Intraventricular dimethyl sulfoxide (DMSO) induces hydrocephalus in a dose-dependent pattern.

Introduction: Dimethyl sulfoxide (DMSO), a widely utilized solvent in the medical industry, has been associated with various adverse effects, even at low concentrations, including damage to mitochondrial integrity, altered membrane potentials, caspase activation, and apoptosis. Notably, therapeutic molecules for central nervous system treatments, such as embolic agents or some chemotherapy drugs that are dissolved in DMSO, have been associated with hydrocephalus as a secondary complication. Our study investigated the potential adverse effects of DMSO on the brain, specifically focusing on the development of hydrocephalus and the effect on astrocytes. Methods: Varied concentrations of DMSO were intraventricularly injected into 3-day-old mice, and astrocyte cultures were exposed to similar concentrations of DMSO. After 14 days of injection, magnetic resonance imaging (MRI) was employed to quantify the brain ventricular volumes in mice. Immunofluorescence analysis was conducted to delineate DMSO-dependent effects in the brain. Additionally, astrocyte cultures were utilized to assess astrocyte viability and the effects of cellular apoptosis. Results: Our findings revealed a dose-dependent induction of ventriculomegaly in mice with 2%, 10%, and 100% DMSO injections (p < 0.001). The ciliated cells of the ventricles were also proportionally affected by DMSO concentration (p < 0.0001). Furthermore, cultured astrocytes exhibited increased apoptosis after DMSO exposure (p < 0.001). Conclusion: Our study establishes that intraventricular administration of DMSO induces hydrocephalus in a dose-dependent manner. This observation sheds light on a potential explanation for the occurrence of hydrocephalus as a secondary complication in intracranial treatments utilizing DMSO as a solvent.

Pediatric ping-pong skull fractures treated with vacuum-assisted elevation.

PURPOSE: Depressed ("ping-pong") skull fractures can be treated by different means, including observation, non-surgical treatments, or surgical intervention. The authors describe their experience with vacuum-assisted elevation of ping-pong skull fractures and evaluate variables associated with surgical outcomes. METHODS: The authors present a retrospective review of all ping-pong skull fractures treated with vacuum-assisted elevation at the Children's Hospital of Orange County in 2021-2022. Variables included patient age, mechanism of injury, fracture depth, bone thickness at the fracture site, and degree of elevation. RESULTS: Seven patients underwent vacuum-assisted elevation of ping-pong fractures at the bedside without the use of anesthesia. Fractures caused by birth-related trauma were deeper than those caused by falls (p < 0.001). There was no significant difference between groups in bone thickness at the fracture site (2.10 mm vs 2.16 mm, n.s). Six of the seven patients experienced significant improvement in fracture site depression, with four displaying a complete fracture reduction and two displaying a significant reduction. The degree of fracture reduction was modestly related to the depth of fracture, with the two deepest fractures failing to achieve full reduction. Age appeared to be related to fracture reduction, with the lowest reduction observed in one of the oldest patients in this sample. No complications were observed in any patient other than temporary mild swelling at the suction site, and no re-treatment or surgery for the fractures was required. CONCLUSION: Vacuum-assisted elevation of ping-pong skull fractures is a safe and effective noninvasive treatment option for infants that can be used under certain circumstances. The procedure can be done safely at the bedside and is a relatively quick procedure. It avoids the need for open surgical intervention, anesthesia, or hospital admission, and can lead to excellent outcomes.

Polyvinylpyrrolidone-coated catheters decrease choroid plexus adhesion and improve flow/pressure performance in an in vitro model of hydrocephalus.

