Shizuo Oi

Neuroendoscopic surgery for specific forms of hydrocephalus

Abstract Neuroendoscopic surgery was used to treat patients with various forms of hydrocephalus with specific pathophysiology, including long-standing overt ventriculomegaly in adulthood (LOVA), isolated unilateral hydrocephalus (IUH), isolated IV ventricle (IFV), disproportionately large IV ventricle (DLFV), isolated rhombencephalic ventricle (IRV), isolated quarto-ventriculomegaly (IQV), dorsal sac in holoprosencephaly (DS), and loculated ventricle (LV). A total of 26 operative procedures were performed, with neuroendoscopic surgery in 22 patients, 12 with unique forms of noncommunicating hydrocephalus and 10 with various types of postshunt isolated compartment. These procedures included III ventriculostomy, aqueductal plasty by both rostral and caudal approaches, foraminal plasty in the foramen of Monro/foramen of Magendie, septostomy, IV ventriculostomy, fenestration of septation in the loculated ventricle, fenestration of arachnoid cyst or cystic tumor obstructing a ventricle with or without tumor removal, and dorsal sac ventriculostomy. The characteristics of the cerebrospinal fluid (CSF) dynamics in the individual specific pathophysiologies were delineated by cardiac-gated cine-mode magnetic resonance imaging (MRI) before and after the endoscopic procedure. The consequent success rate (success = restoration of communication of the CSF pathway in the individual patients) was 19/22 (86.4%). The progression of ventricular dilatation was stopped in 17 of 19 patients (89.5%) in whom the endoscopic procedure was successful (radiologically arrested hydrocephalus). Improvement in the clinical symptoms and signs (clinically arrested hydrocephalus) was obtained in 15 of the patients (68.2% of all patients: 5 with LOVA, 3 with IQV, 5 with IUH and 2 with LV). Seven patients (2 LOVA, 2 IFV, 1 DS, 1 DFLV and 1 IRV) underwent a shunt procedure after the neuroendoscopic procedure(s). The postoperative changes of ventriculomegaly were complicated, reflecting the differences in the brain parenchymal compliance and postoperatively corrected CSF flow dynamics in the major CSF pathway.

Slit ventricles as a cause of isolated ventricles after shunting.

In a follow-up study of 164 hydrocephalic children without tumors treated with ventriculoperitoneal shunts, 46 (28.0%) developed slit ventricles, 5 (3.0%) developed isolated fourth ventricles, and 4 (2.4%) developed isolated unilateral hydrocephalus. All of the patients with isolated unilateral hydrocephalus and 3 with isolated fourth ventricles had associated slit ventricles, 2 of whom had enlarged ventricles as double-compartment hydrocephalus. Reopening of the foramen of Monro or the aqueduct was achieved in one of the former and two of the latter cases with re-expansion of the slit ventricles. It is suggested that in some cases, the slit ventricle could be a causative factor in post-shunt isolated ventricle.

Controversy pertaining to therapeutic modalities for tumors of the pineal region: a worldwide survey of different patient populations

The management of tumors of the pineal region differs between Western countries and Japan. This paper reports on a worldwide survey of individual experience and regimens for treating pineal region tumors in different patient populations. Fifteen pediatric neurosurgeons from nine different countries participated in the survey, and a total of 408 pineal region tumors were evaluated. Determination of tumor histology as an initial procedure was strongly supported by the majority of neurosurgeons in North and Central America and Europe (group A), whereas all but one from Asia and Egypt (group B) emphasized initial application of the radiation test. The analysis of patient populations clearly revealed racial differences in tumor type which explain this discrepancy. Germinoma, the most radiosensitive tumor, constituted 43–70% (mean: 53.7%) of tumors in group B, followed by teratoma, pineoplastoma, and others, whereas in group A the incidence of germinoma was only 21–44% (mean: 34.7%), followed by a variety of tumors, such as astrocytoma, pineoblastoma, etc. The age distribution among intracranial germ cell tumors (GCT) obtained from data from the Brain Tumor Registry in Japan also demonstrated clear differences in the incidence of tumor types in different age groups in Japan: while germinoma constituted 70–84% of GCT in patients between the ages of 15 and 35 years, the incidence was much lower before 15 yeras and after 35 years, being 24% of tumors under 4 years and 34% of tumors after 40 years of age. The therapeutic regimen for pineal region tumors should depend on the patient population concerned, because of the differences relating to race and age distribution.

Congenital brain tumors in Japan (ISPN Cooperative Study): specific clinical features in neonates.

