Executive Dysfunction After Fourth-Ventricle Epidermoid Cyst Resection.

Intracranial epidermoid cysts are rare, comprising 0.2% to 1.8% of all primary intracranial expanding lesions, of which <5% occur within the fourth ventricle. Epidermoid cysts are frequently congenital, and patients often present in the fourth decade of life. These cysts produce symptoms as a result of mass effect on surrounding structures, most commonly the cerebellum and cranial nerves. Symptoms can include hearing impairment, trigeminal neuralgia (severe facial pain), facial tics, headaches, double vision, and facial palsy. However, no research has focused on the neuropsychological effects on a patient after surgical resection of these cysts. This case report presents the cognitive profile of a woman after resection of an epidermoid cyst in the fourth ventricle. The 49-year-old patient underwent neuropsychological assessment after removal of the cyst, completing a comprehensive set of cognitive tests of estimated premorbid intelligence, attention, memory, social cognition, language, visual perception, and executive functioning. Test results indicated executive dysfunction and reduced visuospatial memory in the acute stage after surgical removal of the epidermoid cyst. These findings suggest that cognitive deficits can occur after resection of space-occupying lesions in brain regions not typically associated with cognition. To our knowledge, this is the first report of the neuropsychological consequences of surgical removal of a congenital epidermoid cyst in the fourth ventricle. An understanding of the neuropsychological sequelae of this rare cerebral cyst will allow patients, families, and health professionals to better anticipate and manage postoperative difficulties.

Primary Obstruction of the Foramen of Luschka: Anatomy, Histology, and Clinical Significance.

BACKGROUND: The foramen of Luschka is a natural aperture between the fourth ventricle and the subarachnoid space at the cerebellopontine angle. Membranous closure of this foramen is referred to as primary obstruction. Available information about this variant and its role in the development of the cysts of the posterior fossa is contradictory. METHODS: The macroscopic and histologic features of the obstructed foramina were examined in 61 formalin-fixed human brains (122 foramina). Three rhomboid lips of various sizes with lateral recess were used for comparison. Five postoperative cases of diverticulum of the foramen of Luschka were included in this study, with 1 case presented in detail to illustrate anatomic and histologic findings. RESULTS: Primary obstruction was present in 11 of 122 cases. In 1 case, an enlarged rigid pouch with a thick wall was found. The wall of the membrane in primary obstruction and the rhomboid lip were composed of an inner ependymal, a middle glial, and an outer leptomeningeal layer. CONCLUSIONS: The rhomboid lip is a remnant of the roof of the fourth ventricle. Imperforation of the foramen of Luschka results in a pouch in the cerebellopontine angle that contains choroid plexus (Bochdalek's flower basket) and communicates with the fourth ventricle. This pouch has the potential to grow to a diverticulum and cause clinical symptoms. Based on our clinical observations, detailed radiologic and surgical-anatomic criteria were proposed to support the differential diagnosis of a diverticulum of the foramen of Luschka. Treatment strategies were also suggested.

Prenatal sonographic features of triploidy at 12-16 weeks.

OBJECTIVE: The purpose of our study was to describe the sonographic appearance of triploidy in early pregnancy. METHODS: We report the sonographic characteristics of a cohort of fetal triploid cases detected at targeted ultrasonographic vaginal examinations between 12 and 16 weeks of gestation from 2008 to 2014. Indications for fetal karyotype following ultrasound were maternal request, advanced maternal age, increased nuchal translucency, and/or fetal abnormalities. RESULTS: Triploidy was detected in 25 cases during the 6 years of the study period with an estimated incidence of ~1 in 5000 pregnancies. Four cases had molar changes in the placenta. Among the remaining 21 cases, a consistent sonographic pattern was noted, which included the combination of asymmetric growth restriction with abdominal circumference lagging 2 weeks behind head circumference in 21/21, oligohydramnios in 20/21, abnormal posterior fossa or enlarged fourth ventricle in 20/21, and absent gall bladder in 17/21. Other findings present in more than 50% of cases included cardiac (70%) and renal (55%) abnormalities, clenched hands (55%), and hypoplastic lungs (67%). CONCLUSION: Fetal triploidy can manifest at 12-16 weeks with molar changes in the placenta or with a cluster of unusual sonographic findings whose presence should prompt appropriate testing for diagnosis in early pregnancy. © 2016 John Wiley & Sons, Ltd.

Abnormal sonographic appearance of posterior brain at 11-14 weeks and fetal outcome.

