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Biomedical subjects

D E Mattox

Publications and source records attributed to D E Mattox.

At least 19 recordsLinked to original sources
PubMed2001

Immunolocalization of erythropoietin and erythropoietin receptor in vestibular schwannoma.

Vestibular schwannomas constitute approximately 6% of intracranial tumors. Apart from the association with neurofibromatosis-2 (NF-2), where a defect in chromosome 22 has been identified, the pathogenesis of sporadic vestibular schwannomas is largely unknown. Very few studies have explored the role of neurotrophic growth factors in vestibular schwannoma. The objective of this study is to evaluate for the presence and pattern of EPO and EPO-R expression within vestibular schwannomas. Our hypothesis that erythropoietin (EPO) and erythropoietin receptor (EPO-R) were expressed in vestibular schwannomas was based on a recent report of rapid growth of a vestibular schwannoma in a patient undergoing preoperative EPO treatment. Using immunohistochemistry, we have demonstrated that both EPO and EPO-R are expressed in a majority of these tumors.

Cerebellum↗
PubMed2000

Temporal lobe injury in temporal bone fractures.

OBJECTIVE: To determine the incidence of intracranial injury, specifically in the temporal lobe, in patients with longitudinal fractures of the temporal bone. DESIGN: Prospective inception cohort. SETTING: University of Maryland Division of Otolaryngology-Head and Neck Surgery and the Maryland Shock Trauma Center, Baltimore. PATIENTS: Twenty-seven consecutive patients with unilateral or bilateral temporal bone fractures. MAIN OUTCOME MEASURES: Evaluation of temporal bone and intracranial trauma using computed tomography (CT) and magnetic resonance imaging (MRI). RESULTS: Of the 27 patients enrolled in the study, 12 had the complete battery of MRI, CT, and physical and audiological examinations. In all 12 patients, MRI demonstrated adjacent middle cranial fossa meningeal enhancement. Results of non-contrast-enhanced CT and MRI demonstrated ipsilateral temporal lobe contusions in 6 of the 13 fractures for an overall incidence of 46%. In addition, MRI demonstrated 4 cerebral contusions not seen in the results of non-contrast-enhanced CT. CONCLUSIONS: While high-resolution CT remains the criterion standard for evaluation of temporal bone fractures, MRI revealed a higher incidence of related temporal lobe injuries. Magnetic resonance imaging data may be valuable in preoperative evaluation of patients who require surgical intervention through a middle cranial fossa approach to document pre-existing injury and potential morbidity before retraction of the middle cranial fossa dura mater and temporal lobe.

Adolescent↗
PubMed1999

Success of the modified Epley maneuver in treating benign paroxysmal positional vertigo.

OBJECTIVE: Benign paroxysmal positional vertigo (BPPV) is a common condition seen by otolaryngologists. The purpose of this study is to determine the ability of the modified Epley maneuver to treat BPPV. STUDY DESIGN: Retrospective review. METHODS: A retrospective chart review of 107 patients diagnosed with BPPV at our institution between March of 1993 and June of 1995. Each patient was diagnosed with isolated BPPV by history and Hallpike-Dix maneuver. There were no other vestibular symptoms or electronystagmogram abnormalities. Patients diagnosed with BPPV received modified Epley maneuvers, were instructed to remain upright for 48 hours, and wore a soft collar for a week. Patients were followed up with repeat Hallpike-Dix maneuvers at 1 to 2 weeks. If symptoms persisted, the maneuver was repeated for up to a maximum of three times, at which point patients were considered to have failed treatment. RESULTS: The average age of patients was 57.8 years old. Thirty percent were male and the right ear was affected in 54%. The posterior semicircular canal was affected in 105 ears. The average patient received 1.23 Epley maneuvers, with a success rate of 93.4%. No successfully treated patients received mastoid vibration. Seven out of 107 patients failed after three Epley maneuvers. Two failure patients had a history of temporal bone fracture. Two failure patients were treated with posterior semicircular canal block surgery. CONCLUSION: The modified Epley maneuver is an excellent treatment for BPPV.

