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Biomedical subjects

R M Quencer

Publications and source records attributed to R M Quencer.

At least 19 recordsLinked to original sources
PubMed1998

Lack of normal MR enhancement of the pituitary gland: findings in three siblings with combined pituitary hormone deficiency.

We present the MR appearance of the sella turcica in three sibling dwarfs with combined pituitary hormone deficiency in which MR images revealed a peripheral curvilinear band of enhancement about the pituitary gland in all three patients, a normal-size pituitary gland in two siblings, a mildly enlarged pituitary gland in one sibling, and a thin infundibulum and a normal posterior pituitary bright spot in all three siblings. Possible antecedents include an abnormal vascular supply, pituitary gland replacement by a nonfunctioning adenoma, a proteinaceous cyst, or a hamartoma.

Adolescent↗
PubMed1997

Progressive posttraumatic myelomalacic myelopathy: treatment with untethering and expansive duraplasty.

Patients with progressive posttraumatic myelomalacic myelopathy (PPMM), or tethered cord syndrome, present with symptoms and signs similar to those observed in case of progressive posttraumatic cystic myelopathy, that is, sensorimotor function deterioration, local and/or radicular pain, increased spasticity, increased autonomic dysreflexia, and sphincter dysfunction. The authors investigated surgical outcomes of untethering combined with expansive duraplasty. Forty patients with PPMM who presented with functional deterioration underwent untethering of the spinal cord and nerve roots with an expansive duraplasty. Meticulous dissections of adhesions on the dorsal and lateral aspects of the spinal cord and nerve roots were performed. Intraoperative ultrasonography was used to detect the presence of a confluent cyst and to assess the success of untethering. After surgery, the patients were treated using a protocol that involved frequent turning for 48 hours and subsequently mobilization. Preoperative magnetic resonance (MR) imaging, with and without administration of a contrast agent, was obtained in all patients, except one patient who underwent immediate and delayed computerized tomography (CT) myelography. The mean follow-up period was 3 years (range 20-57 months) for the 36 patients available for follow-up review. Spinal cord tethering was observed in all patients preoperatively. Trauma was the most common cause of this pathology, accounting for 31 of the 40 cases. Preoperative MR imaging did not demonstrate tumor recurrence in the group of five patients who had undergone an initial operation for tumor excision. The interval between the causative event and the operation was less than 5 years in half of the patients (20 of 40), with the longest interval lasting up to 37 years. Motor function deterioration was the most frequent manifestation; it was present in 31 of 40 patients. Improvements in motor function, autonomic dysreflexia, pain, sphincter dysfunction, and sensory function were found during the most recent follow-up examination in 79%, 75%, 62%, 50%, and 43% of the patients, respectively. Two patients experienced retethering of the spinal cord and one underwent a second operation. Surgical untethering and expansive duraplasty, followed by postoperative position rotation to avoid retethering, provide symptomatic relief for patients with PPMM.

Adolescent↗
PubMed1997

Spinal cord lesions in patients with AIDS.

In the past, little attention has been given in the imaging literature to spinal cord findings in the human immunodeficiency syndrome. This article summarizes the major pathologic conditions found in the spinal cord in patients with AIDS and compares them to MR features. The details of toxoplasma myelitis, spinal cord lymphoma, HIV myelitis, and tract pallor are demonstrated. A review of literature and a description of the pathologic cord changes will help the reader understand the alterations of the spinal cord in patients with AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1996

MR angiography of normal intradural vessels of the thoracolumbar spine.

PURPOSE: To identify and describe the normal intradural vessels detected on MR angiograms of the thoracolumbar spine. METHODS: Six adult subjects who had clinical evidence of myelopathy, yet normal findings at spinal digital subtraction angiography (DSA), were also studied without and with contrast-enhanced MR imaging and three-dimensional time-of-flight, single-slab MR angiography. Sagittal and coronal subvolume (targeted) maximum intensity projection images were compared with arterial and venous phase DSA images. Angiographic images were then compared with postmortem, formalin-fixed cord specimens. RESULTS: Recognizable intradural vessels were detected only on contrast-enhanced MR angiograms. These vessels corresponded to the posterior and/or anterior median (midline) veins and the great medullary veins. The median veins had variable but mild tortuosity. The medullary veins, which extended from the median veins and coronal venous plexus on the cord surface to the epidural venous plexus, were relatively straight and usually located at T-12 or L-1. The anterior spinal artery could partially contribute to the anterior midline vascular signal. CONCLUSION: The intradural vessels identified on contrast-enhanced MR angiograms are primarily veins, and these are usually the largest vessels on or near the cord surface. The limited number and minimal tortuosity of these veins may serve as a baseline for the examination of patients with clinically suspected arteriovenous malformation or fistula.

Adult↗
PubMed1995

Enhancing meningeal blood vessels masquerading as leptomeningeal spread of tumor in obstructive hydrocephalus.

MR showed an enhancing mass in the pineal region and hydrocephalus and leptomeningeal enhancement, thought to indicate pinealoblastoma with leptomeningeal spread. During resection there was no evidence of spread, and repeat MR showed no residual tumor or meningeal enhancement, so the patient was not treated for metastasis. Because there were no signs of leptomeningeal tumor 4 months after surgery, the meningeal enhancement is thought to have been related to venous stasis secondary to obstructive hydrocephalus.

