Overall Survival Prediction in Stereotactic Radiosurgery Patients with Glioblastoma Via a Deep-Learning Approach

PURPOSE/OBJECTIVE(S)

Accurate and automated early survival prediction is critical for glioblastoma (GBM) patients as their poor prognosis requires timely treatment decision-making. We have developed a deep learning (DL)-based GBM overall survival (OS) prediction model based on a multi-institutional public dataset using only pre-operative basic structural multi-parametric magnetic resonance images (MRIs). The purpose of this study is to evaluate this DL-based OS prediction model with an institutional stereotactic radiosurgery (SRS) clinical trial dataset.

MATERIALS/METHODS

The task of this study is to classify GBM patients into 3 OS classes: long-survivors (>15 months), mid-survivors (between 10 and 15 months) and short-survivors (< 10 months). The proposed OS prediction model is an ensemble of a ResNet-based classifier and a K-NN classifier. The ResNet-based classifier is trained in a Siamese fashion to explore inter-class differences. During testing, training sample features are implemented with a K-NN classifier to ensemble with the ResNet-based classifier. A public dataset from Medical Image Computing and Computer Assisted Intervention (MICCAI) Brain Tumor Segmentation (BraTS) challenge 2020 (235 patients) were used for model establishing and initial validation. Then the validated model was evaluated on 19 GBM patients from an institutional SRS clinical trial. Each data entry consists of pre-operative basic structural multi-parametric MRIs and survival days, as well as patient ages for BraTS data and basic clinical characteristics for institutional data. GBM sub-regions, including contrast-enhancing tumor, peri-tumoral edema, and necrotic/non-enhancing tumor core, were segmented in the multi-parametric MRIs by an in-house DL model for both datasets. The OS prediction model was trained on 90% of the segmented BraTS data and validated on the rest 10%, then further evaluated on the institutional data. The model performance was assessed by prediction accuracy (ACC) and the area under the curve (AUC).

RESULTS

For this 3-class OS classification task, our DL-based prediction model achieved an ACC of 65.22% and an AUC of 0.81 on the BraTS dataset compared with the top-ranked result from the BraTS challenge 2020 (Rank 1st: ACC 61.7%), and an ACC of 52.63% and an AUC of 0.69 on the institutional dataset. Further analysis of the institutional dataset found that the predicted OS class had a statistically significant correlation with treatment volume (p = 0.012) and age (p = 0.006), which matches the analysis that the patients' ground truth OS class is statistical significantly correlated with treatment volume (p = 0.045).

CONCLUSION

Our DL-based OS prediction model for GBM using basic structural multi-parametric pre-operative MRIs has demonstrated promising performance in both public and institutional dataset with minimal manual processing requirements. This OS prediction model can be potentially applied to assist timely clinical decision-making.

Role of Fractionation in Local Control of Spinal Metastases Treated with Stereotactic Radiosurgery

PURPOSE/OBJECTIVE(S)

Optimal fractionation of spinal stereotactic radiosurgery (SRS) for spine metastases remains unknown. Retrospective data suggest decreased local failure (LF) with fractionated SRS of brain metastases. We evaluated our institutional outcomes of spinal SRS with the hypothesis that fractionation improves the rate of local failure compared to single-fraction treatment.

MATERIALS/METHODS

This IRB-approved, retrospective analysis included patients with spine metastases treated with spinal SRS between October 2002 and November 2014 with evaluable follow-up imaging and no prior irradiation to the given segment. The exposure of interest was single- or multi-fraction SRS with a primary endpoint of the cumulative incidence of LF with death as a competing risk. We assessed bivariate associations between fractionation and single-fraction equivalent dose (SFED in Gy10) as well as high-risk features, defined as epidural extension (Bilsky Scale), paraspinous extension, and gastrointestinal (GI) vs non-GI primary. We calculated the rates of LF and vertebral body compression fracture (VCF) at 1-year, and assessed LF by fractionation when limited only to courses receiving SFED>18 Gy. We analyzed the association between fractionation and LF using subdistribution hazard ratios (SHR) estimated from competing risks regression with death as a competing risk and adjusting for lesion-specific characteristics as well as SFED to determine contribution of these variables to the estimated effect of fraction number on LF. We calculated relative attenuation for the contribution of SFED to this association, defined as [SHRfractions-SHRfractions+SFED] ÷ [SHRSFED-1].

RESULTS

In 293 patients with 516 spinal segments, lesions treated with single fraction compared to multi-fraction SRS had less epidural (19% vs 36%, p<0.001) and paraspinous (20% vs 35%, p<0.001) extension, more GI histology (17% vs 10%, p = 0.039), received a higher mean SFED (18.3 Gy vs. 16.6 Gy, p<0.001), and had a lower 1-year LF (8% vs 14%, p = 0.02), with no difference in VCF (7% vs. 5%, p = 0.38). After adjusting for high-risk features, single fraction SRS was associated with lower LF (SHR = 0.45, 95% CI 0.24-0.84, p = 0.02). After adjustment for SFED, this association of fractionation was attenuated by 53% and became insignificant (SHR = 0.78, 95% CI 0.44-1.37, p = 0.38). Overall, 1-year LF for SFED>18 Gy was 6% compared to 15% for <18 Gy (p<0.001). When limited to courses with SFED>18 Gy (n = 261), single fraction SRS had no improvement in 1-year LF compared to multi-fraction (6.6% vs 4.6%, p = 0.77).

CONCLUSION

Single fraction SRS was associated with better local control compared to multi-fraction; however, much of this association was attenuated by SFED but not by high-risk features of treated lesions. To clarify the role of fractionation, we have initiated a prospective, randomized trial of single vs. multi-fraction SRS utilizing the same SFED.

Ultrasound detection of insulin-induced lipohypertrophy in Type 1 and Type 2 diabetes

AIMS

To define standard criteria for the detection of lipohypertrophy using ultrasonography and to determine the accuracy of this method.

METHOD

Individuals using insulin therapy for ≥2 years with unknown lipohypertrophy status were enrolled at a diabetes education centre. A team of diabetes educator nurses performed a clinical examination for evidence of lipohypertrophy and a separate team of ultrasonographers examined participants in a blinded fashion.

RESULTS

The echo signature for lipohypertrophy consisted of location in the subcutaneous layer and lesions that were 1) well circumscribed either by hyperechoic foci with defined borders or a nodular shape with a hypoechoic halo, 2) heterogeneous in echotexture compared with surrounding tissue, 3) associated with distortion of surrounding connective tissue with 4) absence of vascularity and 5) absence of capsule. Ultrasonography identified individuals with lipohypertrophy significantly more frequently than inspection or palpation (P<0.0001). Inter-observer agreement was moderate (κ=0.50) and limited by the presence of subclinical lesions in 73% of the participants.

CONCLUSIONS

The ultrasound detection of lipohypertrophy is consistent with clinical examination and is reproducible using a defined echo signature. (ClinicalTrials.gov registration no: NCT02348099).