Female↗
PubMed1997

External auditory canal wall cholesteatoma: a complication of ear surgery.

Primary external auditory canal wall cholesteatomas are usually present in the inferior portion of the canal lateral to the tympanic membrane. Small inclusion cysts are a common finding along incision lines after ear surgery. This report details 5 cases of large canal wall cholesteatomas after prior ear surgery. The middle ear or mastoid was not directly involved in any of the cases. The largest of these presented 8 years after the initial procedure and eroded in the middle and temporal fossae. A common feature among these patients was an extended period in which the patient was lost to follow-up after surgery. This experience reinforces the need for vigilant long term follow up even in the asymptomatic postoperative patient.

Adolescent↗
PubMed1995

Vestibular adaptation exercises and recovery: acute stage after acoustic neuroma resection.

The use of exercises in the treatment of patients with vestibular deficits has become increasingly popular, and evidence exists that these exercises are beneficial in patients with chronic vestibular deficits. The question as to whether patients with acute unilateral vestibular loss would benefit from vestibular adaptation exercises is particularly compelling, however, because animal studies have demonstrated that the acute stage after unilateral vestibular loss is a critical period for recovery. Deprivation of visuomotor experience during that period can delay the onset of recovery as well as prolong the recovery period. Patients often avoid movement during the early stage because, with movement, they experience an increase in dysequilibrium and nausea. We examined the recovery of postural stability in patients during the acute stage after resection of acoustic neuroma to determine whether vestibular adaptation exercises facilitate the onset of recovery and improve the rate of recovery. The results suggest that vestibular adaptation exercises result in improved postural stability and in a diminished perception of dysequilibrium.

Adult↗
PubMed1994

Histologic and ultrastructural features of explanted Arenberg shunts.

Four Arenberg endolymphatic shunts that had been implanted in patients for 6 years, 3 years, 24 months, and 11 months were removed during retrolabyrinthine nerve sections (two cases), labyrinthectomy (one case), or cochlear implant (one case). The shunts were examined and photographed grossly and the components were prepared for light and scanning electron microscopy. Acellular debris filled the vestibule around the valve in all cases. The same material filled the inside of the valve in two cases and could be seen coming through the valve in two cases. Two shunts had ingrowth of fibrous tissue into the sponge. The finding of greatest concern was multiple erosions seen in the Supramid tube (S. Jackson Inc, Alexandria, Va) that inserts into the endolymphatic sac. On scanning electron microscopy, these erosions appeared as a network of cracks in the outer surface of the tube. The two shunts implanted for the longest time had fenestrae completely through the tube wall. These findings question the long-term functioning and integrity of the Arenberg shunt.

Adult↗
PubMed1993

Single treatment approaches to benign paroxysmal positional vertigo.

OBJECTIVE: To determine the effectiveness of two different physical therapy approaches for benign paroxysmal positional vertigo. DESIGN: Randomized study. SETTING: Outpatient clinic. PATIENTS: Consecutive sample of 60 patients with benign paroxysmal positional vertigo. INTERVENTION: Patients received either a single treatment based on the hypothesis that the vertigo and nystagmus of benign paroxysmal positional vertigo are due to debris adhering to the cupula of the posterior semicircular canal (cupulolithiasis) or a single treatment based on the hypothesis that the debris is free floating in the long arm of the posterior canal (canalithiasis). Patients were reevaluated 1 to 2 weeks after the treatment and again 4 to 6 months later. OUTCOME: Treatment outcome was classified as either asymptomatic, more than 70% improved as rated by the patient, or no change. RESULTS: The treatment designed for cupulolithaisis resulted in remission of vertigo and nystagmus in 70% of the patients and in improvement of the symptoms in another 20%. The treatment designed for canalithiasis resulted in remission of vertigo and nystagmus in 57% of the patients and in improvement in another 33%. There was no statistically significant difference between treatments. CONCLUSIONS: These single-treatment approaches are equally effective treatments for benign paroxysmal positional vertigo. Further studies are needed to look at the long-term effectiveness of these treatments.