Brain Neoplasms↗
PubMed1995

MR of omental myelosynangiosis.

PURPOSE: To describe MR findings in patients who have undergone omental transposition (omental myelosynangiosis) for spinal cord revascularization. METHODS: Spin-echo MR images, without and with intravenous gadolinium, were obtained before and after surgery in three patients using a quadrature spine coil. Three-dimensional time-of-flight spinal MR angiography was also performed. RESULTS: On routine MR, the transposed omentum is an irregular, lobulated fat-equivalent mass, containing serpiginous areas of flow void, which extends through the laminectomy site to lie directly adjacent to the cord surface. MR angiography demonstrated small omental vessels, some coursing to the omentum-cord interface; however, no definite extension into the cord was detected. In all patients, there was alteration in cord size and contour after transposition, but no change in cord signal. Clinical improvement was observed in one of the three patients. The signal characteristics of the transposed omentum changed, showing less homogeneity and a gradual loss of the signal over a period of 4 months. CONCLUSIONS: MR delineates transposed omentum and associated postoperative changes in omental myelosynangiosis. MR angiography is useful as an adjunct to demonstrate the small vessels near the omentum-cord interface, but lacks sufficient resolution to demonstrate neoangiogenesis within the cord.

Adult↗
PubMed1995

MR-pathologic comparisons of wallerian degeneration in spinal cord injury.

PURPOSE: To describe the MR manifestations and temporal course of wallerian degeneration that occurs above and below a spinal cord injury, and to compare the MR findings with postmortem histopathology. METHOD: Twenty-four postmortem spinal cords from patients with cervical (n = 14), thoracic (n = 6), and lumbar (n = 4) cord injuries were studied with axial T1- and T2-weighted spin-echo MR imaging. Injury-to-death intervals varied from 8 days to 23 years. The images were examined for alteration of signal above and below the injury site. Histologic studies of these cords with axon, myelin, and connective tissue stains were performed at levels equivalent to the MR sections. Immunohistochemical analysis using antibodies to glial fibrillary acetic protein was also performed on 19 cords. Pathologic-imaging comparisons were made. RESULTS: MR images showed increased signal intensity in the dorsal columns above the injury level and in the lateral corticospinal tracts below the injury level in all cases in which cord injury had occurred 7 or more weeks before death. In early postinjury survival times (8 days and 12 days) MR findings were normal; histologically there was early wallerian degeneration in only the dorsal columns at 8 days and in both the lateral and dorsal columns at 12 days. MR showed wallerian degeneration in all cases examined at 7 weeks after injury and thereafter. CONCLUSIONS: Wallerian degeneration was demonstrated by histology and MR in all specimens in which the injury-to-death interval was greater than 7 weeks. Recognition of wallerian degeneration on MR allows complete analysis of the injury, explains abnormal MR signals at sites remote from the epicenter of the injury, and may be useful in the future in the timing and planning of therapeutic interventions.

Adolescent↗
PubMed1995

Proton MR spectroscopy of the brain in 14 patients with Parkinson disease.

PURPOSE: To determine whether the proton spectra from patients with clinically diagnosed Parkinson disease differ from the spectra of age-matched healthy subjects with respect to the major cerebral metabolite resonances as well as lactate. METHODS: Fourteen patients with Parkinson disease (38 to 81 years of age) and 13 healthy control subjects (37 to 81 years of age) were studied using image-guided, single-voxel (27-cm3 volume) proton MR spectroscopy of the occipital lobe. RESULTS: The peak area ratios of N-acetyl aspartate to creatine and N-acetyl aspartate to choline for Parkinson patients did not show a statistically significant difference from the corresponding ratios for control subjects. There was a very significant increase in the ratio of lactate to N-acetyl aspartate for patients with Parkinson disease, with the greatest increase (threefold) manifested by the subgroup (n = 4) with dementia. The difference in N-acetyl aspartate to choline between women (n = 7) with Parkinson disease and healthy women (n = 9) approached significance. No dependence of the peak ratios on age, duration of Parkinson disease, or medication (L-dopa) regimen was found. CONCLUSION: Preliminary results indicating an increase in cerebral lactate in patients with Parkinson disease support the hypothesis that Parkinson disease is a systemic disorder characterized by an impairment of oxidative energy metabolism. The larger increases for Parkinson patients with dementia may be diagnostically useful in assessing clinical course and in differentiating Parkinson disease from other causes of dementia. Additional studies are needed, though, to quantitate lactate changes and identify potential contributions from lipid resonances better.

Adult↗
PubMed1994

Imaging in acute basilar artery thrombosis.