The authors present specific clinical features of brain tumors occurring in immature brain in comparison with those of older infants and children. Twenty-six neonatal brain tumors, which accounted for 11.3% of 231 brain tumors diagnosed in the 1st year of life collected in a cooperative study in Japan, were analyzed. Although astrocytomas were invariably common tumors in each age group, comprising 25.0% for all pediatric brain tumors, teratomas were the most common type of neonatal brain tumors and accounted for 33.4% in this age group. Location of tumors in the immature brain was more striking, involving the posterior fossa region less commonly, as in 11.1% in neonatal, 29.5% in infantile, and 41.4% in all pediatric age groups. Surgical intervention was performed in 97.4% of the infantile and 79.1% of the neonatal cases, but total or subtotal resection of the mass was achieved only in 58.9% in the infants and 73.7% in the neonates. There was more strict limitation in performing the adjuvant therapies in the immature age groups. Radiation therapy and chemotherapy were given only in 32.0% and 27.6%, respectively, in the neonatal cases. The prognosis was extremely poor in the immature cases: 1-year, 5-year, and 10-year survivial rates were 59.3%, 26.1%, 11.5% in the infants, and 43.5%, 23.8%, 7.1% in the neonates, respectively. Of the neonates, 76% and of the infants 73.1% were retarded. The present study delineates the characteristic clinical features of tumors involving immature brain and emphasized that establishment of more specific therapeutic modalities is urgent.

Tethered cord syndrome versus low-placed conus medullaris in an over-distended spinal cord following initial repair for myelodysplasia

We present findings obtained from a total of 100 patients who had previously undergone surgery for spina bifida and whose progress had been monitored by magnetic resonance imaging (MRI) in our meningomyelocele clinic. Fourteen of these patients (14.0%) developed delayed symptom(s) of progressive spinal neurologic dysfunction. In those with myeloschisis, increase of motor deficit was the most common clinical manifestation during infancy and early childhood (mean age: 6.8 years), whereas pain on back flexion was seen in patients who were over 15 years of age (mean age: 17.3 years). MRI carried out in myeloschisis patients invariably demonstrated that the conus medullaris was in an abnormally low position, suggesting over-distension of the spinal cord. This was irrespective of whether symptom(s) developed or not and did not correlate with the initial surgical procedure (reconstructive or otherwise) used. Patients with symptom(s) were revealed by MRI to have an extremely low conus set at the spinal level of S-1 or below; neurological examination showed that the motor deficit occurred at high levels in the spine. Results from lipomeningocele patients were more erratic in terms of conus position and delayed development of neurological defects. The authors conclude: (1) that elongation of the spinal cord as an MRI finding seen postoperatively in cases of myeloschisis (radiological finding of a low-placed concus medullaris) does not necessarily imply functional disorder (tethered cord syndrome) and (2) that the pathophysiology of the late onset of progressive neurological deterioration in the spine occurring in patients who have previously undergone lipomeningocele repair may be associated with an invasive or expansile mass effect and should not always be regarded as involving tethered cord syndrome.

Pathophysiology and postnatal outcome of fetal hydrocephalus

At the National Kagawa Childrens or Kobe University Hospital, 24 cases of fetal hydrocephalus were managed between 1982 and 1988. There were 8 simple, 11 dysgenetic, and 5 secondary cases of hydrocephalus, and the fetal age at diagnosis ranged between 24 and 40 weeks of gestation (average 33.4 weeks). All were diagnosed using ultrasonography, with either magnetic resonance imaging or whole-body computed tomography, additionally performed in 10 patients to determine their usefulness in evaluating the morphology. Four patients underwent transabdominal or transvaginal cephalocentesis in the prenatal period and intracranial pressure was measured during the drainage of cerebrospinal fluid in two of these. Postnatal outcome was analyzed for each type of hydrocephalus. The results suggested that in such cases the fetal brain is subjected to extremely high intracranial pressures resulting from a mixture of hydrocephalic pressure and intermittent uterine constriction. Immediately after birth, the biparietal diameter was found to be increased by an average of 7.7 mm and the hydrocephalic state was transformed into the neonatal type characterized by macrocephaly and a relatively low intracranial pressure. Overall mortality was 25% and 16 of the 24 infants underwent the postnatal shunt procedure, largely at the neonatal stage. The follow-up period varied from 4 months to 6 years (average, 25.8 months for nonfatal cases) and the mean intelligence or developmental quotient was 45.2. There were no significant differences in postnatal outcome between the three major types of fetal hydrocephalus. Findings revealed that the length of the gestation period after the diagnosis of hydrocephalus has a significant effect on outcome (P<0.01). Based on these results, it is suggested that fetal hydrocephalus may be extremely hypertensive and that impairment of neuronal functional development accompanying its prenatal progression can be irreversible.

