PubMed Health⌕ Search

Biomedical subjects

J P Rock

Publications and source records attributed to J P Rock.

At least 19 recordsLinked to original sources
PubMed2001

Correlation between magnetic resonance spectroscopy imaging and image-guided biopsies: semiquantitative and qualitative histopathological analyses of patients with untreated glioma.

OBJECTIVE: Since intratumoral heterogeneity of gliomas is not adequately reflected in conventional magnetic resonance imaging (MRI), we sought to determine a correlation between different proton magnetic resonance spectroscopic imaging ((1)H MRSI) metabolic ratios and the degree of tumor infiltration in diffusely infiltrating gliomas. In this report, we describe the microscopic anatomy of gliomas on imaging. METHODS: Image-guided biopsies with semiquantitative and qualitative histopathological analyses from a series of 31 untreated patients with low- and high-grade gliomas were correlated with multivoxel (1)H MRSI referenced to the same spatial coordinates. RESULTS: This series yielded 247 tissue samples and 307 observations. Choline-containing compounds using contralateral creatine and choline for normalization or ipsilateral N-acetylaspartate appear to correlate best with the degree of tumor infiltration. Similar correlations were present within each grade after stratification. Despite the interpatient overlap of metabolic ratios between normal tissue and mild tumor infiltration, preliminary analyses revealed that (1)H MRSI appears more accurate than conventional MRI in defining the tumor boundary and quantifying the degree of tumor infiltration. CONCLUSION: This is the first study showing histopathological validation of tumor boundaries using (1)H MRSI. These results support the conclusion that (1)H MRSI accurately reflects the extent of the disease in patients with gliomas. This has important diagnostic and therapeutic implications for more accurately assessing the burden of disease as well as for planning and assessing response to therapy.

Adolescent↗
PubMed2000

Practice parameters for the management of single brain metastasis.

OBJECT: In January 1998 the Guidelines and Outcomes Committee of the American Association of Neurological Surgeons (AANS) issued a charge for the development of evidence-based practice parameters focusing on the treatment of patients with single metastasis to the brain. The charge was imposed in response to the significant controversy surrounding questions relating to the optimal management strategies for patients with single brain metastasis. METHODS: A team consisting of physicians from the AANS, the American Academy of Neurology, and the American Association of Therapeutic Radiation Oncology convened and the literature was reviewed. Methodically drawing from the best of Class I, II, and III levels of available evidence, authors sought to determine how the literature addressed and disposed of the question of the optimal management for an adult with a known history of cancer and a single metastatic brain lesion. Framing the question in this specific manner allowed researchers to focus directly on treatment issues, without having to consider diagnostic issues. CONCLUSIONS: The results of the evidence-based analysis demonstrated that there was insufficient information to establish standards of care. Data from the literature does, however, support a guideline stating that surgical resection accompanied by whole brain radiation therapy is associated with the best survival rate. Additional lower-quality evidence supports an option for management with radiosurgery.

Brain Neoplasms↗
PubMed2000

Survival of patients with synchronous brain metastases: an epidemiological study in southeastern Michigan.

OBJECT: It has been suggested that synchronous brain metastases (that is, those occurring within 2 months of primary cancer diagnosis) are associated with a shorter survival time compared with metachronous lesions (those occurring more than 2 months after primary cancer diagnosis). In this study the authors used data obtained from the National Cancer Institute's Surveillance, Epidemiology, and End Results program to determine the incidence of synchronous brain metastases and length of survival of patients in a defined population of southeastern Michigan residents. METHODS: Data obtained in 2682 patients with synchronous brain metastases treated between 1973 and 1995 were reviewed. Study criteria included patients in whom at least one brain metastasis was diagnosed within 2 months of the diagnosis of primary cancer and those with an unknown primary source. The incidence per 100,000 population increased fivefold, from 0.69 in 1973 to 3.83 in 1995. The most frequent site for the primary cancer was the lung (75.4%). The second largest group (10.7%) consisted of patients in whom the primary site was unknown. The median length of survival was 3.2 months. There was no significant difference in the median survival of patients with primary lung/bronchus and those with an unknown primary site (3.3 months and 3.2 months, respectively). CONCLUSIONS: Patients who present with synchronous lesions have a poor prognosis, and the predominant cause of death, in more than 90% of cases, is related to systemic disease; however, despite poor median survival times, certain patients will experience prolonged survival.