The aim of this study was to review the imaging features in acute (< 24 h) basilar artery thrombosis. CT and MR studies in 11 patients with clinical diagnosis of acute basilar artery thrombosis were retrospectively reviewed. MR angiography was obtained in 4 patients. Correlation with clinical symptoms was performed. Multiple cranial nerve palsies and hemiparesis were the most common clinical symptoms at presentation. CT revealed hyperdense basilar arteries (n = 7) and hypodensities in the posterior circulation territory (n = 8). In one instance, the infarction was hemorrhagic. MR imaging showed absence of flow void within the basilar in 6 patients and MRA (using both PC and TOF techniques) confirmed absence of blood flow in 4 basilar arteries. One week after presentation, 5 patients died. Autopsy was obtained in 1 case and confirmed the diagnosis of basilar artery thrombosis. Basilar artery thrombosis has fairly typical imaging features by both CT and MR. MRA may be used to confirm the diagnosis. Prompt recognition may lead to early thrombolytic treatment and may improve survival.

Acute Disease↗
PubMed1994

MR angiography of occlusive disease of the arteries in the head and neck: current concepts.

MR angiography has many applications in the evaluation of cerebrovascular disease (aneurysm, vascular malformation, neoplasm, arterial and venous occlusive disease) [1]. Of these, the most common application may be in the assessment of arterial occlusive disease in patients at risk for stroke [2]. Consequently, the accuracy of MR angiography vs conventional angiography in this assessment will most likely determine the extent to which MR angiography is routinely used in clinical practice. In this paper, we review the results of clinical trials in which MR angiography has been used to evaluate arterial occlusive disease in the head and neck and describe those recent developments that promise improved visualization of the vasculature.

Arterial Occlusive Diseases↗
PubMed1994

Acute spinal subdural hematoma: MR and CT findings with pathologic correlates.

PURPOSE: To determine the MR and CT findings that characterize acute spinal subdural hematoma (ASSH). METHODS: The MR, CT, and clinical findings in three patients with surgically proved ASSH were reviewed and also correlated with the postmortem MR, CT, and cryomicrotome findings in three other patients, two with ASSH and one with an acute spinal epidural hematoma. RESULTS: Imaging findings in ASSH included: (a) hyperdense lesions on plain CT within the dural sac, distinct from the adjacent low-density epidural fat and silhouetted against the lower-density spinal cord and cauda equina, which it compressed; (b) lack of direct continuity with the adjacent osseous structures; (c) clumping, loculation, and streaking of blood within the dural sac on both MR and Ct; and (d) an inhomogeneous and variable signal intensity to the ASSH on all MR pulse sequences, but, nevertheless, a striking low signal intensity on T2-weighted spin-echo or T2-weighted gradient-echo to a major part of the ASSH because of deoxyhemoglobin. Plain CT was most helpful in compartmentalizing the hematoma. CONCLUSION: When MR and plain CT are obtained as complementary studies, they provide characteristic findings that allow the prompt diagnosis of ASSH.

Adult↗
PubMed1994

Progressive posttraumatic myelomalacic myelopathy: imaging and clinical features.

PURPOSE: To describe the imaging features, surgical management, and clinical outcome of progressive posttraumatic myelomalacic myelopathy (PPMM), a relatively unrecognized but important cause of progressive myelopathy in patients with previous spinal cord injuries. METHODS: The clinical records, imaging studies, and postoperative outcome of 10 patients with PPMM were reviewed. Fifteen preoperative and five postoperative MRs were analyzed for intramedullary signal abnormalities, the nature of these signal abnormalities, and cord tethering. All patients had intraoperative sonography. RESULTS: Neurologic signs and symptoms found in our patients included 1) progressive loss of motor function (6/10), 2) sensory level changes (4/10), 3) increased spasticity (4/10), 4) autonomic dysreflexia (4/10), 5) loss of bowel or bladder control (4/10), and 6) local and/or radicular pain (4/10). Preoperative MR in nine patients revealed intramedullary T1/T2 lengthening (9/9), extramedullary tethering/adhesions (9/9), ill-defined lesional borders (6/9), cord expansion (5/9), and increased signal intensity of the lesion on T1-weighted images compared with CSF (7/9). Proton density images in five patients demonstrated a relative increase in signal intensity over CSF. In all five postoperative MRs, there was evidence of untethering of the spinal cord and a decrease in cord size in two patients. Intraoperative sonography revealed cord tethering and abnormal cord echotexture in all cases. Postoperative clinical evaluation revealed neurologic improvement in nine patients. CONCLUSIONS: PPMM may clinically and radiographically mimic progressive posttraumatic cystic myelopathy (PPCM). MR provides clues to the diagnosis of myelomalacia preoperatively. Intraoperative sonography confirms the absence of a confluent cyst. These points are crucial in the surgical procedures in PPMM vs PPCM. In PPMM, lysis of intradural adhesions results in an improvement in symptoms in a manner similar to the shunting of PPCM.

Adult↗
PubMed1994

Magnetic resonance imaging of unusual intracranial infections.

We review the etiologic agents, epidemiology, pathogenesis, pathology, clinical manifestations, and imaging features of several unusual intracranial infections that have not been discussed elsewhere in this issue. The central nervous system (CNS) infections discussed are Creutzfeldt-Jakob disease (CrJaD), neurosyphilis, primary amebic meningoencephalitis (PAM), granulomatous amebic encephalitis (GAE), cerebral amebiasis, and cerebral hydatid disease.

Brain↗