Ultra-narrow linewidth quantum dot coherent comb lasers with self-injection feedback locking

We have used an external cavity self-injection feedback locking (SIFL) system to simultaneously reduce the optical linewidth of over 39 individual wavelength channels of an InAs/InP quantum dot (QD) coherent comb laser (CCL). Linewidth reduction from a few MHz to less than 200 kHz is observed. Measured phase noise spectra clearly indicate a significant decrease in phase noise in the frequency range above 2 kHz. The RF beating signal between two adjacent channels also shows a substantial reduction in 3-dB linewidth from 10 kHz to 300 Hz with the SIFL system, and a corresponding drop in baseline level (-27 dB to -50 dB).

High performance InAs/InP quantum dot 34.462-GHz C-band coherent comb laser module

We have developed an InAs/InP quantum dot (QD) C-band coherent comb laser (CCL) module with actively stabilized absolute wavelength and power, and channel spacing of 34.462 GHz with ± 100 ppm accuracy. The total output power is up to 46 mW. The integrated average relative intensity noise (RIN) values of the lasing spectrum and a filtered single channel at 1540.19 nm were -165.6 dB/Hz and -130.3 dB/Hz respectively in the frequency range from 10 MHz to 10 GHz. The optical linewidth of the 45 filtered individual channels between 1531.77 nm to 1543.77 nm ranged from 850 kHz to 2.16 MHz. We have also analyzed the noise behaviors of each individual channel.

Patient Outcomes and Cerebral Infarction after Ruptured Anterior Communicating Artery Aneurysm Treatment

BACKGROUND AND PURPOSE

Anterior communicating artery aneurysm rupture and treatment is associated with high rates of dependency, which are more severe after clipping compared with coiling. To determine whether ischemic injury might account for these differences, we characterized cerebral infarction burden, infarction patterns, and patient outcomes after surgical or endovascular treatment of ruptured anterior communicating artery aneurysms.

MATERIALS AND METHODS

We performed a retrospective cohort study of consecutive patients with ruptured anterior communicating artery aneurysms. Patient data and neuroimaging studies were reviewed. A propensity score for outcome measures was calculated to account for the nonrandom assignment to treatment. Primary outcome was the frequency of frontal lobe and striatum ischemic injury. Secondary outcomes were patient mortality and clinical outcome at discharge and at 3 months.

RESULTS

Coiled patients were older (median, 55 versus 50 years; P = .03), presented with a worse clinical status (60% with Hunt and Hess Score >2 versus 34% in clipped patients; P = .02), had a higher modified Fisher grade (P = .01), and were more likely to present with intraventricular hemorrhage (78% versus 56%; P = .03). Ischemic frontal lobe infarction (OR, 2.9; 95% CI, 1.1-8.4; P = .03) and recurrent artery of Heubner infarction (OR, 20.9; 95% CI, 3.5-403.7; P < .001) were more common in clipped patients. Clipped patients were more likely to be functionally dependent at discharge (OR, 3.2; P = .05) compared with coiled patients. Mortality and clinical outcome at 3 months were similar between coiled and clipped patients.

CONCLUSIONS

Frontal lobe and recurrent artery of Heubner infarctions are more common after surgical clipping of ruptured anterior communicating artery aneurysms, and are associated with poorer clinical outcomes at discharge.

Computational Identification of Tumor Anatomic Location Associated with Survival in 2 Large Cohorts of Human Primary Glioblastomas

BACKGROUND AND PURPOSE

Tumor location has been shown to be a significant prognostic factor in patients with glioblastoma. The purpose of this study was to characterize glioblastoma lesions by identifying MR imaging voxel-based tumor location features that are associated with tumor molecular profiles, patient characteristics, and clinical outcomes.

MATERIALS AND METHODS

Preoperative T1 anatomic MR images of 384 patients with glioblastomas were obtained from 2 independent cohorts (n = 253 from the Stanford University Medical Center for training and n = 131 from The Cancer Genome Atlas for validation). An automated computational image-analysis pipeline was developed to determine the anatomic locations of tumor in each patient. Voxel-based differences in tumor location between good (overall survival of >17 months) and poor (overall survival of <11 months) survival groups identified in the training cohort were used to classify patients in The Cancer Genome Atlas cohort into 2 brain-location groups, for which clinical features, messenger RNA expression, and copy number changes were compared to elucidate the biologic basis of tumors located in different brain regions.

RESULTS

Tumors in the right occipitotemporal periventricular white matter were significantly associated with poor survival in both training and test cohorts (both, log-rank P < .05) and had larger tumor volume compared with tumors in other locations. Tumors in the right periatrial location were associated with hypoxia pathway enrichment and PDGFRA amplification, making them potential targets for subgroup-specific therapies.

CONCLUSIONS

Voxel-based location in glioblastoma is associated with patient outcome and may have a potential role for guiding personalized treatment.

Abscess formation in ovarian endometriomas after failure of mifepristone-induced abortion

OBJECTIVE

To report a case of abscess formation in bilateral ovarian endometriomas after failure of mifepristone-induced abortion.

CASE REPORT

A-36-year-old multiparous woman with bilateral ovarian endometriomas conceived spontaneously and received mifepristone to induce an abortion at 35 days' gestation. Fever and lower abdominal pain occurred 28 days after the abortion. The patient then underwent surgical curettage for an incomplete abortion complicated by endometritis. Her symptoms and signs became aggravated, and computed tomography showed a large ovarian abscess. She underwent laparoscopic drainage of the abscess plus the enucleation of the ovarian endometriomas, and received intravenous antibiotic treatment. She resumed menstruation one month later and was doing well at the 11-month follow-up.

CONCLUSION

This case demonstrates the importance of combining antibiotic therapy with mifepristone to induce abortions in women with known ovarian endometriomas.

CT appearances of abdominal tuberculosis

The purpose of this article is to review and illustrate the spectrum of computed tomography (CT) appearances of abdominal tuberculosis. Tuberculosis can affect any organ or tissue in the abdomen, and can be mistaken for other inflammatory or neoplastic conditions. The most common sites of tuberculosis in the abdomen include lymph nodes, genitourinary tract, peritoneal cavity and gastrointestinal tract. The liver, spleen, biliary tract, pancreas and adrenals are rarely affected, but are more likely in HIV-seropositive patients and in miliary tuberculosis. This article should alert the radiologist to consider abdominal tuberculosis in the correct clinical setting to ensure timely diagnosis and enable appropriate treatment.

