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Biomedical subjects

D M Long

Publications and source records attributed to D M Long.

At least 37 records · Page 2Linked to original sources
PubMed1999

The operating room of the future.

The operating room of the future will be designed to have peri-operative integration of all imaging capabilities. Pre-operative planning will become increasingly important, as will integrated intra-operative neuro-navigation. The operative work space will be redesigned to have robotic capabilities. Operating rooms will be isolated. Self-contained modular and robotic monitoring will become remote through improved sensors. The operating microscope will disappear. Light and magnification will be supplied by means other than optical microscopes.

Biomedical Engineering↗
PubMed1999

Association between peridural scar and activity-related pain after lumbar discectomy.

The purpose of this study was to investigate the correlation between activity-related pain six months after first surgery for herniated lumbar disc, and the extent of lumbar epidural fibrosis present at the surgical site, assessed by magnetic resonance imaging. The 298 patients who underwent surgery for lumbar disc herniation were studied in a randomized, controlled, double-blind multicenter clinical trial to test the effectiveness of the scar-inhibiting device ADCON-L. Clinical assessments were conducted pre-operatively and at 1, 3, and 6 month intervals post-operatively, and included wound examination, magnetic resonance imaging scar assessment, and the Johns Hopkins activity-related pain questionnaire. In addition, a longer-term follow-up assessment was conducted at 12 months post-operatively. The association between the presence of epidural scar and activity-related pain was analyzed at the 6-month interval, when successful surgical excision of protruding disc material should have eliminated chronic pain. Logistic regression analysis demonstrated a significant association (p = 0.02, odds ratio = 0.7) whereby the odds of extensive scar decreased by 30% for every 31% decrease in activity-related pain score. In addition, those patients receiving ADCON-L at surgery developed significantly less scar in the months following operation (p = 0.01, 6 and 12 months post-operatively). Repeated measures analysis demonstrated that patients who received treatment with ADCON-L at the time of surgery experienced less activity-related pain through the 12-month assessment (p = 0.05). A significant association between extensive epidural scar and activity-related pain is demonstrated. Patients with less scar had less activity related pain, confirming the finding that the use of the scar inhibitor ADCON-L has a positive effect on surgical outcome.

Adolescent↗
PubMed1999

Harvey Cushing at Johns Hopkins.

Harvey Cushing began surgical training with William Halsted at Johns Hopkins in 1896. Cushing joined the Johns Hopkins faculty in 1900 and spent 1 year in Europe in the laboratory of Theodore Kocher. He returned to Johns Hopkins, where he founded neurosurgery as an independent specialty, established the concept of the clinician scientist, discovered the hormonal properties of the pituitary gland and founded endocrinology, introduced intraoperative x-rays into surgical practice, introduced blood pressure monitoring into the operating room, and wrote the first definitive text on neurosurgery. Although there have been many pioneers in our field, Cushing, more than anyone else, developed neurosurgery as a specialty and left a legacy of talented neurosurgeons to develop and expand the field.

Baltimore↗
PubMed1999

Acoustic neuroma: outcome of surgical resection and study on the anatomy of facial and cochlear nerves.

The treatment of acoustic neuroma (vestibular schwannoma) has evolved greatly. In this report, we studied the history of acoustic tumour surgery, and documented the value of technical advances in benefiting patients. We also present our outcome of surgery for this benign tumour in support of its use as the treatment of choice. In 611 patients undergoing initial surgery at Johns Hopkins from 1973-1994, complete resection was obtained in all but one case (intentional), and permanent morbidity and mortality rate was 0.3%. Including temporary morbidity, the rate was 3.8%. Tumour recurrence was seen in only 0.8% of cases. The facial nerve was preserved in 97.6% and function at one-year was House-Brackmann grade 1 or 2 in 89.7%. Lastly, we present results of an anatomical study localizing the nerves and vessels, and the frequency of involvement by tumour, associated with acoustic neuromas in 1006 surgical cases. We continue to offer surgery as the best treatment option for the majority of our patients, and prefer the suboccipital route because of its unrestricted access to all posterior fossa structures, and ability to preserve hearing.