PURPOSE: Proximal catheter obstruction is the leading cause of ventricular shunt failure in pediatric patients. Our aim is to evaluate various types of shunt catheters to assess in vitro cellular adhesion and obstruction. METHODS: Four catheter types were tested: (1) antibiotic and impregnated, (2) barium-stripe polyvinylpyrrolidone coated (PVP), (3) barium-stripe, and (4) barium-impregnated. Catheters were seeded with choroid plexus epithelial cells to test cellular adhesion and inoculated with the same cells to test flow/pressure performance under choroid plexus growth conditions. Ventricular catheters were placed into a three-dimensional printed phantom ventricular replicating system through which artificial cerebrospinal fluid (CSF) was pumped. Differential pressure sensors were used to measure catheter performance. RESULTS: PVP catheters had the lowest median cell attachment (10 cells) compared to antibiotic-impregnated (230 cells), barium stripe (513 cells), and barium-impregnated (146 cells) catheters after culture (p < 0.01). In addition, PVP catheters (- 0.247 cm H2O) and antibiotic-impregnated (- 1.15 cm H2O) catheters had significantly lower pressure in the phantom ventricular system compared to the barium stripe (0.167 cm H2O) and barium-impregnated (0.618 cm H2O; p < 0.01) catheters. CONCLUSIONS: PVP catheters showed less cellular adhesion and, together with antibiotic-impregnated catheters, required less differential pressure to maintain a consistent flow. Our findings suggest clinical relevance for using PVP ventricular catheters in patients with recurrent catheter obstruction by choroid plexus.

Partial Obstruction of Ventricular Catheters Affects Performance in a New Catheter Obstruction Model of Hydrocephalus.

OBJECTIVE: One of the major causes of cerebral ventricular shunt failure is proximal catheter occlusion. We describe a novel ventricular cerebrospinal fluid (CSF) flow replicating system that assesses pressure and flow responses to varying degrees of catheter occlusion. METHODS: Ventricular catheter performance was assessed during conditions of partial and complete occlusion. The catheters were placed into a three-dimensionally-printed phantom ventricular replicating system. Artificial CSF was pumped through the ventricular system at a constant rate of 1 mL/min to mimic CSF flow, with the proximal end of the catheter in the phantom ventricle. Pressure transducer and flow rate sensors were used to measure intra-phantom pressure, outflow pressure, and CSF flow rates. The catheters were also inserted into silicone tubing and pressure was measured in the same manner for comparison with the phantom. RESULTS: Pressure measured in the ventricle phantom did not change when the outflow of the ventricular catheter was partially occluded. However, the intraventricular phantom pressure significantly increased when the outflow catheter was 100% occluded. The flow through the catheter showed no significant difference in rate with any degree of partial occlusion of the catheter. At the distal end of the partially occluded catheters, there was less pressure compared with the nonoccluded catheters. This difference in pressure in partially occluded catheters correlated with the percentage of catheter hole occlusion. CONCLUSIONS: Our model mimics the physiological dynamics of the CSF flow in partially and completely obstructed ventricular catheters. We found that partial occlusion of the catheter had no effect on the CSF flow rate, but did reduce outflow pressure from the catheter.

AQP4, Astrogenesis, and Hydrocephalus: A New Neurological Perspective.

Aquaporin 4 (AQP4) is a cerebral glial marker that labels ependymal cells and astrocytes' endfeet and is the main water channel responsible for the parenchymal fluid balance. However, in brain development, AQP4 is a marker of glial stem cells and plays a crucial role in the pathophysiology of pediatric hydrocephalus. Gliogenesis characterization has been hampered by a lack of biomarkers for precursor and intermediate stages and a deeper understanding of hydrocephalus etiology is needed. This manuscript is a focused review of the current research landscape on AQP4 as a possible biomarker for gliogenesis and its influence in pediatric hydrocephalus, emphasizing reactive astrogliosis. The goal is to understand brain development under hydrocephalic and normal physiologic conditions.

AQP4 labels a subpopulation of white matter-dependent glial radial cells affected by pediatric hydrocephalus, and its expression increased in glial microvesicles released to the cerebrospinal fluid in obstructive hydrocephalus.

