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Biomedical subjects

S D Chang

Publications and source records attributed to S D Chang.

At least 55 records · Page 3Linked to original sources
PubMed1998

Treatment of hemangioblastomas in von Hippel-Lindau disease with linear accelerator-based radiosurgery.

OBJECTIVE: Stereotactic radiosurgery is increasingly being used to treat hemangioblastomas, particularly those that are in surgically inaccessible locations or that are multiple, as is common in von Hippel-Lindau disease. The purpose of this study was to retrospectively evaluate the effectiveness of radiosurgery in the treatment of hemangioblastomas. METHODS: From 1989 to 1996, 29 hemangioblastomas in 13 patients with von Hippel-Lindau disease were treated with linear accelerator-based radiosurgery. The mean patient age was 40 years (range, 31-57 yr). The radiation dose to the tumor periphery averaged 23.2 Gy (range, 18-40 Gy). The mean tumor volume was 1.6 cm3 (range, 0.07-65.4 cm3). Tumor response was evaluated in serial, contrast-enhanced, computed tomographic and magnetic resonance imaging scans. The mean follow-up period was 43 months (range, 11-84 mo). RESULTS: Only one (3%) of the treated hemangioblastomas progressed. Five tumors (17%) disappeared, 16 (55%) regressed, and 7 (24%) remained unchanged in size. Five of nine patients with symptoms referable to treated hemangioblastomas experienced symptomatic improvement. During the follow-up period, one patient died as a result of progression of untreated hemangioblastomas in the cervical spine. Three patients developed radiation necrosis, two of whom were symptomatic. CONCLUSION: Although follow-up monitoring is limited, stereotactic radiosurgery provides a high likelihood of local control of hemangioblastomas and is an attractive alternative to multiple surgical procedures for patients with von Hippel-Lindau disease.

Adult↗
PubMed1998

Stereotactic radiosurgery of angiographically occult vascular malformations: 14-year experience.

OBJECTIVE: Radiosurgery is generally effective in obliterating true arteriovenous malformations, but less is known about its effects on angiographically occult vascular malformations (AOVMs). Since July 1983, 57 patients with surgically inaccessible AOVMs of the brain were treated using helium ion (47 patients) or linear accelerator (10 patients) radiosurgery. This study retrospectively evaluates the response of these AOVMs to treatment. METHODS: All patients presented with previous hemorrhage. The mean patient age was 35.6 years (range, 13-71 yr). The mean AOVM volume was 2.25 cm3 (range, 0.080-15.2 cm3), treated with a mean of 18.0 Gy equivalent (physical dose x relative biological effectiveness, which is 1.3 for helium ion Bragg peak) (range, 7.0-40 Gy equivalent). The Drake scale scores before treatment were as follows: excellent (25 patients), good (26 patients), and poor (6 patients). The mean follow-up period was 7.5 years (range, 9 mo-13.8 yr). RESULTS: Eighteen patients (32%) bled symptomatically (20 hemorrhages) after radiosurgery. Sixteen hemorrhages occurred within 36 months after radiosurgery (9.4% annual bleed rate; 16 hemorrhages/171 patient yr); 4 hemorrhages occurred more than 36 months after treatment (1.6% annual bleed rate; 4 hemorrhages/257 patient yr) (P < 0.001). Complications included symptomatic radiation edema (four patients, 7%), necrosis (one patient, 2%), and increased seizure frequency (one patient, 2%). Eight patients underwent surgical resection of their AOVMs 8 to 59 months after radiosurgery because of subsequent hemorrhage. The Drake scale scores after treatment were as follows: excellent (25 patients), good (24 patients), poor (3 patients), and dead (5 patients, 3 of whom died as a result of causes unrelated to the AOVMs or radiosurgery). CONCLUSION: Radiosurgery may be useful for AOVMs located in surgically inaccessible regions of the brain. A significant decrease in bleed rate exists more than 3 years after treatment compared with the bleed rate within 3 years of treatment. Because current neuroradiological techniques are not able to image obliterative response in these slow-flow vascular lesions, longer term clinical follow-up is required.