Adult↗
PubMed1993

Frameless stereotaxic integration of CT imaging data: accuracy and initial applications.

To evaluate the spatial accuracy of a rapid interactive method of transferring computed tomographic (CT) information between its display on a computer screen to its source (test object, operating field), a multidimensional computer combined with a six-jointed position-sensing mechanical arm was tested with a Plexiglas model consisting of 50 rods of varied height and known location, a plastic replica of the skull, and, subsequently, three patients. The median error value between image and real location was 1-2 mm (P > .95), regardless of the registration target sites. The accuracy, however, increased with the selection of widespread registration points, and 95% of all errors were below 3.70 mm (P > .95). The results compare favorably with the four most commonly used stereotaxic framed units. A misregistration error of 0.3-2.2 mm was found during intraoperative correlation between anatomy on the CT display and actual anatomic location in the operative field.

Child↗
PubMed1992

Complications and early outcome of anterior craniofacial resection.

OBJECTIVE: To evaluate the complications of anterior craniofacial resection and correlate their impact with tumor control status. DESIGN: We conducted a retrospective review of 32 consecutive, operable patients' records seen over a 6-year period, requiring 35 procedures. SETTING: Academic tertiary referral medical center. PARTICIPANTS: Twenty-six patients (81%) had malignant lesions (esthesioneuroblastoma, squamous cell carcinoma, and a group of miscellaneous malignant tumors). Six patients had various benign neoplasms. INTERVENTION: The surgical approach involved bifrontal craniotomy coupled with lateral rhinotomy in 19 cases (61%), facial degloving in 10 cases (32%), a total rhinectomy in one case, and endoscopic sinusectomy without facial incision in two cases. OUTCOME MEASURE: Clinically noted complications and oncologic outcome. RESULTS: There was one avoidable perioperative death indirectly associated with the patient's procedure. Nine patients suffered significant intracranial neurological complications such as tension pneumocephalus and delayed epidural abscess. All of these complications were managed successfully. Of patients with malignant tumors, 13 (52%) are alive with no evidence of disease and one is alive with recurrence after a mean follow-up period of 28.9 months. The 10 patients who succumbed to disease had a mean postoperative survival of 22.9 months. CONCLUSIONS: In contrast to the perspective of only a decade ago, we conclude that craniofacial resection is a relatively safe, versatile, and effective procedure for surgical management of tumors involving the anterior skull base.

Adult↗
PubMed1992

The utility of magnetic resonance imaging in the diagnosis of intranasal meningoencephaloceles.

We present three patients in whom the diagnosis of intranasal meningoencephalocele was made by magnetic resonance imaging. The initial clinical evaluation and computed tomographic examinations of these patients failed to distinguish between chronic inflammation and intranasal meningoencephalocele. Although both computed tomography and magnetic resonance imaging are used to distinguish between normal, inflammatory, and neoplastic tissue in the nasal cavity and paranasal sinuses, limitations do exist and these are the focus of our communication. A clear understanding of the efficacy of these radiographic modalities will enhance surgical planning and can preclude severe complications.

Encephalocele↗
PubMed1991

Sutureless vascular anastomosis with biocompatible heat-shrink tubing.

We have tested a new method of vascular repair using biocompatible, low-temperature, heat-shrinkable tubing on canine carotid arteries. All of 16 canine carotid arteries were patent immediately after the anastomosis. None of the anastomoses leaked after the clamps were released. Average time from severing the vessel to releasing the clamps was 12 minutes. At 2 weeks, nine of 12 vessels were patent; the three failures were attributed to infection of a seroma that occurred in all of the dogs' necks. Histologic evaluation of the uninfected cases showed no inflammatory exudate around the prosthesis. Macroscopic and electron microscopic examination confirmed healing of the endothelium across the anastomoses. Sutureless vascular anastomosis with biocompatible heat-shrink tubing is a potential new modality for the acute repair of severed vessels.

