Ommaya Reservoir Insertion Research Articles

NFS-13. UNUSUAL NEUROFIBROMATOSIS TYPE 1-ASSOCIATED PILOCYTIC ASTROCYTOMAWITH MALIGNANT TRANSFORMATION IN A 7-YEAR-OLD GIRL

Abstract INTRODUCTION Neurofibromatosis type 1(NF1) is a tumor predisposition syndrome with germline NF 1 gene aberrations with overactivation of the RAS–MAPK signaling pathway. NF1-associated gliomas in children are usually low-grade Glioma with indolent course. Malignant transformation in NF1 associated LGG is predominated in adults is scarce in children METHOD A 7-year-old girl diagnosed as NF1-based on diagnostic criteria and germline NF1 gene mutation, presented with progressive RT side hemiplegia, Brain MRI showed a large left thalamic cystic and solid mass and obstructive hydrocephalus she had VPS insertion and stereotactic biopsy.pathological examination revealed aggressive High-grade Glioma HGG features diffuse brain infiltration, endothelial hyperplasia, increased mitotic activity necrosis, and High Ki67. Immunohistochemically and molecular analysis showed NF1 mutation in addition to TP53 mutation, retained ATRX, negative CDKN2A/B, and high tumor mutational burden (6 Muts/Mb). Tumor methylation profiling (DKFZ CNS v12.5) classified as Supratentorial midline pilocytic astrocytoma (score 0.6878). debulking of the tumor and ommaya reservoir insertion was done with recurrent aspiration of the cystic component. The second biopsy demonstrated low-grade pilocytic astrocytoma, confirmed by methylation profiling (score 0.9377). Immunohistochemically and molecular analysis showed NF1 mutation, negative TP53, and Retained ATRX RESULT She was treated with low-grade glioma chemotherapy carboplatin/ vincristine, with improved clinical and neurological condition and stable MRI evaluation. One year after diagnosis while on maintenance LGG chemotherapy MRI imaging showed tumor progression Subtotal resection of the mass was performed, morphology and molecular studies confirmed HGG, and she received focal radiation therapy. Up till now, the patient is currently stable clinically and by imaging surveillance. CONCLUSION Our case characterized a transformed glioma in a child with NF1 illustrating the intratumoral heterogeneity and presence of transformed/anaplastic clone within NF1-associated pilocytic astrocytoma and demonstrate the complexity of molecular genetics of gliomas in children with NF1.

Supraorbital minicraniotomy for open Ommaya reservoir placement in pediatric craniopharyngiomas: a case series and technical report.

Craniopharyngiomas with a predominant cystic component are often seen in children and can be treated with an Ommaya reservoir for aspiration and/or intracystic therapy. In some cases, cannulation of the cyst can be challenging via a stereotactic or transventricular endoscopic approach due to its size and proximity to critical structures. In such cases, a novel placement technique for Ommaya reservoirs via a lateral supraorbital incision and supraorbital minicraniotomy has been used. The authors conducted a retrospective chart review of all children undergoing supraorbital Ommaya reservoir insertion from January 1, 2000, to December 31, 2022, at the Hospital for Sick Children, Toronto. The technique involves a lateral supraorbital incision and a 3 × 4-cm supraorbital craniotomy, with identification and fenestration of the cyst under the microscope and insertion of the catheter. The authors assessed baseline characteristics and clinical parameters of surgical treatment and outcome. Descriptive statistics were conducted. A review of the literature was performed to identify other studies describing a similar placement technique. A total of 5 patients with cystic craniopharyngioma were included (3 male, 60%) with a mean age of 10.20 ± 5.72 years. The mean preoperative cyst size was 11.6 ± 3.7 cm3, and none of the patients suffered from hydrocephalus. All patients suffered from temporary postoperative diabetes insipidus, but no new permanent endocrine deficits were caused by the surgery. Cosmetic results were satisfactory. This is the first report of lateral supraorbital minicraniotomy for Ommaya reservoir placement. This is an effective and safe approach in patients with cystic craniopharyngiomas, which cause local mass effect but are not amenable to traditional Ommaya reservoir placement stereotactically or endoscopically.

Preservation of endocrine function after Ommaya reservoir insertion in children with cystic craniopharyngioma.

