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Biomedical subjects

D P Chason

Publications and source records attributed to D P Chason.

At least 19 recordsLinked to original sources
PubMed2000

Safety of MR scanning in patients with nonferromagnetic aneurysm clips.

The purpose of this study was to report our surveillance of patients with nonferromagnetic aneurysm clips (NFAC) who have undergone magnetic resonance imaging (MRI). Forty-six patients with NFAC underwent MRI over a 7-year period. Medical records were studied for evidence of subjective or objective clinical findings as a result of the MRI scan. In two patients with subjective complaints, computed tomograms (CT) were reviewed and patient interviews conducted. No significant neurologic signs or longterm symptoms were experienced. Two patients did not complete their MRI scans due to transient unilateral head pain in one and head "pressure" in another. CT scans in these patients demonstrated no evidence for hemorrhage or visible change in clip position. We documented no objective adverse outcome of patients undergoing MRI with NFAC, confirming that MRI can be performed safely in patients with nonferromagnetic aneurysm clips. The cause of subjective complaints in two of our patients is unknown.

Adult↗
PubMed2000

Recurrent (nonfamilial) hemangioblastomas involving spinal nerve roots: case report.

OBJECTIVE AND IMPORTANCE: Spinal nerve root hemangioblastomas are rare and are reported mainly in patients with von Hippel-Lindau (VHL) syndrome. The pathogenesis of so-called nonfamilial lesions is virtually unknown. We discuss, mainly from a molecular perspective, a unique patient with sporadic, recurrent hemangioblastomas restricted to spinal nerve roots. CLINICAL PRESENTATION: A 53-year-old man who had had a surgically corrected lumbosacral meningomyelocele presented on at least three occasions during a 17-year period with multifocal capillary hemangioblastomas involving spinal nerve roots. On each occasion, tumors appeared on a different nerve root, with the majority located in the midcervical segments. The patient had no clinical features or family history of VHL syndrome. TECHNIQUE: To obtain a clearer understanding of the pathogenesis of this unusual case and its relationship to VHL syndrome, molecular analysis of the VHL gene was performed by use of complete sequence analysis and loss of heterozygosity studies on deoxyribonucleic acid derived from the patient's blood leukocytes and three separately resected hemangioblastomas. CONCLUSION: Germ-line molecular analysis performed on all three exons in the VHL gene coding region did not indicate that any mutations were present. Loss of heterozygosity analysis of deoxyribonucleic acid from the three hemangioblastoma resections showed normal heterozygosity in the 3p25-26 region. Complete VHL gene sequence analysis did not demonstrate a somatic mutation in the coding region of the VHL gene in any of the three tumors, thereby supporting the loss of heterozygosity data that a molecular event directly involving the VHL gene may not be the causative factor in their tumorigenesis.

Base Sequence↗
PubMed1998

Dementia associated with cortical dysplasia.

Detailed neuropathologic examination was performed on a 47.5-year-old man with an unusual adult-onset dementing illness. His initial symptoms were those of depression, memory loss, and personality change. He developed progressive cognitive decline with prominent psychiatric symptoms. Seizures began approximately 11 months prior to death and he died 5.5 years after onset of symptoms. Pathologic examination of the brain at autopsy revealed organizing necrosis of the hippocampi, felt to be the result of his seizures. More significant was the finding of widespread microscopic nodular cortical dysplasia. The dysplastic nodules were composed of clusters of abnormal cells with enlarged, pleomorphic, vesicular nuclei, many of which contained nucleoli and had ballooned cytoplasm. There were no mitoses. Cortical dysplasia is most commonly associated with childhood-onset seizures. It has not, to our knowledge, been reported as a cause of dementia. Whether or not the dysplasia was the basis of the patient's dementia is difficult to say with certainty, but we discuss possible pathoetiologic mechanisms of dementia due to cortical dysplasia.

Brain↗
PubMed1998

Treatment of femur fracture with associated head injury.

OBJECTIVES: The aim of this study was to determine (a) whether delay in femur fracture stabilization beyond twenty-four hours in patients with head injury increased the risk of pulmonary complications and (b) whether immediate (up to twenty-four hours) femur fracture stabilization increased the risk of central nervous system (CNS) complications. DESIGN: Retrospective analysis. MATERIALS AND METHODS: Thirty-two patients with femur fracture and head injury were identified. Fourteen underwent immediate stabilization of their fractures, and eighteen underwent delayed (four-teen patients) or no (four patients) stabilization of their fractures. RESULTS: In the immediate stabilization group, five patients had severe head injuries [Glasgow Coma Score (GCS) < or = 8] and nine had mild head injuries (GCS > 8). In the mild head injury group, no patient had a pulmonary complication and one had a CNS complication. In the severely head-injured group, one patient had a pulmonary complication and no patient had a CNS complication. In the delayed stabilization group, six patients had mild head injuries (GCS > 8) and twelve had severe head injuries (GCS < or = 8). In the mildly head injured group, one patient had a pulmonary complication, two patients had CNS complications, and one patient died. In the severely head injured group, nine patients had pulmonary complications, three patients had CNS complications, and one patient died. Logistic regression identified delay in femur stabilization as the strongest predictor of pulmonary complication (p = 0.0042), followed by severity of chest Abbreviated Injury Score (AIS; p = 0.0057) and head AIS (p = 0.0133). Delaying fracture stabilization made pulmonary complications forty-five times more likely. Each point increase in the chest AIS and head/neck AIS increased the risk of pulmonary complication by 300 percent and 500 percent, respectively. A statistically significant predictor of CNS complications could not be identified by using logistic regression. CONCLUSION: Delay in stabilization of femur fracture in head-injured patients appears to increase the risk of pulmonary complications. However, due to selection bias in this patient sample, this question cannot be definitively answered. Early fracture stabilization did not increase the prevalence of CNS complications.

