Present status of intrauterine treatment of hydrocephalus and its future

Isolated Fetal Ventriculomegaly: Diagnosis and Treatment in the Prenatal Period

Fetal ventriculomegaly (VM) is a defect of the central nervous system, typically diagnosed during the second-trimester ultrasound in fetuses with an atrial diameter (AD) of >10 mm. Non-isolated ventriculomegaly (NIVM) is heterogeneous in nature, coexisting with additional intracranial and/or extracranial malformations and genetic syndromes, resulting in an unfavorable prognosis for the further development of the child. Both the pregnancy management and counseling are dependent on the findings of combined ultrasound/MRI, genetic testing, and gestational age at diagnosis. The purpose of this review is to propose a hypothesis that diagnostic advancements allow to define the process of identification of the isolated forms of VM (IVM). Based on the evidence presented in the literature, we consider whether prenatal decompression for severe isolated VM (ISVM) is supported by the experimental trials and whether it might be implemented in clinical practice. Also, we describe the evolution of the diagnostic methods and expert opinions about the previously used prenatal decompression techniques for ISVM. In conclusion, we introduce the idea that fetal surgery centers have either reached or nearly reached the necessary level of expertise to perform such procedures. Endoscopic cystoventriculostomy (ETV) appears to be the most promising, as it is associated with minimal perinatal complications and favorable neurological outcomes in the neonatal period. Randomized trials with long-term neurodevelopmental follow-up of children who underwent prenatal decompression due to ISVM are necessary.

Fetal therapy for congenital hydrocephalus-where we came from and where we are going

Despite unfavorable outcomes during the early experience with in utero intervention for congenital hydrocephalus, improvements in prenatal diagnosis, patient selection, and fetal surgery techniques have led to a renewed interest in fetal intervention for congenital hydrocephalus. Research studies and clinical evidence shows that postnatal cerebrospinal fluid diversion to release intraventricular pressure and cerebral mantle compression usually arrives late to avoid irreversible brain damage. Make sense to decompress those lateral ventricles as soon as possible during the intrauterine life when hydrocephalus is antenatally detected. We present a historical review of research in animal models as well as clinical experience in the last decades, traveling until the last years when some research fetal therapy groups have made significant progress in recapitulating the prenatal intervention for fetuses with congenital obstructive hydrocephalus.

Fetal ventriculomegaly: postnatal management

INTRODUCTION

It is the current status of fetal ventriculomegaly that although the technology for diagnosis is advanced, it does not have significant impact on the management outcome. Fetal ventriculomegaly is mainly treated after birth.

METHODS

We reviewed the literature and suggested policies of postnatal evaluation and surgical management of fetal hydrocephalus. Our experience of 44 cases of fetal ventriculomegaly diagnosed by fetal ultrasonography, in which major poor prognostic factors were absent and for which prenatal pediatric neurosurgical consultation was sought, was also presented.

RESULTS

Our experience showed etiologic heterogeneity of fetal ventriculomegaly although our cases seemed to be surgical candidates more likely than whole group of fetal ventriculomegaly. There were limitations in prenatal evaluation of fetal hydrocephalus. The first step for postnatal management is etiologic classification. It should be clarified after birth whether there is remarkable disturbance of cerebrospinal fluid dynamics or not. The rate of postnatal progression of ventricular dilatation is also important for the decision of treatment plan. For surgical treatment in very young children, special considerations should be paid on technical feasibility, rate of postoperative infection or malfunction, prevention of rapidly developing nervous system from the possible damage, and great plasticity of young brain.

CONCLUSION

Indication, methods, and timing of surgical treatment must be individually tailored according to the etiology, degree and rate of progression of ventriculomegaly, and patient's age when surgical treatment is considered.

