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David W. Roberts

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Robert Elliott and David H. Harter

Rhombencephalosynapsis (RES) is a rare congenital malformation of the cerebellum characterized by hypogenesis or agenesis of the vermis and fusion of the cerebellar hemispheres with or without fusion of the dentate nuclei and superior cerebellar peduncles. No genetic or chromosomal abnormalities have been identified for RES. Although the occurrence of RES is presumed to be sporadic, no clear pattern of inheritance has been identified. The authors report on a 17-year-old girl with autosomal dominant polycystic kidney disease Type 1 as well as RES.

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S. Scott Lollis and David W. Roberts

Object

Robotic applications hold great promise for improving clinical outcomes and reducing complications of surgery. To date, however, there have been few widespread applications of robotic technology in neurosurgery. The authors hypothesized that image-guided robotic placement of a ventriculostomy catheter is safe, highly accurate, and highly reproducible.

Methods

Sixteen patients requiring catheter ventriculostomy for ventriculoperitoneal (VP) shunt or reservoir placement were included in this retrospective study. All patients underwent image-guided robotic placement of a ventricular catheter, using a preoperatively defined trajectory.

Results

All catheters were placed successfully in a single pass. There were no catheter-related hemorrhages and no injuries to adjacent neural structures. The mean distance of the catheter tip from the target was 1.5 mm. The mean operative times were 112 minutes for VP shunt placement and 42.3 minutes for reservoir placement. The mean operative times decreased over the course of the study by 49% for VP shunts and by 19% for reservoir placement.

Conclusions

The robotic placement of a ventriculostomy catheter using a preplanned trajectory is safe, highly accurate, and highly reliable. This makes single-pass ventriculostomy possible in all patients, even in those with very small ventricles, and may permit catheter-based therapies in patients who would otherwise be deemed poor surgical candidates because of ventricle size. Robotic placement also permits careful preoperative study and optimization of the catheter trajectory, which may help minimize the risks to bridging veins and sulcal vessels.

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David G. Storrs and Robert B. King

✓ Five cases of congenital extracranial arteriovenous malformations are reported. The need for careful preoperative definition of all feeding vessels by selective arteriography is stressed. The radiographic phenomenon of “washout” may preclude the recognition of some arterial feeders at the time of the initial contrast studies. The surgical management of these patients using repeated selective angiography, embolization, and ligation of the major arterial supply, followed by total excision of the malformation, is described.

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Robert Cavaliere and David Schiff

✓Cerebral metastases remain a common complication among patients with cancer. Surgery and radiotherapy remain the principal therapeutic interventions. In contrast, the benefit of chemotherapy has long been viewed with skepticism. Nonetheless, as survival in cancer patients improves and the incidence of cerebral metastases increases, so does the demand for effective therapies. It is now recognized that the blood–brain barrier within metastases is permeable and thus allows entry of otherwise excluded drugs. Limited data have suggested that cerebral metastases have modest sensitivity to chemotherapy. Furthermore, novel agents and delivery strategies have been developed to facilitate central nervous system penetration. Nonetheless, data are limited by methodological flaws, including heterogeneous inclusion criteria, small sample sizes, lack of randomization, and inconsistencies in defined end points and response assessment criteria. Well-designed clinical trials are needed to address the effect of chemotherapy. Acceptable control arms must be established to measure the effect of chemotherapies. Standardized response criteria and disease-specific studies are essential.

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Robert J. Spinner, Robert L. Tiel and David G. Kline

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Robert E. Harbaugh, David W. Roberts and Jonathan D. Fratkin

✓ A 44-year-old woman presented with intraventricular hemorrhage and a calcified avascular mass lesion in the anterior third ventricle. This lesion proved to be a densely calcified variant of cavernous hemangioma, namely, hemangioma calcificans. Twelve previous cases of this lesion have been reported in the neurosurgical literature. Association with spontaneous intraventricular hemorrhage has not been previously reported. The clinical presentation, radiological appearance, surgical findings, and histopathology of this lesion are discussed and a brief review of the literature is presented.

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Surgery for acoustic neurinoma

An analysis of 100 translabyrinthine operations

David G. Hardy, Robert Macfarlane, David Baguley and David A. Moffat

✓ A consecutive series of 100 translabyrinthine operations for removal of acoustic neurinoma is reported. Complete tumor removal was achieved in 97% of cases. There were three perioperative deaths, and the postoperative morbidity rate was low. The facial nerve was preserved anatomically in 82% of patients. Preoperative facial weakness and tumor size larger than 2.5 cm were predictive of poor facial recovery. In patients with an intact nerve but complete facial palsy 1 week after surgery, electroneuronography was a good predictor of the final facial outcome and may influence the timing of rehabilitative procedures. With the exception of patients who have small tumors and good speech discrimination (where a suboccipital approach may preserve hearing acuity), the translabyrinthine operation is the procedure of choice for removal of acoustic neurinomas in patients who have normal hearing in the contralateral ear.

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Robert D. Brown Jr., David O. Wiebers and Douglas A. Nichols

✓ This long-term follow-up study of 54 patients clarifies the angiographic predictors of intracranial hemorrhage (ICH) and clinical outcome in individuals with unoperated intracranial dural arteriovenous fistulae (AVF's). All of these patients were examined at the Mayo Clinic between 1976 and 1989, and all available cerebral arteriograms were reviewed by a neuroradiologist. Follow-up information was obtained for 52 patients (96%) until death or treatment intervention, or for at least 1 year after diagnosis, with a mean follow-up period of 6.6 years.

Throughout this 6.6-year follow-up period, ICH related to dural AVF occurred in five of the 52 patients, for a crude risk of hemorrhage of 1.6% per year. The risk of hemorrhage at the time of mean follow-up examination was 1.8% per year. Angiographic examination revealed several characteristics that were considered potential predictors of ICH during the follow-up period. Lesions of the petrosal sinus and straight sinus had a higher propensity to bleed, although the small numbers in the series precluded a definite conclusion. A person suffering from a dural AVF with a venous varix on a draining vein had an increased risk of hemorrhage, whereas no hemorrhage was seen in the 20 patients without a varix (p < 0.05). Lesions draining into leptomeningeal veins had an increased occurrence of hemorrhage, although this increased risk was not statistically significant. Patients' initial symptoms were compared to those at follow-up evaluation. Pulsatile tinnitus improved in more than half of the 52 patients, and resolved in 75% of those showing some improvement. Individuals without a sinus or venous outflow occlusion at initial cerebral angiography were more likely to improve or remain stable (89%), whereas patients with an occlusion showed infrequent improvement (11%; p < 0.05).