OBJECTIVE: The aim of this retrospective study was to describe the sonographic appearance of the posterior brain anatomy in normal fetuses at 11 to 14 weeks of pregnancy and to determine the fetal outcome when one of the posterior brain anatomical space is not recognized. METHODS: Two groups of patients were included in the study: a control group of consecutive 311 healthy fetuses with a normal sonogram and a study group of 21 fetuses with absence of one of the three posterior brain spaces. In each fetus, images of the mid-sagittal view of the fetal face and brain at 11 to 14 weeks of gestation were obtained. RESULTS: In all fetuses with absence of one of the three posterior brain spaces, a severe anomaly, including open spina bifida, cephalocele, Dandy-Walker complex, and chromosomal aberrations, was associated. CONCLUSION: Our study indicates that the sonographic finding characterized by the absence of one of the three posterior brain spaces seems to facilitate not only the detection of open spina bifida, as previously reported, but also of other neural tube defects, such as cephalocele, and is an important risk factor for cystic posterior brain anomalies, and/or chromosomal abnormalities. Thus it seems a poor prognostic finding for major fetal abnormalities.

Prenatal abnormal features of the fourth ventricle in Joubert syndrome and related disorders.

Joubert syndrome and related disorders (JSRD) are characterized by absence or underdevelopment of the cerebellar vermis and a malformed brainstem. This family of disorders is a member of an emerging class of diseases called ciliopathies. We describe the abnormal features of the brain, particularly the fourth ventricle, in seven fetuses affected by JSRD. In three cases abnormality of the fourth ventricle was isolated and in four cases there were associated malformations. The molar tooth sign (MTS) was always present and visible on two-dimensional ultrasound and, when performed, on three-dimensional ultrasound and magnetic resonance imaging. The fourth ventricle was always abnormal, in both axial and sagittal views, presenting pathognomonic deformities. It is important to identify JSRD, preferably prenatally or at least postnatally, due to its high risk of recurrence of about 25%. A detailed prenatal assessment of the fourth ventricle in several views may help to achieve this goal.

Open fourth ventricle prior to 20 weeks' gestation: a benign finding?

OBJECTIVE: To evaluate the role of the brainstem-vermis (BV) angle in the diagnosis of fetal posterior fossa abnormalities at 15-18 weeks' gestation. METHODS: We examined retrospectively three-dimensional (3D) ultrasound volumes acquired at 15-18 gestational weeks in fetuses with normal posterior fossa (controls) and in those with cystic posterior fossa. Whether the fourth ventricle appeared open posteriorly in axial views was noted and the BV angle was measured. A detailed follow-up was obtained in all cases. RESULTS: Of the 139 controls, 46 cases were excluded because of inadequate quality of the 3D volumes. Of the 93 remaining normal fetuses, 84 (90.3%) had a closed fourth ventricle and a BV angle < 20°, whereas 9/93 (9.7%) had an open fourth ventricle and a BV angle between 20° and 37°. The study group of 11 fetuses included seven with Dandy-Walker malformation and four with Blake's pouch cyst. In abnormal cases as a whole, the BV angle was significantly increased compared with that in controls (P < 0.0001). However, fetuses with Blake's pouch cyst and normal fetuses with an open fourth ventricle had strikingly similar sonograms: the BV angle was between 20° and 37° and the fourth ventricle appeared open only when viewed using a more steeply angulated scanning plane than that of the standard transcerebellar plane; in fetuses with Dandy-Walker malformation the fourth ventricle was widely open posteriorly, even in the standard transcerebellar view, and the BV angle was > 45°, significantly increased compared both with that in normal fetuses (P < 0.0001) and with that in fetuses with Blake's pouch cyst (P = 0.004). CONCLUSION: An open fourth ventricle is found in about 10% of normal fetuses at 15-18 weeks' gestation. Measurement of the BV angle is useful in such cases, as a value ≥ 45° is associated with a very high risk of severe posterior fossa malformation.

Endoscopic aqueductoplasty and stenting.

OBJECTIVE: This paper discusses indications for and the technique of endoscopic aqueductoplasty with stenting. METHODS: We review and summarize the clinical experience with endoscopic aqueductoplasty gained over the last 15 years on pediatric and adult patients. RESULTS: Endoscopic aqueductoplasty with stenting presents a safe procedure. In well selected patients, it provides a long-term, stable clinical course. Aqueductoplasty alone has a high reclosure rate and should be avoided. CONCLUSIONS: Aqueductoplasty with stenting is the procedure of choice for the treatment of isolated fourth ventricle. Membranous and tumor-related aqueductal stenosis should be treated by endoscopic third ventriculostomy.