Adolescent↗
PubMed1998

Late-onset facial nerve degeneration after vestibular schwannoma surgery: incidence, putative mechanisms, and prevention.

Delayed facial nerve dysfunction after vestibular schwannoma surgery is a poorly understood phenomenon that has been reported to occur in 15 to 29% of patients undergoing microsurgery. It is a condition characterized by spontaneous deterioration of facial nerve function in a patient who has otherwise normal or near-normal facial function in the immediate postoperative period. This delayed paralysis is generally reported to occur in the first few days postsurgery, with the majority of patients eventually recovering their immediate postoperative facial function. However, infrequently, it can also occur more than 1 week after surgery (so-called late-onset facial nerve palsy). The authors reviewed facial nerve outcome in 611 patients who underwent microsurgery between 1973 and 1994. The facial nerve was anatomically preserved in 596 patients (97.5%), and 90% of patients had House-Brackmann[6] Grade 1 or 2 function 1 year after surgery. Late-onset facial dysfunction was seen in 13 patients (2.1%). All of these had significant deterioration in facial nerve function between 1 and 4 weeks postoperatively, and all showed improvement by 1 year. In this study, the focus on these patients who developed late-onset facial palsy. The incidence, treatment strategies, and outcomes will be discussed with emphasis on possible pathophysiological mechanisms that contribute to this relatively rare condition.

Journal Article↗
PubMed1998

In vivo addition of telomeric repeats to foreign DNA generates extrachromosomal DNAs in the taxol-producing fungus Pestalotiopsis microspora.

Transformation of the taxol-producing filamentous fungus Pestalotiopsis microspora with a plasmid containing the bacterial hygromycin resistance gene fused to Aspergillus regulatory sequences resulted in the in vivo formation of extrachromosomal DNAs with telomeric repeats in the majority of transformants. Repeats of the telomeric sequence 5'-TTAGGG-3' were appended to nontelomeric transforming DNA termini. No fungal sequences other than telomeric repeats were detected in extrachromosomal DNAs. Transformants contained three to six different sizes or conformational forms of extrachromosomal DNAs. The DNAs showed no change in size or internal structure during 6 months of growth with selection, but were lost after 20 days of growth without selection. Transformation of wild-type P. microspora with a PCR-amplified extrachromosomal DNA having terminal telomeric repeats produced up to 50-fold more transformants than the original transformation vector. The addition of telomeric repeats to foreign DNA is unusual among fungi and may have important adaptive or developmental implications.

Aspergillus nidulans↗
PubMed1998

The current status of electrical stimulation of the nervous system for the relief of chronic pain.

Neuroaugmentation techniques have been in common use for nearly 30 years. Spinal stimulation is the most important treatment mode for many patients with failed back syndrome. Stimulation can replace or supplement reoperation. Stimulation has been shown to be useful in many other chronic pain states and deserves wider application. However, it is not a technique to be used casually. Effective use requires a thorough understanding of the pain states to be treated, appreciation of the comorbidities that accompany chronic pain, an infrastructure to support the patient and the surgeon, and a dedication to lifelong care for the patient with the implant. All of these mean that patients are better handled by a few dedicated individuals than by wide dispersion of the technique among neurosurgeons who see only a few such patients each year. Peripheral nerve stimulation is very effective, but the number of potential candidates is small. Brain stimulation remains investigative and has not yet found a clearly defined place in pain management. If these techniques are to continue to evolve, more basic research on the mechanisms of action will be necessary if efficacy is to be improved. Most of the research to date has been in clinical efficacy. Defining the mechanisms of action will be the next important step.

Electric Stimulation Therapy↗
PubMed1997

Patient characteristics associated with diagnostic imaging evaluation of persistent low back problems.