Adolescent↗
PubMed1998

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.

Adult↗
PubMed1998

Management of intracranial aneurysms.

Intracranial aneurysms are lesions commonly encountered by neurosurgeons, usually as a result of subarachnoid hemorrhage. The preferred treatment of these aneurysms is either surgical clipping or endovascular coiling, both of which eliminate the aneurysm from the normal circulation to prevent aneurysmal enlargement or additional hemorrhage. Despite advances over the last several decades in the understanding of intracranial aneurysms, morbidity from treatment of these lesions remains significant. This review will discuss the epidemiology, anatomy and pathophysiology, clinical and radiographic diagnosis, various treatment options, and potential complications from aneurysm treatment.

Embolization, Therapeutic↗
PubMed1998

Clinical experience with image-guided robotic radiosurgery (the Cyberknife) in the treatment of brain and spinal cord tumors.

The Cyberknife is an image-guided "frameless" dedicated radiosurgical device. This instrument has several distinct advantages over frame-based systems, including improved patient comfort, increased treatment degrees of freedom, and the potential to target extracranial lesions. Clinical results thus far with respect to the treatment of malignant intracranial tumors has been promising. Additionally, the Cyberknife will likely revolutionize the application of radiosurgery to extracranial sites. A description of the components, treatment planning, and clinical results of the Cyberknife will be reviewed.

Arteriovenous Malformations↗
PubMed1998

Microsurgical resection of incompletely obliterated intracranial arteriovenous malformations following stereotactic radiosurgery.

Radiosurgery is effective in obliterating small arteriovenous malformations (AVMs), but less successful in thrombosing larger AVMs. This study reviewed patients who underwent surgical resection of their large AVMs following failed radiosurgical obliteration. AVMs from 36 patients (aged 7 to 64 years, mean 29.9) were surgically resected 1 to 11 years after radiosurgery. Initial AVM volumes were 0.7 to 117 cm3 (mean 21.6 cm3), and radiosurgical doses ranged from 4.6 to 45 Gray equivalent (GyE) (mean 21.1 GyE). Thirty AVMs (83%) were located in eloquent tissue. Venous drainage was deep (14), superficial (13), or both (9). Spetzler grades were II (2), III (12), IV (18), and V (4). Nine patients suffered rehemorrhage after radiosurgery but prior to surgery, while three patients developed radiation necrosis. Twenty-seven patients underwent endovascular embolization prior to surgery. During microsurgical resection, the AVMs were found to be significantly less vascular and more easily resected, compared to AVMs in patients who had not received radiosurgery. Histology showed endothelial proliferation with hyaline and mineralization in vessel walls. Partial or complete thrombosis of some AVM vessels, and evidence of vessel and brain necrosis were noted in many cases. Clinical outcome was excellent or good in 34 cases, with two patients dying of rebleeding from residual AVM. Five patients were neurologically worse following microsurgical resection. Final outcome was largely related to the pretreatment grade. Radiosurgery several years prior to surgical resection appears useful in treating unusually large and complex AVMs.

Adolescent↗
PubMed1998

Acute hearing loss following fractionated stereotactic radiosurgery for acoustic neuroma. Report of two cases.

Two cases of acute hearing loss are reported following fractionated stereotactic radiosurgery for acoustic neuroma. Both patients had neurofibromatosis type 2 and were treated with a peripheral tumor dose of 21 Gy delivered in three fractions (7 Gy each) with a minimum interfraction interval of 10 hours. One patient who had previously undergone surgical resection of the treated tumor presented with only rudimentary hearing in the treated ear secondary to an abrupt decrease in hearing prior to treatment. That patient reported total loss of hearing before complete delivery of the third fraction. The second patient had moderately impaired hearing prior to treatment; however, within 10 hours after delivery of the final fraction, he lost all hearing. Both patients showed no improvement in response to glucocorticoid therapy. Possible explanations for this phenomenon are presented.