Hydrocephalus is a distension of the ventricular system associated with ventricular zone disruption, reactive astrogliosis, periventricular white matter ischemia, axonal impairment, and corpus callosum alterations. The condition's etiology is typically attributed to a malfunction in classical cerebrospinal fluid (CSF) bulk flow; however, this approach does not consider the unique physiology of CSF in fetal and perinatal patients. The parenchymal fluid contributes to the glymphatic system, and plays a fundamental role in pediatric hydrocephalus, with aquaporin 4 (AQP4) as the primary facilitator of these fluid movements. Despite the importance of AQP4 in the pathophysiology of hydrocephalus, it's expression in human fetal life is not well-studied. This manuscript systematically defines the brain expression of AQP4 in human brain development under control (n = 13) and hydrocephalic conditions (n = 3). Brains from 8 postconceptional weeks (PCW) onward and perinatal CSF from control (n = 2), obstructive (n = 6) and communicating (n = 6) hydrocephalic samples were analyzed through immunohistochemistry, immunofluorescence, western blot, and flow cytometry. Our results indicate that AQP4 expression is observed first in the archicortex, followed by the ganglionic eminences and then the neocortex. In the neocortex, it is initially at the perisylvian regions, and lastly at the occipital and prefrontal zones. Characteristic astrocyte end-feet labeling surrounding the vascular system was not established until 25 PCW. We also found AQP4 expression in a subpopulation of glial radial cells with processes that do not progress radially but, rather, curve following white matter tracts (corpus callosum and fornix), which were considered as glial stem cells (GSC). Under hydrocephalic conditions, GSC adjacent to characteristic ventricular zone disruption showed signs of early differentiation into astrocytes which may affect normal gliogenesis and contribute to the white matter dysgenesis. Finally, we found that AQP4 is expressed in the microvesicle fraction (p < 0.01) of CSF from patients with obstructive hydrocephalus. These findings suggest the potential use of AQP4 as a diagnostic and prognostic marker of pediatric hydrocephalus and as gliogenesis biomarker.

Polyvinylpyrrolidone-Coated Catheters Decrease Astrocyte Adhesion and Improve Flow/Pressure Performance in an Invitro Model of Hydrocephalus.

The leading cause of ventricular shunt failure in pediatric patients is proximal catheter occlusion. Here, we evaluate various types of shunt catheters to assess in vitro cellular adhesion and obstruction. The following four types of catheters were tested: (1) antibiotic- and barium-impregnated, (2) polyvinylpyrrolidone, (3) barium stripe, and (4) barium impregnated. Catheters were either seeded superficially with astrocyte cells to test cellular adhesion or inoculated with cultured astrocytes into the catheters to test catheter performance under obstruction conditions. Ventricular catheters were placed into a three-dimensional printed phantom ventricular replicating system through which artificial CSF was pumped. Differential pressure sensors were used to measure catheter performance. Polyvinylpyrrolidone catheters had the lowest median cell attachment compared to antibiotic-impregnated (18 cells), barium stripe (17 cells), and barium-impregnated (21.5 cells) catheters after culture (p < 0.01). In addition, polyvinylpyrrolidone catheters had significantly higher flow in the phantom ventricular system (0.12 mL/min) compared to the antibiotic coated (0.10 mL/min), barium stripe (0.02 mL/min) and barium-impregnated (0.08 mL/min; p < 0.01) catheters. Polyvinylpyrrolidone catheters showed less cellular adhesion and were least likely to be occluded by astrocyte cells. Our findings can help suggest patient-appropriate proximal ventricular catheters for clinical use.

Baclofen Toxicity Mimicking Brain Death: A Case Report of a Pediatric Patient.

BACKGROUND: Baclofen is commonly used in both pediatric and adult patients to treat spasticity secondary to spinal cord and cerebral pathology. A broad range of symptoms and severity of baclofen toxicity have been described. However, to our knowledge, there are no reports to date of baclofen toxicity mimicking brain death in pediatric patients. OBJECTIVE: We reviewed the presentation, clinical course, diagnostic studies including imaging and electroencephalography, and outcome of a patient with transient coma and loss of brainstem reflexes mimicking brain death secondary to baclofen toxicity. METHODS: During a baclofen pump refill, a 12-year-old boy with cerebral palsy had inadvertent injection of 12,000 µg of baclofen into the pocket around his pump. Within an hour, he presented with acute altered mental status that rapidly progressed to a comatose state with absent brainstem reflexes. RESULTS: After appropriate management, the patient returned to his neurological baseline by hospital day 3. DISCUSSION: We reviewed the literature for varying presentations of baclofen toxicity and associated electroencephalography findings, mechanism of overdose, and different management options. In this case, the mechanism of baclofen toxicity was suspected to be secondary to extravasation from the pump pocket and subsequent systemic absorption. CONCLUSIONS: Patients with baclofen toxicity may have a dramatic presentation and an initial examination mimicking brain death. Given its rarity, this clinical entity may not be readily recognized, and there is potential for misinterpretation of diagnosis and prognosis. It is important for physicians to be familiar with this clinical scenario to avoid false declaration of brain death.

Intrathecal Access Through Suboccipital Port in Patients With Spinal Muscular Atrophy and Complex Spines: Case Series and Technical Note.

