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John R. W. Kestle, Lothar Resch, Charles H. Tator and Walter Kucharczyk

✓ A case of spinal cord infarction resulting from embolization of fibrocartilaginous intervertebral disc material is presented. Cases from the literature are reviewed and the theories of pathogenesis are discussed. In all reported cases the diagnosis was not made until postmortem examination.

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John R. W. Kestle, Harold J. Hoffman and Antonio R. Mock

✓ The role of radiotherapy in the management of patients with optic pathway glioma is controversial. In a series of patients with optic pathway glioma treated at The Hospital for Sick Children in Toronto, five children were encountered who developed moyamoya phenomenon after radiotherapy. A retrospective review of the medical records was undertaken in order to assess the relationship between optic pathway glioma, neurofibromatosis type 1 (NF1), radiation therapy, and moyamoya disease.

Forty-seven patients with optic pathway glioma were operated on at The Hospital for Sick Children between 1971 and 1990. The moyamoya phenomenon did not occur in any of the 19 patients not receiving radiotherapy. Among the 28 patients who received radiotherapy, five developed moyamoya disease (two of 23 without NF1 and three of five with NF1). There was a statistically significant relationship between radiotherapy and moyamoya disease when the analysis was stratified according to the presence of NF1 (Mantel-Haensel chi-squared test 15.23, p < 0.01). The high incidence of moyamoya disease (three of five cases, or 60%) in patients with NF1 who have undergone radiotherapy suggests a synergistic relationship that should be considered when formulating a treatment plan for NF1 patients with optic pathway glioma.

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R. Loch Macdonald, M. Christopher Wallace and John R. W. Kestle

✓ The postoperative angiograms in 66 patients who underwent craniotomy for clipping of 78 cerebral aneurysms were reviewed. Indications for urgent postoperative angiography included neurological deficit or repeat subarachnoid hemorrhage. Routine postoperative angiograms were carried out in the remaining patients. Postoperative angiograms were reviewed to determine the incidence of unexpected findings such as unclipped aneurysms, residual aneurysms, and unforeseen major vessel occlusions. Logistic regression analysis was used to test if the following were factors that predicted an unexpected finding on postoperative angiography: aneurysm site or size; the intraoperative impression that residual aneurysm was left or a major vessel was occluded; intraoperative aneurysm rupture; opening or needle aspiration of the aneurysm after clipping; or development of a new neurological deficit after surgery. Kappa values were calculated to assess the agreement between some of these clinical factors and unexpected angiographic findings.

Unexpected residual aneurysms were seen in three (4%) of the 78 occlusions. In addition, three aneurysms were completely unclipped (4%); these three patients were returned to the operating room and had their aneurysms successfully obliterated. There were nine unexpected major vessel occlusions (12%); six of these resulted in disabling stroke and two patients died. Of six major arteries considered to be occluded intraoperatively and shown to be occluded by postoperative angiography, two were associated with cerebral infarction. Logistic regression analysis showed that a new postoperative neurological deficit predicted an unforeseen vessel occlusion on postoperative angiography. Factors could not be identified that predicted unexpected residual aneurysm or unclipped aneurysm.

The inability to predict accurately the presence of residual or unclipped aneurysm suggests that all patients should undergo postoperative angiography. Since a new postoperative neurological deficit is one factor predicting unexpected arterial occlusion, intraoperative angiography may be necessary to help reduce the incidence of stroke after aneurysm surgery. With study of more patients or of factors not examined in this series, it may be possible to select cases more accurately for intraoperative or postoperative angiography.

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Douglas Kondziolka, Thomas Lemley, John R. W. Kestle, L. Dade Lunsford, Gerhard H. Fromm and Peter J. Jannetta

✓ To evaluate the reported benefit of ipsilateral single-application ophthalmic anesthetic eyedrops in patients with typical trigeminal neuralgia, a randomized double-blind placebo-controlled trial was performed. Forty-seven patients were randomly assigned to receive two drops of either proparacaine (25 cases) or saline placebo (22 cases). The experimental and placebo groups were equivalent in regard to patient age, distribution of trigeminal neuralgia pain, duration of pain, current medication regimens, and number of prior procedures performed. Pain response was assessed at 3, 10, and 30 days after instillation using two pain rating scales and a measure of pain frequency. Treatment failure was defined in advance as any of the following: a lack of clinical response, the need for an increase in medication, or the need for surgery. No significant difference in outcomes was found between the two groups either when using a verbal pain rating scale (p = 0.24) or when comparing overall pain status (unchanged, improved throughout the study period, or temporarily improved) (p = 0.98). No difference in the frequency of trigeminal neuralgia attacks between the two treatment groups (scaled within five levels of pain frequency) was detected (p = 0.09). During follow-up monitoring, 11 patients in the test drug group and 14 in the placebo group required surgery because of persistent pain (p = 0.24). The results of this study indicate that single-application topical ophthalmic anesthesia reduces neither the severity nor the frequency of pain in comparison to placebo administration. Although a simple and safe treatment, the single application of topical ophthalmic eyedrops provides no short- or long-term benefit to patients with trigeminal neuralgia.