Esophageal tolerance to high-dose stereotactic ablative radiotherapy

Dose-volume parameters are needed to guide the safe administration of stereotactic ablative radiotherapy (SABR). We report on esophageal tolerance to high-dose hypofractionated radiation in patients treated with SABR. Thirty-one patients with spine or lung tumors received single- or multiple-fraction SABR to targets less than 1 cm from the esophagus. End points evaluated include D(5cc) (minimum dose in Gy to 5 cm(3) of the esophagus receiving the highest dose), D(2cc) , D(1cc) , and D(max) (maximum dose to 0.01 cm(3) ). Multiple-fraction treatments were correlated using the linear quadratic and linear quadratic-linear/universal survival models. Three esophageal toxicity events occurred, including esophagitis (grade 2), tracheoesophageal fistula (grade 4-5), and esophageal perforation (grade 4-5). Chemotherapy was a cofactor in the high-grade events. The median time to development of esophageal toxicity was 4.1 months (range 0.6-6.1 months). Two of the three events occurred below a published D(5cc) threshold, all three were below a D(2cc) threshold, and one was below a D(max) threshold. We report a dosimetric analysis of incidental dose to the esophagus from SABR. High-dose hypofractionated radiotherapy led to a number of high-grade esophageal adverse events, suggesting that conservative parameters to protect the esophagus are necessary when SABR is used, especially in the setting of chemotherapy or prior radiotherapy.

Treatment of cavernous sinus tumors with linear accelerator radiosurgery

Since 1989, 79 patients with benign or malignant cavernous sinus tumors, have been treated at Stanford University with linear accelerator (linac) radiosurgery. Radiosurgery has been used as (1) a planned second-stage procedure for residual tumor following surgery, (2) primary treatment for patients whose medical conditions preclude surgery, (3) palliation of malignant lesions, and (4) definitive treatment for small, well-localized, poorly accessible tumors. Mean patient age was 52 years (range, 18 to 88); there were 28 males and 51 females. Sixty-one patients had benign tumors; 18 had malignant tumors. Mean tumor volume was 6.8 cm(3) (range 0.5 to 22.5 cm(3)) covered with an average of 2.3 isocenter (range, 1 to 5). Radiation dose averaged 17.1 Gy. Mean follow-up was 46 months. Tumor control or shrinkage, or both, varied with pathology. Radiographic tumor improvement was most pronounced in malignant lesions, with greater than 85% showing reduction in tumor size; benign tumors (meningiomas and schwannomas) had a 63% control rate and 37% shrinkage rate, with none enlarging. We concluded that stereotactic radiosurgery is a valuable tool in managing cavernous sinus tumors. There was excellent control and stabilization of benign tumors and palliation of malignant lesions.

Hepatic artery pseudoaneurysms arising from within a hepatocellular carcinoma

We report a case of a 70-year-old man with a large hepatocellular carcinoma (HCC) containing two pseudoaneurysms measuring up to 2 cm in diameter. The pseudoaneurysms and part of the HCC were supplied by branches from the middle colic artery, which arises from the superior mesenteric artery. This complex arterial vasculature was visualised on CT and confirmed with conventional angiography.

Neutral vs positive oral contrast in diagnosing acute appendicitis with contrast-enhanced CT: sensitivity, specificity, reader confidence and interpretation time

OBJECTIVE

The study compared the sensitivity, specificity, confidence and interpretation time of readers of differing experience in diagnosing acute appendicitis with contrast-enhanced CT using neutral vs positive oral contrast agents.

METHODS

Contrast-enhanced CT for right lower quadrant or right flank pain was performed in 200 patients with neutral and 200 with positive oral contrast including 199 with proven acute appendicitis and 201 with other diagnoses. Test set disease prevalence was 50%. Two experienced gastrointestinal radiologists, one fellow and two first-year residents blindly assessed all studies for appendicitis (2000 readings) and assigned confidence scores (1=poor to 4=excellent). Receiver operating characteristic (ROC) curves were generated. Total interpretation time was recorded. Each reader's interpretation with the two agents was compared using standard statistical methods.

RESULTS

Average reader sensitivity was found to be 96% (range 91-99%) with positive and 95% (89-98%) with neutral oral contrast; specificity was 96% (92-98%) and 94% (90-97%). For each reader, no statistically significant difference was found between the two agents (sensitivities p-values >0.6; specificities p-values>0.08), in the area under the ROC curve (range 0.95-0.99) or in average interpretation times. In cases without appendicitis, positive oral contrast demonstrated improved appendix identification (average 90% vs 78%) and higher confidence scores for three readers. Average interpretation times showed no statistically significant differences between the agents.

CONCLUSION

Neutral vs positive oral contrast does not affect the accuracy of contrast-enhanced CT for diagnosing acute appendicitis. Although positive oral contrast might help to identify normal appendices, we continue to use neutral oral contrast given its other potential benefits.

MRI in the diagnosis of incomplete testicular torsion

We present a case of subacute left testicular pain and enlargement. Scrotal Doppler ultrasound revealed an enlarged left testicle with symmetrical intra-testicular colour flow bilaterally. Contrast-enhanced MRI demonstrated incomplete testicular torsion which was verified at surgery. To our knowledge, this is the first report on the use of contrast-enhanced MRI in the diagnosis of incomplete testicular torsion.

Mullerian duct anomalies: from diagnosis to intervention

The purpose of this study was to review the embryology, classification, imaging features and treatment options of Müllerian duct anomalies. The three embryological phases will be described and the appearance of the seven classes of Müllerian duct anomalies will be illustrated using hysterosalpingography, ultrasound and MRI. This exhibit will also review the treatment options, including interventional therapy. The role of imaging is to help detect, classify and guide surgical management. At this time, MRI is the modality of choice because of its high accuracy in detecting and accurately characterising Müllerian duct anomalies. In conclusion, radiologists should be familiar with the imaging features of the seven classes of Müllerian duct anomalies, as the appropriate course of treatment relies upon the correct diagnosis and categorisation of each anomaly.

Neurologic complications of arteriovenous malformation embolization using liquid embolic agents

BACKGROUND AND PURPOSE

Embolization of arteriovenous malformations (AVMs) is commonly used to achieve nidal volume reduction before microsurgical resection or stereotactic radiosurgery. The purpose of this study was to examine the overall neurologic complication rate in patients undergoing AVM embolization and analyze the factors that may determine increased risk.

MATERIALS AND METHODS

We performed a retrospective review of all patients with brain AVMs embolized at 1 center from 1995 through 2005. Demographics, including age, sex, presenting symptoms, and clinical condition, were recorded. Angiographic factors including maximal nidal size, presence of deep venous drainage, and involvement of eloquent cortex were also recorded. For each embolization session, the agent used, number of pedicles embolized, the percentage of nidal obliteration, and any complications were recorded. Complications were classified as the following: none, non-neurologic (mild), transient neurologic deficit, and permanent nondisabling and permanent disabling deficits. The permanent complications were also classified as ischemic or hemorrhagic. Modified Rankin Scale (mRS) scores were collected pre- and postembolization on all patients. Univariate regression analysis of factors associated with the development of any neurologic complication was performed.