Children with craniopharyngiomas (CP) can experience significant morbidities caused by extensive surgery and/or radiation. Ommaya reservoir insertion (ORI) into cystic CP represents a minimally invasive approach allowing immediate decompression and aims to avoid additional injuries. The purpose of this study was to determine the surgical outcome and relevance of upfront ORI (± intracystic treatment) for preservation of endocrine function. We performed a retrospective chart review of children with CP treated at the Hospital for Sick Children between 01/01/2000 and 15/01/2020. Endocrine function was reviewed at the time of initial surgery and throughout follow-up. New endocrinological deficits related to the index procedure were defined as immediate failure (IF), whereas postoperative duration of endocrinological stability(ES) wasanalyzed using the Kaplan-Meier method. The rate of IF and ES was compared between the treatment groups. Seventy-nine patients were included and had a median age of 8.3years (range 2.1-18.0years); 31 were males. Fifty-three patients with upfront surgical treatment, including 29 ORI and 24 gross total or partial resections had sufficient endocrinological follow-up data. Endocrine dysfunction occurring immediately after the index procedure (IF)was observed in 15 patients (62.5%) in the resection group compared to two patients (6.8%) in the ORI group, odds ratio: 0.05 (CI: 0.01-0.26, p < 0.0001). Excluding those with immediate endocrinologicaldeficits, mean ES after ORI was 19.4months (CI: 11.6-34.2), compared to 13.4months (CI:10.6-NA) after surgical resection. Endocrine function was preserved in patients with upfront ORI (± intracystic treatment), which was confirmed as a minimally invasive procedure with an overall low morbidity profile.

RARE-23. Preservation of endocrine function after Ommaya reservoir insertion in children with cystic craniopharyngioma

INTRODUCTION: Children with craniopharyngiomas (CP) can be subjected to significant morbidities caused by radical surgery and/or radiation with deleterious long-term consequences. Ommaya reservoir insertion (ORI) into cystic CP represents a minimally invasive procedure allowing immediate decompression and aims to avoid additional injuries. The purpose of this study was to determine the relevance of upfront ORI (+/- intracystic treatment) for preservation of endocrine function. METHODS: We performed a retrospective chart review of children with CP treated at the Hospital for Sick Children between 01/01/2000 and 15/01/2020 for review of endocrinological outcome after ORI. Endocrine function was reviewed at the time of initial surgery and throughout the course of follow-up. Event-free survival (EFS) was defined as the time to further surgical resection or irradiation. RESULTS: Seventy-nine patients were identified with a median age of 8.3 (range 2.1-18.0) years, 31 were males. Sixty-six patients underwent surgical treatment, including 41 ORI. ORI was performed as upfront treatment in 32 patients; 33 patients underwent gross total or partial resection and 1 patient radiotherapy as first treatment. Fifty-five of 79 patients had sufficient endocrine follow-up data. Endocrine function remained stable after ORI with a mean EFS of 27.64 (± 5.22) months. Surgical resection was associated with worsened endocrine function postoperatively with an EFS of 5.48 (± 1.74) months (p< 0.001). CONCLUSIONS: Upfront ORI (+/- intracystic treatment) resulted in endocrine preservation of all patients and a significantly longer EFS when compared to upfront surgical resection in this single institutional retrospective review. Further analyses will elucidate the implications of ORI with respect to ophthalmological, vascular and neurocognitive outcome.

Lumboperitoneal Shunt Combined With Ommaya Reservoir Enables Continued Intraventricular Chemotherapy for Leptomeningeal Metastasis With Increased Intracranial Pressure.