Adult↗
PubMed1998

Clinical uses of radiosurgery.

Radiosurgery uses stereotactic targeting methods to precisely deliver highly focused, large doses of radiation to small intracranial tumors and arteriovenous malformations (AVMs). This article reviews the most common clinical applications of radiosurgery and the clinical results reported from a number of series using either a cobalt-60 gamma knife or linear accelerator as radiation sources. Radiosurgery is used to treat malignant tumors, such as selected cases of brain metastases and malignant gliomas (for which stereotactic radiosurgical boosts are utilized in conjunction with fractionated radiation therapy), as well as benign tumors, such as meningiomas, acoustic neuromas, and pituitary adenomas. Treatment of small AVMs is also highly effective. Although radiosurgery has the potential to produce complications, the majority of patients experience clinical improvement with less morbidity than occurs with surgical resection.

Arteriovenous Malformations↗
PubMed1997

Laparoscopic surgical staging in cervical cancer--preliminary experience among Chinese.

BACKGROUND: With the availability of modern laparoscopic equipment and the ability to perform advanced operative procedures, there are a growing number of circumstances under which operative laparoscopy is applicable to patients with gynecologic malignancies. METHODS: From May 1992 to December 1995, a total of 67 patients with cervical carcinoma of different FIGO stages underwent pretreatment evaluation of pelvic or para-aortic lymph node status by means of laparoscopic dissection. Four patients with FIGO stage Ia2 and 35 patients with FIGO stage Ib cervical carcinoma received pelvic lymphadenectomy of the external iliac, internal iliac, and the obturator regions; the rest of the 28 patients with advanced FIGO stages had para-aortic lymphadenectomy only. Of these advanced cases, 15 patients were FIGO stage IIb, 8 were FIGO stage IIIa, and 5 were FIGO stage IIIb. All cases were followed up from 6 to 40 months. RESULTS: All the patients tolerated the procedures smoothly except one patient with incomplete procedure due to bleeding from vena cava. In pelvic lymphadenectomy cases, an average of 14.2 nodes from the right side and 12.5 nodes from the left side were removed through laparoscope, and in para-aortic lymphadenectomy cases, an average of 8 lymph nodes was removed from both sides of para-aortic area. Five of the 39 pelvic lymphadenectomy patients showed positive involvement of the obturator nodes and they were later put on the radiation therapy. The other 34 patients with no pelvic lymph node metastasis underwent radical surgery 2 days later or followed immediately by laparoscopic-assisted vaginal radical hysterectomy. No more positive nodes were found. Among the advanced cervical cancer patients, 4 of the stage IIb patients, 3 of the stage IIIa patients, and 3 of the stage IIIb patients showed positive para-aortic lymph node involvement and these patients were put on adjuvant chemotherapy and whole pelvic irradiation or extended field irradiation only. For the remaining 18 patients without para-aortic node involvement, only whole pelvic irradiation was offered. Macroscopic invasion of the para-aortic lymph nodes was detected in only 57% of the patients by computed tomography. CONCLUSIONS: This preliminary experience showed that laparoscopic pelvic or para-aortic lymphadenectomy was an efficient and feasible surgical staging procedure in the pretreatment evaluation of carcinoma of the uterine cervix and elaborates the rationale for the management of cervical cancer.

Adult↗
PubMed1997

Treatment of cranial base meningiomas with linear accelerator radiosurgery.

