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L D Lunsford

Publications and source records attributed to L D Lunsford.

At least 19 recordsLinked to original sources
PubMed1992

Stereotactic diagnosis and treatment of pineal region tumours and vascular malformations.

Diagnosis and treatment of tumours and vascular malformations in the region of the pineal gland continue to challenge the neurosurgeon's skill. Due to vital vascular and brain structures in the region, microsurgical removal of such masses is often impossible. During the past nine years, we have managed 47 patients with pineal region mass lesions using stereotactic techniques for diagnosis and treatment. In order to determine further therapeutic options, 15 patients underwent stereotactic biopsy of pineal region tumours. In all patients, the histologic diagnosis obtained served to direct further therapy. Thirty-two patients were treated with stereotactic radio-surgery for pineal region tumours or vascular malformations. During the follow-up period, one patient underwent delayed microsurgical resection of a midbrain angiographically occult vascular malformation. No other patient required microsurgical intervention after a stereotactic procedure. In all 47 patients, no significant morbidity or mortality occurred after stereotactic biopsy or radiosurgery. Empiric treatment of pineal region tumours with fractionated radiation therapy is no longer warranted. Image-guided stereotactic technology provides a safe method to accurately diagnose and effectively treat selected pineal region masses. After definitive histologic diagnosis is established, proper treatment may be instituted. Options for treatment include stereotactic radiosurgery for selected tumours and vascular malformations, microsurgical resection of benign tumours or fractionated external beam radiation therapy for malignant germ cell and glial tumours. Stereotactic surgery should be the first option in the diagnosis and therapy of pineal region masses.

Adolescent↗
PubMed1992

Radiosurgery and brain tolerance: an analysis of neurodiagnostic imaging changes after gamma knife radiosurgery for arteriovenous malformations.

In order to analyze complications and the factors responsible for the development of serial imaging changes after stereotactic radiosurgery for intracranial arteriovenous malformations, we reviewed serial post-treatment magnetic resonance imaging scans in 72 patients. Median follow-up was 23 months (range 12 to 35 months). Twenty patients developed post-radiosurgical imaging changes consisting of new regions of increased T2 signal on magnetic resonance imaging in brain surrounding the arteriovenous malformation (two year actuarial incidence of 31%). Imaging changes were associated with headache or new neurological deficits in nine of these 20 (45%) and remained asymptomatic in 11 (55%). Symptoms developed in three of 13 patients with imaging changes in the cerebral cortex or cerebellum, in contrast to six of seven patients who had symptoms with imaging changes in the brainstem (p = .028). The onset of imaging changes varied from five to 18 months after radiosurgery (median, 12 months). Serial follow-up scans four to 25 months after the onset of imaging changes were available for review in 16 patients. Post-radiosurgical imaging changes completely resolved within 4 to 19 months in ten patients and have not yet completely resolved after 6 to 25 months in six patients. The projected actuarial rate for resolution of imaging changes was 88%, 19 months after onset; the median time for resolution was 14 months. Univariate analysis revealed that the development of imaging changes was significantly associated with treatment volume (p = .025), the risk predicted from the integrated logistic formula (p = .042), and the number of isocenters treated (p = .042). In multivariate analysis, volume was the only factor significantly associated with the development of imaging changes.

Adolescent↗
PubMed1992

Factors predicting successful stereotactic aspiration of colloid cysts.

Stereotactic aspiration is a valuable surgical alternative for colloid cysts, but due to cyst heterogeneity, it is not uniformly successful as the sole treatment in all patients. Since 1981, we performed CT-guided stereotactic aspiration as the initial procedure in 25 patients with colloid cysts. We retrospectively reviewed our experience in the first 22 patients and found that preoperative CT imaging studies accurately determined size and predicted cyst viscosity. The preoperative CT appearance of a hypodense or isodense cyst correlated favorably with successful aspiration. Preoperative MRI provided excellent anatomic definition of the cyst and its relationship to other structures, but failed to correlate successful aspiration. Unsuccessful aspiration was related to the high viscosity of the intracystic material or deviation of the cyst away from the aspiration probe. These factors were used prospectively in 3 additional patients to accurately predict success of cyst aspiration.

Cerebral Ventricle Neoplasms↗
PubMed1992

Current spectrum of stereotactic irradiation techniques.