Intra-cerebrospinal fluid (CSF) chemotherapy for leptomeningeal metastasis (LM) can be delivered intraventricularly via an Ommaya reservoir. However, hydrocephalus associated with LM can interfere with chemotherapeutic drug distribution, and ventriculoperitoneal shunts can prevent drug distribution to the extra-ventricular CSF space. This study examined the feasibility of combining a lumboperitoneal (LP) shunt with an Ommaya reservoir to both control intracranial pressure and allow for intraventricular chemotherapy. We identified 16 patients with LM who received both an Ommaya reservoir and an LP shunt, either concurrently or sequentially, and subsequently received intraventricular chemotherapy. The feasibility of this combination for intraventricular chemotherapy was evaluated by assessing 1) the distribution of intraventricularly injected drugs in CSF samples collected 0, 6, and 12 h post-injection and 2) adverse events associated with the procedure and drug administration. Patients received a median of seven rounds (range 1-37) of intraventricular chemotherapy during a median follow-up period of 5.2 months after LP shunt insertion. Pharmacokinetic data were obtained from six patients. Baseline methotrexate (MTX) levels from Ommaya reservoirs varied from 339.9 µM to 1,523.5 µM. CSF sampled from LP shunt reservoirs revealed an elimination half-life (t1/2) of 2.63 h, and the mean ratio of MTX concentration at 12 h to that at baseline was 0.05±0.05, ensuring drug distribution from the ventricle to the spinal canal. Nine patients (56%) underwent revision surgery due to catheter migration, malfunction, or infection. Among these patients, CSF infections attributable to intraventricular chemotherapy (n=3) occurred, but no infections occurred in later cases after we began to employ a complete aseptic technique. LP shunt combined with Ommaya reservoir insertion is a feasible option for achieving both intracranial pressure control and the continuation of intraventricular chemotherapy in patients with LM.

Neurosurgical experience of managing optic pathway gliomas

BackgroundOptic pathway gliomas (OPGs), also known as visual pathway gliomas, are debilitating tumors that account for 3–5% of all pediatric brain tumors. They are most commonly WHO grade 1 pilocytic astrocytomas and frequently occur in patients with neurofibromatosis type 1. The location of these tumors results in visual loss and blindness, endocrine and hypothalamic dysfunction, hydrocephalus, and premature death. Their involvement of the visual pathways and proximity to other eloquent brain structures typically precludes complete resection or optimal radiation dosing without incurring significant neurological injury. There are various surgical interventions that can be performed in relation to these lesions including biopsy, cerebrospinal fluid diversion, and partial or radical resection, but their role is a source of debate. This study catalogues our surgical experience and patient outcomes in order to support decision-making in this challenging pathology.MethodsA retrospective review of all cases of OPGs treated in a single center from July 1990 to July 2020. Data was collected on patient demographics, radiographic findings, pathology, and management including surgical interventions. Outcome data included survival, visual function, endocrine, and hypothalamic dysfunction.ResultsOne hundred twenty-one patients with OPG were identified, and 50 of these patients underwent a total of 104 surgical procedures. These included biopsy (31), subtotal or gross total resection (20 operations in 17 patients), cyst drainage (17), Ommaya reservoir insertion (9), or cerebrospinal fluid diversion (27). During the study period, there was 6% overall mortality, 18% hypothalamic dysfunction, 20% endocrine dysfunction, and 42% had some cognitive dysfunction. At diagnosis 75% of patients had good or moderate visual function in at least one eye, and overall, this improved to 83% at the end of the study period. In comparison the worst eye had good or moderate visual function in 56%, and this reduced to 53%. Baseline and final visual function were poorer in patients who had a surgical resection, but improvements in vision were still found—particularly in the best eye.Discussion/conclusionOPG are debilitating childhood tumor that have lifelong consequences in terms of visual function and endocrinopathies/hypothalamic dysfunction; this can result in substantial patient morbidity. Decisions regarding management and the role of surgery in this condition are challenging and include cerebrospinal fluid diversion, biopsy, and in highly select cases cystic decompression or surgical resection. In this paper, we review our own experience, outcomes, and surgical philosophy.

RARE-09. PRESERVATION OF ENDOCRINE FUNCTION AFTER OMMAYA RESERVOIR INSERTION IN CHILDREN WITH CYSTIC CRANIOPHARYNGIOMA

INTRODUCTIONChildren with craniopharyngiomas (CP) can be subjected to significant morbidities caused by radical surgery and/or radiation with severe long-term consequences. Ommaya reservoir Insertion (ORI) into cystic CP represents a minimally invasive procedure that aims to preserve endocrine, hypothalamic and neurocognitive function. The purpose of this study was to determine the relevance of upfront ORI (+/- intracystic treatment) for preservation of endocrine function.METHODSA retrospective chart review of children with CP treated at the Hospital for Sick Children between 01/01/2000 and 15/01/2020 was undertaken. Endocrine function was reviewed at the time of initial ORI or surgical resection and throughout the course of follow-up. Event free survival (EFS) was defined as the time to additional surgical resection or irradiation.RESULTSFifty-five patients with sufficient endocrine follow-up data were included. The median age of diagnosis was 8.3 years (range 2.1–18.0 years), 31 were males. ORI was performed as upfront treatment in 30 patients, gross total or partial resection in 24 patients and radiation in 1 patient, respectively. Endocrine function remained stable after ORI with a median EFS of 19.2 (0 – 105.3) months while the majority of patients who underwent surgical resection had documented worsened endocrine function postoperatively (median of 0; range 0 – 29.4 months) (p< 0.001). The event most commonly related to secondary endocrine deterioration was initial or delayed surgical resection.CONCLUSIONSEndocrine function was preserved in patients with upfront ORI (+/- intracystic treatment). Further studies will elucidate the implications of ORI with respect to ophthalmological, vascular and neurocognitive long-term outcome.