STUDY DESIGN: Post hoc analysis of data from the National Low Back Pain Study, a prospective observational multicenter study of patients referred for the evaluation and treatment of persistent low back problems. OBJECTIVE: To identify patient characteristics associated with use of particular diagnostic imaging examinations in patients with persistent low back problems. SUMMARY OF BACKGROUND DATA: The Agency for Health Care Policy and Research clinical practice guidelines on low back problems suggest that the use of particular diagnostic imaging tests for a given patient should be based on specific characteristics of that patient. METHODS: Use of diagnostic imaging examinations in 2,374 patients with persistent low back problems who were enrolled in the National Low Back Pain Study from 1986 to 1991 was analyzed. Stepwise logistic regression was used to identify patient characteristics that distinguish between enrollees who underwent particular imaging studies. RESULTS: Characteristics that distinguished patients who had undergone magnetic resonance imaging from those who had received only lumbo-sacral spine radiographs included higher socioeconomic status, greater resource use in the preceding 12 months, more functional impairment, presence of sciatica, and presence of neurologic signs/symptoms suggestive of nerve root compromise. Suspected soft tissue involvement was characteristic of enrollees who had undergone magnetic resonance imaging, whereas suspected structural involvement characterized patients who received noncontrast computed tomography. Only nonclinical factors, such as higher annual household income, disability compensation, and male gender distinguished enrollees who had undergone both magnetic resonance imaging and computed tomography-myelography from those who received only computed tomography-myelography. CONCLUSION: Particular patient socioeconomic and clinical characteristics are associated with receipt of specific imaging studies in evaluation of persistent low back problems.

Adult↗
PubMed1997

Enzymatic assay of beta-lactamase using circular dichroism spectropolarimetry.

A method for measuring the rates of enzymatic hydrolysis of beta-lactam antibiotics based on circular dichroism spectropolarimetry is described. Unhydrolyzed beta-lactam antibiotics have high molar ellipticities, but the hydrolyzed compounds are circular dichroism (CD) inactive in the case of penams or have significantly different CD spectra in the case of cephems. By measuring CD at constant wavelength as a function of time for reaction mixtures containing beta-lactamase and beta-lactam antibiotics, rates of hydrolysis and steady-state enzyme kinetic constants can be derived. The method was applied to measurement of a wide range of enzymatic reaction constants for wild-type and four mutant RTEM-1 beta-lactamases. Compared to the commonly employed assay based on ultraviolet spectroscopy, the new method offers several advantages. These include the ability to measure larger enzymatic Michaelis-Menten constants, less interference from high concentrations of beta-lactamase, higher sensitivity, and potentially less interference from other uv-absorbing components of complex reaction mixtures.

Anti-Bacterial Agents↗
PubMed1997

Personality traits, pain duration and severity, functional impairment, and psychological distress in patients with persistent low back pain.

The relationships between psychological distress, pain duration, neuroticism, extraversion, pain severity, and functional impairment were examined in a large group of patients with persistent complaints of low back pain. We evaluated patients on a host of relevant variables before treatment and at 1 year and 2 years after treatment which permitted assessment of the stability of the relationships over time. We found that the levels of psychological distress reported by patients were not related to the duration of their complaint. Rather, levels of psychological distress are related to both aspects of the patients' personalities, and characteristics of their illness. Patients who scored high on neuroticism reported higher levels of psychological distress than patients who scored low on this trait. Similarly, patients who had more severe pain and were more functionally impaired also reported higher levels of psychological distress due to pain. The relative strengths of these relationships varied with treatment status. Before treatment, psychological distress and neuroticism were strongly related, but after treatment, the relationship was moderate. In contrast, the relationship of psychological distress to pain severity and functional impairment was significantly strengthened after treatment. We attributed this shift in the relative strengths of the relationships to change in the patient perception of their illness.

Adult↗
PubMed1997

Trends in diagnostic imaging for low back pain: has MR imaging been a substitute or add-on?

PURPOSE: To assess whether magnetic resonance (MR) imaging has replaced other diagnostic imaging modalities in the evaluation of persistent low back pain. MATERIALS AND METHODS: Data on diagnostic imaging use in 2,374 adult patients with persistent low back pain in 1987-1990 were analyzed. Multiple logistic regression was used to estimate the annual adjusted odds of lumbosacral spine radiography, MR imaging, unenhanced computed tomography (CT), or CT myelography use. The national cost of diagnostic imaging for persistent low back pain in 1990 relative to 1987 was estimated. RESULTS: The adjusted odds of performing MR imaging in 1990 relative to 1987 was 3.44 (95% confidence interval, 2.63, 4.51), which reflects an estimated increase from 22 studies per 100 enrollees in 1987 to 75 studies per 100 enrollees in 1990. Use of MR imaging in combination with radiography, unenhanced CT, or CT myelography increased. The additional national cost of diagnostic imaging for persistent low back pain in 1990 relative to 1987 was estimated at $70-$176 million. CONCLUSION: MR imaging was used primarily as an add-on rather than a substitute for other imaging modalities in the evaluation of persistent low back pain. Thus, the volume and cost of diagnostic imaging for persistent low back pain have increased.