Our 10-year experience with stereotactic irradiation techniques was evaluated in a series of 709 patients. Stereotactic intracavitary radiation of cystic neoplasms, brachytherapy of malignant glial neoplasms and radiosurgery represent effective and contemporary primary adjuvant or alternative methods to treat a wide variety of brain tumors and vascular malformations.

Brachytherapy↗
PubMed1992

A comparison between magnetic resonance imaging and computed tomography for stereotactic coordinate determination.

The spatial accuracy of magnetic resonance imaging (MRI) has not been established for stereotactic surgery. Magnetic susceptibility artifacts may lead to anatomical distortion and inaccurate stereotactic MRI coordinates, especially when targets are in regions of the brain out of the center of the magnetic field. MRI-guided stereotactic localization, however, provides better multiplanar target resolution than is available with computed tomographic (CT) scanning. Therefore, we compared the accuracy of stereotactic coordinates determined by MRI and CT studies in 41 patients (53 targets). Coordinates were measured in each plane and as vector distances between the target and the center of the stereotactic frame on axial or coronal MRI studies. Absolute axial plane MRI and CT distances varied an average of 2.13 +/- 1.59 mm. The mean difference in measurements in the X (left-right) dimension was 1.19 mm and 1.55 mm in the Y (anterior-posterior) dimension. Central targets (located less than 2 cm from the frame center) had a mean MRI-CT difference of 2.09 +/- 1.79 mm; peripheral targets (greater than 2 cm from the frame center) differed by 2.17 +/- 1.3 mm. The voxel volumes were calculated for all compared images. Although differences between the physical properties of data acquisition with each imaging modality could explain the observed CT-MRI discrepancies, a 1-pixel difference in target selection could account totally for all the variance observed. MRI field strength (0.5 vs. 1.5 T) did not correlate with coordinate determination accuracy. We conclude that MRI-guided stereotactic localization can be used with confidence for most diagnostic, functional, and therapeutic stereotactic procedures.

Artifacts↗
PubMed1992

Radiobiology of radiosurgery: Part I. The normal rat brain model.

Because limited histological information is available from clinical radiosurgical experience, animal investigations are needed to answer questions regarding the biological response of both normal and pathological tissues. To determine the radiosurgical dose-response relationship of normal brain, we irradiated the right frontal lobe of 18 rats with a single 4-mm isocenter of stereotactic irradiation using the 201-source 60Co gamma unit. Maximal single-fraction doses varied from 30 to 200 Gy (2 rats per dose). All animals were observed for 90 days, killed, and histologically examined. No animal developed neurological dysfunction during that interval, regardless of dose. Animals that received 30, 40, 50, or 60 Gy had no pathological changes. In those given 70 Gy, we found occasional shrunken neurons, and at 80 Gy, rare arteriolar wall thickening. One animal that received 100 Gy had marked capillary endothelial cell degeneration and protein extravasation in the target volume, and the other had a 4-mm diameter necrotic region. Circumscribed cerebral necrosis also was identified in all 4 rats treated with either 150 or 200 Gy; astrocytosis, edema, and microhemorrhage were noted within the surrounding 1 to 2 mm of adjacent brain, and tissue outside that volume had a more normal appearance. We constructed a dose-response relationship based on the cellular, spatial, and temporal effects of focused single-fraction irradiation of the rat brain. To determine the temporal evolution of a known necrotic lesion (200 Gy), 12 other animals were killed (2 each) 1, 7, 14, 21, 30, or 60 days after radiosurgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Radiobiology of radiosurgery: Part II. The rat C6 glioma model.

We developed an experimental animal model to evaluate the potential role of stereotactic radiosurgery for glial neoplasms. Rats were randomized to control or treatment groups after implantation of C6 glioma cells into the right frontal region; 14 days later, 19 rats underwent stereotactic radiosurgical treatment of the induced tumor, using the 4-mm collimator of the gamma unit. Both groups were observed for up to 65 days after implantation. Treated animals had a mean survival of 39.2 days; the 22 control animals lived a mean of 29.4 days before death from tumor growth (P = 0.07). Six treated animals (32%), but only one control animal, survived the full observation period (P = 0.07). The mean tumor diameter in the control group was 9.64 mm; in the radiosurgery group, it was 6.47 mm (P = 0.001). Compared with tumors in control animals, treated tumors had a hypocellular appearance (P less than 0.001) and demonstrated cellular edema (P less than 0.005) under light microscopy, indicating a direct cytotoxic response to treatment. No difference was identified in the amount of tumor necrosis, intratumor hemorrhage, or degree of brain invasion between the two groups. Variations in the maximum treatment dose (30, 40, 50, 70, or 100 Gy) did not result in observed differences in tumor response. This in vivo rat malignant glioma model is a valuable tool to evaluate the tumoricidal effects of single-fraction, focused irradiation. Additional studies are warranted to evaluate dose-response relationships, radiation sensitizers, and use of radiosurgery with other adjuvant treatments.