Ommaya Reservoir Insertion: A Technical Note.

Ommaya reservoir insertion is an elective neurosurgical procedure to deliver repeated intraventricular therapy, but placement can be complicated by malposition of the catheter, clogging, infection or poor postoperative cosmesis. Here, we describe the technique used by the senior author for accurate placement including preassembly of the reservoir and catheter, and recessing of the reservoir so that others may consider the technique for their practice. Results in a consecutive series of 27 Ommaya placements were reviewed. Catheter tip placement accuracy, complications and surgical times were reported. Indications were leptomeningeal cancer or infection. Postoperative imaging showed the catheter tip was located in the frontal horn (96%) or body (4%) of the ipsilateral lateral ventricle. The median surgical time was 36 minutes (range 17-63 minutes). There were no parenchymal or subarachnoid hemorrhages. Infections occurred in 7% (n=2) of cases, and both infections presented greater than 60 days postoperative. In conclusion, we have found that image guidance can optimize accuracy in placement, that preassembly of the reservoir and catheter may be used with a 25-gauge spinal needle stylet to minimize risk of clogging during placement, and that recessing of the reservoir produces the best aesthetic result.

RARE-17. PRIMARY DIFFUSE LEPTOMENINGEAL GLIOMATOSIS OF HIGH GRADE TUMORS

Abstract Primary diffuse leptomeningeal gliomatosis(PDLG) of high grade glioma(HGG) is a rarely documented phenomenon observed in less than 5% of glioblastoma(GBM). Purposes of this study are to investigate the clinical outcomes of PDLG of HGG and to analyze the results according to the procedures of operations. We retrospectively reviewed the medical records of 469 patients of HGG at our institute between 2004 and 2019 and 9 of who with PDLG were enrolled in our study. These 9 patients satisfying the condition of Karnofsky performance status ≥70 and Eastern Cooperative Oncology Group performance status ≤2 were conducted the primary surgical biopsy with or without intracranial pressure control. All patients finished the surgery within about 11 days after the detection of leptomeningeal seeding(LMS) on preoperative MRI images and completed the concurrent chemoradiotherapy(CCRT) with temozolomide(TMZ). Among 9 patients, 7 patients started adjuvant temozolomide and 3 patients completed the six cycles of it. 7 patients had done ICP control operation such as ommaya reservoir insertion, extraventricular drainage, and ventriculoperitoneal shunt within 23.3 days after defined as PLDG and survived nearly 10 months. Their pathologic findings were turned out to be seven glioblastomas and two anaplastic astrocytomas. Their median overall survival was 14 months and the 1- and 2-year overall survival rates were 50.8±17.7% and 16.9±15%, respectively. Compared to the 10-year study of GBM in the same institute between 2004 and 2011, in which 67 patients finished with CCRT with TMZ, the median overall survival was 19 months and the 1- and 2-year overall survival rates were 78.3% and 41.7%. The results indicate that PLDG has a worse outcome and overall survival rate is lower than GBM without LMS, so the earlier start of standard CCRT right after aggressive control of increased ICP like conducting CSF diversion might be helpful for the elongation of life expectancy.

