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J F Hahn

Publications and source records attributed to J F Hahn.

At least 19 recordsLinked to original sources
PubMed1995

Identification and characterization of human beta 2-chimaerin: association with malignant transformation in astrocytoma.

Molecular processes resulting in the malignant transformation from low- to high-grade astrocytoma remain poorly understood. Using reverse transcriptase PCR, we identified a gene that is differentially expressed in normal brain and low-grade astrocytoma compared to glioblastoma tissues. This gene is identical to human beta 2-chimaerin, which encodes a 468-amino acid GTPase-activating protein for p21rac. The gene was localized to human chromosome 7p15.3 by fluorescence in situ hybridization mapping. Human beta 2-chimaerin is expressed in a variety of human tissues, with the highest expression level detected in human brain and pancreas. RNase protection assays indicated that the expression level of this gene is high in all the normal brain and low-grade astrocytoma samples tested compared to malignant gliomas. The down-regulation of beta 2-chimaerin expression in the high-grade gliomas suggests that decreased expression of this gene may be a feature of progression in the development of malignant glioma.

Amino Acid Sequence↗
PubMed1995

Childhood ganglioglioma and medically intractable epilepsy. A clinicopathological study of 15 patients and a review of the literature.

Gangliogliomas are an increasingly recognized cause of epilepsy in children. Several studies have shown that early surgical treatment is beneficial, but controversy exists regarding the type of surgical treatment required for optimal seizure control and to prevent tumor recurrence. To address this issue, we performed a retrospective review of 15 children operated on at the Cleveland Clinic during a 7-year period with medically intractable epilepsy who were found to harbor a ganglioglioma during the course of their work-up. Nine patients with mostly nondominant hemisphere tumors underwent tumor resection without the use of electrocorticography to guide additional resection of epileptogenic foci, while 6 other patients with dominant hemisphere tumors had subdural electrode grids placed to extraoperatively map zones of ictal onset and eloquent areas. The extent of tumor resection was then correlated to seizure outcome and tumor recurrence. Of the 11 patients who received a gross total resection, 9 are seizure-free while 2 have a greater than 90% reduction in their seizure frequency (100% 'good' outcome). There was no tumor recurrence in this group. Of the 4 patients who underwent a subtotal tumor resection, 1 is seizure-free while 3 have persistent seizures (25% 'good' outcome). All patients in this group have stable disease on follow-up magnetic resonance imaging. In those patients who received subdural electrode grids, the extent of resection of the zones of ictal onset did not correlate with seizure outcome. The mean follow-up was 42 months. We conclude that complete tumor resection is the most important factor for optimal seizure control and to prevent tumor recurrence.

Adolescent↗
PubMed1995

Antibiotic penetration into cervical discs.

Antibiotics are frequently prophylactically administered in surgical procedures to reduce the incidence of infection. The penetration of antibiotics into lumbar discs has been studied with mixed results, but penetration into cervical discs has not been reviewed. In this study, we examined the penetration of two commonly used antibiotics, oxacillin and cefazolin, into cervical discs. Eighteen patients with a total of 30 discs removed were studied. Two groups, each consisting of four patients with five discs removed, received either 1 g of oxacillin or 1 g of cefazolin by a single, preoperative intravenous infusion. Two other groups, each consisting of five patients with 10 discs removed, received either 2 g of oxacillin or 2 g of cefazolin, also by a single, preoperative intravenous infusion. A blood specimen, from which serum antibiotic levels were determined, was obtained from each patient simultaneously with each discectomy. The time interval between the antibiotic infusion and discectomy/phlebotomy was also recorded. Antibiotic levels were detected in all discs removed but were quantifiable in only 12. Nine of these 12 had been exposed to cefazolin. Of these nine discs, one was from a patient who had received 1 g whereas the other eight were from patients who had received 2 g of cefazolin. This represents 80% of the removed discs exposed to 2 g of cefazolin (10 discs total) and 20% exposed to 1 g (5 discs total). The remaining three discs with quantifiable antibiotic levels had been exposed to 2 g of oxacillin, which represents 30% of the discs (10 total) exposed to that dose of oxacillin. Although cervical disc space infections are rare, they are serious.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Surgical management of syringomyelia: a five year experience in the era of magnetic resonance imaging.

