Biomedical subjects

S D Chang

Publications and source records attributed to S D Chang.

At least 37 records · Page 2Linked to original sources

PubMed2000

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.

Adult↗

PubMed2000

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.

Algorithms↗

PubMed2000

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.

Astrocytoma↗

PubMed2000

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.

Adolescent↗

PubMed2000

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.

Adult↗

PubMed1999

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.

Adolescent↗

PubMed1999

Elevated second-trimester maternal serum hCG in patients undergoing haemodialysis.

Prenatal Down syndrome screening with maternal serum alpha-fetoprotein (AFP) and human chorionic gonadotrophin (hCG) has become common. High levels of maternal serum hCG and low levels of AFP have been associated with an increased risk of fetal Down syndrome. In this paper, we report five pregnancies in patients undergoing long-term haemodialysis, all of whom had false-positive second-trimester Down syndrome screening results. All of our five patients had extremely high levels of maternal serum hCG, but normal AFP values for their gestational age, and all had serious complications during pregnancy.

Adult↗

PubMed1999

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.

Adult↗

PubMed1999

Symptomatic vasospasm after resection of a suprasellar pilocytic astrocytoma: case report and possible pathogenesis.

BACKGROUND: Cerebral vasospasm from pathology other than subarachnoid hemorrhage is uncommon. A case of severe vasospasm after resection of a suprasellar pilocytic astrocytoma is reported. METHODS: A 45-year-old male presented with headache, left facial numbness, bilateral visual loss, and ataxia. Evaluation revealed a large suprasellar tumor, which was resected. Pathologic examination showed pilocytic astrocytoma. The patient developed hemiparesis and aphasia on the fifth postoperative day. Vascular spasm was documented on angiography and by transcranial Doppler. RESULTS: Intraarterial papaverine resulted in moderate angiographic improvement. Attempts to open middle cerebral artery branches with angioplasty were unsuccessful. The patient subsequently developed a left middle cerebral artery infarct. CONCLUSIONS: To our knowledge, this is the first description of vasospasm after resection of an astrocytoma. Possible mechanisms contributing to this unusual complication after resection of tumors are discussed.

Astrocytoma↗

PubMed1999

Ciliary body schwannoma.

PURPOSE: Intraocular schwannomas are very rare, benign, peripheral nerve neoplasms. The authors report a case of ciliary body schwannoma. METHOD: A 39-year-old Korean woman presented with slowly decreasing visual acuity and proptosis of the right eye for 4 years. At the time of her visit, the eyeball protruded and deviated laterally. She could not sense light with her right eye. We enucleated the eyeball. The enucleated eyeball with tumor was examined histopathologically, immunohistochemically, and under electron microscope. RESULTS: Microscopic examination revealed spindle cells and characteristic Antoni type A and B areas with Verocay bodies. Immunohistochemical study showed tumor cell expressions of S-100 and vimentin, but other immunohistochemical studies were negative. Electron microscopic examination demonstrated Luse body. CONCLUSIONS: We diagnosed the tumor as a schwannoma arising from the ciliary body on the basis of the above mentioned results. Schwannomas are very rare intraocular neoplasms, but they are benign so we should differentiate from other intraocular neoplasms.

Adult↗

PubMed1999

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.

Journal Article↗

PubMed1999

Recanalization and rupture of a giant vertebral artery aneurysm after hunterian ligation: case report.

OBJECTIVE AND IMPORTANCE: Recanalization and subsequent rupture of giant aneurysms of the posterior circulation after Hunterian ligation is an extremely rare event that has been noted to occur with basilar apex, basilar trunk, and vertebrobasilar junction aneurysms. We report the case of a giant, previously unruptured right vertebral artery aneurysm, which recanalized from the contralateral vertebral artery and subsequently ruptured after previously performed angiography showed complete thrombosis of the aneurysm. CLINICAL PRESENTATION: A 72-year-old woman presented with headaches, ataxia, and lower extremity weakness. A giant 3-cm right vertebral artery aneurysm was found during the patient evaluation. INTERVENTION: Because of the size of the aneurysm and the absence of a discrete neck, Hunterian ligation was performed. After treatment, angiograms showed no filling of the aneurysm from either the right or left vertebral artery. Nine days later, after the patient developed lethargy and nausea, repeat angiography showed that a small portion of the aneurysmal base had recanalized. The next day, the patient had a massive subarachnoid hemorrhage and subsequently died. CONCLUSION: We think that this is a previously undescribed complication associated with direct arterial ligation of giant vertebral artery aneurysms. Patients with aneurysms treated using Hunterian ligation need to be followed up closely. Even aneurysms that have minimal recanalization are at risk for subarachnoid hemorrhage.

Aged↗

PubMed1999

The use of electrophysiological monitoring in the intraoperative management of intracranial aneurysms.

