Long-term access to cystic brain stem lesions using the Ommaya reservoir: technical case report

Treatment of Pediatric Low-Grade Gliomas

PURPOSE OF REVIEW

Pediatric low-grade gliomas and glioneuronal tumors (pLGG) account for approximately 30% of pediatric CNS neoplasms, encompassing a heterogeneous group of tumors of primarily glial or mixed neuronal-glial histology. This article reviews the treatment of pLGG with emphasis on an individualized approach incorporating multidisciplinary input from surgery, radiation oncology, neuroradiology, neuropathology, and pediatric oncology to carefully weigh the risks and benefits of specific interventions against tumor-related morbidity. Complete surgical resection can be curative for cerebellar and hemispheric lesions, while use of radiotherapy is restricted to older patients or those refractory to medical therapy. Chemotherapy remains the preferred first-line therapy for adjuvant treatment of the majority of recurrent or progressive pLGG.

RECENT FINDINGS

Technologic advances offer the potential to limit volume of normal brain exposed to low doses of radiation when treating pLGG with either conformal photon or proton RT. Recent neurosurgical techniques such as laser interstitial thermal therapy offer a "dual" diagnostic and therapeutic treatment modality for pLGG in specific surgically inaccessible anatomical locations. The emergence of novel molecular diagnostic tools has enabled scientific discoveries elucidating driver alterations in mitogen-activated protein kinase (MAPK) pathway components and enhanced our understanding of the natural history (oncogenic senescence). Molecular characterization strongly supplements the clinical risk stratification (age, extent of resection, histological grade) to improve diagnostic precision and accuracy, prognostication, and can lead to the identification of patients who stand to benefit from precision medicine treatment approaches. The success of molecular targeted therapy (BRAF inhibitors and/or MEK inhibitors) in the recurrent setting has led to a gradual and yet significant paradigm shift in the treatment of pLGG. Ongoing randomized trials comparing targeted therapy to standard of care chemotherapy are anticipated to further inform the approach to upfront management of pLGG patients.

Safety profile of long-term intraventricular access devices in pediatric patients receiving radioimmunotherapy for central nervous system malignancies

BACKGROUND

The use of Ommaya catheters or ventriculoperitoneal shunts with programmable valves (pVP-shunts) for intraventricular drug administration is increasingly more common.

PROCEDURE

We reviewed the safety and complication rate associated with ventricular access devices in patients receiving compartmental intraventricular radioimmunotherapy (cRIT).

RESULTS

One hundred fifty one patients with recurrent primary or metastatic central nervous system (CNS) tumors (1-34 years) had a ventricular access device (143 Ommaya reservoirs, 8 VP shunts with programmable valves) placed for drug administration and cerebrospinal fluid acquisition. Patients received 2-5 serial injections (124) I- or (131) I- labeled monoclonal antibody 3F8 or 8H9. For each injection, catheters remained accessed for pharmacokinetic studies up to 48 hours or were individually accessed 3-6×/injection. Thereafter catheters were accessed for periodic routine cytology. Six patients (4%) had complications including three with catheter migration in the newly-placed setting requiring surgical revision. Two patients had pericatheter cyst formation (with cyst formation before radioimmunotherapy administration in one patient) resulting in elective removal and endoscopic cystoventriculostomy in both patients. There were no catheter-related infections, hemorrhages, seizures, focal deficits, or valve malfunctioning. Four patients later required Ommaya conversion to VP shunts because of hydrocephalus secondary to disease progression.

CONCLUSIONS

We report a long-term safety profile of ventricular access devices in patients receiving cRIT. Minimal acute complications are observed despite the frequency of cerebrospinal fluid acquisition; long-term complications are rare. Programmable VP shunts appear to be a safe and effective alternative to Ommaya catheters.

A rare case of ectopic recurrence of a craniopharyngioma diagnosed 17 years after initial presentation

Ectopic recurrence of craniopharyngioma 17 years after initial diagnosis is exceedingly rare in pediatric neuro-oncology. Only 23 cases of ectopic recurrence in children with craniopharyngioma are described in the literature with a median time to recurrence of 3 years. We describe a patient diagnosed at 5 years of age, presenting with neck pain and ataxia 17 years after diagnosis. Her original follow-up care was fragmented and included surveillance imaging for 10 years after surgery and endocrine management of panhypopituitarism. Rare, extremely late relapse of this tumor highlights the importance of extended multidisciplinary follow-up care that includes neuro-oncologists in a late-effects/survivorship program.