Third ventriculostomy and fourth ventricle outlets obstruction.

A dilated fourth ventricle due to outlet obstruction is a clinical-radiologic entity with symptoms similar to those of a posterior fossa space-occupying lesion. Indeed, blockage of the foramina of Luschka and Magendie and of the aqueduct results in a "trapped" fourth ventricle. Continued cerebrospinal fluid (CSF) production within the fourth ventricle leads to cystic dilatation of the fourth ventricle. We could not, until now, understand the phenomenon, mainly on exploring endoscopically the permeability of the whole aqueduct. In adults, we call this condition the functional trapped fourth ventricle because in none of our cases have we found physical obstruction of CSF flow. Third ventricle-fourth ventriculostomy is by far the most frequently used technique for cannulation of the aqueduct in a trapped fourth ventricle. In our reported cases, we have introduced a silicone tube stent from below after accessing the fourth ventricle through a small suboccipital craniectomy, ascending it on the aqueduct in order to reach the third ventricle. Management of this infrequently isolated fourth ventricle, but communicated with the rest of ventricular system, remains a challenge for neurosurgeons. Lack of knowledge of the pathophysiology makes it difficult to treat a problem that we do not understand.

Retrospective review of diagnostic performance of intracranial translucency in detection of open spina bifida at the 11-13-week scan.

OBJECTIVES: To evaluate diagnostic performance of intracranial translucency (IT) for detection of open spina bifida and interobserver agreement for visualization of IT during the 11-13-week scan. METHODS: A retrospective study was undertaken in a tertiary referral center. Two hundred 11-13-week scans for nuchal translucency, performed by sonographers certified by The Fetal Medicine Foundation, U.K., were reviewed independently for IT by two expert observers. When IT was not seen, the observers determined whether this was due to poor IT image quality or the presence of spina bifida. Discordant cases were reviewed by a third observer and the majority decision was used for analysis. All observers were blinded to individual pregnancy outcome and the number of cases with spina bifida. RESULTS: There were 191 normal fetuses, eight fetuses with open spina bifida and one with closed spina bifida (this case was excluded from analysis). IT was seen in 150 fetuses and all were normal. In six of the 49 cases in which IT was not seen, IT non-visibility was attributed to open spina bifida; among these cases, four fetuses had open spina bifida and two were normal. In the remaining 43 cases (including 39 normal fetuses), IT non-visibility was attributed to inadequate image quality. Sensitivity was 50% (4/8) and specificity was 99% (150/152). Concordance between the two observers concerning IT visibility was 79%, (κ = 0.47, representing moderate agreement). CONCLUSION: There was moderate interobserver agreement for visualization of IT on images obtained for nuchal translucency measurement at 11-13 weeks. When IT was confidently seen, open spina bifida could be excluded. However, non-visibility of IT correctly diagnosed only 50% of fetuses with open spina bifida.

Fourth ventriculostomy: an alternative treatment for hydrocephalus due to atresia of the Magendie and Luschka foramina.

Atresia of the foramina of Magendie and Luschka is a rare cause of obstructive hydrocephalus. Although this condition has been classically treated by CSF shunting, recent treatments have also included endoscopic third ventriculostomy. In the present study, the authors present the case of a patient with hydrocephalus in whom an alternative method was used following a CSF shunt malfunction. A young female patient in whom a shunt was placed during the patient's 1st year of life was faring well until she was 8 years old. She was admitted to the emergency department 5 times with signs of CSF shunt malfunction. Each time, the CT scan showed a slight dilation of the lateral and third ventricles and a large increase in the size of the fourth ventricle. In comparison, ventricles were smaller in a previous imaging study obtained when the patient was asymptomatic. Magnetic resonance imaging showed the same slight dilation of all the ventricles and a significant increase in the fourth ventricle. There was no aqueductal stenosis. An important enlargement of both lateral recesses of the fourth ventricle suggested the possibility of an atresia of the foramina. The foramen of Monro and the width of the third ventricle would not allow the passage of an endoscope. The decision was made to open those foramina endoscopically through the fourth ventricle. After induction of general anesthesia, with the patient in the prone position, a bur hole was made in the left paramedian and suboccipital region. The endoscope was introduced underneath the cerebellar hemisphere. The authors were then able to distinguish the floor of the fourth ventricle and other anatomical landmarks. Navigation through the lateral recesses allowed them to see the fine membranes closing the foramina. These membranes were opened with a monopolar cautery as a blunt instrument. The orifice was then enlarged with a 3 Fr Fogarty catheter. The authors also opened a bulging thin membrane located at the foramen of Magendie. During the postoperative period, the authors observed a marked improvement in the state of the patient's alertness as well as a disappearance of her headaches and cessation of vomiting. In addition, the patient's gait ataxia improved slowly. Six-month postoperative MR imaging demonstrated an unequivocal reduction in the size of the fourth ventricle. The patient was still doing well 36 months after the surgery. Endoscopic fourth ventriculostomy, the opening of the 3 foramina of the fourth ventricle, may be an alternative treatment in cases in which these structures are congenitally closed.