Introduction Many patients with the spinal muscular atrophy (SMA) have complex spinal anatomy, secondary to thoraco-lumbar spinal fusions. Their fragile musculoskeletal anatomy potentiates limb and joint injury if conventional spinal fluid access modalities are utilized. This creates a challenge when attempting to deliver intrathecal medications such as nusinersen (Spinraza®). Catheter placement in the cervical subarachnoid space with a caudally directed tip is potentially beneficial. This article describes our experience with Spinraza injections into the thecal space through a suboccipital port. This allowed for simple, chronic, and reliable cerebrospinal fluid (CSF) aspiration and intrathecal injections. Methods A total of 15 patients with SMA and complex spinal anatomy were implanted with a cervical subarachnoid catheter, connected to a suboccipital access port. We retrospectively reviewed the charts of these patients for clinical outcomes and complications. All patients then underwent serial port cannulation, aspiration of CSF, and injection of Spinraza following standard manufacturer dosage guidelines. Results The age range was 3 to 49. Two had type-1 SMA, 10 had type-2 SMA, and three had type-3 SMA. We were able to successfully cannulate the port, aspirate CSF, and inject Spinraza during all access attempts. Two incidents of subcutaneous CSF leaks were resolved through reoperation and one incident of transient CSF leak was resolved without surgical repair. Conclusion Patients with SMA requiring intrathecal injections of Spinraza can be treated safely and efficiently with this novel implantation technique. The complication rates are low and the injection time is dramatically lower than with conventional injection techniques.

A Noninvasive Retrograde Flushing System for Shunted Hydrocephalus: Initial Case Series of 25 Patients.

Hydrocephalus is a common neurosurgical pathology associated with high patient morbidity and systemwide healthcare costs. A significant portion of these costs are related to the failure of ventricular shunting systems. Despite decades of research and technological development, the rate of shunt failure and revision has not significantly improved. The Reflow™ Ventricular System (Anuncia, Inc., Lowell, MA) is a recent technological development with the potential to prolong the shunt lifespan. This system introduces a noninvasive means of flushing a shunt proximally with a controlled, repeatable pulse of cerebral spinal fluid (CSF) and of creating a new ventricular opening for occluded shunts. In this multicenter case series, we present the early clinical experiences with this device and discuss its potential.

Sublaminar fixation for traumatic lumbar fracture subluxation with lateral listhesis in a 2-year-old patient.

Pediatric spinal trauma can present a surgeon with difficult management decisions given the rarity of these cases, pediatric anatomy, and a growing spine. The need to stabilize a traumatically unstable pediatric spine can be an operative challenge given the lack of instrumentation available. The authors present a surgical technique and an illustrative case that may offer a novel, less disruptive method of stabilization. A 2-year-old girl presented after an assault with an L1-2 fracture subluxation with lateral listhesis and fractured jumped facets exhibited on CT scans. CT also showed intact growth plates at the vertebral body, pedicles, and posterior elements. MRI showed severe ligamentous injury, conus medullaris compression, and an epidural hematoma. Neurologically, the patient moved both lower extremities asymmetrically. Given the severity of the deformity and neurological examination and disruption of the stabilizing structures, the authors made the decision to surgically decompress the L-1 and L-2 segments with bilateral laminotomies, evacuate the epidural hematoma, and reduce the deformity with sublaminar stabilization using braided polyester cables bilaterally, thus preserving the growth plates. They also performed a posterolateral onlay fusion at L-1 and L-2 using autograft and allograft placed due to the facet disruption. At the 42-month follow-up, imaging showed fusion of L-1 and L-2 with good alignment, and the hardware was subsequently explanted. The patient was neurologically symmetric in strength, ambulating, and had preserved alignment. Her bones and spinal canal continued to grow in relation to the other levels.

The impact of bilingualism on working memory in pediatric epilepsy.

Impairments in executive skills broadly span across multiple childhood epilepsy syndromes and can adversely affect quality of life. Bilingualism has been previously shown to correlate with enhanced executive functioning in healthy individuals. This study sought to determine whether the bilingual advantage in executive functioning exists in the context of pediatric epilepsy. We retrospectively analyzed neuropsychological data in 52 children with epilepsy and compared executive function scores in monolingual versus bilingual children with epilepsy while controlling for socioeconomic status and ethnicity. Bilingual children performed significantly better on the Working Memory Index than did monolingual children. There were no significant differences on the remaining executive function variables. The bilingual advantage appears to persist for working memory in children with epilepsy. These findings suggest that bilingualism is potentially a protective variable in the face of epilepsy-related working memory dysfunction.