Stereotatic implantation of Ommaya reservoir in the management of brain abscesses

We evaluated the effectiveness of computed tomography (CT)-guided stereotatic implantation of Ommaya reservoir in the management of brain abscess. Forty-five patients with brain abscesses were treated with CT-guided stereotatic implantation of Ommaya reservoir and followed up between September 1998 and February 2008. The Glasgow Outcome Scale (GOS) was use to evaluate the effectiveness of the Ommaya Reservoir treatment. The GOS score at 3-months post-operation was 5 for 41 patients (91.1%), 4 for 2 patients (4.4%) and 3 for 2 patients (4.4%), respectively. The results suggest that the CT-guided stereotatic implantation of Ommaya reservoir is a potential technique that can be safely used to treat the brain abscess.

Indigenous customized sponge shunt for a recurrent brainstem cyst

BACKGROUND

Various treatment modalities are available for treatment of cystic lesions of the brainstem. However, cyst refilling and recurrences are very common. This article describes a young boy who presented with an intra-axial brainstem cyst following radiation for a pilocytic astrocytoma.

METHODS

The cyst was decompressed surgically once but it soon refilled. The use of a novel customized synthetic sponge acting as a shunt for the treatment of a cystic brainstem lesion is discussed. The sponge was fashioned like a dumbbell and inserted across the fenestration in the cyst wall.

RESULTS

The dumbbell design made it self-retaining. The characteristics of the sponge permitted continuous capillary drainage, with a low risk of occlusion. There was a dramatic decrease in the cyst size on follow-up scans, with resolution of clinical deficits.

CONCLUSIONS

A customized sponge shunt can serve as an easily available and effective internal shunt for intra-axial craniospinal cysts.

Sustained local drug delivery from a radiopaque implanted reservoir

A new polymeric biomaterial that contains covalently bound iodine, and is therefore radiopaque, was used to construct a sustained local drug-delivery device. A polymeric wall was designed to be porous (i.e., passage of low-molecular-weight molecules across the wall is possible), self-healing, and biocompatible. Once implanted, the sphere cavity can be filled and refilled with a concentrated solution of a (cytostatic) drug, which is subsequently released by slow diffusion into the tissue region surrounding the sphere. This principle of sustained local drug delivery is shown by a series of in vitro experiments on the release of 5-fluorouracil, and in vivo animal experiments, using x-ray fluoroscopic and scintigraphic techniques.

Stereotactic brachytherapy for a cystic metastatic brain tumor in the midbrain. Case report

The authors report a rare case of a cystic metastasis in the midbrain that was successfully treated by brachytherapy following stereotactic biopsy and aspiration of the intratumoral cyst. Stereotactic aspiration of cystic lesions can lead to clinical improvement and brachytherapy prevents cyst recurrence. A 46-year-old man was referred to the authors' institution with a 2-month history of a left hemisensory disturbance and a 1-month history of progressive hemiparesis. Magnetic resonance (MR) imaging revealed a ring-enhancing cystic mass in the midbrain. On the basis of this imaging study, a differential diagnosis that included brainstem abscess, glioma, and metastatic tumor was made. Magnetic resonance imaging-guided stereotactic biopsy and aspiration of the intratumoral cyst were performed, yielding 5 ml of yellowish-white fluid. Histological examination provided a diagnosis of adenocarcinoma. During the surgery, a catheter through which brachytherapy would be delivered was inserted at a predetermined target. The patient's left hemiparesis and sensory disturbance were markedly improved and brachytherapy was begun 2 days postoperatively. Three radioactive isotopes composed of iridium-192 were implanted to irradiate the tumor tissue. The total dose at the tumor periphery was 30 Gy, which was administered over 100 hours. External-beam radiotherapy (20 Gy) was added after completion of the brachytherapy. At discharge from the hospital, the patient was alert and all his neurological symptoms had resolved. Follow-up MR imaging revealed stabilization of the cyst and no recurrence of the tumor. The patient is alive and well 18 months following the brachytherapy. This case suggests that brachytherapy can delay cyst recurrence, suppress tumor growth, and prolong survival in patients with cystic brainstem metastasis.