Adolescent↗
PubMed1998

Vascular endothelial growth factor expression and vascular density as prognostic markers of survival in patients with low-grade astrocytoma.

UNLABELLED: It has long been recognized that some patients with low-grade astrocytoma may survive for many years, whereas in others the disease follows a more malignant course resulting in a short survival time, usually due to malignant transformation into higher-grade tumors. OBJECT: The aim of this study was to investigate angiogenesis in the initial biopsy specimen of tumor tissue as a biological marker to identify patients with low-grade astrocytoma who are at high risk of malignant tumor transformation or death. METHODS: Tumor tissue was studied in 74 consecutively treated adult patients in whom a diagnosis of diffuse supratentorial hemispheric histologically proven fibrillary low-grade astrocytoma was made and who underwent surgery between January 1972 and January 1994. Studies were conducted using monoclonal antibodies to the antigens of the proliferation-associated Ki-67 (MIB-1), factor VIII, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF). The overall 5-year survival rate for the entire patient population was 65%, with a median survival time of 7.5 years. The total mean follow-up period was 6.1 years. All tumors showed a low proliferative potential at the time of the initial operation, as demonstrated by an MIB-1 labeling index of less than 1.5%. Patients with more than seven microvessels in tumor tissue (29 cases) had a shorter survival time (mean 3.8 years) than those with seven or fewer microvessels (mean survival 11.2 years). This difference in survival times was significant by univariate (p = 0.001) and stepwise multivariate analyses (p < 0.001). Tumors with a larger number of microvessels also had a greater chance of undergoing malignant transformation (p = 0.001). Similarly, significant staining for VEGF was correlated with shorter survival times when using univariate (p = 0.003) and multivariate (p = 0.008) analyses and with a greater chance of malignant transformation (p = 0.002). Patients with tumors staining positive for VEGF (39 individuals) had a median survival time of 5.3 years, and those with tumors negative for VEGF (35 patients) had a median survival time of 11.2 years. No association was observed between bFGF, EGF, and survival or malignant transformation. The stepwise multivariate analysis included histological and clinical variables simultaneously. CONCLUSIONS: The authors have shown that microvessel density and VEGF levels are independent prognostic markers of survival in fibrillary low-grade astrocytoma. This finding leads them to propose that fibrillary diffuse low-grade astrocytoma is not a single pathological entity but is composed of a spectrum of tumors with differing propensities to undergo malignant transformation that is at least partly based on their inherent angiogenic potential.

Adolescent↗
PubMed1997

TSH-Secreting Pituitary Adenoma: Current Management and Review.

The neurosurgical literature contains little information about the current management of patients with thyroid-stimulating hormone (TSH)-secreting pituitary adenomas or about the usefulness of the somatostatin analogue octreotide in such cases. While TSH-secreting pituitary adenomas are rare, our review and illustrative case demonstrate the effectiveness of pretreating patients with octreotide therapy not only to reduce tumor size prior to surgical resection but also to increase the possibility of clinical remission.A 52-year-old male presented with signs and symptoms of hyperthyroidism and elevated TSH, thyroxine, and triiodothyronine. Magnetic resonance imaging revealed a pituitary macroadenoma with extension into the suprasellar cistern. The patient was treated with octreotide for 6 months prior to surgery. Approximately 3 months after initiation of octreotide therapy, the patient exhibited excellent biochemical and clinical response. Tumor shrinkage of nearly 50% was associated with resolution of suprasellar extension and optic nerve compression. Subsequent transsphenoidal surgery for resection of residual adenoma was followed by symptomatic and hormonal remission without the need for reinstitution of octreotide therapy.Pretreatment with octreotide for TSH-secreting pituitary adenomas has a beneficial effect on disease symptoms and reduces tumor mass. We suggest that patients with these rare tumors can be managed with a combination of octreotide therapy and subsequent surgical removal of residual tumor. Although this combination treatment helps to facilitate clinical remission, only short-term follow-up has been reported and thus the optimal management of these patients remains to be determined.