Adolescent↗
PubMed1998

Supratentorial giant cell ependymoma: a case report.

Ependymomas are neoplasms of the central nervous system that are capable of demonstrating remarkably heterogeneous histologic features. These tumors originate from ependymal cells lining the ventricles, the choroid plexus, the central canal of the spinal cord, and the filum terminale, so they are therefore seen throughout the neuraxis. We describe the case of a 26-year-old man who experienced a 3-week history of right-sided numbness and a 1-week history of worsening bifrontal headache. Computed tomographic scanning and magnetic resonance imaging of his head demonstrated an irregularly enhancing mass involving the left medial frontal lobe, with extension across the corpus callosum and expansion into the body and atrium of the left lateral ventricle. Histologic, immunohistochemical, and electron microscopic findings were consistent with an anaplastic ependymoma. Unique to this neoplasm was the presence of multiple tumor giant cells. The presence of pleomorphic tumor giant cells is a characteristic feature of the subependymal giant cell astrocytoma, and it is also commonly seen in pleomorphic xanthoastrocytoma and glioblastoma multiforme. Bizarre giant cells were recently described in two filum terminale ependymomas. This report presents the first case of a supratentorial giant cell ependymoma with anaplastic features.

Adult↗
PubMed1996

Diabetic muscle infarction: radiologic evaluation.

OBJECTIVE: Diabetic muscle infarction (DMI) is frequently misdiagnosed clinically as abscess, neoplasm, or myositis, and is often biopsied. Clinical and radiologic findings are presented here to enable the radiologist to suggest the correct diagnosis. DESIGN AND PATIENTS: Four patients with severe diabetes mellitus presenting with acute thigh pain, tenderness, and swelling were evaluated by imaging techniques and biopsy. RESULTS AND CONCLUSIONS: Edema in the affected muscles was seen in two patients with MRI studies. Femoral artery calcification and mild muscle swelling was present in one patient who underwent CT. Decreased echogenicity was seen in the involved muscle in a patient studied with ultrasound. Serum enzymes were normal or mildly elevated in three patients (not reported in one). Biopsy demonstrated necrosis and regenerative change in all cases. MRI, although nonspecific, is the best imaging technique to suggest the diagnosis of DMI in the appropriate clinical setting, thereby obviating biopsy.

Adult↗
PubMed1996

Central nervous system lymphoma not detectable on single-photon emission CT with thallium 201.

A 33-year-old man with acquired immunodeficiency syndrome had an erosive supraglottic mass visible on CT scans of the neck; biopsy was postponed because of the patient's debilitated condition. Two weeks later, he was admitted with altered mental status; an MR image of the brain obtained at that time showed multiple bilateral mass lesions, the largest of which was 5 cm. Findings on a thallium-201 single-photon emission CT (SPECT) scan of the brain were normal. Ten days later, the patient died and autopsy showed both the neck and the brain lesions to be large-cell lymphoma. This case is counterevidence to the reported 100% sensitivity of thallium-201 brain SPECT for demonstrating lymphoma of the central nervous system.

Adult↗
PubMed1995

High-voltage electric injury: assessment of muscle viability with MR imaging and Tc-99m pyrophosphate scintigraphy.

PURPOSE: To evaluate use of magnetic resonance (MR) imaging and technetium-99m pyrophosphate (PYP) scintigraphy in preoperative assessment of muscle viability after high-voltage electric injury. MATERIALS AND METHODS: Twelve injured limbs were studied. Immediate, equilibrium, and delayed Tc-99m PYP scintigrams and gadolinium-enhanced and unenhanced MR images were obtained. Imaging results were compared with clinical findings. RESULTS: Scintigraphy demonstrated nonperfusion in four limbs that were subsequently amputated, but MR imaging had poor sensitivity in nonperfused regions owing to lack of edema. Tc-99m PYP uptake increased at transition zones between normal and nonperfused regions. MR imaging allowed further characterization of these zones by demonstrating edema as enhancing (perfused) or nonenhancing (nonperfused). In all nonamputated limbs, edema showed enhancement. CONCLUSION: In high-voltage electric injury, gadolinium-enhanced MR imaging appears able to demonstrate zones of potential viability within radionuclide-avid tissue but has poor perfusion sensitivity when used alone.