OBJECTIVE: Radiosurgery is increasingly being used to treat cranial base tumors. Since 1989, 55 patients with cranial base meningiomas were treated at Stanford University Medical Center with linear accelerator radiosurgery. An analysis of the clinical and radiographic results of this patient population was the focus of this study. METHODS: The mean patient age was 55.1 years (range, 28-82 yr). The mean tumor volume was 7.33 cm3 (range, 0.45-27.65 cm3). The radiation dose averaged 18.3 Gy (range, 12-25 Gy), delivered with an average of 2.2 isocenters (range, 1-5). Patients were evaluated retrospectively through clinic notes from follow-up examinations, and residual tumor volume was measured during follow-up imaging studies. The length of follow-up averaged 48.4 months (range, 17-81 mo). RESULTS: Tumor stabilization after radiosurgery was noted in 38 patients (69%), shrinkage in 16 patients (29%), and enlargement in only 1 patient (2%). The results of follow-up magnetic resonance imaging demonstrated decreased central contrast uptake in 11 meningiomas (20%), possibly indicating evidence of central tumor necrosis or tumor vessel obliteration. Neurological status was improved in 15 patients in the series (27%) and unchanged in 34 patients (62%). Three patients (5%) died during the follow-up period, all as a result of causes other than tumor progression. Three patients (5%) developed new permanent symptoms (one patient with seizures, one patient with mild right hemiparesis, and one patient with both vagal and hypoglossal nerve palsy). All other complications were transient, including partial trigeminal nerve palsy in seven patients and diplopia in three patients. The 2-year actuarial tumor control rate was 98%. CONCLUSIONS: Although our follow-up period is short, this experience corroborates previous reports that radiosurgery can be used to ablate selected small cranial base meningiomas, with good clinical results and modest morbidity.

Adult↗
PubMed1997

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.

Algorithms↗
PubMed1997

Mixed arteriovenous malformation and capillary telangiectasia: a rare subset of mixed vascular malformations. Case report.

In this report, the authors discuss the case of a patient with a mixed cerebrovascular malformation in which an arteriovenous malformation (AVM) was associated with a capillary telangiectasia. Recent reports have contained reviews of various subsets of mixed malformations. To the authors' knowledge, however, this is the first report of a mixed vascular malformation with both arterial and capillary components. The patient underwent complete resection of the AVM after presenting with a clinical hemorrhage. She required a second operation to resect the capillary telangiectasia after new symptoms developed several months following the first procedure. The authors conclude that a mixed AVM-capillary telangiectasia is a rare but distinct entity.

Adult↗
PubMed1997

Minimally-invasive early prenatal diagnosis using fluorescence in situ hybridization on samples from uterine lavage.

A two-phase study was undertaken to examine the efficiency of using transcervical cells (TCCs) collected by uterine lavage and fluorescence in situ hybridization (FISH) for early prenatal diagnosis of fetal chromosome aneuploidy. Uterine lavage was performed in 50 women scheduled for elective termination of pregnancy (TOP, n = 35) or chorionic villus sampling (CVS, n = 15) between 6 and 11 weeks of gestation. TCCS were dissociated by trypsin and collagenase, and interphase FISH was carried out for chromosomes X, Y, 13/21, and 18. The phase I study comprised 36 women. The FISH results were compared with the cytogenetic analysis from long-term culture of villus samples collected at TOP or CVS. Among the 36 samples, 15 had a normal male karyotype and 21 had a normal female karyotype. FISH on TCCs correctly identified 13 out of the 15 pregnancies with a male fetus. In phase II, uterine lavage was performed on 14 women. The samples were first tested for the presence of trophoblasts with an anti-trophoblast antibody, GB25, by immunohistochemical staining. Among 12 GB25-positive samples, the FISH results corresponded to the fetal karyotype. One of the GB25-positive samples had five signals for the chromosome 13/21 probe. The cytogenetic analysis confirmed that the fetus had a karyotype of 47, XX, +21. In the GB25-negative samples, FISH failed to identify one male pregnancy. Follow-up was carried out on 13 ongoing pregnancies and no maternal or fetal complications were discovered. This study demonstrates that fetal chromosome numeration can be carried out using FISH on uterine lavage samples in early pregnancy. However, a specific fetal cell marker, such as specific anti-trophoblast antibody, is necessary to avoid a false-negative result.