Ependymal alterations in sudden intrauterine unexplained death and sudden infant death syndrome: possible primary consequence of prenatal exposure to cigarette smoking.

BACKGROUND: The ependyma, the lining providing a protective barrier and filtration system separating brain parenchyma from cerebrospinal fluid, is still inadequately understood in humans. In this study we aimed to define, by morphological and immunohistochemical methods, the sequence of developmental steps of the human ependyma in the brainstem (ventricular ependyma) and thoracic spinal cord (central canal ependyma) of a large sample of fetal and infant death victims, aged from 17 gestational weeks to 8 postnatal months. Additionally, we investigated a possible link between alterations of this structure, sudden unexplained fetal and infant death and maternal smoking. RESULTS: Our results demonstrate that in early fetal life the human ependyma shows a pseudostratified cytoarchitecture including many tanycytes and ciliated cells together with numerous apoptotic and reactive astrocytes in the subependymal layer. The ependyma is fully differentiated, with a monolayer of uniform cells, after 32 to 34 gestational weeks. We observed a wide spectrum of ependymal pathological changes in sudden death victims, such as desquamation, clusters of ependymal cells in the subventricular zone, radial glial cells, and the unusual presence of neurons within and over the ependymal lining. These alterations were significantly related to maternal smoking in pregnancy. CONCLUSIONS: We conclude that in smoking mothers, nicotine and its derivatives easily reach the cerebrospinal fluid in the fetus, immediately causing ependymal damage. Consequently, we suggest that the ependyma should be examined in-depth first in victims of sudden fetal or infant death with mothers who smoke.

Hydrocephalus associated with cystic dilation of the foramina of Magendie and Luschka.

Cystic malformations in the posterior cranial fossa result from developmental failure in the paleocerebellum and meninges. The authors present the case of an infant with hydrocephalus associated with cystic dilation of the foramina of Magendie and Luschka. This 7-month-old female infant presented with sudden onset of tonic-clonic seizures. Computed tomography revealed tetraventricular hydrocephalus. Magnetic resonance imaging demonstrated a cyst communicating with the fourth ventricle and projecting to the cisterna magna and the cerebellopontine cisterns through the foramina of Magendie and Luschka. A suboccipital craniotomy was performed for removal of the cyst wall, and the transparent membrane covering the foramen of Magendie was removed under a microscope. After the surgery, the patient's hydrocephalus improved and a phase contrast cine MR imaging study showed evidence of normal CSF flow at the level of the third and fourth ventricles. Three weeks later, however, the hydrocephalus recurred. An endoscopic third ventriculocisternostomy was performed to address the possibility of stagnant CSF flow in the posterior cranial fossa, but the hydrocephalus continued. Finally the patient underwent placement of a ventriculoperitoneal shunt, resulting in improvement of her symptoms and resolution of the hydrocephalus. On the basis of this experience and previously published reports, the authors speculate that the cystic malformation in their patient could be classified in a continuum of persistent Blake pouch cysts. Hydrocephalus was caused by a combination of obstruction of CSF flow at the outlets of the fourth ventricle and disequilibrium between CSF production and absorption capacity.

Endoscopic diagnosis and treatment of far distal obstructive hydrocephalus.