Brain tumors diagnosed in the first year of life in five Far-Eastern countries

A statistical survey is presented of brain tumors diagnosed in the first year of life (from five Far-Eastern countries) in relation to the racial differences in tumor types, congenital factors, and general clinical features. Of the 307 cases collected, 262 were verified histologically, and astrocytomas comprised 23.3%, medulloblastomas 17.2%, ependymomas 11.1%, choroid plexus papillomas 10.7%, teratomas 8.4%, primitive neuroectodermal tumors 4.2%, meningiomas 2.3%, and others 22.9%. There were statistically significant racial differences in comparison with the worldwide survey done by the International Society for Pediatric Neurosurgery Education Committee (1987) on the same subject. In the Far-Eastern population, medulloblastoma and teratoma were more common (P<0.05), whereas astrocytoma was less frequent (P<0.01) than reported in the worldwide survey. The malformative factors were suggested in 18 cases in which various associated congential anomalies were observed. Vascular anomalous lesions, mostly in the extracranial organs, were most common, comprising 61.1% of the associated malformations. Hereditary factors were less commonly demonstrated in these tumors than were anomalies in the major congenital central nervous system. Among the 307 cases, there was one instance (0.3%) of nearly identical tumors occurring in twin brothers. The specific clinical manifestations of brain tumors involving the immature brain were again apparent in this survey, as were the poor survival rates and poor functional prognosis.

Massive congenital intracranial teratoma diagnosed in utero

The authors describe a case of congenital intracranial teratoma. The patient was diagnosed to be hydrocephalic at 29 weeks gestation, and to have a huge intraventricular mass lesion at 34 weeks gestation. Subsequently, the patient underwent subtotal resection of the mass, resulting in a significant decrease in the remarkably elevated alpha-fetoprotein in serum and cerebrospinal fluid. Histological analysis revealed a malignant teratoma, also with alpha-fetoprotein-positive elements in the immunohistochemical study.

Neurological and medico-social problems of spina bifida patients in adolescence and adulthood

Chronological changes in the neurological manifestations of spina bifida are well recognized in the early developmental periods: fetal, neonatal, infantile, pre-school and school life. However, little has been written about the medical and medico-social problems of spina bifida patients in adulthood. Patients now in this age group had the condition diagnosed and managed in an era when modern neurosurgical concepts were only just beginning to be established with the aid of invasive methodology. In our series of 141 cases of spina bifida, 18 patients (13.5%) were over 16 years of age. These included 9 cases each of spina bifida aperta (myeloschisis) and spina bifida occulta (spinal lipoma). The ages ranged from 16 to 47 years (mean: 23.5 years) in the former and from 16 to 57 years (mean: 29.2 years) in the latter group. During the long-term follow-up with quantitative analysis of the spinal neurological changes using the spina bifida neurological scale (SBNS), the final outcomes appeared very grave. Except for 1 case in each group-1 grade III in the spina bifida aperta group and 1 grade II in the spina bifida occulta group-all patients over the age of 27 years were classed as having grade IV disease. There were 2 patients with spina bifida aperta in whom postoperative paraplegia appeared after delayed radical repair (at the ages of 3 years and 18 years) and 3 patients with spina bifida occulta in whom obvious neurological deterioration was observed as the natural history with ongoing paraparesis at the spinal level or late onset of sexual problems. The other group included 2 patients with spinal lipoma in whom late neurological deterioration was observed and who were obliged to undergo a second operation in spite of aggressive early procedures performed during infancy. Among the patients with spina bifida aperta, 2 had marked ventriculomegaly as a form of long-standing overt ventriculomegaly in the adult (LOVA). After the CSF shunt procedure both these patients had problems with delicate shunt dependence and requested fine shunt flow regulation. Two patients in this group also suffered from severe depression. This study involves a limited number of patients, but it may be useful for reference on various points: (1) future prospects for the management of pediatric cases of spina bifida as practiced in the majority of hospitals; (2) natural histories of untreated cases and surgical indications for preventive procedure in spinal lipoma in early infancy; and (3) internationally differing levels of management of spina bifida and the historical development of individual countries approaches to the problems.

Ependymoma diagnosed in the first year of life in Japan in collaboration with the International Society for Pediatric Neurosurgery

During 1987, 23 survey forms for ependymoma cases diagnosed in the 1st year of life were selected from 88 neurosurgical institutes in Japan in collaboration with the International Society for Pediatric Neurosurgery. There were no specific perinatal episodes. The most common clinical manifestations were symptoms of intracranial hypertension and hydrocephalus. Two of seven children with infratentorial ependymomas were alive, and all of the children with such supratentorial tumors were still alive. Of those with ependymoma, three of four in the total extirpation group, and three of seven in the subtotal or partial removal group were alive. The 1-year survival rate was 54% for ependymoma and 58.3% for ependymoblastoma. For 36% of the cases with ependymoma and 14.6% with ependymoblastoma, a 2-year survival rate was observed. Since the prognosis of these tumors is poor, they should be extirpated as often as possible. Collins law held true in approximately half of the cases.