Communicating hydrocephalus: a reversible complication of the Mustard operation with serial hemodynamics and long-term follow-up

Subarachnomegaly-venous congestion of infancy

PURPOSE

Multiple names within the literature refer to a clinical picture affecting infants and consisting of a large or fast growing head circumference with enlarged cortical subarachnoid spaces (CSAS) while cranial sutures are open. This myriad of terms demonstrates the confusion about the entity, that may even group together different etiological processes. In this review, we aim to shed light on this matter in an effort to restate the defining features of the clinical picture and sum the evidence and current understanding of its pathophysiology and related imaging findings.

METHODS

Extensive and updated review of the literature with special focus on defining features, clinical history with long term evaluation and pathophysiological process.

RESULTS

Functional and molecular CSF studies as well as clinical evidence challenges the common pathophysiological theory based on non-functional arachnoid villi. Conversely, there is increasing evidence supporting cerebro-venous system abnormalities as the main pathophysiological factor. Additionally, long term cohorts studies show that it may have subtle but irreversible neurodevelopmental consequences.

CONCLUSION

Subarachnomegaly is an age-related condition of the infancy with radiological enlargement of CSAS and often self limiting course. However, considering the evidence on pathophysiology as outlined herein and long term outcome reports, further research effort is needed to assess the consequences of venous outflow impairment and enlarged CSAS and how this relates to imaging findings and neurodevelopment test results later in life.

Refractory cerebrospinal fluid leak following posterior fossa surgery secondary to superior vena cava obstruction: a case report

We report a case of refractory post-operative cerebrospinal fluid leak from a posterior fossa operative site secondary to superior vena cava construction. The patient developed the leak after a posterior fossa craniotomy and resection of a cerebellar lung metastasis. The leak persisted despite conservative measures and lumbar drain insertion. Suspicion of superior vena cava obstruction was raised following clinical examination. She was managed with stenting of the superior vena cava, with cessation of leak.

Cerebro-venous hypertension: a frequent cause of so-called "external hydrocephalus" in infants

INTRODUCTION

External hydrocephalus (eHC) is commonly defined as a subtype of infant "hydrocephalus" consisting of macrocepahly associated with enlarged subarachnoid space and no or mild ventriculomegaly. This status is thought to be related to impaired CSF absorption because of arachnoid villi immaturity. However, other factors like the venous system might be involved in the development of the clinical picture.

METHODS

All patients diagnosed with eHC received prospectively contrast-enhanced 3D MR phlebography. Venous sis abnormalities were graded depending on the number of affected sinus segments and type. External CSF space volume was quantified planimetrically.

RESULTS

Seventeen patients with the typical clinical feature of eHC were included. In 15, venous sinus abnormalities were found. There was a significant correlation between the volume of the widened cortical subarachnoid space (CSAS) and the number of venous sinus segments affected. Conversely, ventricular volume was not correlated.

CONCLUSION

These results support the hypothesis that impaired venous outflow plays a major role in external hydrocephalus development. Raised venous pressure increases intracranial pressure accelerating head growth, resulting in an enlargement of the cortical subarachnoid space. Increased venous pressure increases the capillary bed pressure and brain turgor preventing ventricular space to enlarge forcing displacement of ventricular CSF to the subarachnoid space. As a result, ventriculomegaly is rarely found. The descriptive term "external hydrocephalus" implying a primary etiology within the CSF system is misleading and this work supports the notion that venous hypertension is the leading cause of the clinical picture.

Does superior caval vein pressure impact head growth in Fontan circulation?

BACKGROUND

Patients with bidirectional cavopulmonary anastomosis have unphysiologically high superior caval vein pressure as it equals pulmonary artery pressure. Elevated superior caval vein pressure may cause communicating hydrocephalus and macrocephaly. This study analysed whether there exists an association between head circumference and superior caval vein pressure in patients with single ventricle physiology.

METHODS

We carried out a retrospective analysis of infants undergoing Fontan completion at our institution from 2007 to 2013. Superior caval vein pressures were measured during routine catheterisation before bidirectional cavopulmonary anastomosis and Fontan completion as well as head circumference, adjusted to longitudinal age-dependent percentiles.

RESULTS

We included 74 infants in our study. Median ages at bidirectional cavopulmonary anastomosis and Fontan were 4.8 (1.6-12) and 27.9 (7-40.6) months, respectively. Head circumference showed significant growth from bidirectional cavopulmonary anastomosis until Fontan completion (7th (0-100th) versus 20th (0-100th) percentile). There was no correlation between superior caval vein pressure and head circumference before Fontan (R2=0.001). Children with lower differences in superior caval vein pressures between pre-bidirectional cavopulmonary anastomosis and pre-Fontan catheterisations showed increased growth of head circumference (R2=0.19).

