Frederick A. Boop
Jean-François Hirsch and Christian Sainte-Rose
✓ A cortical incision performed with inflation of a balloon to create a channel has been used in an approach to deep lesions with minimal damage to cerebral tissue. The balloon is slipped over a blunt needle and, once in place, is inflated through the needle. Postoperative sealing of the incision with fibrin glue avoids the subdural collection of cerebrospinal fluid such as is sometimes observed when the ventricle is opened during surgery.
Christian Sainte-Rose, Michael D. Hooven and Jean-François Hirsch
✓ To date, most patients suffering from hydrocephalus have been treated by insertion of differential-pressure valves that have fairly constant resistance. Since intracranial pressure (ICP) is a variable parameter (depending on such factors as patient's position and rapid eye movement sleep) and since cerebrospinal fluid (CSF) secretion is almost constant, it may be assumed that some shunt complications are related to too much or too little CSF drainage. The authors suggest a new approach to treating hydrocephalus, the aim of which is to provide CSF drainage at or below the CSF secretion rate within a physiological ICP range. This concept has led the authors to develop a three-stage valve system. The first stage consists of a medium-pressure low-resistance valve that operates as a conventional differential-pressure valve until the flow through the shunt reaches a mean value of 20 ml/hr. A second stage consists of a variable-resistance flow regulator that maintains flow between 20 and 30 ml/hr at differential pressures of 80 to 350 mm H2O. The third stage is a safety device that operates at differential pressures above 350 mm H2O (inducing a rapid increase in CSF flow rate) and therefore prevents hyper-elevated ICP. An in vitro study is described that demonstrates the capability of this system to maintain flow rates close to CSF production under a range of pressures similar to those observed under various human physiological and postural conditions. Promising clinical results in 19 patients shunted with this valve are summarized.
Dominique Renier, Christian Sainte-Rose, Daniel Marchac and Jean-François Hirsch
✓ In this study, intracranial pressure (ICP) was recorded with an epidural ensor for periods of 12 to 24 hours in 92 cases of craniosynostosis. Pre- and postoperative recordings were performed in 23 patients, and 55 children underwent preoperative psychometric testing. The ICP was found to be normal in one-third of the cases, was obviously elevated in one-third, and was borderline in one-third. Waves of increased ICP were recorded during rapid eye movement (REM) sleep. After surgery, ICP decreased progressively and returned to normal in several weeks. A significant statistical relationship was found between the patients' ICP and their mental level: the higher the ICP the lower the mental level. The regression curve of ICP as a function of age shows that ICP is maximal at the age of 6 years and decreases later. The significance of these results is discussed. The authors recommend that ICP be recorded in cases of craniosynostosis since it is of some help in deciding whether patients should undergo surgery.
Raphael Guzman, Arjun V. Pendharkar, Michel Zerah and Christian Sainte-Rose
Endoscopic third ventriculostomy (ETV) has become the procedure of choice for treatment of obstructive hydrocephalus. While patient selection is the most critical factor in determining the success of an ETV procedure, the technical challenge lies in the proper site of fenestration and the successful creation of a patent stoma. Positioning of a single balloon catheter at the level or below the floor of the third ventricle to achieve an optimal ventriculostomy can at times be challenging. Here, the authors describe the use of a double-barrel balloon catheter (NeuroBalloon catheter), which facilitates positioning across, as well as dilation of, the floor of the third ventricle. The surgical technique and nuances of using the NeuroBalloon catheter and the experience in more than 1000 cases are described. The occurrence of vascular injury was less than 0.1%, and the risk of balloon rupture was less than 2%. The authors found that the placement and deployment of this balloon catheter facilitate the creation of an adequate ventriculostomy in a few simple steps.
Anne-Laure Boch, Éric Hermelin, Christian Sainte-Rose and Spiros Sgouros
Object. The authors studied new and calcified shunt catheters to identify the prevalence of failures caused by aging materials in the shunt. Complications associated with these devices have various origins. Among late complications, fracture or migration of the system is related to the subcutaneous adhesion of the distal tubing in a growing child. A review of a cohort of 64 children who underwent shunt placement in 1980 with barium-impregnated distal catheters showed that 10 of these patients underwent reoperation for complications related to aging of the shunt material. This group represents 15% of the whole series and 30% of those children who were followed for more than 3 years. The true impact of aging of materials on shunt function is probably underestimated.
Methods. The authors performed physical, chemical, and mechanical analyses of the retrieved aged catheters and also of new catheters, resulting in the following findings: 1) calcifications were observed only on the external surface of the catheter, predominantly in its subcutaneous segment at the level of the neck and anterior chest wall; 2) calcifications contained particles of free silicon and barium sulfate, signifying fragmentation of the polymer; 3) the microstructure of the silicone polymer was modified: microfractures and alteration of the polymeric network were observed; 4) silanol groups were observed on the external surface of the catheter; and 5) the mechanical properties of the silicone rubber were degraded, and the aged catheters were more brittle than the new ones, with ruptures at elongations and fracture energy much lower than that seen in new catheters.