The treatment of angiocentric glioma: case report and literature review.

Angiocentric glioma is a recently described tumor recognized since 2007 by the World Health Organization Classification of Tumours of the Central Nervous System. We present the only case of angiocentric glioma at our institution in the last 15 years and review the literature in an attempt to establish prognostic parameters. Our search revealed only 27 cases of angiocentric glioma in the literature. The most common presenting symptom of angiocentric glioma was seizures. Gross total resection of the lesion was curative, without need for radiation or chemotherapy.

Hydroxyapatite cement resistant to fragmentation following full cerebrospinal fluid bathing.

Prolonged cerebrospinal fluid bathing of cranioplasty cement frequently results in breakdown of the cement implants. A 5-year-old boy with a history of severe head trauma at 2 weeks of age presented with marked protrusion of the entire superior temporal bone and inferior parietal bone. The defect was elevated by more than 1 cm and was associated with a 4.5 x 3-cm skull defect located above and behind the right ear. There also was pulsatile tissue at the depths of the defect. A computed tomographic scan taken of the head revealed an expanding skull fracture from a dural defect with underlying brain herniation. The cranial lesion was repaired with OsteoVation hydroxyapatite cement. Within 8 weeks, the fluid encased the cranioplasty site. This resolved following implantation of a shunting device. At 2 and 12 months after the repair, the implant was still palpably solid without breakdown and did not fragment despite the prolonged bathing in cerebrospinal fluid.

Vault reduction cranioplasty for extreme hydrocephalic macrocephaly.

Due to early diagnosis and treatment of hydrocephalus, neurosurgeons rarely are called upon to treat patients with extreme hydrocephalic macrocephaly. Macrocephaly can limit mobility and hygiene. The critical evaluation and surgical correction of the morphological problem of macrocephaly secondary to hydrocephalus is complex. Various techniques such as quadrantal, picket fence, crossbar, and modified rr techniques have been used to reduce the size of the cranial vault to decrease cranial volume while achieving good cosmesis. Limitations of vault reduction cranioplasty include the inability to alter the anteroposterior and lateral diameters of the skull base, the inability to shorten the superior sagittal sinus, and the need to avoid infolding of the brain due to the risk of venous infarcts. Reduction cranioplasty is indicated in the occasional patient whose large head size represents a mechanical or cosmetic problem of sufficient magnitude to seriously interfere with motor development and functioning, with resultant development of pressure sores and difficulties with nursing care. Reduction cranioplasty should be avoided in patients under the age of 3 years.

Early propofol infusion syndrome following cerebral angiographic embolization for giant aneurysm repair. Case report.

The authors report a case of short-term high-dose propofol-related metabolic acidosis in a 3-year-old girl. The patient initially presented at another institution with left fourth cranial nerve palsy, and examination revealed a large, wide-necked 19 x 22 x 17-mm aneurysm in the left internal carotid artery. She had undergone three previous unsuccessful attempts at endovascular coil embolization, which were complicated by repeated coil protrusions into the parent vessel. During angiography and a balloon occlusion test (BOT) 80 mg propofol was given for 3 hours followed by 200 microg/kg/min for another 4 hours. The 20-minute BOT was well tolerated, and the aneurysm was occluded with stent-assisted coil embolization. Following the procedure the patient developed severe acidosis, hypotension, tachycardia, and signs of cardiac failure. On postoperative Day 3 her metabolic acidosis resolved, and she was weaned off sedatives. She continued to improve and was discharged from the hospital on postoperative Day 7. The metabolic acidosis and hypotension were thought to be due to propofol-related infusion syndrome.

Cranial vault reduction cranioplasty in children with hydrocephalic macrocephaly.