In Reply to the Letter to the Editor Regarding “Adjunctive Gamma Knife Surgery or Wait and Scan Policy After Optimal Resection of Large Vestibular Schwannomas: Clinical and Radiologic Outcomes”

The use of image guidance (IG) in neurosurgery is ubiquitous, even though evidence from patient outcome data has remained limited to smaller, mostly observational, studies. Ommaya reservoir insertion (ORI) has been available as a treatment option for targeted intraventricular pharmacotherapy since the 1960s, far preceding the modern neuronavigation era. We conducted a systematic review and meta-analysis investigating the impact of IG on surgical outcome from ORI.A systematic database search of MEDLINE and EMBASE was performed to identify studies on operative outcomes from ORI. Only studies reporting patient demographics and perioperative outcomes (hemorrhage, infection, malposition, malfunction, and mortality) were included. Study quality was assessed via MINORS criteria.Of the 3560 records screened, 43 studies met study inclusion criteria, for a total of 1995 ORI procedures. Pooled rates of outcome for IG compared with non-IG were 6.4% versus 14.1% for overall complications; 2.0% compared with 2.8% for catheter malfunction; 2.3% compared with 3.3% for catheter malposition; 0.7% compared with 4.5% for early infection; and 0.6% compared with 1.4% for mortality. Postoperative hemorrhage was increased at 3.4% compared with 2.4%. Subgroup analysis revealed a difference in early infection rate between frameless and frame-based IG at 0.0% versus 1.9%. Meta-regression revealed a relationship between publication date and all operative outcomes except for catheter malposition and hemorrhage.This study offers a historical context on the evolution of the practice of ORI and comprises the largest observational analysis of operative outcomes providing objective support for the use of IG in neurosurgery.

Image-guided Ommaya reservoir insertion for intraventricular chemotherapy: a retrospective series.

Ayub Ommaya proposed a surgical technique for subcutaneous reservoir and pump placement in 1963 to allow access to intraventricular cerebrospinal fluid (CSF). Currently, the most common indication for Ommaya reservoir insertion (ORI) in adults is for patients with hematologic or leptomeningeal disorders requiring repeated injection of chemotherapy into the CSF space. Historically, the intraventricular catheter has been inserted blindly based on anatomical landmarks. The purpose of this study was to examine short-term complication rates with ORI with image guidance (IG) and without image guidance (non-IG). We retrospectively evaluated all operative cases of ORI from 2000 to 2014 by the senior author. Patient demographic data, surgical outcomes, and peri-operative complications were collected. Accurate placement and early (30-day) morbidity or mortality were considered primary outcomes. Fifty-five consecutive patients underwent ORI by the senior author over the study period (43.5 ± 16.6years; 40.0% female). Indications for placement included acute lymphoblastic leukemia, diffuse large B-cell lymphoma, and leptomeningeal carcinomatosis. There were seven (12.7%) total complications: three (37.5%) with no-IG versus four (8.5%) with IG. Catheter malpositions were significantly higher in the non-IG group at 37.5% compared to 2.1%. Catheters were also more likely to require multiple passes with non-IG at 25% compare to 0% with IG. There were no early infections in either group. We demonstrate improved accuracy and decreased complications using an image-guided approach compared with a traditional approach. Our results support routine use of intra-operative image guidance for proximal catheter insertion in elective ORI for intraventricular chemotherapy.

P.092 Ommaya reservoir placement for intraventricular chemotherapy: a retrospective case series in the image-guidance era

Background: In 1963, Ayub Ommaya proposed a surgical technique for placement of a subcutaneous reservoir and pump to allow access to intraventricular cerebrospinal fluid (CSF). Currently, the most common indication for Ommaya reservoir insertion in adults is for patients with hematologic or leptomeningeal disorders who require repeated injection of chemotherapy into the CSF space. Historically, the intraventricular catheter has been inserted blindly based on anatomical landmarks. The purpose of this study was to determine short-term complication rates from Ommaya reservoir placement in the image-guidance era. Methods: We retrospectively evaluated all operative cases of image-guided Ommaya reservoir insertion from 2004-2014 by the senior author (JFM). Patient demographic data and peri-operative complications were collected. Results: We identified 28 patients over the study period (43.3+/-17.3 years; 64.3% male). Indications for placement included acute lymphoblastic leukemia, diffuse large B-cell lymphoma, and leptomeningeal carcinomatosis. There was one asymptomatic peri-operative intracranial hemorrhage (3.6%), and one early infection (3.6%). All catheters were well-positioned and functional. Conclusions: In our retrospective single-centre case series, all catheters were placed accurately. Our results support routine use of intra-operative image guidance for proximal catheter insertion in elective Ommaya reservoir placement for intraventricular chemotherapy.