OBJECTIVES: Somatosensory evoked potentials (SSEPs) and brainstem auditory evoked potentials (BAEPs) have been increasingly utilised during surgery for intracranial aneurysms to identify cerebral ischaemia. Between July 1994 and April 1996, we surgically treated 70 aneurysms in 49 consecutive patients (58 operations) with the aid of intraoperative evoked potential monitoring. This study sought to evaluate the usefulness of SSEP and BAEP monitoring during intracranial aneurysm surgery. METHODS: Mean patient age was 51.9 (range 18-79) years. The sizes of the aneurysms were 3-4 mm (15), 5-9 mm (26), 10-14 mm (11), 15-19 mm (seven), 20-24 mm (six), and >25 mm (five). SSEPs were monitored in 58 procedures (100%) and BAEPs in 15 (26%). The neurological status of the patients was evaluated before and after surgery. RESULTS: Thirteen of the 58 procedures (22%) monitored with SSEPs had SSEP changes (12 transient, one persistent); 45 (78%) had no SSEP changes. Three of 15 patients (20%) monitored with BAEPs had changes (two transient, one persistent); 12 (80%) had no BAEP changes. Of the 14 patients with transient SSEP or BAEP changes, these changes resolved with adjustment or removal of aneurysm clips (nine), elevating MAP (four), or retractor adjustment (one). Mean time from precipitating event to electrophysiological change was 8.9 minutes (range 3-32), and the mean time for recovery of potentials in patients with transient changes was 20.2 minutes (range 3-60). Clinical outcome was excellent in 39 patients, good in five, and poor in three (two patients died), and was largely related to pretreatment grade. CONCLUSIONS: SSEPs and BAEPs are useful in preventing clinical neurological injury during surgery for intracranial aneurysms and in predicting which patients will have unfavourable outcomes.

Adolescent↗

PubMed1999

Intracranial nasal dermoid sinus cyst associated with colloid cyst of the third ventricle. Case report and new concepts.

A case of a 16-year-old male with both a nasal dermoid sinus cyst (NDSC) and a third ventricle colloid cyst is presented. The NDSC was excised via a single-stage combined intracranial-extracranial approach and the third ventricle colloid cyst was resected endoscopically. The pathogenetic theories of NDSC and third ventricle colloid cyst are discussed, and an embryological explanation for the simultaneous development of the two lesions in this patient is explored. This case is best classified among congenital developmental malformations in a category we propose to call 'anterior neuropore corridor defects.'

Adolescent↗

PubMed1999

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.

Adolescent↗

PubMed1999

Second trimester maternal serum screening using alpha fetoprotein, free beta human chorionic gonadotropin and maternal age specific risk: result of chromosomal abnormalities detected in screen positive for Down syndrome in an Asian population.

BACKGROUND: This study was to determine the incidence of chromosome abnormalities in Taiwanese women undergoing prenatal chromosome analysis after a second trimester Down syndrome screening by using maternal age and serum dual-marker testing (alpha-fetoprotein and free-beta unit human chorionic gonadotropin). METHODS: A total of 10,098 Taiwanese women with pregnancy between 15 and 23 weeks' gestation received second-trimester Down syndrome risk evaluation by dual-marker and maternal age specific risk testing in a single medical center. The study took 22 months. Ninety-seven percent of this study population was less than 34 years old. Ninety-six percent of our cases were screened between 15-20 weeks of gestation. This population was included only after a routine ultrasonography scan for correction of gestational age and exclusion of major structural anomalies. By using an algorithm to detect Down's syndrome, with a risk of 1:270 as a cut-off value, 816 patients were screen-positive for Down syndrome (screen-positive rate 8.0%). Karyotypes were reviewed for 670 (82.1%) mothers who received prenatal karyotype analysis. RESULTS: Twelve cases of Down syndrome were identified in the screen positive group with an estimated detection rate of 67% (false positive rate 8%). Three cases of Down syndrome were detected in late trimester among the screen-negative group. Seven other fetal chromosome abnormalities were also found among the screen-positive pregnancy. In addition, seven cases were screen-positive for trisomy 18; all of these patients received amniocentesis and only one case was confirmed. CONCLUSION: These findings indicate that this screening program combining alpha-fetoprotein (AFP), free beta human chorionic gonadotropin (free-hCG) and maternal age-specific would achieve a screening efficiency in Taiwanese populations as comparable to those obtained in Caucasian populations. Our results also suggest that approximately 3% of pregnancies with a positive dual marker and maternal age-specific screen results will have a chromosome abnormality despite having a normal routine ultrasound scan. Mothers with positive screening results should be made aware of the implications of a positive result.

Adult↗

PubMed1999

Acardiac acephalus: a case report and implications on expectant management.

Acardiac acephalus is a rare occurrence resulting from extensive anastomoses between the vessels of the monochorionic twins which invariably leads to death of the "perfused" twin and an estimated 50% perinatal mortality rate in the "pump" twin, due mainly to premature delivery or congestive heart failure. Once diagnosis has been documented, blocking the vascular flows between the twins has been the principle goal of treatment with the assumption that a more favorable chance of survival in the pump twin can be achieved. However, hasty surgical intervention without a well-designed preoperative evaluation may result in unfavorable outcomes. A 21-year-old nullipara was found to carry an acardiac parabiotic twin in a monochorionic twin pregnancy at 28 weeks of gestation and was referred to us from a local clinic. Expectant management based on the close monitoring of the well-being of the healthy co-twin is presented in this article along with review of published works on the management of this rare condition.

Abnormalities, Multiple↗

PubMed1998

Bilateral cavernous malformations resulting from cranial irradiation of a choroid plexus papilloma.

We report a case of multiple parietal cavernous malformations in a thirteen year old female who received cranial irradiation following incomplete resection of a choroid plexus papilloma. The cavernous malformations, which developed within the prior parietal radiation ports, were diagnosed nine years after the patients' radiation treatment when the patient presented with increasing frequency of seizures. Family history was negative for familial cavernous malformations. Due to the worsening frequency of seizures, the patient underwent resection of these two cavernous malformations with diagnosis confirmed by pathology. Post-operative, there was a significant reduction in seizure frequency. The origin and pathophysiology of cavernous malformations remains controversial. Cranial radiation treatment for tumors, particularly in children, may possibly lead to the development of these lesions, as occurred in this case. This is, to our knowledge, the first case of multiple cavernous malformations occurring within a previous radiation field following radiotherapy for a neoplasm.

Adolescent↗