Original Paper
Pcdiatr Ncurosurg 1992:18:263 265
Dallas. Tex.. USA
Ventriculosubgaleal Shunts: Management of Posthemorrhagic Hydrocephalus in Premature Infants
Introduction
The management of hydrocephalus in the premature infant after intraventricular hemorrhage remains a contro versial topic in pediatric neurosurgery. Most treatment strategies involve temporizing tactics to provide time for the infant to grow. Traditional treatment options include conservative therapy (no treatment), cerebrospinal fluid (CSF) inhibitors, serial lumbar punctures, ventricular taps (percutaneous or through an implanted reservoir), and ventriculostomy. On the other hand, a ventriculoperi toneal shunt may be undertaken. Traditional shunting of these tiny infants is plagued with numerous technical and neonatal problems and complications. In the present pa per. a surgical alternative to ventriculoperitoneal shunting is described as it pertains to the premature infant; ventric ular fluid is diverted to the subgaleal space. This paper presents the Dallas experience with ventriculosubgaleal shunts in premature infants.
Materials and Methods The present series spans a 6-year period and includes 62 prema ture infants who developed progressive hydrocephalus after intraven tricular hemorrhage. All of the infants had hydrocephalus associated with systemic clinical symptoms, such as apnea or bradycardia, or showed signs of raised intracranial pressure. Nearly all infants repre sented a failure to control the hydrocephalus with serial lumbar punctures. The average weight at the lime of the subgaleal shunt was 1.205 g: the smallest child weighed 750 g. These infants were referred
from multiple neonatal units in Dallas. Typically, they were returned to their original unit 4 or 5 days after their neurosurgical procedure. The subgaleal shunts were left in place until it was clear that they were no longer effective, as indicated by the adherence of the under mined scalp to the skull or the presence of proximal shunt obstruc tion. If the hydrocephalus was still active, the subgaleal shunt was removed and a ventriculoperitoneal shunt was placed. A few of the infants required a second subgaleal shunt because of their small size. On occasion the hydrocephalus showed evidence of clincal progres sion despite an apparently functioning subgaleal shunt. In these instances, conversion to a ventriculoperitoneal shunt system was undertaken. On the other hand, if the hydrocephalus appeared to arrest, the subgaleal shunt was left in place and removed electively when the child reached 6 months of age. Surgical Technique o f Shunt Placement In nearly all of the infants, the surgery was done under general endotracheal anesthesia. Local anesthesia was used in a single case early in the series. A curvilinear incision is made in the scalp. A small scalp flap is reflected, and the scalp is undermined widely. In most of the patients in this series, the shunt was positioned in the parieto-occipital region. More recently, the shunts have been placed frontally. A sharp perforator bit is used without a Hudson brace to create a small opening in the skull. Rongeurs are used to enlarge the opening to the size of a burr hole. When the shunt is positioned frontally, it is placed over the frontal or parietal bone, adjacent to the fontanelle. Positioning the shunt on the fontanelle is avoided. The shunt is preassembled. It is comprised of a 12-mm low pressure Pudenz pumping device ( Heyer-Schulte), a radiopaque ven tricular catheter (Codman). and a low pressure antireflux slit peri toneal catheter ( Heyer-Schulte). This slit catheter is cut 5 mm proximal to the most distal slit openings. Care is taken to make certain that the slits are not held open by the connector serving to secure the catheter to the Pudenz valve. This shunt arrangement drains ventricular CSF not only according to the pressure gradient characteristics of the valve but also by manual pumping.
Frederick Sklar. M I) 7777 Forest Lane (703. Dallas TX 75230 (USA)
< 1992 S. Karger AG. Basel 1016 2291/92/0186 0263 S2.75/0
Downloaded by: University Toronto Libr. 142.150.190.39 - 1/29/2018 10:18:46 PM
Frederick Sklar Andrew Adegbite Kenneth Shapiro Kim Miller
Small holes are made in the bone around the burr hole with a towel clip. The ventricle is tapped with a Cone needle, and the shunt is introduced along the needle tract. The slit catheter is positioned in the subgaleal space. The Pudenz valve is sutured to the bone (not the pericranium) to prevent the shunt from floating into the subgaleal fluid collection. The scalp wound is closed water-tight. Shunt Conversion In those infants in which the scalp had become adherent to the skull, the subgaleal shunt is removed and a new ventriculoperitoneal shunt is placed at the same cranial site. However, in those children with a significant subgaleal fluid collection at the time of conversion to a ventriculoperitoneal shunt system, the new shunt is usually placed at a distance from the original subgaleal shunt to prevent the subsequent coiling of the peritoneal catheter in the subgaleal space. For instance, a right parieto-occipital ventriculoperitoneal shunt would be placed on removing a right frontal subgaleal system. In these instances, redundant scalp is usually excised at the time of removal of the subgaleal shunt.
