Child's Nerv Syst (1996) 12:34-37 © Springer-Verlag 1996

Frank Van Calenbergh Jan Goffin Paul Casaer Chris Plets

Received: 4 March 1995

E Van Calenbergh ([]) • J. Goffin • C. Plets Department of Neurosurgery, University Hospital Gasthuisberg, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium R Casaer Department of Pediatrics (Neuropediatrics), University Hospital Gasthuisberg, Catholic University of Leuven, Herestraat 49, B-3000 Leuven, Belgium

Use of a ventriculosubgaleal shunt in the management of hydrocephalus in children with posterior fossa tumors

Abstract We p r e s e n t our experience with the use o f v e n t r i c u l o s u b galeal shunting ( V S G S ) for the m a n agement of hydrocephalus associated with p o s t e r i o r f o s s a t u m o r s in a consecutive series o f 63 children. In 42 children, a t e m p o r a r y V S G S was inserted. T h e r e were no c o m p l i c a tions a s s o c i a t e d with the p r o c e d u r e , and it g a v e a p e r i o d o f several days in w h i c h to i m p r o v e the g e n e r a l condition o f the child, and to p e r f o r m

Introduction T h e s y m p t o m s o f p o s t e r i o r f o s s a tumors (PFT) in c h i l d r e n u s u a l l y a p p e a r very i n s i d i o u s l y and the d i a g n o s i s is freq u e n t l y m a d e o n l y after a d e l a y o f several months. A large p e r c e n t a g e o f c h i l d r e n p r e s e n t with a c o n s i d e r a b l e d e g r e e o f h y d r o c e p h a l u s [11, 19], c a u s e d b y o b s t r u c t i o n o f the a q u e d u c t o f the IV ventricle. M a n a g i n g the h y d r o c e p h a l u s therefore r e m a i n s an i m p o r t a n t a s p e c t in the treatment o f c h i l d r e n with PFT. Various techniques have b e e n used [2, 8, 9, 11, 12, 13, 17, 20], but n o n e is perfect. In our D e p a r t ment, the v e n t r i c u l o s u b g a l e a l shunt ( V S G S ) has been in use for m o r e than 60 years [7, 23], and even t h o u g h m o d ern i m a g i n g techniques, earlier d i a g n o s i s , and safer external d r a i n a g e have g r a d u a l l y r e d u c e d the i n d i c a t i o n s for V S G S , h y d r o c e p h a l u s a s s o c i a t e d with P F T r e m a i n s in our e x p e r i e n c e an e x c e l l e n t i n d i c a t i o n for V S G S .

Patients and methods Surgical technique The VSGS catheter is inserted through a classical right frontal burr hole. A curved skin incision is preferred in smaller children, while

the n e c e s s a r y i m a g i n g studies, without an e n c u m b e r i n g external drainage device. In m o s t cases the V S G S could be r e m o v e d after the p o s t e r i o r f o s s a surgery, without new general anesthesia. Other a d v a n t a g e s and d r a w b a c k s o f this t e c h n i q u e are discussed. Key words Posterior fossa tumor • Hydrocephalus • V e n t r i c u l o s u b g a l e a l shunt

in older children and adults a linear incision can be used. The subgaleal space is widely dissected in a plane between the galea aponeurotica and pericranium, in a lateral and posterior direction (in order to avoid excessive swelling of the eyelids). After opening the dura and coagulating the pial vessels, the frontal horn is cannulated using a de Martel catheter or a small-bore nasogastric tube. These devices are made of relatively hard plastic polymers and can be bent at a right angle without kinking. Alternatively, a right-angled silicone catheter can be used. The catheter is rigidly sutured to the pericranium at the bone edge, cut at approximately 4 cm from this edge, and directed with its loose end into the subgaleal pocket. The skin is closed meticulously in two layers. In infants, older children and adults, the procedure is performed under local anesthesia, sometimes together with light sedation. In toddlers, we use general anesthesia. Normally, the catheter is removed at the end of surgery for the PFT.

Patient series A retrospective review was performed of 63 consecutive patients with PFT treated in our Department from 1983 to 1993. Before 1983, almost all children with PFT received a VSGS followed by ventriculography during the same procedure, irrespective of the presence or absence of hydrocephalus and raised intracranial pressure. It is because of this much broader indication for VSGS before 1983, that we only reviewed patients treated from 1983 onwards. In our series there were 25 patients with medulloblastomas, 24 with astrocytomas, and 14 with other histological types. The clinical and operative reports and the radiological records of the patients were analyzed to determine the usefulness and safety of

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the VSGS. The necessity for permanent ventriculoperitoneal or ventriculoatrial shunting was determined. The VSGS was usually inserted as an emergency procedure. It was our policy to operate for the PFT a few days after the VSGS insertion, and steroids were not used in the study period.

