.

Slit ventricle syndrome after cyst-peritoneal shunting for temporal arachnoid cyst in children--a clinical entity difficult to detect on neuroimaging study.

Slit ventricle syndrome, known to occur from malfunction of the shunt procedure for hydrocephalus, is reported after cyst-peritoneal shunt for temporal arachnoid cyst. Two children aged 12 and 10 years, who underwent cyst-peritoneal shunting for a large temporal arachnoid cyst at the age of 10 and 5 years, respectively, recently experienced several episodes of severe headache. Prior to admission, repeated CT scans did not reveal any morphological change in either of these two patients. Evidence of high intracranial pressure by lumbar tap revealed shunt malfunction. Both patients became free of neurological complaints and deficits after shunt revision. Despite elevated intracranial pressure due to shunt malfunction, neuroimaging studies showed no morphological changes in slit ventricle syndrome. Delay in both the diagnosis and prompt treatment may result in complete loss of visual acuity and even death. It is important to suspect this complication in patients with persistent elevated intracranial pressure symptoms and signs after any shunting procedure, regardless of unchanged neuroimaging studies. Once this is suspected, lumbar tap may be necessary and the choice of treatment is shunt revision.

Heavily T2 weighted MR images of anterior optic pathways in patients with sellar and parasellar tumours - prediction of surgical anatomy.

Summary Objective. Location of anterior optic pathways in sellar and parasellar tumours was preoperatively evaluated, by use of heavily T2 weighted MR images. Methods. Heavily T2 and conventional T1 weighted images were studied in 20 patients with sellar and parasellar tumours who underwent craniotomy. Pathology revealed pituitary adenoma in 5 patients, craniopharyngioma in 8 and parasellar meningioma in 7. Maximum sizes ranged from 15 mm to 58 mm. Sequence parameters of TR/TE for heavily T2 weighted and T1 weighted images were 5800/220 msec and 600/20 msec, respectively, and slice thickness was 3 mm for both. Results. The anterior optic pathway was detected in 95% on heavily T2 weighted images and 50% on T1 weighted images. All preoperative heavily T2 weighted images were compatible with operative findings. The optic chiasms were most commonly supero-posterior in pituitary adenomas, anterior (prefixed) in craniopharyngiomas and posterior in meningiomas. The optic nerves were commonly located superior or lateral to the tumours. However, parasellar meningiomas, off the midline, revealed the optic nerves in various locations, depending on the tumour origin. In such tumours, heavily T2 weighted images provided surgical information on the width of the working space through prechiasmal and/or optico-carotid spaces in the pterional approach. Spatial relation of the tumours to the lamina terminalis, anterior commissure and anterior communicating artery complex was clearly shown in craniopharyngioma patients, who underwent the anterior interhemispheric approach. Conclusion. Heavily T2 weighted MR images are useful in determining the location of optic pathways and surgical approach and in individual prediction of the anatomy for even large sellar and parasellar tumours.

Fascicular arrangement within the oculomotor nerve MRI analysis of a midbrain infarct

The fascicular arrangement of the oculomotor nerve within the midbrain is not adequately elucidated in humans. We treated a patient with a partial oculomotor palsy who had impaired adduction and supraduction on the left side, which were attributed to an ipsilateral lacunar infarct. CT and MRI revealed a discrete lesion in the centre of the midbrain tegmentum in the rostrocaudal plane. This case suggests that the oculomotor fibres for extraocular movement are located in the middle of the the midbrain, and supports the fascicular proximity of the superior and medial rectus muscles. The fascicular arrangement of the midbrain oculomotor nerve is speculated to be pupillary component, extraocular movement and eyelid elevation in that rostrocaudal order, based on the previous reports of neuro-ophthalmological impairment and MRI findings, which are analogous to the nuclear arrangement proposed by Warwick.

Oedema along the optic tracts due to pituitary metastasis

The MRI finding of oedema along the optic tract has been reported in patients with craniopharyngioma, as a useful diagnostic sign among common pituitary tumours. We report two patients with pituitary metastasis with this MRI finding. A 59-year-old woman and a 54-year-old man had diabetes insipidus and extraocular impairment due to a pituitary metastasis from adenocarcinoma of lung and colon, respectively. Several months later, they noticed rapidly deteriorating visual field and acuity impairment. MRI revealed enlarged pituitary mass accompanied by marked oedema along the bilateral optic tracts. To our knowledge, this is the first MRI report of oedema along the optic pathway due to pituitary metastasis. Our cases and review of literature indicate that this MRI sign is non-specific. Appearance of the oedema well corresponded to the initiation of visual complaint, which make a good contrast to reported clinical presentations of craniopharyngioma. Clinical significance and pathomechanism of this MRI sign are discussed.