Results
Seventy ventriculosubgaleal shunts were done in 62 patients; 8 patients had two subgaleal shunt procedures. The effects of subgaleal shunting on ventricular size were determined by ultrasound or computerized tomography in 41 of the 62 patients. In these infants, the ventricles got smaller in 80%. Frequently, the ventricles became normal in size despite the presence of only a modest subgaleal fluid collection. These children required shunt pumping to generate subgaleal fluid in order to prevent the scalp from
264
Discussion
Ventriculosubgaleal shunts are certainly not new to neurosurgery. According to a review by Davidoff [I], Miculicz. in 1896. devised a tube made of gold which he inserted in two stages. First, a perforated disk was posi tioned under the scalp. A flanged tube was then passed through the hole in the disk and skull into the ventricle. In 1903, Senn [2] used a perforated rubber tube. Kausch [3] reported his experience with a subgaleal shunt system in 1908. More recently in 1977. Perret and Graff [4] reported the use of subgaleal shunts in the management of obstruc tive hydrocephalus in patients with tumors, in addition to those with subdurals. In 1986, Saladino et al. [5] reported a single case of a premature treated successfully for post hemorrhagic hydrocephalus with a bilateral ventricular shunt draining to a subcutaneous supraclavicular pocket. Ventriculoperitoneal shunting presents significant tech nical and clinical problems in the tiny premature infant. These infants require very special equipment. From a parieto-occipital approach, an ideally positioned ventricu lar catheter in the frontal horn of a 1,000 gram infant will
Sklar/Adegbitc/Shapiro/M iller
Management o f Posthemorrhagic Hydrocephalus in Premature Infants
Downloaded by: University Toronto Libr. 142.150.190.39 - 1/29/2018 10:18:46 PM
Fig. 1. Developmental outcome of surviving 55 children of origi nal series of 62 premature infants. Shaded bars indicate patients who required permanent shunts; open bars, patients who became shuntindependent.
adhering to the pericranium. Twenty-one children were transferred back to their outlying neonatal units before radiological follow-up of ventricular size was undertaken, and these results are not available. Forty-seven infants (76%) required a second shunt. Of this group, 8 (17%), required a second ventriculosubgaleal shunt, because they were still considered too small to undergo placement of a permanent shunt system or be cause of poor clinical condition. In 37 (79%), the second shunt procedure was a ventriculoperitoneal system; in 2 (4%), a ventriculoatrial shunt. Of the entire group of 62 infants, 6 (10%) have not required permanent shunting and are shunt-free. There were 7 deaths (11%). Only 1 death directly related to the shunt procedure. In this child, there was scalp necrosis and infection, leading to the child’s death. There were 6 shunt infections in the initial series of 62 subgaleal shunts (10%). There were numerous prematures in this series who developed necrotizing ente rocolitis, unrelated to their neurosurgical problems. Of the 6 infants with arrested hydrocephalus, all even tually underwent removal of the subgaleal shunt. From a developmental standpoint. 4 of the 6 are normal. Two have shown delay of milestones and spasticity. Thirteen of the 48 infants (27%) who required permanent shunting were normal. These results are summarized in figure 1.