PURPOSE: Obstruction of the CSF circulation distal to the fourth ventricle is a rare cause of noncommunicating hydrocephalus. Endoscopic third ventriculostomy (ETV) represents one of the treatment options, but reports of results are rare. METHODS: Between March 1997 and June 2008, 20 ETVs in 20 patients (mean 32.4 years, range 1 month-79 years) for noncommunicating hydrocephalus distal to the fourth ventricle were undertaken. All patients suffered from severe internal hydrocephalus and typical clinical symptoms. In addition to the standard ETV, a transaqueductal inspection of the posterior fossa with a flexible scope was performed. All patients were prospectively followed. RESULTS: An ETV was achieved in all patients. It was clinically successful in 15 of 20 patients (75%) with an improvement of 50% (three out of six) of the pediatric and of 83% (12 out of 14) of the adult population. A reduction of ventricle size was found in ten (50%). Five patients (25%) received ventriculoperitoneal shunting. A transaqueductal inspection of the posterior fossa cerebrospinal fluid (CSF) pathways was performed in 16. In the remaining four patients, no inspection with the flexible scope was done. One clinically silent fornix contusion and one CSF fistula which was treated conservatively occurred. There was no permanent morbidity. CONCLUSIONS: ETV is a successful treatment option in CSF pathway obstructions distal to the fourth ventricle. Although the success rate particularly of the pediatric population appears to be lower than with other indications of obstructive hydrocephalus, a relevant part of the patient population improves after ventriculostomy and shunting can be avoided.

Association of Chiari malformation type I and tethered cord syndrome: preliminary results of sectioning filum terminale.

OBJECTIVE: The pathogenesis of CM-I is incompletely understood. We describe an association of CM-I and TCS that occurs in a subset of patients with normal size of the PCF. METHODS: The prevalence of TCS was determined in a consecutively accrued cohort of 2987 patients with CM-I and 289 patients with low-lying cerebellar tonsils (LLCT). Findings in 74 children and 244 adults undergoing SFT were reviewed retrospectively. Posterior cranial fossa size and volume were measured using reconstructed 2D computed tomographic scans and MR images. Results were compared to those in 155 age- and sex-matched healthy control individuals and 280 patients with generic CM-I. The relationships of neural and osseus structures at the CCJ and TLJ were investigated morphometrically on MR images. Intraoperative CDU was used to measure anatomical structures and CSF flow in the lumbar theca. RESULTS: Tethered cord syndrome was present in 408 patients with CM-I (14%) and 182 patients with LLCT (63%). In 318 patients undergoing SFT, there were no significant differences in the size or volume of the PCF as compared to healthy control individuals. Morphometric measurements demonstrated elongation of the brain stem (mean, 8.3 mm; P < .001), downward displacement of the medulla (mean, 4.6 mm; P < .001), and normal position of the CMD except in very young patients. Compared to patients with generic CM-I, the FM was significantly enlarged (P < .001). The FT was typically thin and taut (mean transverse diameter, 0.8 mm). After SFT, the cut ends of the FT distracted widely (mean, 41.7 mm) and CSF flow in the lumbar theca increased from a mean of 0.7 cm/s to a mean of 3.7 cm/s (P < .001). Symptoms were improved or resolved in 69 children (93%) and 203 adults (83%) and unchanged in 5 children (7%) and 39 adults (16%) and, worse, in 2 adults (1%) over a follow-up period of 6 to 27 months (mean, 16.1 months +/- 4.6 SD). Magnetic resonance imaging 1 to 18 months after surgery (mean, 5.7 months +/- 3.8 SD) revealed upward migration of the CMD (mean, 5.1 mm, P < .001), ascent of the cerebellar tonsils (mean, 3.8 mm, P < .001), reduction of brain stem length (mean, 3.9 mm, P < .001), and improvement of scoliosis or syringomyelia in some cases. CONCLUSIONS: Chiari malformation type I/TCS appears to be a unique clinical entity that occurs as a continuum with LLCT/TCS and is distinguished from generic CM-I by enlargement of the FM and the absence of a small PCF. Distinctive features include elongation and downward displacement of the hindbrain, normal position of the CMD, tight FT, and reduced CSF flow in the lumbar theca. There is preliminary evidence that SFT can reverse moderate degrees of tonsillar ectopia and is appropriate treatment for cerebellar ptosis after Chiari surgery in this cohort.

Increased nuchal translucency thickness: a potential indicator for Ritscher-Schinzel syndrome.