We summarize our experience with 59 consecutive surgically managed cases of syringomyelia (SM) over a 5 year period. All cases had magnetic resonance imaging (MRI) preoperatively and postoperatively. Twenty-eight patients presented with SM and the adult Chiari (Chiari I) malformation (SM-ACM), 6 patients had post traumatic syrinxes, 14 patients had syrinxes associated with an intramedullary neoplasm, 3 patients had syringomyelia associated with spinal arachnoiditis and 8 patients had idiopathic syringomyelia. Holocord syrinxes were more often associated with SM-ACM, while focal syrinxes were associated with posttraumatic, spinal arachnoiditis and neoplastic conditions. In all cases with neoplasms the MRI revealed parenchymal intramedullary signal abnormalities in addition to the syrinx cavity. Posterior fossa decompression with obex plugging (the Gardner operation) was the procedure of choice for SM-ACM and for idiopathic holocord syringomyelia. Exploration and drainage of the syrinx with or without shunting was carried out mainly for focal syrinxes associated with trauma and neoplasm. Patients with SM-ACM responded well to posterior fossa decompression with satisfactory results in 24/28 patients. Idiopathic SM is probably a forme fruste of SM-ACM and when treated with the Gardner procedure showed good results in all 8 patients. Posttraumatic and neoplastic SM had the least predictable results with surgery. The disappearance of the syrinx on postoperative MRI correlated well with a good surgical outcome.

Adolescent↗
PubMed1991

Delayed facial nerve palsy after temporal lobectomy for epilepsy: report of four cases and discussion of possible mechanisms.

Four cases of idiopathic peripheral facial nerve palsy were documented after 110 consecutive resections of the temporal lobe for intractable epilepsy. In 3 of the 4 cases, the palsy was ipsilateral to the side of the temporal lobectomy. The onset of facial weakness was delayed 7 to 13 days after surgery (mean, 9.7 days). One patient underwent facial electroneurography, which documented 17% of normal facial motor function at the height of his weakness and the absence of the acoustic stapedius reflex. All patients were treated with prednisone (60-80 mg per day by mouth for 10-14 days, tapering off throughout the subsequent week). Facial function recovered fully in all patients within 6 to 8 weeks. Possible mechanisms are discussed, including heat and/or mechanical trauma to the facial nerve near the geniculate ganglion during resection of mesial temporal lobe structures.

Adult↗
PubMed1991

Symptomatic Chiari malformation in adults: a new classification based on magnetic resonance imaging with clinical and prognostic significance.

Thirty-five consecutive adults with Chiari malformation and progressive symptoms underwent surgical treatment at a single institution over a 3-year period. All patients underwent magnetic resonance imaging scan before and after surgery. Images of the craniovertebral junction confirmed tonsillar herniation in all cases and allowed the definition of two anatomically distinct categories of the Chiari malformation in this age group. Twenty of the 35 patients had concomitant syringomyelia and were classified as Type A. The remaining 15 patients had evidence of frank herniation of the brain stem below the foramen magnum without evidence of syringomyelia and were labeled Type B. Type A patients had a predominant central cord symptomatology; Type B patients exhibited signs and symptoms of brain stem or cerebellar compression. The principal surgical procedure consisted of decompression of the foramen magnum, opening of the fourth ventricular outlet, and plugging of the obex. Significant improvement in preoperative symptoms and signs was observed in 9 of the 20 patients (45%) with syringomyelia (Type A), as compared to 13 of the 15 patients (87%) without syringomyelia (Type B). Postoperative reduction in syrinx volume was observed in 11 of the 20 patients with syringomyelia, including all 9 patients with excellent results. Magnetic resonance imaging has allowed a classification of the adult Chiari malformation in adults based on objective anatomic criteria, with clinical and prognostic relevance. The presence of syringomyelia implies a less favorable response to surgical intervention.

Adult↗
PubMed1989

Correlation between magnetic resonance imaging and surgical findings in the tethered spinal cord.