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Paul Steinbok, Bengt Gustavsson, John R. W. Kestle, Ann Reiner and D. Doug Cochrane

✓ At British Columbia's Children's Hospital, the criteria used in selective functional posterior rhizotomy (SFPR) evolved in three distinct phases. In Phase 1 the electrophysiological criteria for abnormality included a low threshold to a single stimulation, a sustained response to 50-Hz stimulation, and spread outside the segmental level being stimulated. In Phase 2 the electrophysiological criteria were unchanged, but fewer L3–4 nerve roots were cut. In Phase 3, fewer L3–4 nerve roots were cut, as in Phase 2, but based on the results of posterior nerve root stimulation in nonspastic controls, the only electrophysiological criterion used was contralateral and suprasegmental spread. The present study examined the relationship between the criteria used in each phase and patient outcome.

The records of 77 consecutive children who underwent SFPR and had a minium follow-up period of 1 year were reviewed, comprising 25, 19, and 33 patients in Phases 1, 2, and 3, respectively. Outcome parameters included quantitative assessments of lower-limb spasticity and range of motion, and qualitative assessments of lower-limb function.

In Phase 3, 52% of the nerve roots were cut, compared to 66% in Phases 1 and 2. In all three phases there was a significant decrease in lower-limb spasticity and an increase in range of movement, with the smallest decrease in spasticity in Phase 3. Over 90% of children in each phase improved with respect to lower-limb function, and excluding independent walkers and quadriplegics confined to a wheelchair, improvement in the level of ambulation occurred in 87.5%, 71.4%, and 73.7% of patients, in Phases 1, 2, and 3, respectively.

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Douglas Kondziolka, L. Dade Lunsford and John R. W. Kestle

✓ To determine the natural history of brain cavernous malformations, the authors entered patients referred to their center into a prospective registry between 1987 and 1993. All patients underwent magnetic resonance imaging, which showed the typical appearance of this lesion, and conservative management was recommended in all. Patients or their referring physicians were contacted for follow-up data. The purpose of the study was to define the rate of symptomatic hemorrhage and to determine the outcome in those patients who had suffered seizures.

Follow-up data were available for 122 patients with a mean age at entry of 37 years (range 4–82 years). The malformation was located in the brainstem in 43 cases (35%), the basal ganglia/thalamus in 20 (17%), and a hemispheric area in 59 (48%). Fifty percent of patients had never had a symptomatic hemorrhage, 41% had one bleed, 7% had two, and 2% had three. Seizures were reported in 23% of patients and headaches in 15%. Lesions were solitary in 80% of patients and multiple in 20%. The retrospective annual hemorrhage rate (61 bleeds/4550.6 patient-years of life) was 1.3%.

The mean prospective follow-up period was 34 months. There were nine bleeds during this time, six with new neurological deficits. In patients without a prior bleed, the prospective annual rate of hemorrhage was 0.6%. In contrast, patients with prior hemorrhage had an annual bleed rate of 4.5% (p = 0.028). Patient sex (p = 0.97) or the presence of seizures (p = 0.11), headaches (p = 0.06), or solitary versus multiple lesions (p = 0.15) were not significant predictors of later hemorrhage. There was no difference in the rate of bleeds between brain locations. Four patients with seizures became seizurefree and four patients without seizures later developed seizures; only one patient developed intractable seizures. Fourteen patients (11%) underwent surgery (two after hemorrhage, five with seizures, and seven with progressive deficits), and five had radiosurgery. No patient died in the follow-up period. This study indicates that conservative versus operative management strategies may need to be redefined, especially in patients who present with hemorrhage and who appear to have a significantly increased risk of subsequent rehemorrhage.