Case Reports↗
PubMed1996

Skull base cerebrospinal fluid leakage control with a fibrin-based composite tissue adhesive.

Cerebrospinal fluid (CSF) leaks can be responsible for significant patient morbidity and mortality. While the majority of leaks induced after head trauma will seal without intervention, spontaneous or surgically-induced leaks often require operative repair. Many modifications on standard surgical technique are available for repair of CSF fistulae, but none assures adequate closure. We have studied the efficacy of a novel fibrin-based composite tissue adhesive (CTA) for closure of experimentally-induced CSF leaks in rats. Fistulae were created in two groups of animals. Two weeks after creation of the leaks, the animals were sacrificed and analyzed for persistence of leak. A 58% leakage rate was noted in the control group (n = 12), and no leaks were noted in the experimental group closed after application of CTA to the surgical defect followed by skin closure (n = 11). Comparing the control group to the experimental group, results were statistically significant (p = 0.015). These data suggest that CTA may be effective as an adjunct for the closure of CSF fistulae.

Journal Article↗
PubMed1996

Preventive management of cerebrospinal fluid leakage in translabyrinthine surgery.

A simple technique can be used to prevent cerebrospinal fluid (CSF) leakage through the nose and the wound in translabyrinthine surgery. This method, evolved from Glasscock's technique of packing the eustachian tube, adds only 5 to 10 minutes to the procedure. The procedure was modeled in the temporal bones of 20 human cadavers, and the findings are described. With this technique, no nasal CSF leaks occurred in a consecutive series of 25 patients who underwent acoustic tumor surgery. Factors thought to be necessary for the success of the technique are discussed.

Adolescent↗
PubMed1996

Spinal epidural abscess: evaluation of factors influencing outcome.

OBJECTIVE: The goal of this study was to critically evaluate the predictive efficacy of various clinical factors in spinal epidural abscess influencing outcome after surgical and/or medical treatment. METHODS: A retrospective analysis of 41 cases of spinal epidural abscess treated at Henry Ford Hospital between 1984 and 1992 was performed. RESULTS: Thirty patients underwent open surgery and received antibiotic therapy, and 11 patients received medical treatment alone. After a mean follow-up period of 20.9 months (range, 4-45 mo), 24 patients (58.5%) had no or minimal deficits, 9 patients (22%) had severe paresis or plegia and/or bowel/bladder dysfunction, and 8 patients (19.5%) died. Univariate analysis revealed patient age, degree of thecal sac compression, spinal location, surgical findings, and septic presentation to be significantly associated with outcome. In multiple logistic regression analysis, increasing age and degree of thecal sac compression were the only factors with significant independent association with poor outcome (P = 0.01 for both). A simple grading system (Grades 0-III) was developed, with patient age, degree of thecal sac compression, and duration of symptoms as the determining criteria. The incidence of poor outcome for patients with Grade 0 was 0%, compared to 85.7% for patients with Grade III. CONCLUSION: We conclude that long-term outcome after treatment of spinal epidural abscess can be predicted with the use of the proposed grading scheme. Surgical drainage plus parenterally administered antibiotics remains the recommended treatment, although medical treatment alone can also be used for certain patients.

Abscess↗
PubMed1995

Primary craniofacial chordoma: case report.