Results In 42 patients, a VSGS was inserted (group 1). In 4 patients (group 2), controlled external drainage (ED) was preferred: in two cases it was explicitly stated in the files that this was because of extremely severe hydrocephalus and fear of upward herniation, while in the other two no explicit reason was stated (one patient with mild, one with moderate hydrocephalus). In the remaining 17 children (group 3), there was no need for preoperative CSF diversion. In Table 1 the average age, tumor diameter, and preoperative occurrence of papilledema in the three groups is shown. As expected, the CSF diversion techniques were used in patients with larger tumors. In all patients with papilledema, either a VSGS or an ED was used. In Fig. 1, we compare the degree of hydrocephalus on CT scan with the type of CSF diversion used. Among the 14 patients with normal ventricles a VSGS was inserted in only 1. There were 12 patients with mild hydrocephalus:

7 received a VSGS, 1 ED, and 4 no drainage. All of the 27 patients with moderate and the 10 with severe hydrocephalus were managed using the VSGS, except 3 in whom ED was used, as described above. None of the 42 patients with VSGS experienced any complication: there were no infections, no skin problems or CSF leakage, and no instances of upward herniation or intratumoral hemorrhage. In one case, an ED was inserted after a few days because of insufficient subgaleal resorption. Although the retrospective nature of this study precludes detailed analysis of symptoms like somnolence, headache, or vomiting, all patient files report an improved condition of the child after the VSGS insertion. Decrease of papilledema was not systemically studied. The operative reports of all cases mention a normal or slack posterior fossa. In some cases a ventricular tap was done immediately before positioning the child for surgery, using the burr hole of the VSGS. A permanent shunt was inserted at some time following the PFT surgery in 12 of our patients (19%). It was used in 10 of the patients managed with VSGS, in none of the 4 cases managed with ED, and in 2 patients of the group without preoperative CSF diversion.

Discussion Table 1 Average age, tumor size, and occurrence of papilledema in the children without preoperative drainage, with external drainage,

and with ventriculosubgaleal shunt (VSGS) No drainage No. of cases

17

Average age (months) Tumor diameter (mm) Papilledema (no. of cases)

84.5 27 0

100 8O

External drainage 4

78 35 2

42

84.6 43 20

,...,.-,,..,• ,,.,,%...,* ,.,,,,.,.,,,,., ,,,,-.,,.,,.,., , .,.,. -,, ,.. ,o. ,, ., -, .. .-,,,....-, , . .,.,,....., ,,,%.,,..,, ,,.%.,... ,...,,,.,°%.,,

[ ] None [ ] ED • VSGS

o~ 6 0 ~.,,..,,-,-,..-

•~ 4012. 20-

VSGS

,,,,,,,,,% ° - • .,,,.., -,-.,°, .., ,, • .,,,.,,,,,

,,

:i:!:i:!:i:i:! None

Mild

Moderate

Severe

Hydrocephalus Fig. 1 Type of preoperative cerebrospinal fluid diversion used in 63 patients with posterior fossa tumors, compared to the degree of hydrocephalus

Ventriculosubgaleal shunting is a very old technique, first described in 1896 by Miculicz (quoted by Davidoff [6]). With varying technical details, the procedure has been used for all kinds of temporary CSF diversion by different authors, and seems to be receiving renewed interest today [16, 18, 21, 22]. We have used the technique in our Department for PFTassociated hydrocephalus since the early 1930s, and this experience has twice been reported in the francophone literature [7, 23]. There are many theoretical advantages to VSGS compared to either a ventriculoperitoneal (VP) shunt or external drainage. The main advantage in comparison to the VP shunt is the fact that VSGS is a small and easy procedure, often performed under local anesthesia, and that removal does not imply a separate anesthesia. We believe that with proper skin closure a subcutaneous pressure builds up, reducing the risk of upward herniation or intratumoral hemorrhage as found in about 3-5% of cases managed with VP shunts [2, 9, 13]. To prove this, of course, a large comparative trial would be necessary, and the low incidence of these dangerous complications renders this unrealistic. A final advantage may be the decreased risk of trans-shunt metastases, a well-known complication with VP shunts [3], but here also, proof would be very difficult to obtain. Compared to external drainage, the primary advantage of VSGS is the fact that it is a closed system, reducing the