Congenital brain tumors: diagnostic pitfalls and therapeutic interventions

Congenital brain tumors are rare, accounting for 0.5% to 4% of all pediatric brain tumors. A 10-year retrospective study based on autopsy and neurosurgical clinical reports with a diagnosis of congenital/fetal/neonatal brain tumor identified 6 cases. Four cases were diagnosed antenatally by neuroradiology. Clinical outcomes in 5 cases resulted in death; 1 patient with choroid plexus papilloma underwent successful resection of the tumor and is still alive. Tumor pathologies consisted of 2 teratomas, 2 choroid plexus papillomas, 1 gemistocytic astrocytoma, and 1 glioblastoma multiforme. A literature review of all fetal cases specific to the pathologies presented in this series was also performed. Relative to the literature, this series contains a rare case of congenital gemistocytic astrocytoma. This series further sheds light on the diagnostic, histological, prognostic, and therapeutic differences between congenital brain tumors and tumors of the same pathology in older pediatric and adult populations.

Fetal hydrocephalus, intrauterine diagnosis and therapy considerations: an experimental rat model

MATERIALS AND METHODS

Fetal hydrocephalus is induced by a single intraperitoneal injection of 8 mg/kg 6-aminonikotinamide (6-AN), a niacinamide antagonist, in Sprague-Dawley rats on day 13 of gestation. Laparotomy was carried out in some rats 3, 6, 7 and 8 days after the intraperitoneal injection. The fetuses were collected by uterotomy and fixed in a formalin solution after measuring head circumference and body length for further histological investigations. The ventricular areas and volumes of the lateral ventricles were measured using a computer morphometric technique after all fetuses were serially sectioned sagittally or coronally. Furthermore, 8 maternal rats (4 treated with 6-AN and 4 controls) were used for ultrasound investigation. The fetal ventricular system and the central canal were demonstrated and compared by transabdominal ultrasound in the 6-AN and control groups. On day 19 of gestation the cerebrospinal fluid (CSF) was drained in some fetuses for 18 h through a thin micro-catheter, which was inserted into the lateral ventricle. In some other fetuses the intracranial pressure (ICP) and the intra-amniotic pressure (IAP) were measured after Doppler sonography of the cerebral blood flow (CBF). These measurements were carried out using a transuterine approach following the laparotomy.

RESULTS

Hydrocephalus was produced due to the closure of all outlets of the fourth ventricle. Macrocephalus was clear on day 17 (4 days after 6-AN injection). The entire ventricular system was dilated, including the aqueduct and foramen of Monro, and cerebellar hypoplasia was revealed.

CONCLUSION

Increased ICP in 6-AN fetuses was associated with decreasing CBF. The cerebral mantel was better developed after CSF drainage. The intra-amniotic pressure was increased in all pregnant rats and was either similar to or higher than ICP.

Fetal hydrocephalus--prenatal treatment

PATIENTS AND METHODS

From January 1986 to January 2001, 85 cases of hydrocephalus were referred to the Pediatric Neurosurgery and Fetal Medicine Sections of the São Paulo Federal University and the Santa Joana Maternity Hospital in São Paulo, Brazil. Thirty-nine of these cases concerned fetuses ranging from 24 to 32 weeks' gestation, who underwent intrauterine treatment. The hydrocephalus etiologies consisted of: aqueduct stenosis (18 cases), intraventricular hemorrhage (8 cases), Dandy-Walker malformation (4 cases), Chiari type II (4 cases), and other diverse etiologies (5 cases). Twenty fetuses underwent repeated cephalocentesis: 18 received a ventriculo-amniotic shunt and in 1 case endoscopic third ventriculostomy was performed. The follow-up period varied between 1 and 14 years (median 5 years). Out of 39 patients, 26 have been considered as normal (IQ above 70), 6 have mild or moderate handicaps (IQ from 35 to 70), and 7 are severely handicapped (IQ below 35). After birth, 38 patients underwent ventriculoperitoneal shunting with low-pressure valves.

CONCLUSION

In the absence of chromosomopathies, when the gestational age ranges between 24 and 32 weeks, progressive fetal hydrocephalus of a non-infectious origin can obtain benefit from intraventricular decompression performed during the fetal period. New methods of diagnosis and treatment should be developed, especially in those countries where interruption of gestation is not permitted by law, for the benefit of those families who, due to social or religious factors, do not accept abortion.

Diagnosis, outcome, and management of fetal abnormalities: fetal hydrocephalus

INTRODUCTION

It has been recognized that the morphological fetal CNS findings detected in early development are not always the final features: occasionally they may not be determined in diagnosis and may change developmentally or chronologically during the fetal life in utero.

