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Biomedical subjects

B M Montalvo

Publications and source records attributed to B M Montalvo.

At least 19 recordsLinked to original sources
PubMed2001

Using MR cholangiopancreatography to evaluate iatrogenic bile duct injury.

OBJECTIVE: The purpose of this study was to assess the role of MR cholangiopancreatography (MRCP) in the evaluation of iatrogenic bile duct injuries. SUBJECTS AND METHODS: In this prospective study, MRCP was performed in 10 postoperative patients (nine female and one male, ranging in age from 17 to 79 years) suspected of having bile duct injury as a result of surgery. Presence or absence of biliary dilatation, excision injury, stricture, fluid collection, and free fluid was noted. Excision injury was diagnosed if a segment of bile duct was not visible on any of the MRCP sequences. Positive cases were classified according to anatomic location and extent of injury. Results were compared with endoscopic retrograde cholangiopancreatography in five patients, percutaneous transhepatic cholangiography in one, surgery in four, and clinical follow-up in three. RESULTS: Three patients had normal findings on MRCP and remained asymptomatic on clinical follow-up. Four patients had bile duct excision injury on MRCP that was surgically proven, and one had stricture, confirmed by percutaneous transhepatic cholangiography. Of these five patients, one had Bismuth type I injury, two had type II, one had type III, and one had type IV. Two patients had findings suggestive of cystic duct leak on MRCP that were confirmed on cholangiography. CONCLUSION: MRCP can accurately diagnose postoperative biliary strictures and excision injuries and can characterize and anatomically classify these injuries for planning reparative surgery. It can also suggest the presence of cystic duct leaks in patients who have undergone cholecystectomy.

Adolescent↗
PubMed1997

Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 5. Lower extremity blood flow and hyperemic responses to occlusion are augmented by ambulation training.

OBJECTIVE: To test whether 12 weeks of exercise conditioning using functional neuromuscular stimulation (FNS) ambulation alters the resting lower extremity blood flow and hyperemic responses to vascular occlusion in subjects with paraplegia, and to determine whether an association exists between limb flow and lower extremity fat-free mass. DESIGN: Pretest, posttest. SETTING: Academic medical center. PARTICIPANTS: Subjects with chronic neurologically complete paraplegia. INTERVENTION: Thirty-two sessions of microprocessor-controlled ambulation using electrically stimulated contractions of lower extremity muscles and a rolling walker. OUTCOME MEASURES: Subjects underwent quantitative Doppler ultrasound examination of the common femoral artery (CFA) before and after training. End-diastolic arterial images and arterial flow-velocity profiles obtained at rest and after 5 minutes of suprasystolic thigh occlusion were computer-digitized for analysis of heart rate (HR), CFA peak systolic velocity (PSV), CFA cross-sectional area (CSA), flow velocity integral (FVI), pulse volume (PV), and CFA (arterial) inflow volume (AIV). RESULTS: Significant effects of training on CSA (p < .0001), FVI (p < .05), computed PV (p < .001), and computed AIV (p < .01) were observed. Resting HR was lower following training (p < .05). The change for resting PSV approached but did not reach significance (p = .083). Analysis of postocclusion PV and AIV showed significant effects for conditioning status (p values < .01), postcompression time (p values < .0001), and their interaction (p values < .01). At 1 minute after occlusion, the posttraining AIV response was 78.2% greater in absolute magnitude and 17.4% more robust when expressed as a percentage change from its resting value than before training. Significant correlations were found between thigh fat free mass and both AIV and PV (p values < .05). CONCLUSION: Exercise training using FNS ambulation increases the resting lower extremity AIV in individuals with paraplegia and augments the hyperemic response to vascular occlusion. Improved posttraining blood flow is attributable both to vascular structural changes and upregulation of vascular flow control mechanisms. Limb mass is associated with the volume of arterial blood flow.

Adult↗
PubMed1996

Lower extremity blood flow and responses to occlusion ischemia differ in exercise-trained and sedentary tetraplegic persons.