Adult↗
PubMed1997

Persistent low back pain in patients suspected of having herniated nucleus pulposus: radiologic predictors of functional outcome--implications for treatment selection.

PURPOSE: To assess the relationship between imaging findings, therapy, and functional outcome in patients with persistent low back pain who are suspected of having herniated nucleus pulposus. MATERIALS AND METHODS: Data collected during a multicenter, longitudinal study were retrospectively analyzed (n = 1,084). Multivariate regression was used to determine the association between imaging findings, therapy, and functional outcome. The patient outcome measure was disability days: the number of days the patient was unable to perform work-related activities. RESULTS: In patients with at least one normal advanced (imaging other than plain radiography) diagnostic study or with an unconfirmed diagnosis of herniated nucleus pulposus, outcome at 2-year follow-up was no better in patients who were treated than in those who were not. In patients with only abnormal advanced imaging results or with a concordant diagnosis based on clinical and imaging findings, outcome was better in patients who underwent surgery than in those treated nonsurgically. Patients with a free fragment, protrusion, or extrusion that was treated surgically had fewer disability days than patients treated nonsurgically. CONCLUSION: Advanced diagnostic imaging studies can play an important role in treatment selection in patients with persistent low back pain who are suspected of having herniated nucleus pulposus.

Absenteeism↗
PubMed1997

Facial nerve injury in acoustic neuroma (vestibular schwannoma) surgery: etiology and prevention.

Facial nerve injury associated with acoustic neuroma surgery has declined in incidence but remains a clinical concern. A retrospective analysis of 611 patients surgically treated for acoustic neuroma between 1973 and 1994 was undertaken to understand patterns of facial nerve injury more clearly and to identify factors that influence facial nerve outcome. Anatomical preservation of the facial nerve was achieved in 596 patients (97.5%). In the immediate postoperative period, 62.1% of patients displayed normal or near-normal facial nerve function (House-Brackmann Grade 1 or 2). This number rose to 85.3% of patients at 6 months after surgery and by 1 year, 89.7% of patients who had undergone acoustic neuroma surgery demonstrated normal or near-normal facial nerve function. The surgical approach appeared to have no effect on the incidence of facial nerve injury. Poor facial nerve outcome (House-Brackmann Grade 5 or 6) was seen in 1.58% of patients treated via the suboccipital approach and in 2.6% of patients treated via the translabyrinthine approach. When facial nerve outcome was examined with respect to tumor size, there clearly was an increased incidence of facial nerve palsy seen in the immediate postoperative period in cases of larger tumors: 60.8% of patients with tumors smaller than 2.5 cm had normal facial nerve function, whereas only 37.5% of patients with tumors larger than 4 cm had normal function. This difference was less pronounced, however, 6 months after surgery, when 92.1% of patients with tumors smaller than 2.5 cm had normal or near normal facial function, versus 75% of patients with tumors larger than 4 cm. The etiology of facial nerve injury is discussed with emphasis on the pathophysiology of facial nerve palsy. In addition, on the basis of the authors' experience with these complex tumors, techniques of preventing facial nerve injury are discussed.

Adolescent↗
PubMed1996

In vivo accuracy testing and clinical experience with the ISG Viewing Wand.