Between October 1982 and August 1987, 20 patients underwent magnetic resonance imaging (MRI) and subsequent surgical release of a tethered spinal cord. The tethering was caused by a thick filum terminale in 6 patients. On MRI scans, the conus medullaris was at L4 in 2 patients, at L2 in 3 patients, and the filum terminale appeared thick in 1 patient. The spinal cord was tethered to an intradural lipoma correctly demonstrated by MRI in 6 patients. Increased epidural fat was misdiagnosed as an intradural lipoma in one patient and a lipomatous stalk was not identified in 2 other patients. Scar tissue resulting from repair of a meningocele had tethered the cord in the remaining 8 patients. On MRI scans, the conus medullaris was located between L3 and S3; in 5 of the patients, scar tissue was apparent on the MRI scan. This correlative study supports the use of MRI as the initial, and possibly the only, imaging modality when a tethered spinal cord is suspected. Improved or more recent MRI techniques will help demonstrate these anomalies better.

Adolescent↗
PubMed1989

Intracranial meningiomas in the aged: surgical outcome in the era of computed tomography.

Seventy-five patients older than 60 years of age underwent surgical resection of intracranial meningiomas during a 10-year period at a single institution. All patients had a computed tomographic scan preoperatively, and all were followed for at least 3 months postoperatively. There were 50 patients 61 to 70 years of age (Group A), and 25 patients older than 70 years (Group B). Sixteen patients (21%) were asymptomatic, and no patient was severely disabled preoperatively. Operative morbidity and mortality and outcome at 3 months were assessed and correlated with age, preoperative neurological status, and tumor size and location. Operative mortality was 6.6% (6% in Group A; 8% in Group B). Perioperative morbidity (including medical and surgical complications and worsening in neurological status) was 48% (46% in Group A; 52% in Group B). Neurological status 3 months after surgery was improved by at least one grade as compared to before surgery in 40% of patients (38% in Group A; 44% in Group B), unchanged in 29% (34% in Group A; 20% in Group B), and worsened in 31% (28% in Group A; 36% in Group B). While nearly half of the patients were asymptomatic 3 months after surgery, 11 patients (15%) had died or remained seriously disabled. Outcome at 3 months correlated significantly with low neurological grade preoperatively and with a tumor location over the cortical convexity. There was no significant correlation with age or tumor size. We conclude that resection of intracranial meningiomas is associated with significant morbidity and mortality in the elderly.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Extraoperative cortical functional localization in patients with epilepsy.

Functional localization prior to cortical resections for intractable seizures has usually been performed in the operating room in awake patients. Chronically placed subdural electrodes offer the possibility of performing such testing outside of the operating room and without the unavoidable stresses and time limitations of the surgical setting. The use of the technique is reviewed.

Electrodes, Implanted↗
PubMed1987

Acoustic (loudspeaker) facial EMG monitoring: II. Use of evoked EMG activity during acoustic neuroma resection.

Facial electromyographic (EMG) activity was continuously monitored via loudspeaker during eleven translabyrinthine and nine suboccipital consecutive unselected acoustic neuroma resections. Ipsilateral facial EMG activity was synchronously recorded on the audio channels of operative videotapes, which were retrospectively reviewed in order to allow detailed evaluation of the potential benefit of various acoustic EMG patterns in the performance of specific aspects of acoustic neuroma resection. The use of evoked facial EMG activity was classified and described. Direct local mechanical (surgical) stimulation and direct electrical stimulation were of benefit in the localization and/or delineation of the facial nerve contour. Burst and train acoustic patterns of EMG activity appeared to indicate surgical trauma to the facial nerve that would not have been appreciated otherwise. Early results of postoperative facial function of monitored patients are presented, and the possible value of burst and train acoustic EMG activity patterns in the intraoperative assessment of facial nerve function is discussed. Acoustic facial EMG monitoring appears to provide a potentially powerful surgical tool for delineation of the facial nerve contour, the ongoing use of which may lead to continued improvement in facial nerve function preservation through modification of dissection strategy.

Adult↗
PubMed1987

Normal pressure hydrocephalus in children and young adults.