Long-term Karnofsky performance status and neurological outcome in patients with neurohypophyseal germinomas

Long-term posttreatment Karnofsky Performance Status (KPS) and neurological status of 16 patients with neurohypophyseal (NH) germinomas were retrospectively analysed, in order to deduce the best treatment modality to achieve a good outcome. The average age at treatment was 15.5 years (rouge 6‘26) and they were followed up for 107.3 months (26‘209). The KPS averaged 81.5 (0‘100). Three patients were below 60 in the KPS. The first one had hemiparesis due to a delayed cerebrovascular accident (CVA), and the second became indifferent and inactive with recent memory loss. The third died from marginal recurrence of tumour and subsequent systemic metastasis. The low scores were all more or less attributable to complications related to irradiation: delayed CVA, diffuse cortical atrophy and inappropriate selection of irradiation field, respectively. The second case had the tumour origin at the hypothalamus, which indicates intraparenchymal tumour location as another factor to worsen the quality of life (QOL). Visual field and acuity, and EOM impairment were observed in eight and five patients, respectively. It improved in all patients but one. The visual and EOM dysfunction recovered satisfactorily and was not a disabling factor. The intraparenchymal lesion resulting in hemiparesis and higher cortical dysfunction due to either irradiation-related complications or tumour invasion is a major determining factor of lower KPS. Irradiation related complications are considered to be avoidable by reducing radiation dosage with appropriate chemotherapy and/or proper selection of irradiation field. Patients with smaller tumour size of less than 20 mm had higher KPS. Accordingly, repeated studies of tumour markers and neuroimages are required in patients with idiopathic diabetes insipidis, in order to detect the tumour, if present, at the small-sized and early stage.

Heavily T2 weighted MR assessment of fornical injury after anterior interhemispheric approach for large suprasellar tumors.

Summary Fornical injury in transforaminal approach is well known. Its injury in the anterior interhemispheric approach (AIA) has been rarely highlighted. We report 2 cases with a large suprasellar tumor who underwent AIA. Postoperative heavily T2 weighted reversed (T2R) MR images demonstrated its unilateral injury. The clinical significance of symptom-free fornical injury after AIA is discussed. Cases 1 and 2 were a 15 year-old girl with a meningioma and a 49-year-old woman with a craniopharyngioma, respectively. They underwent AIA. Postoperative T2R images revealed unilateral fornical crus atrophy. They did not present associated memory deficits. Case 1 had the injury of both fornical column and anterior commissure. They were speculatively torn by intra-operative lateral retraction of the frontal lobes. Case 2 had unilateral atrophy of the mammillary body and postcommissural fornix, which were probably caused by ischemic damage related to surgical manipulation, since case 2 had an associated anterior thalamic infarct. During the operation for large suprasellar tumors, excessive laterally directed brain retraction should be avoided, since such manipulation may easily tear the overstretched anterior commissure and fornical column. Once we notice or suspect fornical injury on MR studies in cases of re-operation, we have to choose a surgical approach and operative manipulation to preserve an intact fornix. The MR evaluation of fornix should be included in the peri-operative radiological assessment, since patients with unilateral fornical injury were free of memory disturbance, and T2R imaging is a useful MR sequence for depicting the anatomy related to the fornix.

Postnatal development of Blake's pouch cyst: a case report and new insight for its pathogenesis

Blake’s pouch cyst (BPC), a rare cystic malformation in the posterior fossa, is believed to be caused by the congenital expansion of the posterior membranous area that normally regresses during embryogenesis. However, due to the wide spectrum of the onset pattern and age of patients, the natural history and the pathogenesis are poorly understood. The authors describe the case of a girl who admitted with headache and right abducens nerve paresis at the age of 3 years and 10 months. Magnetic resonance (MR) imaging demonstrated a tetraventricular hydrocephalus, an open aqueduct, and a posterior fossa cyst compatible with BPC. Multiple tumors were also noticed in the ventricular wall. Tumor biopsy and an endoscopic third ventriculostomy were performed. Intraoperative observation confirmed the BPC, and pathological diagnosis was pilomyxoid astrocytoma. In retrospect, MR imaging was performed twice in the past, at the age of 8 months and again at 22 months, and no anomaly was detected, suggesting that Blake’s pouch was once regressed. Therefore, a BPC in this patient was certainly developed after her second or third year of life. The ventricular tumors may influence the cerebrospinal fluid (CSF) absorption, which triggered the re-expansion of BPC from the possible remnant of Blake’s pouch. This is a rare but important report providing evidence that in addition to the classic congenital BPC in which the remnant of Blake’s pouch remains persistent, there could be postnatal or secondary BPC, which develops after birth. Possible mechanisms include that the remnant of Blake’s pouch, which originally disappears, may re-expand postnatally in association with unknown trigger or a change in CSF dynamics or absorption.