Animals↗
PubMed1992

Tumor control after stereotactic radiosurgery in neurofibromatosis patients with bilateral acoustic tumors.

During a 4-year interval, 17 patients with bilateral acoustic tumors (vestibular schwannomas) underwent unilateral stereotactic radiosurgery using a multisource gamma unit; 2 patients underwent radiosurgery of both tumors in separate sessions. Eleven patients with unoperated contralateral tumors served as concurrent controls to compare the effects of radiosurgery with the natural history of acoustic tumors. After radiosurgery, the tumor control and regression rates were 89.5 and 21.1%, respectively (median neuroimaging follow-up, 1.4 years; range, 0.3-3.9). The tumor regression rate increased to 40% for patients evaluated at least 12 months after radiosurgery. In comparison to the unoperated contralateral tumors, stereotactic radiosurgery achieved tumor control, as assessed by the ultimate change in tumor size at follow-up (P, 0.012), the change in tumor size over time (P, 0.006), and tumor growth rates (P, 0.003). This study provided convincing evidence that tumor stabilization after radiosurgery (as assessed by neuroimaging) truly represented tumor control. The incidence of delayed facial neuropathy after radiosurgery compared favorably with the incidence reported after microsurgical removal. Some hearing was preserved in one-third of the patients who had preoperative hearing, including three patients who were contralaterally deaf. Stereotactic radiosurgery should be considered as a primary surgical modality for many patients with neurofibromatosis Type II.

Adolescent↗
PubMed1992

Stereotactic radiosurgery: current spectrum and results.

Stereotactic radiosurgery has an important role as primary or adjuvant therapy for selected cerebral vascular malformations and brain tumors. Over the next decade, both extended clinical experience, basic radiobiologic studies, and improvements in dose planning are expected to enhance its overall efficacy and safety.

Adult↗
PubMed1992

Stereotactic radiosurgery in the treatment of patients with acoustic tumors.

Stereotactic radiosurgery is performed under local anesthesia, and most patients can be discharged from the hospital within 24 hours of treatment. All patients in our series returned to their preoperative level of employment or function within 5 to 7 days of treatment, and this functional level was maintained over the period of follow-up. "Tumor control" was achieved in 96% of patients during an average follow-up of 1.7 years. Tumor shrinkage occurred in 45% of patients who had at least 1.5 years of follow-up. Useful hearing preservation rates were 50% at 6 months and 30% 1 year after treatment. New delayed facial or trigeminal neuropathy occurred in 34% and 32% of patients, respectively, with a median onset of 5 to 6 months after treatment. The vast majority of cranial neuropathies were partial at onset and tended to improve over time. Other complications included tumor growth (4%), communicating hydrocephalus (4%), and transient adjacent brain parenchymal changes best seen on T2-weighted MRI (9%). Stereotactic radiosurgery is an important alternative treatment for carefully selected patients with acoustic tumors. Indications for treatment include sufficient medical problems to pose excessive surgical risk, advanced age, the presence of bilateral acoustic tumors or contralateral deafness, recurrent tumor despite surgical resection, or refusal to undergo microsurgery. Radiosurgery is contraindicated in patients with symptomatic brain stem or cerebellar compression from a large acoustic tumor. Previous posterior fossa radiotherapy is a relative contraindication that must be considered on a patient to patient basis. Stereotactic radiosurgery should be viewed as an additional weapon in our arsenal for combating acoustic tumors rather than feared as a potential replacement for surgical excision. The strategic role of stereotactic radiosurgery in the overall treatment of patients with acoustic tumors will continue to be refined as longer-term, carefully assessed results become available.

Adolescent↗
PubMed1992

Stereotactic radiosurgery for acoustic tumors.