Amputation, Surgical↗
PubMed1994

Cervical spine movement during orotracheal intubation: comparison of the Belscope and Macintosh blades.

This study was designed to compare the degree of cervical spine movement during laryngoscopy and tracheal intubation using the Belscope and Macintosh laryngoscope blades. Twenty ASA 1 and 2 patients scheduled for elective surgery requiring tracheal intubation were studied. Following induction of anaesthesia and muscle relaxation, a neutral cross-table lateral cervical spine X ray was taken. Laryngoscopy was then performed in each patient using both the Belscope and Macintosh blades. After visualisation of the vocal cords and tracheal intubation the cervical spine X ray was repeated. Movement of the cervical spine was evaluated by tracing bony landmarks on each film and then superimposing the neutral and intubating films. We were unable to demonstrate a difference in the amount of cervical spine movement comparing the two blades. Using the Belscope blade, intubation took longer (median 18 s) than the Macintosh blade (median 12 s, p < 0.01) and was unsuccessful in two patients despite adequate visualisation of the vocal cords.

Adolescent↗
PubMed1993

Denervated human skeletal muscle: MR imaging evaluation.

Because determination of neurologic integrity after severe limb trauma is crucial in patient care, the authors assessed magnetic resonance (MR) imaging as a tool to map denervated motor units of skeletal muscle in patients with traumatic peripheral neuropathy. Denervation was confirmed in 22 patients with use of electromyography, surgery, or both. MR imaging was performed with moderately T1- and T2-weighted spin-echo and short-tau inversion-recovery (STIR) sequences. MR imaging was unreliable in depicting acute denervation. Muscles of patients with subacute denervation had prolonged T1 and T2, which contributed to conspicuous hyperintensity on STIR images. Chronically denervated muscles showed marked atrophy, variable changes on STIR images, and conspicuous fatty infiltration on T1-weighted images. Normal variants in motor unit anatomy were seen in denervated muscle volumes outside the expected distribution of the injured nerve. MR imaging is promising for the noninvasive mapping and monitoring of denervated muscle in subacute and chronic phases of peripheral neuropathy.

Extremities↗
PubMed1993

Muscle proton T2 relaxation times and work during repetitive maximal voluntary exercise.

We studied the effects of progressive maximal voluntary handgrip contractions (MVCs) on muscle proton spin-spin (T2) relaxation times and work, measured as the integrated force vs. time curve (FTI). Six healthy volunteers performed 10, 20, 40, and 80 MVCs in a 0.35-T magnet on four separate occasions. Repeated measures analyses of variance of increases in T2 and FTI during successive bouts were significant (P < 0.005 and P < 0.001, respectively). FTI increased with successive bouts to a greater extent than did muscle T2 (P < 0.05). For T2, the Helmert contrast judged the 10-MVC response lower than the mean of the remaining responses (P < 0.005), and the differences between all others compared with the means of subsequent responses were not significant, indicating a "flattening" of the T2 response after the increase from 10 to 20 repetitions. For FTI, all the single degree of freedom Helmert contrasts were significant (P < 0.001), indicating a continual increase in response over increased MVCs. The curved nature of the T2 response conformed best to a hyperbolic function, suggesting that a limit of approximately 32% exists for the change in T2 during progressively longer bouts of MVCs. A limit in the T2 response is consistent with the existence of a limit in the amount of water that muscle can take up from the vasculature during exertion.

Adult↗
PubMed1991

Movement disorder following herpes simplex encephalitis.

Two children, an eight-year-old girl and a seven-month-old boy, recovered from herpes simplex encephalitis with minimal neurological residua following acyclovir treatment. Subsequently, they experienced marked deterioration, interpreted as either recrudescent infection or a post-infectious phenomenon. Features of the deterioration included encephalopathy and hyperkinetic movement disorder. MRI studies showed extensive neocortical damage, without involvement of the basal ganglia, thalamus or subthalamic nuclei. With aggressive supportive care, both children made a slow, steady recovery over several months. This supportive care is best provided in a closely supervised interdisciplinary setting.

Acyclovir↗
PubMed1984

Barrett's esophagus: radiological and clinical considerations.

We reviewed the radiographic findings in thirty patients with columnar-lined (Barrett's) esophageal mucosa. Gastroesophageal reflux was observed in 90%, hiatal hernia in 83%, stricture in 80% and esophageal ulceration in 33%. Superficial nodular mucosal changes were detected on 50% of the air contrast esophagrams. Prominence of this pattern may be associated with dysplastic or early malignant change. In addition, four conditions associated with secondary lower esophageal sphincter incompetence were identified in our patient group. These were scleroderma, previous myotomy for achalasia, previous gastric surgery and long-term indwelling nasogastric tubes.

Adult↗