Adult↗
PubMed1996

Surgical resection of large incompletely treated intracranial arteriovenous malformations following stereotactic radiosurgery.

Although radiosurgery is effective in obliterating small arteriovenous malformations (AVMs), it has a lower success rate for thrombosing larger AVMs. The authors surgically resected AVMs from 33 patients ranging in age from 7 to 64 years (mean 30.4 years) 1 to 11 years after radiosurgery. Initial AVM volumes were 0.8 to 117 cm3 (mean 21.6 cm3), and doses ranged from 4.6 to 45 GyE (mean 21.2 GyE). Of 27 AVMs in eloquent or critical areas, 10 were located in language, motor, sensory, or visual cortex, 11 in the basal ganglia/thalamus, one each in the brainstem, hypothalamus, and cerebellum, and three in the corpus callosum. Venous drainage was deep in 13, superficial in 12, or both in eight lesions. Spetzler-Martin grades were II in one, III in 12, IV in 16, and V in four patients. Eight patients experienced rebleeding after radiosurgery but prior to surgery. Three patients developed radiation necrosis and 25 underwent endovascular embolization prior to surgery. At surgery the AVMs were found to be markedly less vascular, partially thrombosed, and more easily resected, compared to those seen in patients who had not undergone radiosurgery. Pathological investigation showed endothelial proliferation with hyaline and calcium in vessel walls. There was partial or complete thrombosis of some AVM vessels and evidence of vessel and brain necrosis in many cases. Complete resection was achieved in 28 patients and partial resection in five. Clinical outcome was excellent or good in 31 cases, and two patients died of rebleeding from residual AVM. Four patients' conditions worsened following microsurgical resection. Final clinical outcome was largely related to the pretreatment grade. Radiosurgery several years prior to open microsurgery may prove to be a useful adjunct in treating unusually large and complex AVMs.

Adolescent↗
PubMed1996

Interphase fluorescence in situ hybridization in a Turner syndrome variant with IsoXq. A case report.

BACKGROUND: Performing fluorescence in situ hybridization (FISH) on uncultured amniotic fluid cells has been known to produce rapid diagnoses of major chromosomal aberrations. However, if the aberration involves a structural chromosomal anomaly, the FISH result may be not only uninformative but misleading. CASE: FISH with alpha-satellite probes of chromosomes X and Y was performed on the uncultured amniocytes of a prenatal amniotic fluid specimen. Eighty-five percent of the hybridized interphase nuclei displayed two signals when probing with X; no significant hybridization was found when probing with Y. This FISH result was interpreted as normal, disomic for chromosome X. Cytogenetic analysis later, however, disclosed the fetal karyotype to be 46,X,i(Xq). CONCLUSION: Interphase FISH with an alpha-satellite probe (or probe made of repeat centromeric sequences) may be useful in the detection of a numerical anomaly of a chromosome but not of a structural anomaly within the chromosome itself.

Amniotic Fluid↗
PubMed1996

Comparison of laparoscopic presacral neurectomy and laparoscopic uterine nerve ablation for primary dysmenorrhea.

OBJECTIVE: To compare laparoscopic presacral neurectomy and laparoscopic uterine nerve ablation for primary dysmenorrhea. STUDY DESIGN: Sixty-eight patients with primary dysmenorrhea and a poor response to medical treatment were randomized into two groups. One group (33 patients) had laparoscopic presacral neurectomy (LPSN) and the other group (35 patients), laparoscopic uterine nerve ablation (LUNA). RESULTS: There were no complications, and all the patients left the hospital within 24 hours after surgery. The efficacy of both surgical methods was almost equal (87.9% vs. 82.9%) at the 3-month postoperative follow-up visit, but the efficacy of LPSN was significantly better than that of LUNA (81.8% vs 51.4%) at the 12-month visit. CONCLUSION: LPSN is a valid option for treating primary dysmenorrhea.

Adolescent↗