A 37-year-old man presented with right facial pain and a nonpalpable mass over the malar eminence. An incisional biopsy via the intraoral route was performed and interpreted as a vascular malformation with degenerative changes. His symptoms persisted, and a repeat biopsy was suggestive of an epithelioid nerve sheath tumor. Total resection of the tumor was planned to include the infraorbital and malar regions, the infratemporal fossa, and the pterygopalatine fossa. At surgery, the tumor was removed with tumor-free margins obtained along the course of the maxillary nerve just before its entrance into the cavernous sinus. The pathological findings and the immunohistochemistry demonstrated a typical chordoma with no chondroid or sarcomatous dedifferentiation. We think that with greater use of immunohistochemical markers and electron microscopy, patients with chordoma in this location may be diagnosed promptly and accurately.

Adult↗
PubMed1995

Prolonged external ventricular drainage with percutaneous long-tunnel ventriculostomies.

External ventricular drainage has been used extensively for management of several neurosurgical disorders. The main limitation of this procedure has been the high risk of infection, especially with prolonged drainage. In an effort to minimize the risk of infection, the authors have used a new ventriculostomy technique that involves tunneling the ventricular catheter subcutaneously to an exit site in the lower chest or upper abdomen. This report describes the results of this procedure on 100 consecutive cases. Patients requiring emergency ventriculostomies had short-tunnel ventriculostomies placed at the bedside that were converted to long-tunnel ventriculostomies in the operating room within 5 days. The average duration of drainage was 18.3 days (range 5-40 days). Cerebrospinal fluid was routinely sent for Gram staining and culture to monitor for infection. Prophylactic antibiotic medications were administered only perioperatively. No infection was observed during the first 16 days of drainage in any patient. The overall incidence of infection was 4% and blockage occurred in 6% of the cases. In this series the incidence of ventricular infection was 2.37 per 1000 ventricular drainage days, one of the lowest reported incidences of infection in the literature. This procedure provides a simple and effective method of maintaining long-term ventricular drainage with a very low risk of infection or blockage.

Adolescent↗
PubMed1995

Proliferation indices of vestibular schwannomas by Ki-67 and proliferating cell nuclear antigen.

Two immunohistologic demonstrations of markers of proliferating cells, Ki-67 and proliferating cell nuclear antigen, were applied to tissues from 10 vestibular schwannomas. Each method demonstrated three distinct rates of positively stained cells (p < .01 and p < .015, respectively, for each method). There was a one-to-one correspondence between the two immunohistologic methods in the assignment of cases to each growth rate category except for two cases (Spearman rank correlation r = 0.76, p < .05). These data support the concept of distinct growth rates in vestibular schwannoma. Tissues were also sampled from different areas of the same tumor within nine samples. The results suggest that tumor growth is not homogeneous within a tumor, but that proliferation may be more active near the surface.

Adult↗
PubMed1994

The transcondylar approach to the jugular foramen: a comparative anatomic study.

The standard neurosurgical approach to the jugular foramen involves suboccipital craniectomy with access along the petrous bone. However, even after wide removal of the foramen magnum, only limited access into the infratemporal fossa can be obtained. The neurootologic exposures provide excellent infratemporal access but limited exposure to the posterior fossa, resulting in hearing loss and facial paresis or paralysis. Using cadaver specimens, we exposed the jugular foramen region by the transcondylar approach. A retromastoid incision is extended into the neck. The transverse foramen of the atlas is opened and the vertebral artery transposed medially, thereby providing exposure into the infratemporal fossa. A suboccipital craniectomy extending anterior to the sigmoid sinus is performed, and the posterolateral occipital condyle is resected. After resection of the sigmoid sinus, cranial nerves 9 through 12 are easily identified extracranially in the infratemporal fossa and can be followed proximally through their foramina to the brain stem. We compared the transcondylar approach to three standard approaches, morphometrically and anatomically, and found that the transcondylar approach not only compares favorably but also offers advantages in that it preserves auditory and facial nerve function and is useful for one-stage tumor resection.

Cadaver↗
PubMed1994

Obstructive sleep apnea syndrome and acromegaly.