OBJECTIVE: To test whether lower extremity blood flow and hyperemic responses to vascular occlusion differ among electrically stimulated exercise trained and sedentary tetraplegic persons and subjects without tetraplegia (control). DESIGN: Blinded cross-sectional comparison, control group. SETTING: Academic medical center. PARTICIPANTS: Ten sedentary tetraplegic men, 10 tetraplegic persons previously habituated to electrically stimulated cycling exercise for 0.4 to 7 years, and 10 nondisabled controls. OUTCOME MEASURES: Subjects underwent quantitative Doppler ultrasound examination of the common femoral artery (CFA). End-diastolic arterial images and arterial flow-velocity profiles obtained at rest and following five minutes of suprasystolic thigh occlusion were computer digitized for analysis of heart rate (HR), CFA peak systolic velocity (PSV), CFA cross-sectional area (CSA), flow velocity integral (FVI), and computed CFA inflow volume (IV). RESULTS: No group main effects were observed for resting HR or FVI. At rest, trained tetraplegic men had 14.9% greater PSV, 29.8% larger CSA, and 51.3% greater IV (p values < .05) than sedentary tetraplegic subjects. Resting PSV and IV of the trained subjects did not differ from controls, although CSA was smaller than controls (p < .05). Following occlusion, PSV, CSA, and IV averaged 16.5%, 33.4%, and 65.1% greater for trained tetraplegics persons, respectively, than sedentary tetraplegic subjects (p values < .05). Only CSA differed between the control and the trained groups (p < .05). CONCLUSION: Tetraplegic persons conditioned by electrically stimulated cycling have greater lower extremity blood flow and hyperemic responses to occlusion than do their sedentary counterparts.

Adult↗
PubMed1996

Acute lipodermatosclerosis is associated with venous insufficiency.

BACKGROUND: Acute lipodermatosclerosis is characterized by pain and tenderness in the medial aspect of the leg. It is thought to be the result of venous insufficiency and to be the acute counterpart of chronic lipodermatosclerosis, a hallmark of venous disease. However, there is no direct evidence linking acute lipodermatosclerosis to venous disease. OBJECTIVE: Our purpose was to determine whether acute lipodermatosclerosis is associated with venous insufficiency. METHODS: With air plethysmography, we determined the venous filling index, the ejection fraction, and the residual volume fraction in 15 sequential patients with acute lipodermatosclerosis. RESULTS: Ten of the 15 patients (67%) had at least one abnormal result, eight (53%) had two, and two (13%) had three. In four patients (27%), abnormalities of both reflux and ejection were noted. Duplex venous ultrasonography, in two of the patients with normal results from air plethysmography, showed incompetent perforators at sites of lipodermatosclerosis. CONCLUSION: Acute lipodermatosclerosis is associated with objective findings of venous insufficiency in a high percentage of patients. It is likely that this condition is the result of venous disease.

Acute Disease↗
PubMed1996

Color Doppler sonography in penetrating injuries of the neck.

PURPOSE: To determine whether color Doppler sonography can be a sensitive alternative to screening arteriography for identifying arterial injury in patients with penetrating traumatic neck injuries. METHODS: Fifty-two patients admitted to our trauma center with penetrating neck injuries (gunshot wounds and lacerations) were examined prospectively with color Doppler sonography, and findings were compared with the results of angiography (n = 44), with findings at surgery (n = 4), and with clinical status (n = 4). RESULTS: Color Doppler sonography correctly detected all serious injuries of the carotid arteries (n = 6; 5 diagnosed at angiography and 1 at surgery) and all injuries of the vertebral arteries (n = 4; all diagnosed at angiography). Sonography missed 1 instance of reversible narrowing of the internal and external carotid arteries and did not show 2 normal vertebral arteries. CONCLUSION: Color Doppler sonography was as accurate as angiography in screening clinically stable patients with zone II or III injuries and no signs of active bleeding. Our initial results suggest that in the future, sonography may be used as a screening examination for arterial lesions in patients with penetrating neck injuries.

Adolescent↗
PubMed1991

Complications of epidural anesthesia: MR appearance of abnormalities.

