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  • By Author: Kulkarni, Abhaya V. x
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Abhaya V. Kulkarni, James M. Drake, Derek C. Armstrong and Peter B. Dirks

Object. The goal of this study was to determine and compare imaging correlates in pediatric patients who underwent successful or failed endoscopic third ventriculostomies (ETVs). To this end, the authors measured ventricular size changes and the presence of cerebrospinal fluid (CSF) flow void in both groups of children following ETV.

Methods. Images obtained in children with hydrocephalus immediately before and at least 30 days after having undergone ETV were reviewed by four independent observers (two blinded and two nonblinded). Each observer independently measured the frontal and occipital horn ratio ([FOR], a reliable and valid measure of ventricular size) and provided a subjective assessment of the presence of a flow void at the ETV site, the degree of periventricular edema, and the amount of CSF over the cerebral hemispheres.

There were 29 children whose mean age was 6.6 years at the time of ETV and who had a mean postoperative follow-up period lasting 1.6 years. Postoperatively, the mean reduction in ventricular size (as measured using the FOR) was 7% (95% confidence interval [CI] 3–11%) in cases that were deemed failures (eight patients) and 16% (95% CI 12–20%) in clinically successful cases (21 patients). This reduction was significantly greater in cases of clinical success compared with those that were deemed failures (p = 0.03, t-test). There were no substantial differences between blinded and nonblinded assessments. Flow void was present in 94% of successes and absent in 75% of failures (p = 0.01, Fisher's exact test). The other subjective assessments were not significantly different between the groups of successes and failures.

Conclusions. Ventricular size appears to be somewhat reduced in both groups of patients who underwent clinically successful and failed ETV; however, the reduction is significantly greater among clinically successful cases. The presence of a flow void also appears to correlate with clinical success and its absence with clinical failure.

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Abhaya V. Kulkarni, Laurence E. Becker, Venita Jay, Derek C. Armstrong and James M. Drake

✓ Primary cerebellar glioblastomas multiforme are exceedingly rare in children. The authors therefore retrospectively characterized the clinical behavior and pathological features of these tumors. A review of the database at the Hospital for Sick Children, Toronto, Canada revealed four patients with cerebellar tumors that displayed significant pleomorphism, hypercellularity, mitoses, and necrosis with pseudopalisading. The authors performed a detailed clinical, radiological, histological, and immunohistochemical analysis of the tumors in these four children (three boys and one girl; average age at presentation 7 years; range 21 months–15 years). Magnetic resonance imaging and computerized tomography most commonly revealed a large lesion with minimal edema, inhomogeneous contrast enhancement, and a discrete border. Tumor resection was subtotal in one patient and gross total in three patients. Immunostaining of the tumor cells with antisera to glial fibrillary acidic protein and vimentin was positive in varying degrees. Initial adjuvant therapy consisted of local radiation only (one patient), chemotherapy only (one patient), and radiation and chemotherapy (one patient). One patient received no adjuvant therapy. Tumor recurrence was documented in all patients: two local recurrences (at 3.5 and 7 months), one spinal recurrence (at 14 months), and one local recurrence with ventricular and spinal spread (at 8 months). Ultimately, three of the four patients developed leptomeningeal tumor spread. Patient follow up ranged from 8 to 17 months (mean 12.5 months). Three patients were dead at last follow up with a mean survival of 15 months.

The prognosis for patients with cerebellar glioblastomas is extremely poor, and the tumor has a tendency for cerebrospinal fluid dissemination. The optimal management of patients harboring of these difficult-to-treat tumors, including the role of craniospinal radiation and chemotherapy, has not yet been achieved.

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Paul D. Chumas, Derek C. Armstrong, James M. Drake, Abhaya V. Kulkarni, Harold J. Hoffman, Robin P. Humphreys, James T. Rutka and E. Bruce Hendrick

✓ Although the development of tonsillar herniation (acquired Chiari malformation) in association with lumboperitoneal (LP) shunting is well recognized, it has previously been considered rare. In order to ascertain the incidence of this complication after LP shunting, the authors undertook a retrospective study of all patients in whom this form of shunt had been inserted between 1974 and 1991 at The Hospital for Sick Children, Toronto. In the 143 patients, the mean age at insertion was 3.3 years and the indications for shunt placement were hydrocephalus (81%), pseudotumor cerebri (7%), cerebrospinal fluid fistula (6%), and posterior fossa pseudomeningocele (6%). The mean follow-up period was 5.7 years, during which time there was one shunt-related death due to unsuspected tonsillar herniation. Five other patients developed symptomatic tonsillar herniation treated by suboccipital decompression.

Review of all computerized tomography (CT) scans not degraded by artifact showed evidence of excess soft tissue at the level of the foramen magnum in 38 (70%) of 54 patients so studied. In order to confirm that this CT finding represented hindbrain herniation, sagittal and axial magnetic resonance (MR) images were obtained for 17 asymptomatic patients and revealed tonsillar herniation (range 2 to 21 mm) in 12 (70.6%). In addition, some of these asymptomatic patients had evidence of uncal herniation and mesencephalic distortion. Similarities and distinctions are drawn between the morphological changes occurring after LP shunting and those seen in association with the Chiari I and II malformations. Although less than 5% of this study population required treatment for tonsillar herniation, the incidence of this complication was high in asymptomatic patients; MR imaging surveillance for patients with LP shunts is therefore recommended.