RESULTS

Four hundred eighty-nine embolization procedures were performed in 192 patients. There were 6 Spetzler-Martin grade I (3.1%), 26 grade II (13.5%), 71 grade III (37.0%), 57 grade IV (29.7%), and 32 grade V (16.7%) AVMs. Permanent nondisabling complications occurred in 5 patients (2.6%) and permanent disabling complications or deaths occurred in 3 (1.6%). In addition, there were non-neurologic complications in 4 patients (2.1%) and transient neurologic deficits in 22 (11.5%). Five of the 8 permanent complications (2.6% overall) were ischemic, and 3 of 8 (1.6% overall) were hemorrhagic. Of the 178 patients who were mRS 0-2 pre-embolization, 4 (2.3%) were dependent or dead (mRS >2) at follow-up. Univariate analysis of risk factors for permanent neurologic deficits following embolization showed that basal ganglia location was weakly associated with a new postembolization neurologic deficit.

CONCLUSION

Embolization of brain AVMs can be performed with a high degree of technical success and a low rate of permanent neurologic complications.

Postpartum urinary retention after cesarean delivery

OBJECTIVE

To investigate the incidence of postpartum urinary retention (PUR) after cesarean delivery and determine which obstetric factors contribute to this problem.

METHOD

A prospective study recruited 605 pregnant women who had a cesarean delivery. Each patient's postvoid residual bladder volume (PVRBV) was estimated with an ultrasound scan after first micturition. The women were divided into 2 groups: PUR (PVRBV > or =150 mL) and normal. Patients' characteristics, obstetric parameters, and prevalence of lower urinary tract symptoms at 3 months postpartum were compared.

RESULT

The overall incidence of PUR was 24.1%. The incidence of overt and covert PUR was 7.4% and 16.7%, respectively. Morphine-related postoperative analgesia, multiple pregnancy, and low body mass index were significantly associated with PUR. At 3-month follow-up, 5.0% of patients had obstructive voiding symptoms and 9.1% had irritative voiding symptoms.

CONCLUSION

Our results revealed PUR was a common phenomenon in patients who had a cesarean delivery, and morphine-related postoperative analgesia was the main contributing factor.

The use of stereotactic radiotherapy boost to improve local control in patients with locally advanced nasopharyngeal carcinoma (NPC)

6056

Background: To determine the long term outcomes and delayed side effects in patients receiving stereotactic radiotherapy (SRT) as a boost following external beam radiotherapy (EBRT) for locally advanced NPC. Methods: 82 NPC patients received a STR boost after EBRT at our institution between 9/1992 and 5/2006. Nine patients had T1, 31 had T2, 12 had T3, and 30 had T4 tumors (1997 AJCC staging). Sixteen patients had stage II, 20 had stage III, and 46 had stage IV neoplasms. Most patients received 66 Gy of EBRT followed by a single fraction STR boost of 7–15 Gy, delivered 2–6 weeks after EBRT. 70 patients also received cisplatin-based chemotherapy delivered concurrently with and adjuvant to EBRT. Results: At median follow-up of 40.7 months for living patients (range: 6.5 –144.2 months), there was only 1 local failure in a patient with a T4 tumor. At five years, the freedom from local relapse rate was 98%, freedom from nodal relapse was 83%, freedom from distant metastasis was 68%, freedom from any relapse was 67% and overall survival was 69%. Late toxicity included unresolved V2 or V3 numbness in 2, radiation-related retinopathy in 1, carotid aneurysm in 1, and radiographic temporal lobe necrosis in 9 patients, of which 2 were symptomatic with seizures. All but one patient with temporal lobe necrosis had intracranial tumor extension at diagnosis. Conclusions: STR boost after EBRT resulted in excellent local control. However, the incidence of temporal lobe necrosis approached 11% in these patients and higher in patients with intracranial extension. Improved target delineation and dose homogeneity of radiation delivery for both EBRT and STR is important to avoid long-term complications.

No significant financial relationships to disclose.

Spontaneous ureterocolic fistula secondary to calculous pyohydroureteronephrosis

We report a case of ureterocolic fistula secondary to urolithiasis in a 70-year-old female imaged with both CT and an antegrade nephrostogram. The ureterocolic fistula was managed with insertion of an antegrade ureteral stent.

Acute appendicitis within a femoral hernia: multidetector CT findings

We present a case of surgically proved acute appendicitis strangulated in a femoral hernia sac. Multidetector computed tomography with multiplanar reformations was thought to be helpful in evaluating acute appendicitis in a femoral hernia sac. An awareness of computed tomographic findings may avoid a delay in recognition and management of a patient with this unusual condition.

Case report: Renal replacement lipomatosis associated with renal transplantation

We report a case of extensive renal replacement lipomatosis demonstrated by ultrasound (US) and computed tomography (CT) in a 57-year-old woman with a history of two cadaveric renal transplants. One transplant was non-functional due to chronic rejection. The second renal transplant is functioning normally and the renal replacement lipomatosis did not cause mass effect on either of the renal transplants.

Parent vessel occlusion for vertebrobasilar fusiform and dissecting aneurysms

BACKGROUND AND PURPOSE

Previous reports of outcome with permanent vessel occlusion (PVO) for large, giant, or fusiform aneurysms in the posterior circulation have been limited. We undertook this study to evaluate the perioperative (within 30 days) and follow-up outcomes for patients treated with permanent occlusion of the vertebral artery for vertebrobasilar fusiform and dissecting aneurysms.

METHODS

Thirteen consecutive patients were studied. Two groups were defined for the study. Group I patients underwent PVO to achieve complete thrombosis of the aneurysm. Group II patients underwent PVO to reduce flow to the aneurysm where complete thrombosis was not desirable. Modified Rankin scores were obtained at presentation and at follow-up (follow-up range, 1-76 months; mean, 22.0 months).

RESULTS

All group I aneurysms were shown to be thrombosed on the angiograms obtained at the immediate follow-up examinations. Improvement in outcome scores was achieved by all group I patients. Improvement in Rankin scores after endovascular treatment was statistically significant (P =.026). All group II patients had complete occlusion of the vertebral artery; however, continued filling of the fusiform aneurysm was still observed. Four patients in group II died during the follow-up period. Two of these deaths were attributable to the aneurysms. Of the remaining three patients, two experienced clinical worsening and one remained stable.

CONCLUSION

In this series, PVO for chronic fusiform and acute dissecting aneurysms of the vertebrobasilar system proved to be a useful therapeutic endovascular technique. Long-term outcomes suggest that patients with aneurysms involving only one vertebral artery, where complete thrombosis can be achieved, have better clinical outcomes than those who have aneurysms involving the basilar artery or both vertebral arteries, where complete thrombosis cannot achieved by using PVO.

Robotics and radiosurgery--the cyberknife

The Cyberknife is a dedicated image-guided robotic radiosurgical device. While clinical results with intracranial lesions are comparable to frame-based radiosurgical techniques, recent experience demonstrates the potential to broadly expand the scope of radiosurgery to many extracranial sites.

