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J F Hahn

Publications and source records attributed to J F Hahn.

81 records · Page 5Linked to original sources
PubMedDate not supplied

Melanotic neuroectodermal tumors of the brain and skull.

A case of melanotic neuroectodermal tumor in the cerebellum of a 21-year-old man is presented. Melanin was found mainly in small neoplastic cells rather than in large epithelioid cells. The tumor also contained neurons, as well as neoplastic tissue of ependyma, choroid plexus; and astrocytes. We propose that this neuroectodermal tumor resulted from a combination of cells originating in the neural crest and in the neural tube. The small cells have been described as medulloblasts, but they may be poorly differentiated ependymal cells, or, sympathicoblasts. The presence of pigment in these cells is compatible with an origin in the neural crest. The so-called melanotic progonoma, occurring most often in the maxilla of infants, is reviewed in relation to the melanotic neuroectodermal tumor of the brain. The tumor in facial bone occurs in adults as well as infants, in locations other than the maxilla, and has malignant forms. Melanotic neuroectodermal tumors, whether in brain or bone, are therefore similar in behavior as well as histologic appearance. The finding of similar tumors in these different locations is readily explained embryologically.

Adult↗
PubMedDate not supplied

Extent of resection in temporal lobectomy for epilepsy. I. Interobserver analysis and correlation with seizure outcome.

The extent of resection was assessed in 45 temporal lobectomies for medically intractable epilepsy with mapped temporal lobe foci. Postoperative magnetic resonance imaging (MRI) in the coronal plane was used to quantify the extent of resection of superior lateral, inferior lateral, basal, and medial structures, including the amygdalohippocampal complex. A new 20-compartment model of the temporal lobe was used for this assessment. Blinded interobserver variability was minimal. Intraoperative measurements and maps routinely overestimated the actual extent of resection, especially of medial structures. One year after surgery, 70% of patients remained seizure-free (except for auras). Seizure-free outcome was accomplished despite varying degrees of resection, but was more likely achieved with more extensive resections in all compartments. Among patients with mesiobasal foci, seizure-free outcome correlated significantly with extent of resection of amygdalohippocampal complex. We conclude that assessment of extent of resection by postoperative MRI provides an objective basis of evaluating outcome after temporal lobectomy. It allows a rational approach to understanding of operative failures and is potentially useful in comparing efficacy of various surgical approaches.

Epilepsy↗
PubMedDate not supplied

Intractable epilepsy and structural lesions of the brain: mapping, resection strategies, and seizure outcome.

Forty-seven patients with structural brain lesions on neuroimaging studies and partial epilepsy intractable to medical therapy were studied. Prolonged noninvasive interictal and ictal EEG recording was performed, followed by more focused mapping using chronically implanted subdural electrode plates. Surgical procedures included lesion biopsy, maximal lesion excision, and/or resection of zones of epileptogenesis depending on accessibility and involvement of speech or other functional areas. The epileptogenic zone involved exclusively the region adjacent to the structural lesion in 11 patients. It extended beyond the lesion in 18 patients. Eighteen other patients had remote noncontiguous zones of epileptogenesis. Postoperative control of epilepsy was accomplished in 17 of 18 patients (94%) with complete lesion excision regardless of extent of seizure focus excision. Postoperative control of epilepsy was accomplished in 5 of 6 patients (83%) with incomplete lesion excision but complete seizure focus excision and in 12 of 23 patients (52%) with incomplete lesion excision and incomplete focus excision. The extent of lesion resection was strongly associated with surgical outcome either in itself (p less than 0.003), or in combination with focus excision. Focus resection was marginally associated with surgical outcome as a dichotomous variable (p = 0.048) and showed a trend toward significance (p = 0.07) only as a three-level outcome variable. We conclude that structural lesions are associated with zones of epileptogenesis in neighboring and remote areas of the brain. Maximum resection of the lesion offers the best chance at controlling intractable epilepsy; however, seizure control is achieved in many patients by carefully planned subtotal resection of lesions or foci.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Carcinoembryonic antigen in a metastatic brain tumor.

A case is presented in which 10 ml of cystic fluid from a metastatic brain tumor contained a high concentration of carcinoembryonic antigen (CEA). The use of CEA as a prognostic indicator and adjunctive therapeutic monitor in tumors is reviewed.

Brain Neoplasms↗
PubMedDate not supplied

Gardner's hydrodynamic theory of syringomyelia revisited.

Several theories have been put forth to explain the pathogenesis of syringomyelia, the formation of longitudinal, fluid-filled cavities within the spinal cord. Chief among them is Gardner's hydrodynamic theory, widely accepted for more than two decades. Gardner attributed the genesis of syringomyelia to craniospinal pressure differentials in the setting of fourth ventricular outlet obstruction; these differentials favor cerebrospinal fluid shifts from the fourth ventricle of the brain through the central canal of the spinal cord. Gardner's theory has been questioned, and several alternative theories of syringomyelia have been proposed. Physiological data and new information from magnetic resonance imaging support many of Gardner's concepts; however, a more comprehensive elucidation of the pathophysiologic mechanisms of syringomyelia requires incorporating facets of the other theories. We propose a unified theory of the pathogenesis of syringomyelia based on recent experience with magnetic resonance imaging, and on elements of other current theories.

Cerebrospinal Fluid Pressure↗