wind up in the trigone as the child gets larger. The premature infant requires a low pressure rather than a medium pressure system. Finally, there may be problems related to the abdominal catheter such as respiratory embarrassment and necrotizing enterocolitis. Traditionally, the alternatives to shunt surgery lend to treat the hydrocephalus suboptimally. First, there is an inherent tendency to wait until the patient is 'stable’. CSF inhibitors such as furosemide or acetazolamide are of little practical use and may result in significant metabolic dis turbances in these frail infants. Daily taps by lumbar puncture are relatively noninvasive, but they are fre quently ineffective. CSF can leak from the lumbar thecal sac into the subdural space, resulting in compression and collapse of the subarachnoid space. 'Dry taps’ result. Moreover, removing a volume of CSF only once daily is less than ideal in the treatment of the infant's ongoing hydrocephalus problem, especially since the fluid is re placed by newly formed CSF in just a few hours. Con versely, ventricular decompression can be achieved by percutaneous taps or through an implanted ventricular reservoir [6]. Not only are these techniques more invasive, but they do not satisfy the criticism that these therapeutic efforts treat the disease process suboptimally on an inter mittent basis. Obviously, continuous ventricular drainage would be ideal were it not for the risk of infection. On the other hand, a functioning ventriculosubgaleal shunt provides continuous ventricular decompression.
Like a VP shunt or ventricular drain, this shunt system maximally treats the infant’s hydrocephalus. Because the shunt is intended to be temporary, the equipment is cho sen to be appropriate for the tiny premature without consideration as to what the shunt needs may be when the child is older. The subgaleal shunt avoids the potential abdominal complications of a peritoneal system. More over, the infant is not committed to a permanent shunt unless it is clear that he needs one. In the present series, 10% did not require a permanent shunt. Finally, the 10% infection rate and 11% mortality rate appear high in the present review, but these figures do not exceed those of other small series of VP shunts in low birth weight prema tures [7. 8], Although formal ncuropsychologic testing was not done in the present study, at least 27% of the original 62 patients were felt to be normal in follow-up: 11 children were lost to follow-up in this regard. These results com pare favorably to those of the VP shunted prematures [7, 8], although all of these series are too small to make meaningful comparison. How do subgaleal shunts work? It is possible that the CSF is actually absorbed by the scalp. On the other hand, it is possible that the shunt dampens intracranial pulsa tions which are pathologically augmented in hydro cephalus [9, 10]. Whatever the mechanism of action, the ventriculosubgaleal shunt is a relatively safe and effective temporizing measure to manage posthemorrhagic hydro cephalus in premature infants.
References 6 McComb JG, Ramos AD. Plalzker ACG. Henderson DJ. Scgall HD: Management of hydrocephalus secondary to intraventricular hemorrhage in the preterm infant with a sub cutaneous ventricular catheter reservoir. Neu rosurgery 1983:13:295 300. 7 Boynton BR, Boynton CA. Merritt TA, Vaucher YF„ James HE, Bejar RE': Ventricu loperitoneal shunts in low birth weight infants with intracranial hemorrhage: Ncurodevelopmcntal outcome. Neurosurgery 1986:18:141 145.
8 Licchly EA. Bull MJ. Bryson CQ, Kalsbcck JE. Jansc RD, Lemons JA. Schreiner RL: De velopmental outcome of very low birth weight infants requiring a ventriculoperitoneal shunt. Childs Brain 1983:10:340 349. 9 Sklar EH. Diehl JT. Beyer CW Jr. Clark WK: Brain elasticity changes with vcntriculomegaly. J Neurosurg 1980;53:173 -179. 10 Linder M. Nichols J. Sklar E'H: The effect of meningomyelocele closure on the intracranial pulse pressure. Childs Brain 1984:11:176 182.
265
Downloaded by: University Toronto Libr. 142.150.190.39 - 1/29/2018 10:18:46 PM
1 Davidoll' LM: Treatment of hydrocephalus. Historical review and description of a new method. Arch Surg 1929:18:1737 1762. 2 Senn N: Internal hydrocephalus. Ini Clin 1903:13:131-135. 3 Kausch W: Die Bchandlung des Hydro cephalus dcr klcincn Kinder. Arch Klin Chir 1908:27:709 796. 4 Perret GE, G raf CJ: Subgaleal shunt for tem porary ventricle decompression and subdural drainage. .1 Neurosurg 1977:47:590 595. 5 Saladino A. Gainsburg D, Zmora E. Roncn Y. Tibcrin P: Vcntriculosubcutancous shunt for temporary treatment of neonatal postIVH hydrocephalus: A technical note. Child's Ncrv Sysl 1986:2:206 207.