Spontaneous rupture of congenital hydrocephalous: a rare complication

Hydrocephalous represents a diverse group of conditions that result from impaired circulation and/or absorption of CSF, or in rare circumstances, from increased production of CSF by choroid plexus papilloma. Hydrocephalous could be classified as communicating and non communicating. Hydrocephalous resulting from obstruction within ventricular system is called obstructive or non communicating hydrocephalous whereas that resulting from obliteration of subarachanoid cisterns or malfunction of arachanoid villi is called communicating or non obstructive hydrocephalous. Both forms can be congenital or acquired. The first surgical treatment reported in literature was performed by Hippocrates in 5th century B.C., who punctured the lateral ventricle in a patient with obstructive HC. Several procedures and devices have been developed since then, such as external ventricular drainage, external lumbar drainage, repeated lumbar puncture, Ommaya reservoir insertion, or ventriculosubgaleal diversion, ventriculoperitoneal and ventriculoatrial shunts.In untreated cases, head size may continue to increase. Spontaneous external rupture of hydrocephalous is rare presentation. Very few cases have been reported till date.

Retrospective Analysis of Cerebrospinal Fluid Profiles in 228 Patients with Leptomeningeal Carcinomatosis : Differences According to the Sampling Site, Symptoms, and Systemic Factors.

ObjectiveElevated cell counts and protein levels in cerebrospinal fluid (CSF) result from disease activity in patients with leptomeningeal carcinomatosis (LMC). Previous studies evaluated the use of CSF profiles to monitor a treatment response or predict prognosis. CSF profiles vary, however, according to the sampling site and the patient's systemic condition. We compared lumbar and ventricular CSF profiles collected before intraventricular chemotherapy for LMC and evaluated the association of these profiles with patients' systemic factors and LMC disease activity.MethodsCSF profiles were retrospectively collected from 228 patients who underwent Ommaya reservoir insertion for intraventricular chemotherapy after a diagnosis of LMC. Lumbar samples taken via lumbar puncture were used for the diagnosis, and ventricular samples were obtained later at the time of Ommaya reservoir insertion. LMC disease activity was defined as the presence of LMC-related symptoms such as increased intracranial pressure, hydrocephalus, cranial neuropathy, and cauda equina syndrome.ResultsCell counts (median : 8 vs. 1 cells/mL) and protein levels (median : 68 vs. 17 mg/dL) significantly higher in lumbar CSF than in ventricular CSF (p<0.001). Among the evaluated systemic factors, concomitant brain metastasis and previous radiation were significantly correlated with higher protein levels in the lumbar CSF (p=0.01 and <0.001, respectively). Among the LMC disease activity, patients presenting with hydrocephalus or cauda equina syndrome showed higher lumbar CSF protein level compared with that in patients without those symptoms (p=0.049 and p<0.001, respectively). The lumbar CSF cell count was significantly lower in patients with cranial neuropathy (p=0.046). The ventricular CSF cell counts and protein levels showed no correlation with LMC symptoms. Carcinoembryonic antigen (CEA), which was measured from ventricular CSF after the diagnosis in 109 patients, showed a significant association with the presence of hydrocephalus (p=0.01).ConclusionThe protein level in lumbar CSF indicated the localized disease activity of hydrocephalus and cauda equina syndrome. In the ventricular CSF, only the CEA level reflected the presence of hydrocephalus. We suggest using more specific biomarkers for the evaluation of ventricular CSF to monitor disease activity and treatment response.

Placement of Ommaya reservoir following endoscopic third ventriculostomy in pediatric hydrocephalic patients: a critical reappraisal

Endoscopic third ventriculostomy (ETV) has become standard for obstructive hydrocephalus. Even a successful ETV can obstruct, leading to recurrence of symptoms and even death. A possible solution to this problem is leaving an Ommaya reservoir (OR) following the ETV. OR can be tapped in an emergency and for diagnostic purposes. No specific complications have been attributed to OR in this setting. We present our experience with OR in children undergoing ETV for hydrocephalus. A retrospective study was conducted in hydrocephalic children that underwent ETV with OR insertion over 13years (1997-2010) from a single institution. Data were collected from charts and follow-ups. Twelve patients (from 200 patients who had an ETV) underwent placement of OR with ETV. OR was reserved for a subgroup of patients in whom we anticipated complications-in children that presented with acute hydrocephalus and were in deteriorating condition, for pathologies believed to have a low predicted ETV success rate, or when the surgeon felt that the ETV procedure was suboptimal. OR was tapped in eight patients. Complications occurred in four patients: two cases of subdural effusion, one case of chronic subdural hematoma, and one CSF leak. Four ORs were removed due to complications, and four were converted to shunts. OR should be considered in selected patients undergoing ETV. Despite its obvious advantages, OR may be associated with a relatively high risk of extraaxial fluid collections. This association requires further investigation.