Assessment of low-flow CSF drainage as a treatment for AD: results of a randomized pilot study

OBJECTIVE

This prospective, randomized, controlled study was designed to investigate the safety, feasibility, and preliminary efficacy of long-term CSF drainage via a low-flow ventriculoperitoneal shunt in subjects suffering from AD.

METHODS

Twenty-nine subjects selected for probable AD (National Institute of Neurological and Communicative Diseases and Stroke-Alzheimer's Disease and Related Dementias Association criteria) were screened to exclude normal pressure hydrocephalus or other etiologies of dementia and randomized to treatment (shunt) or no treatment groups. The study endpoint was the comparison of group performance on psychometric testing at quarterly intervals for 1 year. Shunted subjects had CSF withdrawn for MAP-tau and Abeta((1-42)) assays at the same time intervals.

RESULTS

There was no mortality from the surgical procedure, and no patient sustained a subdural hematoma. Five notable postoperative adverse events, which resolved without permanent neurologic deficit, were reported in the shunt group. Group mean Mattis Dementia Rating Scale total scores showed little change over the year in the shunt-treatment group, in contrast to a decline in the control group (p = 0.06). Mini-Mental State Examination mean scores supported a trend in favor of shunt treatment (p = 0.1). There was a concomitant decrease in ventricular CSF concentrations of AD biomarkers MAP-tau and Abeta((1-42)).

CONCLUSIONS

The surgical procedure and the device are reasonably safe. Adverse events were consistent with shunt procedures for hydrocephalus in this older population. The endpoint data show a trend in favor of the treated group. A larger, randomized, double-blinded, controlled, clinical trial is underway.

Increased fetal nuchal fold leading to prenatal diagnosis of ring chromosome 15

We report on the prenatal diagnosis of ring chromosome 15 in a fetus with increased nuchal fold and intrauterine growth restriction (IUGR). A 27-year-old woman gravida 2, para 1 had normal maternal serum screen tests in the early second trimester of the index pregnancy. Fetal nuchal fold thickening up to 8 mm was incidentally found during the routine obstetric ultrasound scan at 20 weeks' gestation. Amniocentesis was undertaken and the fetal karyotype was found to be 46,XY,r(15) on cytogenetic study. Fluorescence in situ hybridization (FISH) using a telomeric probe of chromosome 15 demonstrated a terminal deletion on the q arm of the ring-shaped chromosome 15. This is the first report of a prenatally diagnosed case of ring chromosome 15. Moreover, nuchal fold thickness in the second trimester may have a role in its prenatal diagnosis.

Interphase FISH--assisted second-trimester termination of a trisomy 21 fetus in an IVF-ET twin pregnancy. A case report

BACKGROUND

When confronting a dizygotic pregnancy with one fetus affected with chromosomal aberrations, most couples would opt for selective termination of the affected twin.

CASE

Routine genetic amniocentesis was performed for an in vitro fertilization-embryo transfer twin pregnancy at 18 weeks' gestation due to advanced maternal age. After two weeks, cytogenetic analysis revealed that both twins were male and one was affected with trisomy 21. At that time, ultrasound examination could not tell them apart with certainty. With the aid of interphase fluorescence in situ hybridization (FISH), we had no trouble locating the affected twin and performed feticide successfully with an intracardiac potassium chloride injection. At 37 weeks of gestation, a normal male was delivered along with a macerated trisomy 21 fetus.

CONCLUSION

In a dizygotic twin pregnancy discordant for chromosome aberrations, when ultrasound cannot distinguish the affected twin, performing interphase FISH with an appropriate chromosome probe proves very useful in quickly and accurately locating the chromosomally abnormal twin for selective termination.

The cerebrospinal fluid production rate is reduced in dementia of the Alzheimer's type

OBJECTIVE

To evaluate the production rate of CSF in patients with differing disease states.

METHODS

The authors measured the production rate of CSF in three groups of patients: five patients with PD below age 60 (aged 51 +/- 4 years, mean +/- SD), nine with PD over age 60 (aged 69 +/- 6 years, mean +/- SD), and seven with dementia of the Alzheimer's type (AD) (aged 72 +/- 9 years, mean +/- SD). This method, based on the Masserman technique, employs ventricular rather than a lumbar access to the CSF space. Furthermore, the volume of CSF removed during the procedure is only 3 mL rather than 10 mL.

RESULTS

These measurements indicate that the mean rate of CSF production in patients with PD under age 60 was 0.47 +/- 0.13 mL/minute, in patients with PD aged 60 or older the mean rate was 0.40 +/- 0.12 mL/minute, and in patients with AD the mean rate was 0.20 +/- 0.06 mL/minute.

CONCLUSION

These results indicate that the rate of CSF production in patients with PD is normal, and that the rate of CSF production in patients with AD is markedly reduced.

Image-guided hypo-fractionated stereotactic radiosurgery to spinal lesions

OBJECTIVE

This article demonstrates the technical feasibility of noninvasive treatment of unresectable spinal vascular malformations and primary and metastatic spinal tumors by use of image-guided frameless stereotactic radiosurgery.

METHODS

Stereotactic radiosurgery delivers a high dose of radiation to a tumor volume or vascular malformation in a limited number of fractions and minimizes the dose to adjacent normal structures. Frameless image-guided radiosurgery was developed by coupling an orthogonal pair of x-ray cameras to a dynamically manipulated robot-mounted linear accelerator that guides the therapy beam to treatment sites within the spine or spinal cord, in an outpatient setting, and without the use of frame-based fixation. The system relies on skeletal landmarks or implanted fiducial markers to locate treatment targets. Sixteen patients with spinal lesions (hemangioblastomas, vascular malformations, metastatic carcinomas, schwannomas, a meningioma, and a chordoma) were treated with total treatment doses of 1100 to 2500 cGy in one to five fractions by use of image-guided frameless radiosurgery with the CyberKnife system (Accuray, Inc., Sunnyvale, CA). Thirteen radiosurgery plans were analyzed for compliance with conventional radiation therapy.

RESULTS

Tests demonstrated alignment of the treatment dose with the target volume within +/-1 mm by use of spine fiducials and the CyberKnife treatment planning system. Tumor patients with at least 6 months of follow-up have demonstrated no progression of disease. Radiographic follow-up is pending for the remaining patients. To date, no patients have experienced complications as a result of the procedure.

CONCLUSION

This experience demonstrates the feasibility of image-guided robotic radiosurgery for previously untreatable spinal lesions.

Three-dimensional ultrasonic images of normal fetus

BACKGROUND

The purpose of this study was to assess the usefulness and feasibility of 3-dimensional (3D) ultrasound for routine fetal observation.