Pcdiatr Ncurosurg 1992:18:263 265
Dallas. Tex.. USA
Ventriculosubgaleal Shunts: Management of Posthemorrhagic Hydrocephalus in Premature Infants
Introduction
The management of hydrocephalus in the premature infant after intraventricular hemorrhage remains a contro versial topic in pediatric neurosurgery. Most treatment strategies involve temporizing tactics to provide time for the infant to grow. Traditional treatment options include conservative therapy (no treatment), cerebrospinal fluid (CSF) inhibitors, serial lumbar punctures, ventricular taps (percutaneous or through an implanted reservoir), and ventriculostomy. On the other hand, a ventriculoperi toneal shunt may be undertaken. Traditional shunting of these tiny infants is plagued with numerous technical and neonatal problems and complications. In the present pa per. a surgical alternative to ventriculoperitoneal shunting is described as it pertains to the premature infant; ventric ular fluid is diverted to the subgaleal space. This paper presents the Dallas experience with ventriculosubgaleal shunts in premature infants.
Materials and Methods The present series spans a 6-year period and includes 62 prema ture infants who developed progressive hydrocephalus after intraven tricular hemorrhage. All of the infants had hydrocephalus associated with systemic clinical symptoms, such as apnea or bradycardia, or showed signs of raised intracranial pressure. Nearly all infants repre sented a failure to control the hydrocephalus with serial lumbar punctures. The average weight at the lime of the subgaleal shunt was 1.205 g: the smallest child weighed 750 g. These infants were referred
from multiple neonatal units in Dallas. Typically, they were returned to their original unit 4 or 5 days after their neurosurgical procedure. The subgaleal shunts were left in place until it was clear that they were no longer effective, as indicated by the adherence of the under mined scalp to the skull or the presence of proximal shunt obstruc tion. If the hydrocephalus was still active, the subgaleal shunt was removed and a ventriculoperitoneal shunt was placed. A few of the infants required a second subgaleal shunt because of their small size. On occasion the hydrocephalus showed evidence of clincal progres sion despite an apparently functioning subgaleal shunt. In these instances, conversion to a ventriculoperitoneal shunt system was undertaken. On the other hand, if the hydrocephalus appeared to arrest, the subgaleal shunt was left in place and removed electively when the child reached 6 months of age. Surgical Technique o f Shunt Placement In nearly all of the infants, the surgery was done under general endotracheal anesthesia. Local anesthesia was used in a single case early in the series. A curvilinear incision is made in the scalp. A small scalp flap is reflected, and the scalp is undermined widely. In most of the patients in this series, the shunt was positioned in the parieto-occipital region. More recently, the shunts have been placed frontally. A sharp perforator bit is used without a Hudson brace to create a small opening in the skull. Rongeurs are used to enlarge the opening to the size of a burr hole. When the shunt is positioned frontally, it is placed over the frontal or parietal bone, adjacent to the fontanelle. Positioning the shunt on the fontanelle is avoided. The shunt is preassembled. It is comprised of a 12-mm low pressure Pudenz pumping device ( Heyer-Schulte), a radiopaque ven tricular catheter (Codman). and a low pressure antireflux slit peri toneal catheter ( Heyer-Schulte). This slit catheter is cut 5 mm proximal to the most distal slit openings. Care is taken to make certain that the slits are not held open by the connector serving to secure the catheter to the Pudenz valve. This shunt arrangement drains ventricular CSF not only according to the pressure gradient characteristics of the valve but also by manual pumping.
Frederick Sklar. M I) 7777 Forest Lane (703. Dallas TX 75230 (USA)
< 1992 S. Karger AG. Basel 1016 2291/92/0186 0263 S2.75/0
Downloaded by: University Toronto Libr. 142.150.190.39 - 1/29/2018 10:18:46 PM
Frederick Sklar Andrew Adegbite Kenneth Shapiro Kim Miller
Small holes are made in the bone around the burr hole with a towel clip. The ventricle is tapped with a Cone needle, and the shunt is introduced along the needle tract. The slit catheter is positioned in the subgaleal space. The Pudenz valve is sutured to the bone (not the pericranium) to prevent the shunt from floating into the subgaleal fluid collection. The scalp wound is closed water-tight. Shunt Conversion In those infants in which the scalp had become adherent to the skull, the subgaleal shunt is removed and a new ventriculoperitoneal shunt is placed at the same cranial site. However, in those children with a significant subgaleal fluid collection at the time of conversion to a ventriculoperitoneal shunt system, the new shunt is usually placed at a distance from the original subgaleal shunt to prevent the subsequent coiling of the peritoneal catheter in the subgaleal space. For instance, a right parieto-occipital ventriculoperitoneal shunt would be placed on removing a right frontal subgaleal system. In these instances, redundant scalp is usually excised at the time of removal of the subgaleal shunt.