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Douglas Kondziolka, L. Dade Lunsford, John C. Flickinger and John R. W. Kestle

✓ The benefits of radiosurgery for cavernous malformations are difficult to assess because of the unclear natural history of this vascular lesion, the inability to image malformation vessels, and the lack of an imaging technique that defines “cure.” The authors selected for radiosurgery 47 patients who harbored a hemorrhagic malformation in a critical intraparenchymal location remote from a pial or ependymal surface. Of these, 44 patients had experienced at least two hemorrhages before radiosurgery. The mean patient age was 39 years; six patients had previously undergone attempted surgical removal. The malformation was located in the pons/midbrain in 24 cases, the medulla in three, the thalamus in nine, the basal ganglia in three, deep in a parietal lobe in four, and deep in a temporal lobe in four. Patients had sustained initial hemorrhages from 0.5 to 12 years prior to radiosurgery (mean 4.12 years). In these patients, who were not typical of the majority of patients with cavernous malformations, there were 109 bleeds before radiosurgery in 193 prior observation-years, for a 56.5% annual hemorrhage rate (including the first hemorrhage), or an annual rate of 32% subsequent to the first hemorrhage.

The mean follow-up period after radiosurgery was 3.6 years (range 0.33–6.4 years). The proportion of patients with hemorrhage after radiosurgery was significantly reduced (p < 0.0001), as was the mean number of hemorrhages per patient (p = 0.00004). In the first 2 years after radiosurgery, there were seven bleeds in 80 observation-years (8.8% annual hemorrhage rate). In the 2- to 6-year interval after radiosurgery, the annual rate decreased to 1.1% (one bleed). After radiosurgery, 12 patients (26%) sustained neurological worsening that correlated with imaging changes. In eight patients these deficits were temporary; two underwent surgical resection and died. Two patients had new permanent deficits (4%). A significant reduction was observed in the hemorrhage rate after radiosurgery in patients who had deep hemorrhagic cavernous malformations, especially after a 2-year latency interval. This evidence provides further support to the belief that radiosurgery is an effective strategy for cavernous malformations, especially when located within the parenchyma of the brainstem or diencephalon.

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Paul Steinbok, D. Douglas Cochrane and John R. W. Kestle

✓ The purpose of this study was to determine the significance of “asymptomatic bacteriological shunt contamination” (ABSC), defined as a positive bacteriological culture found on a ventricular shunt component in the absence of bacteria in the cerebrospinal fluid (CSF) culture and/or clinical evidence of infection.

Of 174 ventriculoperitoneal shunt revisions, 19 cases of ABSC were identified and reviewed retrospectively. In all but one case, no antibiotic medications were instituted because of the positive bacteriological culture. The most common infecting organisms were coagulase-negative staphylococci (seven) and propionibacteria (eight). A comparison of the 19 study cases with the authors' overall shunt experience, as documented in the British Columbia's Children's Hospital shunt database for the time period of the study, lead the authors to suggest that ABSC was not of significance in causing the shunt failure at which contamination was identified and, more importantly, did not increase the risk of future shunt malfunction.

The results of this study indicate that in the absence of clinical evidence of shunt infection or a positive bacteriological culture from CSF, bacteria in a shunt component removed at revision in a child almost always represents a contaminant that may be ignored. Therefore, the authors advise that routine culture of shunt components removed at revision of a shunt is not indicated.

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Paul Steinbok, Stephen Hentschel, D. Douglas Cochrane and John R. W. Kestle

✓ The rationale for obtaining surveillance computerized tomography (CT) scans or magnetic resonance (MR) images in pediatric patients with brain tumors is that early detection of recurrence may result in timely treatment and better outcome. The purpose of this study was to investigate the value of surveillance cranial images in a variety of common pediatric brain tumors managed at a tertiary care pediatric hospital.

A retrospective chart review was performed of children with astrocytoma of the cerebral hemisphere, cerebellum, optic chiasm/hypothalamus, or thalamus; cerebellar or supratentorial high-grade glioma; supratentorial ganglioglioma; posterior fossa or supratentorial primitive neuroectodermal tumor (PNET); and posterior fossa ependymoma. Data were analyzed to determine the frequency with which recurrences were identified on a surveillance image and how the type of image at which recurrence was identified related to outcome.

In 159 children, 17 of 44 recurrences were diagnosed by surveillance imaging. The percentage of recurrences identified by surveillance imaging was 64% for ependymoma, 50% for supratentorial PNET, 43% for optic/hypothalamic astrocytoma, and less than 30% for other tumors. The rate of diagnosis of recurrence per surveillance image varied from 0% to 11.8% for different tumor types. Only for ependymomas did there appear to be an improved outcome when recurrence was identified prior to symptoms.

Our results indicate that, using the protocols outlined in this study, surveillance imaging was not valuable in identifying recurrence of cerebellar astrocytoma or supratentorial ganglioglioma during the study period, but was probably worth-while in identifying recurrence of posterior fossa ependymoma and optic/hypothalamic astrocytoma and, possibly, medulloblastoma. Surveillance protocols could be made more effective by individualizing them for each type of tumor, based on current data on the patterns of recurrence.