METHODS

Eighty-five normal pregnancies with gestational ages of 20-36 weeks were studied. A conventional ultrasound scanner with a specially designed operation unit, frame memory, and 3D probe was the apparatus used in this study. The unit has a circuit board consisting of digital integrated circuit chips designed to make calculations of volume ray tracings for volume rendering in real time. For each fetus, scanning was performed with different levels of opacity in the equation for volume rendering. In areas where there was an inadequate amniotic fluid pocket to perform an adequate examination, the pregnant woman was asked to push the fetus to the opposite side by gently pressing on her abdomen.

RESULTS

Face, limbs, and fingers which are difficult to visualize on conventional ultrasonography could be seen clearly. Extremely satisfactory images were obtained at between 24 and 34 weeks of gestation that produced sonographic pictures easily recognized even by laypersons. Beyond 34 weeks of gestation due to the relative decrease in the size of amniotic fluid pockets, and before 24 weeks of gestation due to frequent fetal movement, the soft tissue of fetuses is thin and its acoustic impedance is virtually the same as that of water, so surface-rendered images are less satisfactory. In addition, the anterior wall placenta, multiple pregnancies, and oligohydramnios made viewing even more difficult.

CONCLUSION

Between 24 and 34 weeks of gestation, 3D ultrasound is a feasible and useful procedure for routine antenatal examination.

Posterior cerebral circulation revascularization

Posterior circulation revascularization has evolved as a method to treat selected patients with vertebrobasilar ischemia who have inaccessible atherosclerotic occlusive disease and who have failed maximal medical therapy. In addition, complex unclippable aneurysms of the posterior circulation are another indication for revascularization of the vertebrobasilar territory. Careful preoperative evaluation and meticulous attention to detail intraoperatively yield good patient outcomes with minimal morbidity and mortality. This article reviews the vascular anatomy of the posterior circulation and the indications, preoperative evaluation, operative techniques, clinical outcomes, and alternative treatments for patients requiring posterior circulation revascularization procedures.

MRI of spinal hardware: comparison of conventional T1-weighted sequence with a new metal artifact reduction sequence

OBJECTIVE

This study was designed to compare diagnostic quality of MR images of patients with spinal hardware acquired using a conventional T1-weighted spin-echo sequence and a new metal artifact reduction sequence (MARS).

CONCLUSION

The new MARS sequence effectively reduces the degree of tissue-obscuring artifact produced by spinal fixation hardware and subjectively improves image quality compared with the conventional T1-weighted spin-echo sequence.

Phenotype II triploid pregnancy and study of the parental origin of the extra set of chromosomes with fluorescence microsatellite analysis: case report

Triploidy can reflect diandry (dispermy or diploid sperm) or digyny(diploid ovum). The former is likely to result in the type I phenotype with a partial mole with an appropriate-for-gestational age fetus rarely surviving beyond 20 weeks and a large, cystic placenta. The latter, however, is characterized by a type II phenotype with severe intrauterine growth retardation (IUGR) with longer in utero survival and a small, non-molar placenta. We report on a 22-year-old woman, gravida 2, para1, in the 31st week of gestation who was referred to our prenatal clinic for evaluation of severe IUGR and oligohydramnios. Late cytogenetic karyotyping from cordocentesis revealed a triploidy of 69, XXX. In the 33rd week of gestation, the mother went through spontaneous labor delivering an IUGR 1180 gm fetus and a small, non-molar placenta. The fetus died immediately and was sent for autopsy. In addition to cleft lip and palate, the infant had pulmonary lobation abnormalities. Fluorescence microsatellite analysis of fetal and parental samples confirmed that the extra set of chromosomes present in the proband was a result of a maternal meiosis I nondisjunction error. This may help study of genomic imprinting on human development.

The Cyberknife: a frameless robotic system for radiosurgery

The Cyberknife is a unique instrument for performing frameless stereotactic radiosurgery. Rather than using rigid immobilization, the Cyberknife relies on an image-to-image correlation algorithm for target localization. Furthermore, the system utilizes a novel, light-weight, high-energy radiation source. The authors describe the technical specifications of the Cyberknife and summarize the initial clinical experience.

Stereotactic radiosurgery and hypofractionated stereotactic radiotherapy for residual or recurrent cranial base and cervical chordomas

Object

In patients with chordomas the lesions often recur. Furthermore, the location of some chordomas within the base of the skull and the cervical spine can prevent complete resection from being achieved. Previous series have shown that stereotactic radiosurgery can be used as a treatment for residual chordomas with good overall results. The authors review their experience in using linear accelerator (LINAC) stereotactic radiosurgery to treat patients with recurrent and/or residual cranial base and cervical chordomas.

Methods

Ten patients with chordomas (eight with cranial base and two with cervical lesions [below C-2]) underwent LINAC stereotactic radiosurgery. The mean patient age was 49 years (range 30–73 years). There were seven men and three women. Three patients had undergone one prior surgery, five had undergone two previous surgeries, and two had undergone three prior operations. The mean radiation dose was 19.4 Gy (range 18–24 Gy), and the maximum intratumoral dose averaged 27 Gy (range 24.1–33.1 Gy). The mean secondary collimator size was 14.4 mm (range 7.5–20 mm). The volume of the tumor treated ranged from 1.1 to 21.5 ml. In five patients a standard frame-based LINAC radiosurgery system was used, whereas in the other five the CyberKnife, a frameless image-guided LINAC radiosurgical system, was used. All patients were available for follow-up review, which averaged 4 years (range 1–9 years). Over the course of follow up, one chordoma (10%) was smaller in size, seven were stable, and two chordomas progressed (one in a patient who underwent reoperation and a second course of stereotactic radiosurgery, and the second in a patient who underwent reoperation alone). There were no new neurological deficits noted following radiosurgery in the eight of 10 patients in whom there was no tumor progression, and no patient developed radiation-induced necrosis.

Conclusions

Stereotactic radiosurgery can be used to treat patients with recurrent or residual chordomas with excellent tumor control rates. Longer follow-up review in larger series is warranted to confirm these findings.

Current status and optimal use of radiosurgery

The field of stereotactic radiosurgery is rapidly advancing as a result of both improvements in radiosurgical equipment and better physician understanding of the clinical applications of stereotactic radiosurgery. This article will review recent developments in the field of radiosurgery, including advances in our understanding of the treatment of brain metastases and arteriovenous malformations, as well as the use of stereotactic radiosurgery as a boost following conventional radiation for nasopharyngeal carcinoma to minimize the rate of local recurrence. In addition, improved understanding of the radiobiology of normal neurologic structures adjacent to tumors undergoing radiosurgery has led to the use of fractionated stereotactic radiosurgery for the treatment of acoustic neuromas and tumors bordering the anterior visual pathways. Finally, a breakthrough in radiosurgery involving the development and use of frameless, image-guided stereotactic radiosurgery has allowed for both dose homogeneity and treatment of intracranial lesions based on nonisocentric treatment algorithms that result in improved target conformality. This same frameless radiosurgical system has also expanded the scope of radiosurgery to include the treatment of extracranial lesions throughout the body.