Modified stereotactic insertion of the Ommaya reservoir. Technical note.

Ommaya reservoirs are used primarily for the repeated injection of intrathecal chemotherapy for leptomeningeal metastasis from hematopoietic and solid malignancies. Insertion of this device in a relatively large nondisplaced ventricle is not a difficult task, but challenges arise when the ventricle is small and/or displaced. Different techniques have been developed to overcome this difficulty, most of which include the use of stereotactic frames. Further improvements would be beneficial. The technique described in this paper depends on a stereotactic frame; however, the modification proposed by the authors removes the arc system from the surgical field before the actual surgical procedure is begun. Removal of the arc improves access to the surgical field as well as preparation and draping of the surgical site and minimizes potential breaks in sterile technique, which ultimately reduces the incidence of infection. A twist-drill hole along the path of the chosen trajectory becomes an external guide for the ventricular catheter. The technique is easy, user friendly, and results in an unencumbered sterile field and reliable cannulation of small ventricles. A simple stereotactic technique for Ommaya reservoir insertion has been described. It should lower the chance of infection in this group of patients, most of whom have suppressed immune systems.

Permanent 125iodine implants for recurrent malignant gliomas

Purpose: To determine the efficacy and toxicity of permanent 125iodine implants for recurrent malignant gliomas.Methods and Materials: Between January 1989 and January:, 59 patients with histologically confirmed recurrent malignant gliomas (22 nonglioblastoma malignant gliomas, 37 glioblastoma multiforme at the time of implant) received a permanent 125iodine implant. Patients ranged in age from 13–74 years. The median ages for the overall group, nonglioblastoma (nonGBM), and glioblastoma (GBM) groups was 47 years, 39 years, and 53 years, respectively.Results: With a median follow-up of 40 months, the median survival for the 59 total patients is 1.34 years; nonGBM 2.04 years, GBM 0.9 years. Factors predictive for poor prognosis were GBM histology, age 60 years or more, target volume 17 cc or more, and/or tumor location within the corpus callosum or thalamus. Reoperations have been performed in 24 (40%) patients; 15 (25%) for tumor progression; 3 (5%) for radiation necrosis; 2 (3%) for skull necrosis/infection, and 4 (7%) for other reasons (Ommaya reservoir insertion, catheter removal, hematoma evacuation).Conclusion: Permanent 125iodine implants in selected patients with recurrent malignant gliomas are associated with reasonable long-term survival and a low risk of complications. Given the low incidence of radiation necrosis, future plans are to increase dose rate and/or total dose delivered with the permanent implant.

Reversible porencephaly

The cases of four infants (five lesions) are reported, where "porencephalic cysts," located along the ventricular catheter after shunt malfunction and Ommaya reservoir insertion, disappeared after ventriculoperitoneal (VP) shunt revision and combined cyst peritoneal (CP) shunt, or after VP shunt alone. This pathological state is thought to be a rare postoperative complication. Its pathogenesis and therapy are discussed. Shunt malfunction or Ommaya reservoir insertion may result in a hypertensive hydrocephalic state. Cerebrospinal fluid (CSF) flows out through a catheter penetrating the site of the ventricular wall and expands in the surrounding white matter to form a porencephalic cavity. Once this porencephalic state occurs, it will not disappear spontaneously because the CSF flows in one direction. As treatment for closed porencephaly, CP shunt following a VP shunt revision was markedly effective; for communicating porencephaly, a VP shunt revision alone was effective.

Ommaya reservoir insertion guided by computed tomography

The placement of a ventricular catheter in patients with small ventricles carries the risks of catheter malfunction and bleeding. We report the use of computed tomography (CT) to place an Ommaya reservoir in two patients with acute myelogenous leukemia and one patient with lymphoma who had normal to small ventricles. The entire procedure was carried out in the scanner and demonstrates the feasibility of operations performed in the CT scanner. (Neurosurgery 9: 559-561, 1981)