Results
Seventy ventriculosubgaleal shunts were done in 62 patients; 8 patients had two subgaleal shunt procedures. The effects of subgaleal shunting on ventricular size were determined by ultrasound or computerized tomography in 41 of the 62 patients. In these infants, the ventricles got smaller in 80%. Frequently, the ventricles became normal in size despite the presence of only a modest subgaleal fluid collection. These children required shunt pumping to generate subgaleal fluid in order to prevent the scalp from
264
Discussion
Ventriculosubgaleal shunts are certainly not new to neurosurgery. According to a review by Davidoff [I], Miculicz. in 1896. devised a tube made of gold which he inserted in two stages. First, a perforated disk was posi tioned under the scalp. A flanged tube was then passed through the hole in the disk and skull into the ventricle. In 1903, Senn [2] used a perforated rubber tube. Kausch [3] reported his experience with a subgaleal shunt system in 1908. More recently in 1977. Perret and Graff [4] reported the use of subgaleal shunts in the management of obstruc tive hydrocephalus in patients with tumors, in addition to those with subdurals. In 1986, Saladino et al. [5] reported a single case of a premature treated successfully for post hemorrhagic hydrocephalus with a bilateral ventricular shunt draining to a subcutaneous supraclavicular pocket. Ventriculoperitoneal shunting presents significant tech nical and clinical problems in the tiny premature infant. These infants require very special equipment. From a parieto-occipital approach, an ideally positioned ventricu lar catheter in the frontal horn of a 1,000 gram infant will
Sklar/Adegbitc/Shapiro/M iller
Management o f Posthemorrhagic Hydrocephalus in Premature Infants
Downloaded by: University Toronto Libr. 142.150.190.39 - 1/29/2018 10:18:46 PM
Fig. 1. Developmental outcome of surviving 55 children of origi nal series of 62 premature infants. Shaded bars indicate patients who required permanent shunts; open bars, patients who became shuntindependent.
adhering to the pericranium. Twenty-one children were transferred back to their outlying neonatal units before radiological follow-up of ventricular size was undertaken, and these results are not available. Forty-seven infants (76%) required a second shunt. Of this group, 8 (17%), required a second ventriculosubgaleal shunt, because they were still considered too small to undergo placement of a permanent shunt system or be cause of poor clinical condition. In 37 (79%), the second shunt procedure was a ventriculoperitoneal system; in 2 (4%), a ventriculoatrial shunt. Of the entire group of 62 infants, 6 (10%) have not required permanent shunting and are shunt-free. There were 7 deaths (11%). Only 1 death directly related to the shunt procedure. In this child, there was scalp necrosis and infection, leading to the child’s death. There were 6 shunt infections in the initial series of 62 subgaleal shunts (10%). There were numerous prematures in this series who developed necrotizing ente rocolitis, unrelated to their neurosurgical problems. Of the 6 infants with arrested hydrocephalus, all even tually underwent removal of the subgaleal shunt. From a developmental standpoint. 4 of the 6 are normal. Two have shown delay of milestones and spasticity. Thirteen of the 48 infants (27%) who required permanent shunting were normal. These results are summarized in figure 1.