Craniofacial surgeons are rarely presented patients with extreme hydrocephalic macrocephaly due to early diagnosis and treatment of the hydrocephalus. Macrocephaly can significantly limit or prohibit mobility, hygiene and can drastically change lifestyle and developmental issues. The authors herein report on four consecutive total cranial vault reduction cranioplasty procedures for correction of hydrocephalic macrocephaly. The patients had a reduction in cranial volume ranging from 111-641 mL. All patients survived the procedure. Improvement in head control and aesthetics were improved in all patients. All of the patients required at least one shunt revision following the procedure. We conclude that total cranial vault reshaping is safe and effective for the treatment of macrocephaly secondary to hydrocephalus.

Giant intracranial teratoma and lack of cortical development in a fetus. Case report.

Antenatal diagnosis of an intracranial neoplasm is extremely rare. The authors describe a case in which a 21-week-old fetus was found, by using fetal ultrasonography, to have a large intracranial mass. Fetal magnetic resonance (MR) images, obtained at 21 and 25 weeks' gestation, supported the diagnosis of a teratoma. As the tumor increased in size, near-complete brain atrophy ensued. Premature labor was induced, and a nonviable fetus died within minutes of delivery. Postmortem analysis confirmed a teratoma occupying a major portion of the intracranial space. In cases in which abnormal brain development is suspected in a fetus, the use of fetal MR imaging can give a clearer picture of the pathological entity, which may allow for a more accurate diagnosis. The usefulness of fetal MR imaging in monitoring brain development and tumor growth during treatment planning is discussed.

Improved survival in central nervous system aspergillosis: a series of immunocompromised children with leukemia undergoing stereotactic resection of aspergillomas. Report of four cases.

Central nervous system (CNS) aspergillosis remains a daunting diagnosis. This opportunistic mycosis historically carries a mortality rate approaching 100% in immunocompromised patients, with death ensuing within days after the onset of neurological symptoms. From their literature review, the authors concluded that children contracting CNS aspergillosis while undergoing systemic chemotherapy for leukemias represent a particularly unfortunate prognostic group. Antifungal medications prove ineffective for treating CNS aspergillosis in patients immunocompromised because of their chemotherapy regimens. In contrast, withholding chemotherapy to reverse immunosuppression, thereby improving the efficacy of antifungal medications, allows for progression of the primary leukemic disease. The authors present a series of four immunosuppressed patients whose course of treatment for leukemia was complicated by CNS Aspergillus sp. abscesses. Multiple cerebral fungal abscesses developed in two patients and a single cerebral abscess developed in two. All four patients underwent frameless stereotactic resection of the aspergilloma. All children later experienced resolution of their CNS infections and full neurological recovery. At 2- to 4-year follow ups, one patient has died of leukemia and the other three continue to thrive without evidence of recurrent aspergillosis. Given the grave natural history cited in the literature for this disease when medical treatment is instituted alone, the authors stress the crucial role of stereotactic neurosurgery for the intelligent treatment of immunocompromised children suspected of harboring a CNS aspergilloma abscesses. The authors propose that the goal for successful treatment in these patients should be gross-total resection of the abscess, its wall, and its capsule.

Performance and complications associated with the synchromed 10-ml infusion pump for intrathecal baclofen administration in children.

OBJECT: The objectives of this multicenter study were to monitor the performance of a 10-ml pump infusing intrathecal baclofen to treat 100 children with cerebral spasticity, to monitor complications associated with the pump, and to correlate pump-related complications with body habitus. METHODS: Age at implantation of the pump ranged from 1.4 to 16.8 years (mean 8.1 years). The effects of ITB on spasticity in the upper and lower extremities were evaluated using the Ashworth Scale. Data were collected regarding implant site, infection, complication, and body mass index (BMI). Ashworth Scale scores decreased significantly in the upper and lower extremities at 6 and 12 months after pump implantation (p < 0.001). There were four serious system-related complications, all specific to catheters. There were 32 serious procedure-related complications in 21 patients: 11 complications were infections that occurred in nine patients. Four of nine pump-induced infections were treated with pump removal and antibiotic therapy; five infections were treated successfully with antibiotic therapy alone, without pump removal. In children younger than 8 years of age there was a significantly higher incidence of serious procedure-related adverse events than in older children. There was no significant correlation between BMI and the incidence of pump pocket-related complications or infections. CONCLUSIONS: The 10-ml pump can be used therapeutically in small children, particularly those weighing less than 40 lbs, with greater ease and less wound tension, than the conventional 18-ml pump. The incidence of complications associated with the 10-ml pump in younger children appears to be similar to that previously reported with the 18-ml pump in larger-sized children.