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Fig. 2 Magnetic resonance image of the brain in a child with a posterior fossa tumor, showing the two compartments of cerebrospinal fluid - subgaleal and subcutaneous - after ventriculosubgaleal shunt placement incidence of infection. In none of our patients with VSGS for PFT [this report, 7, 23] was an infection seen. In fact, in an estimated 1500 patients with VSGS since 1965, for different indications, only 1 case of ventriculitis was ever noted. The second important advantage, especially in children, is the fact that the patient does not need to be restrained in bed, but can walk around, play, and be transported to the Radiology Department etc. without cumbersome external drainage reservoirs and tubing. Finally, in infants, there is no loss of fluid or electrolytes necessitating substitution. The working mechanism of VSGS may be twofold. A proportion of the CSF is resorbed by the skin tissue, leading to edema of the skin of the hemicranium, and sometimes of the face and the eyelids. In our experience, this mechanism remains functional for only approximately 10 days: after that time, the skin edema disappears and a more or less passive subgaleal fluid collection remains. The second mechanism may even then continue to be effective: the subgaleal pocket functions as a "fifth ventri-

cle", a CSF space not contained within the rigid skull and not subject to the Monroe-Kellie pressure-volume relationship. The VSGS may therefore dampen the high peaks of raised intracranial pressure, even when the resorption mechanism becomes insufficient. On postoperative magnetic resonance imaging the two compartments, the edematous skin and the subgaleal pocket, can clearly be seen (Fig. 2). The use of preoperative (permanent) CSF shunts has been known since the introduction of the ventriculoatrial shunt [1], and some authors have clearly demonstrated lower mortality among shunted patients [2]. However, there are several possible drawbacks: upward herniation [10, 19], seeding of tumor cells [3, 14], intratumoral hemorrhage [24], and all the classical complications of ventricular shunts (infection, obstruction, overdrainage). Figures in the literature on the number of children presenting with hydrocephalus warranting shunting vary enormously [4, 11, 13, 19, 20]: from 91% to 2% [4]. Earlier diagnosis and the use of steroids can certainly help avoid preoperative CSF diversion in a number of cases, but the symptoms of the PFT evolve in many cases so slowly and atypically that the diagnosis is only made when there is severe hydrocephalus and high intracranial pressure. Not all children needing a preoperative shunt need a permanent one, and in recent series [3-5, 9, 15, 29] the percentage of children needing a permanent shunt after surgery for PFT varies between 4% and 40%. Our figures of 19% for the total group and 24% for the VSGS group are well within these limits. We therefore assume that the technique of VSGS as we use it does not predispose to unnecessary long-term shunting. The number of children with PFT needing some kind of preoperative CSF diversion before tumor surgery is decreasing, because of earlier diagnosis, the use of steroids, and earlier operation. However, we believe a substantial percentage will still present with raised intracranial pressure due to obstructive hydrocephalus. In these cases, VSGS is a simple, inexpensive, and efficient method of temporary CSF diversion.

References 1. Abraham J, Chandy J (1963) Ventriculoatrial shunt in the management of posterior fossa tumors. Preliminary report. J Neurosurg 20:252-253 2. Albright L, Reigel DH (1977) Management of hydrocephalus secondary to posterior fossa tumors. J Neurosurg 46:52-55 3. Berger MS, Baumeister B, Geyer JR, Milstein J, Kanev PM, LeRoux PD (1991) The risks of metastases from shunting in children with primary central nervous system tumors. J Neurosurg 74:872-877

4. Cochrane DD, Gustavsson B, Poskitt KP, Steinbok P, Kestle JRW (1994) The surgical and natural morbidity of aggressive resection for posterior fossa tumors in childhood. Pediatr Neurosurg 20:19-29 5. Culley DJ, Berger MS, Shaw D, Geyer R (1994) An analysis of factors determining the need for ventriculoperitoneal shunts after posterior fossa surgery in children. Neurosurgery 34:402-408 6. Davidoff L (1929) Treatment of hydrocephalus. Arch Surg 18:1737-1740

7. Dereymaeker A (1948) De l'utilit6 du drainage ventriculaire prdpdratoire dans les tumeurs de la fosse post6rieure chez l'enfant. J Belg Neurol Psychiatr 2:68-78 8. Dias MS, Albright AL (1989) Management of hydrocephalus complicating childhood posterior fossa tumors. Pediatr Neurosci 15:283-290 9. Epstein FJ (1993) Medulloblastoma: indications for shunt placement. Pediatr Neurosurg 19:300-302