Anastomosis, Surgical↗
PubMed1991

The effects of polyamines and polyamine inhibitors on rat sciatic and facial nerve regeneration.

The effects of exogenous polyamines and polyamine biosynthetic pathway inhibitors on regenerating nerves were examined in adult male rats following nerve transection and surgical repair. Several studies have demonstrated the efficacy of exogenous polyamines in promoting the functional recovery of peripheral nerves following crush or freeze injuries in the rat. In order to simulate clinical peripheral nerve surgery, we studied these effects after complete nerve transection and evaluated regeneration by counting axons. There was no statistical difference in axon number with and without polyamines and in the presence of inhibitors and inhibitors with end product addition. Our study suggests that the difference in recovery seen in previous studies is not mediated by a change in axon number.

Animals↗
PubMed1991

The effects of DFMO on polyamine metabolism in the inner ear.

Difluoromethylornithine (DFMO) is a novel antineoplastic agent that was associated with an unexpected hearing loss in Phase II clinical trials. DFMO interferes with polyamine synthesis by inhibition of the enzyme ornithine decarboxylase (ODC). The objective of the current study was to establish a methodology to determine the effect of DFMO on polyamine levels and ODC activity in the cochlea. Guinea pigs received DFMO in their drinking water and were tested for auditory brainstem response threshold shifts. The organ of Corti, the lateral wall, and the acoustic nerve were assayed for both ODC activity and polyamine levels. In DFMO treated animals there was an inhibition of ODC activity in cochlear tissues as well as in intestinal mucosa. In addition, a significant depletion of cochlear polyamines was observed in the treatment animals. This study suggests that systemically administered DFMO inhibits ODC activity and interferes with polyamine synthesis in the cochlea.

Animals↗
PubMed1991

Central nervous system changes associated with noise-induced hearing loss: an electron microscopic and freeze-fracture study of the chick nucleus magnocellularis.

This investigation assessed the effects of noise-induced hearing loss on the avian nucleus magnocellularis, the homologue of the mammalian cochlear nucleus. Fifteen-day-old chicks were exposed to high-intensity broad-band noise (132 dBA) for 24 to 72 hours. Hearing loss was documented with auditory brain-stem response recordings and scanning electron microscopy of the basilar papilla. Nucleus magnocellularis was assessed with thin-section electron microscopy and freeze-fracture techniques. Freeze-fracture preparations of noise-exposed animals showed a decrease in synaptic vesicle fusion sites at the synaptic active zone, a decrease in re-uptake of presynaptic membrane by coated vesicles, and a shift of the preferential fracture plane at the synapse from the presynaptic membrane to the post-synaptic membrane. These findings support the hypothesis that the effects of noise are not limited to the auditory periphery, but that transneuronal changes extend into the auditory central nervous system.

Animals↗
PubMed1991

Repair of peripheral nerves of unequal diameters.

Four techniques for anastomosis were investigated for the anastomosis of a large proximal segment to a smaller distal segment of rat peripheral nerve with a size disparity of approximately 3 to 1. The techniques were perineural sutures (group I), KTP laser annealing (group II), collagen tubes with a 5-mm gap between the nerve segments (group III), and collagen tubes without a gap between the nerve ends (group IV). At 6 weeks there were no gross nerve distractions in groups I or IV. There were two failures in group II and three in group III. The percentage of fibers that crossed intact anastomoses were: group I, 89%; group II, 75%; group III, 115%; group IV, 125% (P less than .05 for the collagen tube repairs). Our results indicate that the suture technique is still the most reliable method of nerve repair. However, collagen tubes were effective in increasing the percentage of axons crossing the anastomosis.

Anastomosis, Surgical↗