OBJECTIVE: The Ritscher-Schinzel syndrome (RSS), also known as the 3C syndrome, is an autosomal recessive disorder classically comprising craniofacial, cerebellar and cardiac defects. The underlying molecular etiology remains unknown; therefore, prenatal diagnosis of recurrences depends on identification of the associated structural anomalies on second trimester ultrasound examination. Identification of recurrences using first-trimester ultrasound has not been reported previously. METHODS: Two women who presented at our center with fetal nuchal abnormalities on first trimester ultrasound went on to have children with RSS. One of the women had also undergone a previous pregnancy termination for fetal anomalies consistent with RSS. The ultrasound findings and details of these 3 cases were reviewed. RESULTS: Both cases of RSS and the third suspected case were found to have nuchal abnormalities on first-trimester scan. All went on to develop malformations consistent with RSS detectable on second-trimester ultrasound. The later 2 cases continued to term and the children had facial characteristics consistent with RSS. CONCLUSION: First-trimester ultrasound assessment of nuchal translucency could be considered as a method for identifying sib recurrences of RSS. In addition, RSS should be on the differential diagnosis when increased nuchal translucency is seen on first-trimester scan.

A case of a Dandy-Walker variant: the importance of a multidisciplinary team approach using complementary techniques to obtain accurate diagnostic information.

Dandy-Walker malformation is a rare abnormality of the central nervous system (CNS) with a reported incidence of 1 in 25,00-35,00 live births and a slight female predominance. It accounts for 1-4% of cases of antenatally detected hydrocephalus. Dandy Walker variant forms part of the spectrum of Dandy Walker malformation. It is characterized by partial agenesis of the vermis, resulting in communication between the fourth ventricle and the cisterna magna. Dandy Walker malformation demonstrates an enlarged posterior fossa, with high insertion of the torcula herophili, as well as other features. In the diagnostic workup, ultrasound is reliable and accurate for making the diagnosis. In utero, fetal MRI can be used to confirm the diagnosis and also to identify any associated abnormalities. In cases of termination of pregnancy, autopsy will offer the diagnosis and provide additional information to assess the risk for future pregnancies and to help in counselling the parents. Autopsy is considered the gold standard for accurate diagnosis of the fetal abnormality. We report the unexpected finding of complete absence of the cerebellum due to maceration at autopsy, even though it was clearly demonstrated (but abnormal) on the antenatal ultrasound scan and MRI, as well as on post-mortem MRI. To the best of our knowledge, this has not been reported previously. Our case demonstrates the relevance of MRI when approaching a post-mortem examination with CNS malformation, and indicates that the "gold standard" might not always be autopsy.

Endoscopic aqueductoplasty and placement of a stent in the cerebral aqueduct in the management of isolated fourth ventricle in children.

OBJECT: In this study the authors conducted a retrospective evaluation of the effectiveness of endoscopic aqueductoplasty, performed alone or accompanied by placement of a stent, in the treatment of an isolated fourth ventricle (IFV) in seven patients afflicted with loculated hydrocephalus after a hemorrhage or infection. METHODS: Seven children with symptomatic IFV and membranous aqueductal stenosis underwent endoscopic aqueductoplasty alone or combined with placement of a stent in the cerebral aqueduct. The mean age of the patients at the time of surgery was 10 months. The mean duration of follow up was 26 months. In all patients a supratentorial shunt had already been implanted, and in five patients neuroendoscopy had already been performed because other isolated compartments had been present inside the ventricular system. Aqueductoplasty alone was performed in three patients and aqueductoplasty and aqueductal stent placement in four. A precoronal approach was performed in five patients and a suboccipital approach in two. Signs and symptoms of intracranial hypertension resolved in all cases. Stent placement was successful in all five cases, resulting in clinical and neuroimaging-confirmed improvements in the IFV. Restenosis of the aqueduct occurred in two patients in whom stents had not been placed. In one of these patients restenosis was managed by an endoscopic procedure, during which the aqueduct was reopened and a stent implanted; in the other patient a shunt was placed in the fourth ventricle. Hydrocephalus was controlled by a single shunt in six cases (86%) and by a double shunt in one case. CONCLUSIONS: Endoscopic placement of a stent in the aqueduct is more effective in preventing the repeated occlusion of the aqueduct than aqueductoplasty alone and should be indicated as the initial treatment in each case of compatible anatomy.

Sleep-disordered breathing in patients with Chiari malformation: improvement after surgery.

Sixteen consecutive patients with Arnold-Chiari malformation type I and syringomyelia underwent full-night polysomnography (PSG). Sleep apnea syndrome (apnea-hypopnea index > 10) was diagnosed in 12 of 16 patients with 48% of central apneas. In six patients with sleep apnea syndrome, PSG was repeated an average of 203 days after decompression surgery. Postoperative PSG showed a decrease in the central apnea index from 14.9 +/- 5.5 to 1.3 +/- 0.6 (p = 0.03).