Treatment of nasopharyngeal carcinoma: stereotactic radiosurgical boost following fractionated radiotherapy

Treatment of patients with nasopharyngeal carcinoma (NPC) using external beam radiation therapy (XRT) alone results in significant local recurrence. To improve local control, stereotactic radiosurgery (SRS) was used to boost radiation to the primary tumor site following XRT in 23 patients with NPC. SRS was delivered utilizing a frame-based linear accelerator as a boost (range 7-15 Gy, median 12 Gy) following XRT (range 64.8- 70 Gy, median 66 Gy). In all 23 patients (100%) receiving SRS following XRT local control was achieved at a mean follow-up of 21 months (range 2-64 months). There have been no complications of treatment caused by SRS. However, 8 patients (35%) have subsequently developed regional or distant metastases. SRS boost following XRT provides excellent local control in NPC and should be considered for patients with skull base involvement.

LINAC radiosurgery for cavernous sinus meningiomas

Radiosurgery is increasingly used to treat unresectable cavernous sinus tumors. Since 1989, 24 patients with cavernous sinus meningiomas have been treated at Stanford University Medical Center with linear accelerator (LINAC) radiosurgery. The mean age of the patients was 47.8 years (range 28-78). The mean volume treated was 6. 83 cm3 (range 0.45-22.45 cm3), covered with an average of 2.3 isocenters (range 1-5). Radiation dose averaged 17.7 Gy (range 14-20 Gy). This group of patients was retrospectively studied by sending clinical questionnaires to both the patient/family and referring physicians, and reviewing clinic charts. In addition, follow-up imaging studies were obtained to measure residual tumor volume. Follow-up averaged 45.6 months (range 19-80). Tumor control (stabilization) following radiosurgery was noted in 15 (63%) and tumor shrinkage in 9 (37%). Seven meningiomas (29%) showed evidence of central tumor necrosis on MRI imaging 1-3 years after radiosurgery. Neurologic status was improved in 10 patients (42%) and unchanged in 12 patients (50%). There was 1 case of symptomatic brain necrosis and 1 case of radiation edema (asymptomatic). All other complications were transient, including 4 cases of trigeminal hypesthesia and 1 case of worsening diplopia. The 2-year actuarial tumor control rate was 100%. Although follow-up is still short, this experience corroborates prior reports that radiosurgery can be used to treat selected small cavernous sinus meningiomas with good to excellent clinical results and minimal morbidity.

Stereotactic radiosurgery in patients with multiple brain metastases

OBJECT

Patients with multiple brain metastases are often treated primarily with fractionated whole-brain radiation therapy (WBRT). In previous reports the authors have shown that patients with four or fewer brain metastases can benefit from stereotactic radiosurgery in addition to fractionated WBRT. In this paper the authors review their experience using linear accelerator stereotactic radiosurgery to treat patients with multiple brain metastases.

METHODS

Fifty-three patients with 149 brain metastases underwent stereotactic radiosurgery. The mean age of patients was 53.1 years (range 20-78 years). There were 23 men and 30 women. The primary tumor location was lung (27 patients), melanoma (10), breast (six), ovary (six), and other (four). All patients harbored at least two metastatic tumors treated with radiosurgery; 27 patients (51%) harbored two lesions, 17 (32%) three lesions, eight (15%) four lesions, and one patient (2%) harbored five lesions. The mean radiation dose administered was 19.6 Gy (range 14-30 Gy), and the mean secondary collimator size was 15.7 mm (range 7.5-40 mm). One hundred thirty-two (89%) of the 149 treated tumors were available for review on magnetic resonance (MR) imaging at 3 months posttreatment. Fifty-two percent were smaller in size, 31% were stable, 9% had increased in size, and 8% had disappeared. New metastatic tumors appeared in 12 (23%) of the 53 patients on MR imaging within 6 months posttreatment. Radiation-induced necrosis occurred at the site of eight (5.4%) of the 149 tumors at 6 months. Seven tumors (4.7%) subsequently required surgical resection for either tumor progression (four cases) or worsening edema from radiation-induced necrosis (three cases). Median actuarial survival was 9.6 months.

CONCLUSIONS

Stereotactic radiosurgery can be used to treat patients with up to four brain metastases with a 91% rate of either decrease or stabilization in tumor size and a low rate of radiation-induced necrosis. In the authors' study only a small number of patients subsequently required surgical resection of a treated lesion.

Current treatment of patients with multiple brain metastases

The management of patients with multiple brain metastases remains a difficult challenge for neurosurgeons. This patient population has a poor prognosis when compared with those harboring a solitary brain metastasis, and historically treatment has generally consisted of administering whole-brain radiotherapy once the diagnosis of multiple brain metastases is made. Resection can be useful in a subset of patients with multiple metastases in whom one or two of the lesions are symptomatic, as this may provide rapid reduction of mass effect and edema. Furthermore, the authors of recent studies have shown that stereotactic radiosurgery can be used in certain patients with multiple brain metastases as part of the treatment regimen. In this review the authors outline the treatment options and indications as well as a management strategy for the treatment of patients with multiple brain metastases.

Acquired cerebral arteriovenous malformation induced by an anaplastic astrocytoma: an interesting case

High grade gliomas foster an environment rich in angiogenic factors that promote neovascularity. We report a case of a cerebral arteriovenous malformation, which developed in the setting of a high grade astrocytoma. The patient presented with complaints of confusion and left hemiparesis. An initial cerebral angiogram was normal. Repeat angiography six weeks later demonstrated an extremely vascular lesion with arteriovenous shunting involving the right thalamus and occipital lobe. Histopathologic evaluation of open biopsy and autopsy specimens demonstrated a high grade astrocytoma in association with an arteriovenous malformation. Immunohistochemical staining with VEGF was diffusely positive. A possible role for the hyperangiogenic environment of a high grade astrocytoma resulting in the development of an arteriovenous malformation is discussed.

Long-term visual recovery after scleral buckling procedure of rhegmatogenous retinal detachment involving the macula

The long-term visual recovery after a scleral buckling procedure for rhegmatogenous retinal detachment involving the macula was investigated retrospectively. The patients had been treated with a segmental or encircling scleral buckle procedure and in this study the follow-up period was between 5 and 11 years. In order to investigate the natural course of functional recovery of the reattached retina, all cases with a history of intraocular surgery or trauma were excluded. In this investigation, 34 patients were selected in which 35 eyes were studied. The best corrected visual acuities between a 6-month and 5-year postoperative period were compared. They were found to be more improved 5 years after surgery than after 6-month by two or more lines in 19 eyes (54%). In these 19 eyes, the visual acuities continued to improve up to 10 years after surgery. Improvement in the long-term postoperative visual acuity was found to correlate with the shorter duration of macular detachment (30 days), zero or mild myopia (-6 diopters) and to a lesser extent, retinal detachment. the visual function of the reattached human retinas may continue to improve over the long term, especially when these beneficial factors are present.