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10. Epstein FJ, Murali R (1978) Pediatric posterior fossa tumors: hazards of the "preoperative" shunt. Neurosurgery 3:348-350 11. Griwan MS, Sharma BS, Majahan RK, Kak VK (1993) Value of precraniotomy shunts in children with posterior fossa tumours. Child's Nerv Syst 9:462-466 12. Haase J (1993) Ventricular shunts and drainage in the management of posterior fossa tumors. In: Raimondi AJ, Choux M, Di Rocco C (eds) Principles of pediatric neurosurgery: posterior fossa tumors. Springer, New York Berlin Heidelberg, pp 80-85 13. Hoffrnan HJ (1993) Surgical management of medulloblastoma. Pediatr Neurosurg 19:303-305 14. Hoffman HJ, Hendrick EB, Humphreys RP (1976) Metastasis via ventriculoperitoneal shunt in patients with medulloblastoma. J Neurosurg 44:562-566

15. Lee M, Wisoff JH, Abbott R, Freed D, Epstein FJ (1994) Management of hydrocephalus in children with medulloblastoma: prognostic factors for shunting. Pediatr Neurosurg 20:240-247 16. McComb JG, Ramos AD, Platzker ACG, Henderson DJ, Segall HD (1983) Management of hydrocephalus secondary to intraventricular hemorrhage in the preterm infant with a subcutaneous ventricular catheter reservoir. Neurosurgery 13:295-300 17. Papo I, Caruselli G, Luongo A (1982) External ventricular drainage in the management of posterior fossa tumors in children and adolescents. Neurosurgery 10:13-15 18. Perret GE, Graf CJ (1977) Subgaleal shunt for temporary ventricle decompression and subdural drainage. J Neurosurg 47:590-595 19. Raimondi AJ, Tomita T (1981) Hydrocephalus and infratentorial tumors. Incidence, clinical picture, and treatment. J Neurosurg 55:174-182 20. Rappaport ZH, Shalit MN (1989) Perioperative external ventricular drainage in obstructive hydrocephalus secondary to infratentorial brain tumours. Acta Neurochir 96:118-121

21. Saladino A, Gainsburg D, Zmora E, Ronen Y, Tiberin P (1986) Ventriculosubcutaneous shunt for temporary treatment of neonatal post-IVH hydrocephalus: a technical note. Child's Nerv Syst 2:206-207 22. Sklar F, Adegbite A, Shapiro K, Miller K (1992) Ventriculosubgaleal shunts: management of posthemorrhagic hydrocephalus in preterm infants. Pediatr Neurosurg 18:263-265 23. Van den Bergh R, Gybels J, Plets C (1980) Les tumeurs du cervelet chez l'enfant. Technique et r6sultats op6ratoires. Neurochirurgie 26:193-195 24. Vaquero J, Cabezudo JM, DeSola RG, Nombela L ( 1981) Intratumoral hemorrhage in posterior fossa tumors after ventricular drainage. J Neurosurg 54:406-408

A m o n g the various surgical aids adopted by neurosurgeons to deal with increased intracranial pressure, ventriculosubgaleal shunting (VSGS) is a rather unusual one, usually regarded as obsolete, although some interest in it has been resurging in recent years, especially for the temporary control of intracranial hypertension. The main rationale for the utilization of this shunting procedure is the creation o f an artificial communication between intra- and extracranial space, thus giving an extracranial CSF reservoir not subject to the Monro-Kellie pressure-volume

relationship, with the aim of dampening any potentially dangerous increase in intracranial pressure. Theoretically, this procedure is an interesting alternative to other more c o m m o n forms o f temporary ventricular drainage. In particular, obstructive hydrocephalus associated with posterior fossa tumors is an excellent field for its application. In fact, as demonstrated in this paper, VSGS is effective in controlling increased intracranial pressure and in avoiding the incidence of infectious complications connected with shunt surgery. Moreover, V G S G reduces the well-

k n o w n risks of upward cerebellar herniation, intratumoral hemorrhage, or metastatic tumor seeding (brought about by extrathecal CSF drainage) by allowing slower CSF flow. Although this procedure may appear "ancient", even "primitive", its use should be considered in the light of the good results described in this paper. The authors deserve credit for bringing to our attention this interesting alternative to more classical routes of CSF drainage.

Massimo Caldarelli, R o m e