DISCUSSION

Certain factors of the fetal chronology of CNS anomalies can cause irreversible changes during fetal life. These include: significant delay in the neuronal maturation process in fetal hydrocephalus developed in clinico-embryological stage II of the Perspective Classification of Congenital Hydrocephalus (PCCH), secondary neural injury in the intactly developing spinal cord above the neural placode in fetuses with spina bifida aperta (myeloschisis), histological "evolution" of tumors or dysgenetic CNS, and deformity of the normally developed intracranial or intraspinal CNS structures. Considering the current status of fetal surgery in general and technical advances promising improved outcomes, fetal neurosurgery can also be applied to the above-mentioned progressive pathology or pathophysiology in the fetal CNS. However, since the failure of the first trial of fetal neurosurgery in the 1980s, the prerequisites have still not been clarified. In order to use advanced neurosurgery techniques in the management of fetal CNS anomalies, these prerequisites have to be established.

Intrauterine high-resolution magnetic resonance imaging in fetal hydrocephalus and prenatal estimation of postnatal outcomes with "perspective classification"

OBJECT

It is possible to diagnose hydrocephalus prenatally based on the morphological appearance of the fetus on neurodiagnostic images; however, the prognosis of this disease shows wide variation. The authors previously proposed a classification system for the prediction of postnatal outcome based on progression of hydrocephalus and affected brain development, known as the "Perspective Classification of Congenital Hydrocephalus (PCCH)." In this study the authors have used their classification system to analyze long-term follow-up results obtained in each clinicoembryological stage of fetal hydrocephalus.

METHODS

Sixty-one fetuses with hydrocephalus were examined to predict postnatal outcome by using this newly developed classification. The authors' recently developed method of using heavily T2-weighted imaging with a superconducting magnet clearly delineated the cerebrospinal fluid (CSF) space and the malformed brain and spinal cord. Imaging was achieved in less than 1 second per slice and required no sedation of the fetus. The technique appears to be simple and good at delineating intrauterine anatomy. Hydrocephalus was diagnosed in two fetuses at PCCH embryological Stage I (8-21 gestational weeks), in 28 fetuses at Stage II (22-31 weeks), and in 31 fetuses at Stage III (32-40 weeks). Among these 61 fetuses, clinicopathological typing showed that 19 had primary hydrocephalus (nine in Stage II and 10 in Stage III), 34 had dysgenetic hydrocephalus (two in Stage I, 16 in Stage II, and 16 in Stage III), and eight had secondary hydrocephalus (three in Stage II and five in Stage III). When the hydrocephalic state developed during PCCH Stage I or II, the prognosis was very poor, and only one of 18 fetuses with dysgenetic hydrocephalus and none of three fetuses with secondary hydrocephalus had an acceptable postnatal outcome. Even within the same category or subtype of fetal hydrocephalus, such as primary hydrocephalus in its simple form, or hydrocephalus with spina bifida aperta (myeloschisis), the postnatal outcomes differed depending on the time of onset of hydrocephalus. When the diagnosis of hydrocephalus was made during PCCH Stage II, the fetuses had a poorer postnatal outcome compared with those at Stage III (p < 0.05).

CONCLUSIONS

It is emphasized that postnatal prognosis is not simply a function of the form of the diagnosis but is also dependent on the progression of hydrocephalus and the degree to which that process affects neuronal development. Early decompressive procedures, conventionally performed after but, hopefully, performed before birth, are indicated to obtain the optimal postnatal prognosis of fetuses with hydrocephalus diagnosed at PCCH Stage II.

Ventricular volume reduction technique--a new surgical concept for the intracranial transposition of encephalocele

The authors propose a new operative technique for the intracranial transposition of an encephalocele by using the associated hydrocephalic state. In the first stage, the intracranial pressure buffering effect of the encephalocele sac is reduced by the closing of the dural defect. The repaired dural defect allows intraventricular pulse pressure to produce ventriculomegaly. In the second stage or in infants with hydrocephalus, the extracranially herniated brain is transposed into the intracranial cavity during ventricular shunting with appropriate drainage of cerebrospinal fluid.