wind up in the trigone as the child gets larger. The premature infant requires a low pressure rather than a medium pressure system. Finally, there may be problems related to the abdominal catheter such as respiratory embarrassment and necrotizing enterocolitis. Traditionally, the alternatives to shunt surgery lend to treat the hydrocephalus suboptimally. First, there is an inherent tendency to wait until the patient is 'stable’. CSF inhibitors such as furosemide or acetazolamide are of little practical use and may result in significant metabolic dis turbances in these frail infants. Daily taps by lumbar puncture are relatively noninvasive, but they are fre quently ineffective. CSF can leak from the lumbar thecal sac into the subdural space, resulting in compression and collapse of the subarachnoid space. 'Dry taps’ result. Moreover, removing a volume of CSF only once daily is less than ideal in the treatment of the infant's ongoing hydrocephalus problem, especially since the fluid is re placed by newly formed CSF in just a few hours. Con versely, ventricular decompression can be achieved by percutaneous taps or through an implanted ventricular reservoir [6]. Not only are these techniques more invasive, but they do not satisfy the criticism that these therapeutic efforts treat the disease process suboptimally on an inter mittent basis. Obviously, continuous ventricular drainage would be ideal were it not for the risk of infection. On the other hand, a functioning ventriculosubgaleal shunt provides continuous ventricular decompression.
Like a VP shunt or ventricular drain, this shunt system maximally treats the infant’s hydrocephalus. Because the shunt is intended to be temporary, the equipment is cho sen to be appropriate for the tiny premature without consideration as to what the shunt needs may be when the child is older. The subgaleal shunt avoids the potential abdominal complications of a peritoneal system. More over, the infant is not committed to a permanent shunt unless it is clear that he needs one. In the present series, 10% did not require a permanent shunt. Finally, the 10% infection rate and 11% mortality rate appear high in the present review, but these figures do not exceed those of other small series of VP shunts in low birth weight prema tures [7. 8], Although formal ncuropsychologic testing was not done in the present study, at least 27% of the original 62 patients were felt to be normal in follow-up: 11 children were lost to follow-up in this regard. These results com pare favorably to those of the VP shunted prematures [7, 8], although all of these series are too small to make meaningful comparison. How do subgaleal shunts work? It is possible that the CSF is actually absorbed by the scalp. On the other hand, it is possible that the shunt dampens intracranial pulsa tions which are pathologically augmented in hydro cephalus [9, 10]. Whatever the mechanism of action, the ventriculosubgaleal shunt is a relatively safe and effective temporizing measure to manage posthemorrhagic hydro cephalus in premature infants.
References 6 McComb JG, Ramos AD. Plalzker ACG. Henderson DJ. Scgall HD: Management of hydrocephalus secondary to intraventricular hemorrhage in the preterm infant with a sub cutaneous ventricular catheter reservoir. Neu rosurgery 1983:13:295 300. 7 Boynton BR, Boynton CA. Merritt TA, Vaucher YF„ James HE, Bejar RE': Ventricu loperitoneal shunts in low birth weight infants with intracranial hemorrhage: Ncurodevelopmcntal outcome. Neurosurgery 1986:18:141 145.
8 Licchly EA. Bull MJ. Bryson CQ, Kalsbcck JE. Jansc RD, Lemons JA. Schreiner RL: De velopmental outcome of very low birth weight infants requiring a ventriculoperitoneal shunt. Childs Brain 1983:10:340 349. 9 Sklar EH. Diehl JT. Beyer CW Jr. Clark WK: Brain elasticity changes with vcntriculomegaly. J Neurosurg 1980;53:173 -179. 10 Linder M. Nichols J. Sklar E'H: The effect of meningomyelocele closure on the intracranial pulse pressure. Childs Brain 1984:11:176 182.
265
Downloaded by: University Toronto Libr. 142.150.190.39 - 1/29/2018 10:18:46 PM
1 Davidoll' LM: Treatment of hydrocephalus. Historical review and description of a new method. Arch Surg 1929:18:1737 1762. 2 Senn N: Internal hydrocephalus. Ini Clin 1903:13:131-135. 3 Kausch W: Die Bchandlung des Hydro cephalus dcr klcincn Kinder. Arch Klin Chir 1908:27:709 796. 4 Perret GE, G raf CJ: Subgaleal shunt for tem porary ventricle decompression and subdural drainage. .1 Neurosurg 1977:47:590 595. 5 Saladino A. Gainsburg D, Zmora E. Roncn Y. Tibcrin P: Vcntriculosubcutancous shunt for temporary treatment of neonatal postIVH hydrocephalus: A technical note. Child's Ncrv Sysl 1986:2:206 207.