Obstructive sleep apnea syndrome is a complex disorder that has been associated with a variety of abnormalities of the upper airway, including tonsil and adenoid hypertrophy, nasal obstruction, retrognathia, and macroglossia. The cause of the airway obstruction in acromegaly is believed to be related to osseous and soft-tissue changes surrounding the upper airway, which lead to narrowing and subsequent collapse during sleep. We describe the results of treatment in seven patients with both sleep apnea and acromegaly. Four patients were treated by transsphenoidal hypophysectomy alone with a resolution of sleep apnea syndrome. One underwent hypophysectomy followed by postoperative radiation therapy, which reduced his apnea. Three patients underwent unsuccessful uvulopalatopharyngoplasty. Successful treatment of the primary disorder, in this case acromegaly, resulted in improved breathing during sleep in five patients. This series would suggest that acromegalic patients with sleep apnea should be treated for their pituitary tumor to reduce growth hormone before consideration of surgery to enlarge or bypass the upper airway.

Acromegaly↗
PubMed1994

Giant cell tumor of the skull base.

Giant cell tumor of the skull is a rare clinical entity. This report presents the case of a 32-year-old female with Turner's syndrome and a giant cell tumor of the left middle cranial fossa floor. Although there have been sporadic reports of patients with extragonadal tumors, to our knowledge this is the first reported case of giant cell tumor in a patient with Turner's syndrome. Definitive treatment is surgical extirpation; however, recommendations for cases of subtotal excision remain controversial. Management of this patient with giant cell tumor of the skull is described, and current treatment recommendations are discussed.

Adult↗
PubMed1993

Cytogenetic findings in pituitary adenoma: results of a pilot study.

Pituitary adenomas are the most common tumors of the sellar region and are, with rare exception, benign neoplasms. The natural history of these lesions is only poorly understood and, although histologic, immunocytologic, and ultrastructural characteristics have been well established, predicting the natural history of individual tumors is, at best, unreliable. In an effort to better characterize pituitary adenomas, we have analyzed the karyotypes of 18 surgical specimens and attempted to correlate with the morphologic appearance and the clinical data, for example, endocrinologic subtypes, histology, and tumor invasiveness. Most hormonal subtypes were studied including seven growth hormone-prolactin (GH-PRL), two Prolactin (PRL), two Adrenocorticotrophin (ACTH), seven nonsecretory (NULL). No correlations with morphology or invasiveness could be made. Of 7 null cell adenomas, five (71%) had normal karyotypes, whereas of 11 hormone-secreting adenomas three (28%) were normal. Of seven tumors with mixed GH-PRL activity, six had abnormal karyotypes. At least three chromosomes harbored abnormalities shared by more than two tumors. The results demonstrate that chromosome abnormalities are also found in benign tumors. These findings, however, suggest that hormone-secreting adenomas may be more likely to be associated with karyotypic abnormalities especially those of the GH-PRL variety. Genetic abnormalities associated with chromosomes 1, 4, 7, and 19 were common and warrant further investigation.

Adenoma↗
PubMed1993

Transoral surgery: an anatomic study.

The transoral approaches have become commonplace in modern neurosurgical practice for treatment of ventral midline lesions of the clivus and upper cervical spine. Although the standard technique of transoral surgery is conceptually simple, anatomic relationships are not so readily appreciated. The present study was undertaken in an effort to define more clearly the midline anatomic relationships as they pertain to the standard transoral and transpalatine operations. The anatomic relationships involved in planning microsurgical transoral approaches were examined in 15 human cadavers. Landmarks approximating the midline of the skull base and the upper cervical spinal canal were defined to assist the surgeon's orientation. Measurements were made in axial, sagital, and parasagittal planes to various neurovascular structures in the posterior cranial fossa and upper cervical spinal canal. The study revealed that, for the standard transoral and transoral-transpalatine dissections, the carotid arteries, abducens nerves, interior petrosal sinuses, hypoglossal nerves, and vertebral arteries would be a greatest risk being 0.76, 1.06, 1.51, 1.34, and 1.52 cm from the midline at specified locations. The measurements and the computed tomography images provide a useful reference for the surgeon.

Journal Article↗