Microsurgical resection of brainstem, thalamic, and basal ganglia angiographically occult vascular malformations

OBJECTIVE

To evaluate the clinical results for patients who underwent resection of angiographically occult vascular malformations (AOVMs) of the brainstem, thalamus, or basal ganglia, successfully resected after it exhibited rebleeding and presented to a pial surface.

METHODS

Between January 1990 and May 1998, 56 patients with 57 deep AOVMs underwent 63 operations, at Stanford University Medical Center, to treat AOVMs of the brainstem (42 AOVMs), thalamus (5 AOVMs), or basal ganglia (10 AOVMs). The surgical approach was suboccipital midline (27 operations), far lateral suboccipital (10 operations), transsylvian (9 operations), interhemispheric transcallosal or infracallosal (8 operations), infratentorial supracerebellar (6 operations), or subtemporal (3 operations). Four patients experienced recurrent bleeding from the same lesion after surgical resection, requiring a second operation. One patient required a planned second operation, using a different approach, to completely resect the lesion, and one patient underwent two surgical procedures to resect two separate brainstem AOVMs. One patient initially underwent exploration but not resection of her AOVM, because it did not present to a pial or ependymal surface. The AOVM was successfully resected after it exhibited rebleeding and presented to a pial surface.

RESULTS

The immediate outcomes after surgery were unchanged for 31 patients (55%), worsened for 16 (29%), and improved for 9 (16%). The long-term outcomes were unchanged for 24 patients (43%), compared with their presenting grade, worse for 3 (5%), and improved for 29 (52%). Patients who had undergone previous radiotherapy or radiosurgery to treat these lesions experienced more difficult postoperative courses, and radiation necrosis was observed for two patients.

CONCLUSION

AOVMs of the brainstem, thalamus, and basal ganglia can be safely removed, with a long-term neurological morbidity rate of only 5% and a complete lesion resection rate of 93% after the initial planned resection. The use of cranial base surgical approaches and intraoperative electrophysiological monitoring contributes to successful clinical outcomes.

The usefulness of electrophysiological monitoring during resection of central nervous system vascular malformations

GOAL

The purpose of this study was to evaluate the usefulness of electrophysiological monitoring during the resection of vascular malformations.

METHODS

Between September 1994 and April 1996, we surgically resected vascular malformations (31 arteriovenous malformations, 22 angiographically occult vascular malformations) from 53 patients (56 procedures) and used intraoperative evoked potential monitoring. Somatosensory evoked potentials (SSEPs) were monitored in 54 procedures (96%), and brain stem auditory evoked potentials (BAEPs) in 17 (30%). The neurological status of the patients was evaluated before and after surgery.

FINDINGS

Five of the 54 patients (9%) monitored with SSEPs had SSEP changes (4 transient, 1 persistent) coinciding with new clinical neurological deficits in 4 patients (all transient). In all 4 patients who had transient SSEP changes, the changes resolved with adjustment or removal of clips on feeding vessels (2 patients) or with elevating mean arterial pressure (MAP) (2 patients). Forty-seven patients (91%) had neither SSEP or neurological examination alterations. One of 17 patients (6%) monitored with BAEPs had neurological and persistent BAEP changes, 15 (88%) had neither BAEP or neurological changes, and 1 (6%) had a neurological change despite no change in BAEP (false negative). The sensitivity of SSEP and BAEP for predicting a new postoperative deficit (transient or prolonged) in this series was 86% (6/7); specificity was 98% (55/56). Clinical outcome was excellent in 41 patients, good in 11 and poor in 1 (no patients died) and was largely related to pretreatment grade.

CONCLUSION

SSEPs and BAEPs predict the likelihood of clinical neurological injury during resection of vascular malformations with high sensitivity and specificity and may prove a useful adjunct in treating these lesions.

Intraoperative electrical stimulation for identification of cranial nerve nuclei

The purpose of this study was to evaluate the feasibility and usefulness of cranial nerve nuclei monitoring during resection of brainstem cavernous malformations. Eleven patients with brainstem cavernous malformations underwent resection of their malformations utilizing cranial nerve nuclei monitoring. Cranial nerves V and VII were monitored by placing electrodes in muscle groups innervated by these nerves and recording manipulation-induced neurotonic discharges and triggered electromyographic (EMG) activity, after electrical stimulation of the corresponding brainstem nuclei. Seven of 11 procedures (64%) with cranial nerve nuclei monitoring were noted to have cranial nerve nuclei activity corresponding to manipulation of the nuclei. The cavernous malformation was completely resected in 5 of 7 cases with cranial nerve nuclei activity and in all 4 cases without activity. In the remaining 2 cases, the cavernous malformation was not resected due to the proximity of the monitored cranial nerve nuclei to the cavernous malformation and to increasing neurotonic activity as the cavernous malformation was approached. None of the 11 patients had new permanent postoperative deficits corresponding to the cranial nerve nuclei monitored; 1 patient had a transient partial facial palsy lasting 2 days. Preliminary results indicate that cranial nerve nuclei monitoring proves useful in preserving neurologic function and reducing surgical morbidity during resection of brainstem cavernous malformations, particularly indicating when lesion resection places these nuclei at risk.

Stereotactic radiosurgical boost following radiotherapy in primary nasopharyngeal carcinoma: impact on local control

PURPOSE

Treatment of patients with nasopharyngeal carcinoma using external beam radiation therapy (EBRT) alone results in significant local recurrence. Although intracavitary brachytherapy can be used as a component of management, it may be inadequate if there is extension of disease to the skull base. To improve local control, stereotactic radiosurgery was used to boost the primary tumor site following fractionated radiotherapy in patients with nasopharyngeal carcinoma.

METHODS AND MATERIALS

Twenty-three consecutive patients were treated with radiosurgery following radiotherapy for nasopharyngeal carcinoma from 10/92 to 5/98. All patients had biopsy confirmation of disease prior to radiation therapy; Stage III disease (1 patient), Stage IV disease (22 patients). Fifteen patients received cisplatinum-based chemotherapy in addition to radiotherapy. Radiosurgery was delivered using a frame-based LINAC as a boost (range 7 to 15 Gy, median 12 Gy) following fractionated radiation therapy (range 64.8 to 70 Gy, median 66 Gy).

RESULTS

All 23 patients (100%) receiving radiosurgery as a boost following fractionated radiation therapy are locally controlled at a mean follow-up of 21 months (range 2 to 64 months). There have been no complications of treatment caused by radiosurgery. However, eight patients (35%) have subsequently developed regional or distant metastases.

CONCLUSIONS

Stereotactic radiosurgical boost following fractionated EBRT provides excellent local control in advanced stage nasopharynx cancer and should be considered for all patients with this disease. The treatment is safe and effective and may be combined with cisplatinum-based chemotherapy.