Furthermore, in vitro testing with a metastable solution of simulated body fluid demonstrated the critical impact of pH variations in liquid media and surface degradation of the catheters on the precipitation of hydroxylapatite crystals.
Conclusions. Although most shunt complications can be addressed by better patient management and surgical technique, late complications appear to be partly related to aging of the material. Distal tubing calcifications have been observed in barium-impregnated catheters. The industry recently responded to these observations by introducing plain silicone-coated shunt tubing; further evaluation will show what improvement can be expected.
Giuseppe Cinalli, Christian Sainte-Rose, Isabelle Simon, Guillaume Lot and Spiros Sgouros
This study is a retrospective analysis of clinical data obtained in 28 patients affected by obstructive hydrocephalus who presented with signs of midbrain dysfunction during episodes of shunt malfunction.
All patients presented with an upward gaze palsy, sometimes associated with other signs of oculomotor dysfunction. In seven cases the ocular signs remained isolated and resolved rapidly after shunt revision. In 21 cases the ocular signs were variably associated with other clinical manifestations such as pyramidal and extrapyramidal deficits, memory disturbances, mutism, or alterations in consciousness. Resolution of these symptoms after shunt revision was usually slow. In four cases a transient paradoxical aggravation was observed at the time of shunt revision. In 11 cases ventriculocisternostomy allowed resolution of the symptoms and withdrawal of the shunt.
Simultaneous supratentorial and infratentorial intracranial pressure recordings performed in seven of the patients showed a pressure gradient between the supratentorial and infratentorial compartments with a higher supratentorial pressure before shunt revision. Inversion of this pressure gradient was observed after shunt revision and resolution of the gradient was observed in one case after third ventriculostomy. In six recent cases, a focal midbrain hyperintensity was evidenced on T2-weighted magnetic resonance imaging sequences at the time of shunt malfunction. This rapidly resolved after the patient underwent third ventriculostomy.
It is probable that in obstructive hydrocephalus at the time of shunt malfunction, the development of a transtentorial pressure gradient could initially induce a functional impairment of the upper midbrain, inducing upward gaze palsy. The persistence of the gradient could lead to a global dysfunction of the upper midbrain.
Third ventriculostomy contributes to equalization of cerebrospinal fluid pressure across the tentorium by restoring free communication between the infratentorial and supratentorial compartments, resulting in resolution of the patient's clinical symptoms.
A review of 40 cases
Jean-François Hirsch, Alain Pierre-Kahn, Dominique Renier, Christian Sainte-Rose and Elizabeth Hoppe-Hirsch
✓ Forty cases of Dandy-Walker malformation referred to the Hôpital Necker Enfants-Malades between 1969 and 1982 have been reviewed. The incidence of the malformation in hydrocephalus was 2.4%. There was a slight, statistically insignificant, female prevalence.
Hydrocephalus should not be included in the definition of the syndrome. In 80% of the cases, it was actually a post-natal complication of the malformation and most often developed within 3 months after birth. In 80% of the cases, a communication, although insufficient, was found between the dilated 4th ventricle and the subarachnoid space. Since this communication is probably established through the foramina of Luschka, the definition of the Dandy-Walker malformation should only include atresia of the foramen of Magendie. Associated brain and systemic malformations were numerous. Among facial anomalies, facial angiomas were found in 10% of our cases. The association of facial and cardiovascular anomalies favors the hypothesis that the onset of the malformation occurs between the formation and the migration of the cells of the neural crest (that is, between the 3rd and the 4th post-ovulatory week, earlier than previously thought).
Except in selected patients, membrane excision has a high rate of failure and should be abandoned. Cystperitoneal shunting avoids the risk of an entrapped fourth ventricle and is presently the best surgical procedure. The overall mortality in this series was 12.5%. Intelligence quotients were over 80 in 60% of the patients. Other studies will be necessary to understand why the communication between the fourth ventricle and the subarachnoid spaces, sufficient in utero, usually becomes insufficient for a normal cerebrospinal fluid (CSF) circulation in the first months following birth. Two hypotheses are discussed: a change in CSF circulation, or bleeding in the dilated fourth ventricle during delivery.
Anne Morice, Sylvie Fraitag, Catherine Miquel, Christian Sainte Rose and Stéphanie Puget
Juvenile xanthogranuloma (JXG) is a rare disease that belongs to the non-Langerhans cell histiocytoses. It presents a wide clinical spectrum, usually occurs before 5 years of age, and is commonly confined to the skin; however, it can affect multiple sites, including the nervous system, and can lead to severe disorders. Although JXG is a benign disease that usually regresses spontaneously, several curative treatments have been proposed in cases of organ involvement. Treatment options include corticosteroids, chemotherapy, and radiotherapy; however, these can have severe, long-term adverse effects in children.
The authors here describe the first case of spontaneous resolution of an intramedullary spinal cord lesion of JXG associated with cerebral and cutaneous lesions in a young boy with 9 years of follow-up. The initial neurological symptoms resolved without any surgical or medical treatment. This case shows that extracutaneous lesions of JXG, including those with intramedullary spinal cord involvement, can regress without curative treatment—like cutaneous lesions—although both multidisciplinary care and close follow-up should be implemented.