Stereotactic radiosurgery is an important alternative treatment for carefully selected patients with acoustic tumors. We perform radiosurgery under local anesthesia, and 91% of our patients have been discharged from the hospital within 24 hours after treatment. All returned to their preoperative level of function or employment within 5 to 7 days after treatment. Our current tumor control rate is 97%, but reduction in tumor size, judged by strict, objective criteria, was achieved in only 23%. Our actuarial rate of useful hearing preservation after radiosurgery is 38% at 1 year. Three tumors increased in size after treatment. Only one of the three demonstrated increased mass effect on surrounding brain structures by neuroimaging criteria. No increase has led to worsened clinical symptoms or has required surgical excision at this point in follow-up. The 1-year rates for developing new facial or trigeminal neuropathies after radiosurgery were 30% and 33%, respectively. Cranial neuropathies had a delayed onset, with the median onset occurring after 5 to 6 months. The vast majority were partial at onset, and most improved over time. Communicating hydrocephalus requiring ventriculoperitoneal shunts developed after radiosurgery in four patients. Eight patients developed increased signal within adjacent brain parenchyma on T2-weighted MR imaging, consistent with edema or blood-brain barrier breakdown. It is unlikely that stereotactic radiosurgery using the gamma knife will obviate the need for microsurgical removal performed by skilled and experienced microsurgeons. However, radiosurgery is a safe and effective treatment for patients whose medical problems make surgery unacceptably dangerous, those with bilateral tumors or a tumor in their only hearing ear, those who have recurrent tumor despite surgical resection, or patients who refuse microsurgical excision.

Adolescent↗
PubMed1992

Gamma knife surgery for sellar and suprasellar tumors.

Recent advances in neuroimaging, coupled with stereotactic delivery of ionizing radiation, permit precise, single-treatment irradiation of various intracranial tumors. This article describes the authors' experience with the 201-source 60Co gamma knife. Initial results indicate a potential therapeutic role for radiosurgery in controlling tumor growth and hormone hypersecretion in most patients. The authors believe that radiosurgery should be considered for small pituitary adenomas when prior microsurgery has failed to control tumor growth. Radiosurgery is a primary treatment alternative for patients who are elderly, medically infirm, or refuse microsurgical removal. Further follow-up is necessary to evaluate the long-term tumor control rate, hormonal effects, and tolerance of surrounding critical structures to stereotactic radiosurgery.

Adenoma↗
PubMed1992

Radiosurgery of meningiomas.

In early experience, radiosurgery proved to be a relatively safe and effective therapy for selected patients with symptomatic meningiomas, including those for whom surgical resection failed. Radiosurgery also has been an effective primary treatment alternative for patients whose advanced age, medical condition, or high-risk tumor location preclude microsurgery. The long-term response to treatment, as defined by imaging and clinical findings, is not yet available. In addition, further clinical and laboratory work is necessary to determine the appropriate tumoricidal radiosurgical dose, dose-volume relationships for individual tumors, and the variable radiation tolerance of the different brain structures that closely surround meningiomas.

Follow-Up Studies↗
PubMed1992

The role of radiosurgery in the treatment of malignant brain tumors.

Most studies describing the results of radiosurgery have concentrated on the definitive treatment of small, histologically benign lesions such as vascular malformations, acoustic neurinomas, and pituitary adenomas. More recently, the role of radiosurgery using the gamma knife or LINAC-based systems to treat malignant neoplasms has become better defined. Most solitary metastases, ependymomas, well-circumscribed (on imaging studies) AAs, and a few glioblastomas (and other tumors) have responded dramatically to radiosurgery. Provided that the tumor volume was small (less than or equal to 14 cm3; 30-mm diameter), radiosurgery safely has caused tumor disappearance, shrinkage, or stabilization, regardless of prior surgery, conventional fractionated irradiation, or tumor radioresistance. For patients with recurrent or persistent, small, malignant intracranial tumors, radiosurgical treatment has obviated the need for prolonged hospitalization and has eliminated the risks associated with general anesthesia and open craniotomy.

Adolescent↗
PubMed1992

Stereotactic radiosurgery for pineal region tumors.

Our present treatment strategy for treating pineal region tumors is shown in Figure 5. We believe that stereotactic biopsy should be the first procedure in pineal region tumors so that a histologic diagnosis can be obtained. Based on the biopsy findings, the appropriate subsequent therapy, whether microsurgery, fractionated irradiation, or stereotactic radiosurgery, can be administered. Although our experience currently is limited to nine patients, we have found that stereotactic radiosurgery is a valuable alternative to microsurgery in the treatment of selected pineal region tumors.

Adolescent↗