OBJECTIVE: A frameless stereotactic system (the Viewing Wand; Elekta Instruments, Atlanta, GA) has been developed for use with preoperative computed tomography, magnetic resonance imaging, and positron emission tomography as an adjunct for surgical planning and intraoperative navigation. This clinical study was designed to evaluate the safety, efficacy, and accuracy of the Viewing Wand in a variety of intracranial procedures. METHODS: We used this system in 250 patients undergoing a wide range of neurosurgical procedures from July 1990 to July 1994, to assess its clinical usefulness and safety. In a subset of 45 neurosurgical patients studied between March 1993 and March 1994, a battery of objective accuracy measurements was obtained before and during surgery. RESULTS: In this series, there were no instances of adverse outcomes attributable to the use of this system. A comparison of two alternative patient-image registration techniques established that the fiducial-fit method was slightly more accurate than the surface-fit method (geometric means = 2.51 and 3.03 mm, respectively). The clinical accuracy achieved with magnetic resonance imaging was nearly equivalent to that with computed tomography. CONCLUSIONS: On the basis of this clinical series, recommendations are made regarding preoperative scanning parameters, registration techniques, and methods for reestablishing registration if needed during the course of surgery. The primary clinical benefits of the wand in this series were improved intraoperative navigation and surgical safety. For most cases, the wand was also useful in planning the location and size of the scalp incision, craniotomy, or corticotomy, as well as the extent of surgical resection.

Adolescent↗
PubMed1996

State legislation related to breast cancer: 1980-1994.

Increased screening mammography usage is important for reducing breast cancer mortality in the United States. This article summarizes state breast cancer screening legislation enacted between 1980-1994. Forty-three laws were identified and analyzed based on five categories: screening/education programs; third-party reimbursement for screening; third-party reimbursement for reconstruction/prosthesis; mammography facility accreditation; and alternative therapy information. Third-party reimbursement mandates were subdivided into Medicaid/public assistance; state employee health benefits; Medicare supplement insurance; age/frequency provisions; and screening based on risk factors besides age. The larger context of breast cancer screening needs for the present and future are discussed.

Adult↗
PubMed1996

Persistent back pain and sciatica in the United States: patient characteristics.

Low back pain is an extremely common, seriously disabling, nonfatal public health problem worldwide. The National Low Back Pain Study was a multicenter study of a large, heterogeneous group of patients who have been referred to either a neurosurgeon or an orthopedic surgeon for the evaluation and treatment of a persistent complaint of low back pain. In this paper, we characterize persistent low back pain patients and their complaints, describe the impact of persistent low back pain on the patients' functional and psychological status, report on the patients' medical characteristics, and identify treatments that are currently prescribed for these patients. Persistent low back pain is most common among people in their mid-to-late thirties and early-to-mid forties. The patients are mostly white, well educated, and generally affluent. The majority are gainfully employed, but some quit working because of pain and those who do tend to be less educated, and more likely to be involved in litigation. The average patient has had low back pain intermittently for 10 years. The pain is usually well localized but its severity varies considerably. Besides pain, most persistent low back pain patients report a variety of motor and sensory deficits. Patients also report significant functional impairment at work, at play, and at home. The typical patient does not, however, display significant psychological distress. Most patients have consulted multiple health care providers, have received a variety of treatments, and have used a variety of medications to alleviate pain; a few have been subjected to more aggressive treatment measures including surgery, intradiscal therapy, and narcotic and psychoactive drugs. None of these treatments has been effective. Physical examinations of these patients do not provide significant clues for making a definitive diagnosis. Nonspecific abnormalities such as muscle spasm, tenderness, and trigger points are quite common, but motor weakness and sensory deficits in the lower extremities, and reflex changes in the knees and ankles, are much less common. The classic combination of reflex changes, motor weakness, and sensory deficits associated with specific protruded discs are extremely rare even though one of three patients had a diagnosis of disc herniation. Diagnostic imaging studies revealed that the majority of persistent low back pain patients have spondylotic abnormalities involving root compression or lumbar instability or both, with root compression as the primary cause of the complaint. Myofascial syndrome and lumbar instability were the next most common diagnoses. After a thorough evaluation by specialists in spinal disorders, three of five persistent low back pain patients were prescribed an additional course of conservative therapy, one of five was prescribed surgery, and the rest were prescribed no treatment. Persistent low back pain patients appear to be a distinct group of low back pain patients who are different from patients who have similar nonpersistent acute symptoms and those who have the chronic pain syndrome characterized by significant behavioral and psychological co-morbidities.

Adult↗