Normal pressure hydrocephalus (NPH) is generally considered to be a disorder of adult and geriatric patients. We report four patients who are children or young adults with chronic neurological disorders, recent deterioration of their levels of function, normal cerebrospinal fluid (CSF) pressures, and ventricular enlargement. All four patients improved after the placement or revision of a ventriculoperitoneal shunt. Frequent symptoms and signs included irritability (three patients), vomiting (three patients), and abnormal limb posturing (two patients). Correct diagnosis was hampered by two factors: (a) Multiple or prolonged recordings of CSF pressures were invariably well within the normal ranges with respect to age, and (b) the patients had chronic neurological deficits. After ventriculoperitoneal shunting, subjective and objective improvement was seen in all cases. Young patients with large ventricles may benefit from shunting procedures despite low CSF pressures. These patients may be clinically identified by symptoms of new neurological dysfunction in cases of previously static neurological disease or acceleration of slowly progressive neurological dysfunction. Some of these underlying neurological disorders may predispose children and young adults to NPH.

Adult↗
PubMed1986

Magnetic resonance imaging (1.5 tesla) in patients with intractable focal seizures.

Magnetic resonance (MR) (1.5 tesla) studies were performed in ten patients with temporal lobe epilepsy and two with temporofrontal epilepsy. Two patients with temporal lobe epilepsy and one with temporofrontal epilepsy exhibited areas of increased signal intensity on T2-weighted images in the mesiobasal portion of the temporal lobe shown by electroencephalography to be the epileptogenic focus; no analogous abnormalities had been found in these patients on computed tomographic scans. Pathologic studies have not revealed a specific ultrastructural correlate for the MR findings in this group of patients. We found MR to be a useful, noninvasive diagnostic adjunct in the presurgical assessment of some patients with temporal lobe epilepsy. Where abnormalities were found, they corresponded with the epileptogenic focus as defined by electroencephalography.

Adult↗
PubMed1986

Postoperative neurological deficits may occur despite unchanged intraoperative somatosensory evoked potentials.

We describe 6 patients who demonstrated postoperative neurological deficits despite unchanged somatosensory evoked potentials during intraoperative monitoring. Although there is both experimental and clinical evidence that somatosensory evoked potentials are sensitive to some types of intraoperative mishap, the technique should be employed with an awareness of its possible limitations.

Adolescent↗
PubMed1986

Neurophysiological techniques as an aid to surgical treatment of primary brain tumors.

We describe a method of cortical stimulation for localizing functional areas of brain before operation for primary brain tumors that was carried out in 14 patients. The method is unique in that the stimulation is done over several days using chronically indwelling subdural electrode arrays. In addition to cortical stimulation findings, somatosensory evoked potentials were helpful in locating the sensorimotor strip. The neurophysiological data have allowed an aggressive neurosurgical attack without producing a functional deficit.

Adolescent↗
PubMed1986

Symptomatic subependymoma in a 14-year-old girl, diagnosed by NMR scan.

Symptomatic subependymomas in the pediatric age group are rare. A 14-year-old girl with a IV ventricle subependymoma is described. She had a 2-month history of progressive headache, neck stiffness and nausea. Computed tomography revealed hydrocephalus for which a ventriculoperitoneal shunt was inserted. A nuclear magnetic resonance (NMR) scan later displayed a mass lesion in the roof of the IV ventricle. A suboccipital craniectomy was performed with total excision of a subependymoma.

Adolescent↗
PubMed1986

Pituitary apoplexy: a complication of cardiac surgery.

Pituitary apoplexy occurred in 3 patients in the immediate postoperative period following cardiac operation with cardiopulmonary bypass. In this setting, this complication is extremely rare and not widely recognized. Precipitating factors may be related to the extracorporeal bypass apparatus, anticoagulation, low cerebral blood flow, and even anesthetic agents. Neurosurgical decompression can be safely performed in the early postoperative period following open-heart operations.

Cardiopulmonary Bypass↗
PubMed1986

Benign osteoblastoma of the orbit.

Benign osteoblastoma is a rare, solitary, vascular, osteoid-producing tumor that is rich in osteoblasts. This is the first report of a case of osteoblastoma of the orbit not contiguous with a sinus cavity.

Child, Preschool↗