CONCLUSIONS

Patients with moderately elevated superior caval vein pressure associated with single ventricle physiology did not have a tendency to develop macrocephaly. There is no correlation between superior caval vein pressure before Fontan and head circumference, but between bidirectional cavopulmonary anastomosis and Fontan head circumference increases significantly. This may be explained by catch-up growth of head circumference in patients with more favourable haemodynamics and concomitant venous pressures in the lower range. Further studies with focus on high superior caval vein pressures are needed to exclude or prove a correlation.

Benign external hydrocephalus: a review, with emphasis on management

Benign external hydrocephalus in infants, characterized by macrocephaly and typical neuroimaging findings, is considered as a self-limiting condition and is therefore rarely treated. This review concerns all aspects of this condition: etiology, neuroimaging, symptoms and clinical findings, treatment, and outcome, with emphasis on management. The review is based on a systematic search in the Pubmed and Web of Science databases. The search covered various forms of hydrocephalus, extracerebral fluid, and macrocephaly. Studies reporting small children with idiopathic external hydrocephalus were included, mostly focusing on the studies reporting a long-term outcome. A total of 147 studies are included, the majority however with a limited methodological quality. Several theories regarding pathophysiology and various symptoms, signs, and clinical findings underscore the heterogeneity of the condition. Neuroimaging is important in the differentiation between external hydrocephalus and similar conditions. A transient delay of psychomotor development is commonly seen during childhood. A long-term outcome is scarcely reported, and the results are varying. Although most children with external hydrocephalus seem to do well both initially and in the long term, a substantial number of patients show temporary or permanent psychomotor delay. To verify that this truly is a benign condition, we suggest that future research on external hydrocephalus should focus on the long-term effects of surgical treatment as opposed to conservative management.

Age-dependent changes of cerebral ventricular size. Part I: Review of intracranial fluid collections

The age distributions of communicating hydrocephalus (CH), pseudotumour cerebri (PC) slit-ventricle syndrome (SVS), and chronic subdural haematomas (CSH) were reviewed in the medical literature. An age-related incidence was found: CH and CSH predominated in neonates less than 2 years and adults older than 55 years, while PC and SVS occurred mainly in older children and young adults. The latter two patient groups seem to show a greater resistance to ventricular dilatation in the presence of decreased CSF absorption. This may be related to larger volume and state of maturity of the cerebrum. On the other hand, neonates and the elderly more readily develop enlarged ventricles, in association with impairment of CSF absorption, or subdural fluid collections. Factors including status of cranial sutures, cerebral atrophy, cerebral water content, degree of cerebral myelination, and glial cell composition, may contribute to the age-related incidence of the four disorders investigated. Similarly, the development of ventriculomegaly may depend upon cerebral elastic properties besides the pri mary disturbance of CSF dynamics. The authors postulate that the size of cerebral ventricles in disorders of the cerebrospinal fluid (CSF) absorption is related to the elastic properties and volume of the brain. Furthermore, cerebral volume and elastic properties may also contribute to the age distribution of chronic subdural haematomas (CSH).

Detection of caval obstruction by magnetic resonance imaging after intraatrial repair of transposition of the great arteries

Vena caval obstruction may cause significant morbidity after intraatrial repair of transposition of the great arteries (TGA). Two noninvasive methods of diagnosing vena caval obstruction were compared with cardiac catheterization. Echocardiographically gated magnetic resonance imaging (MRI) and echocardiographic evaluation (2-dimensional saline contrast echocardiography and pulsed Doppler flow measurement) were performed on 15 patients 0.7 to 13.5 years after intraatrial repair of TGA (8 Mustard, 7 Senning). At catheterization, complete superior vena cava or partial caval obstruction (gradient greater than 5 mm Hg from cava to systemic venous atrium) was present in 7 of 15 patients. Superior vena cava obstruction was directly visualized by MRI in both patients with catheterization-proved complete superior vena cava occlusion. A dilated azygous/hemiazygous venous complex (greater than or equal to 5 mm cross-sectional diameter) was seen by MRI in 5 of 7 patients with complex or partial vena caval obstruction and in no patient without vena caval obstruction. MRI showed superior vena caval dilatation (ratio of superior vena caval diameter to aortic diameter greater than 1.45) in 3 of 5 patients with partial vena caval obstruction and in 0 of 8 without vena caval obstruction. Direct visualization of narrowing within the atrium was unreliable for any MRI plane because of the 3-dimensional nature of the intraatrial baffle. Two-dimensional saline contrast echocardiography, successfully performed in 12 of 15 patients, detected complete superior vena caval obstruction only in the 2 patients with catheterization-proved complete superior vena cava occlusion. Contrast echocardiography failed to identify any of the 5 patients with partial vena caval obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)