An epidemiologic study of environmental and genetic factors in congenital hydrocephalus

Risk factors were studied in 96 children with congenital hydrocephalus (CH) coming from 118,265 consecutive births of known outcome. Hydrocephalus with neural tube defects, intracranial tumors or secondary to brain atrophy were excluded. The prevalence of CH was 0.81 per thousand. Diagnosis was performed prenatally in 41 cases. Forty-three (44.8%) of the cases had hydrocephalus without other malformations (isolated hydrocephalus), 18 (18.7%) infants had recognized chromosomal or non-chromosomal syndromes and 35 children (36.4%) had multiple malformations. Each case was matched to a control. Weight and length at birth of children with hydrocephalus were less than in the controls (p < 0.001). The weight of the placenta was lower than in the controls (p < 0.05). The pregnancy with a hydrocephalic child was more often complicated by threatened abortion, polyhydramnios and oligohydramnios. The mothers of children with hydrocephalus and multiple malformations had used oral contraceptives during the first trimester of pregnancy more often than the mothers of the controls. No differences appeared between the mothers of children with CH and the controls for the other risk factors studied: parental age, parity, previous pregnancies, previous stillbirths, smoking, diabetes, epilepsy, X-rays, hypertension, fever "flu", medication and occupational exposure. There was an increase of parental consanguinity in the parents of our patients (6.2% v. 1.1%, p < 0.001) and first degree relatives had more non-cerebral malformations than the controls (7.3% v. 3.2%, p < 0.05).

Arachidonic acid metabolites: effects on inflammation of fetal rabbit excisional wounds

Uncovered fetal rabbit excisional wounds do not exhibit any classic signs of healing; wounds covered with an impermeable cover do contract, reepithelialize, and exhibit inflammation. Prostaglandin E2 (PGE2) is elevated in amniotic fluid, acting as an immunosuppressant at the maternal-fetal interface. Full-thickness excisional wounds were made on 25-day gestational age rabbit fetuses. Half the wounds were covered with an impermeable cover. Tissue from covered, uncovered, and nonwounded fetuses was examined 72 h after wounding for arachidonic acid metabolites. Uncovered wounds had significantly (P less than or equal to 0.05) elevated levels of PGE2, PGF2 alpha, and 12-HETE versus covered wounds and control tissue. Covered wounds had significantly elevated levels of 15-HETE compared to uncovered and control tissue. The elevated PGE2 in uncovered wounds may act as a fetal immunosuppressant; covered wounds (lower PGE2) developed cellular inflammation. Further investigations of these interactions may permit modulation of adult inflammation.

Cellular inflammation of fetal excisional wounds: effects of amniotic fluid exclusion

The development of an cellular inflammatory response secondary to mechanical wounding has not been observed previously in the fetus. The effect of amniotic fluid exclusion on the inflammatory response in fetal rabbits subjected to full-thickness dorsal excisional wounds on day 25 of gestation (term = 31-32) was examined. The fetuses were either returned immediately to the uterus; a silicone cover was sutured over the wound; or a silicone cover with a centrally located hole was sutured over the wound. Seventy-two hours after wounding, uncovered wounds (19 live fetuses) exhibited only occasional inflammatory cells. Covered wounds (14 live fetuses) showed a pronounced cellular inflammatory response. Partially covered wounds (six live fetuses) showed a peripheral, intermediate response. The findings suggest that amniotic fluid contains factors inhibitory to inflammation, which the cover effectively excludes.

Pathophysiology and postnatal outcome of fetal hydrocephalus

At the National Kagawa Children's 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 less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Heterogeneity and recurrence risk for congenital hydrocephalus (ventriculomegaly): a prospective study

We report on 261 prospectively ascertained pregnancies studied to determine the recurrence risk of congenital hydrocephalus. Our results suggest that couples who have had one previous child with hydrocephalus have a recurrence risk of 4%. Such couples should be offered prenatal diagnosis in the second trimester of all subsequent pregnancies. It is suggested that, apart from the X-linked recessive cases, ventriculomegaly is mostly multifactorially determined.