Eight patients with acquired intradural arachnoid abnormalities caused by epidural anesthesia were evaluated with magnetic resonance (MR) imaging (eight patients) and intraoperative ultrasound imaging (four patients). Subarachnoid cysts were found in the lower cervical and thoracic spine in six patients. Irregularity of the surface of the cord was noted in seven cases. Associated intramedullary cysts and myelomalacia were seen in two patients. Arachnoiditis was unsuspected clinically in four patients; findings at MR imaging first suggested the cause of the patients' symptoms. The underlying mechanism for the intradural and cord abnormalities in seven of the eight patients was a chemically induced arachnoiditis produced by the administration of epidural anesthesia; in the eight case, an infection introduced at the time of the epidural injection was the cause of the abnormalities. The authors postulate that the preservative agents in the vials of anesthetic may have been the causative factor of this inflammation in the majority of the cases.

Adult↗
PubMed1990

Left hepatic duct anatomy: implications.

A review of the findings of a 10-year experience with biliary interventional procedures in 838 patients led to consideration of the anatomy of the left hepatic duct. To better illustrate the findings, 15 normal human livers obtained at autopsy were fixed and dissected. Fifty-five percent of the patients had a single left hepatic duct that was formed by the intrahepatic union of ducts draining segments II and III (segmental nomenclature follows Couinaud) lateral to the falciform ligament. Central to this ligament, the left duct became extrahepatic and was joined by ducts from segments I and IV. The real and theoretical implications of the unpredictable variability of biliary anatomy, the frequency of right lateral duct drainage into the left hepatic duct, and the extrahepatic contiguous relationship between the left hepatic duct and the left portal vein are discussed.

Bile Ducts, Intrahepatic↗
PubMed1990

Intrauterine spermatic cord torsion in the newborn: sonographic and pathologic correlation.

In five newborn patients with spermatic cord torsion, sonography demonstrated an enlarged and globular testis, hydrocele, and skin thickening. In four of these patients the testicular parenchyma was heterogeneous. Peripheral hypoechoic areas were seen in two of the four patients; the other two had a central hypoechoic region and a peripheral echogenic rim. The testis in the fifth patient was diffusely hyperechoic. Duplex Doppler sonography performed in two patients failed to demonstrate any signal in the spermatic cord in either the abnormal or contralateral hemiscrotum. Scintigraphic findings were positive for testicular torsion in two patients and equivocal in three patients. Surgery was performed 2-12 days after sonography and established the diagnosis of spermatic cord torsion. Pathologic examination demonstrated hemorrhagic infarction of the entire testis as well as scattered calcifications. The authors conclude that a solid globular testicular mass seen during the neonatal period is suggestive of intrauterine spermatic cord torsion.

Humans↗
PubMed1990

Lumbar disk herniation and canal stenosis: value of intraoperative sonography in diagnosis and surgical management.

One hundred four patients with preoperative diagnoses of lumbar canal stenosis, disk herniation, or a combination of both were evaluated with intraoperative sonography with the intent of (1) describing the sonographic characteristics of herniated disks and distinguishing these from bulging anuli, epidural fat, scar tissue, and spondylolisthesis; (2) establishing criteria for adequate decompression of canal stenosis; and (3) determining the usefulness of sonography in monitoring disk removal. Disk material demonstrates medium echogenicity, different in its sonographic features from bone, epidural fat, scar tissue, and epidural veins. A sonographic diagnosis of disk herniation was made in 43 cases, 41 of which were confirmed during surgery. Sonography established the presence or absence of disk herniation (confirmed by surgery) in 14 of 19 patients who had equivocal preoperative findings. After routine diskectomy, residual disk material was found in 17 (41%) of 41 patients, which led to further surgery in 16 patients with removal of the additional disk fragments. In 84 patients undergoing decompressive surgery for canal stenosis, sonography detected residual canal compression in 19 (23%), which led to a widened decompression in 15 of these patients. Sonography can differentiate disk material from other normal or abnormal structures in the canal; therefore, sonographic monitoring helps to ensure adequate bony decompression and complete diskectomy. We conclude that intraoperative sonography is an important tool in the surgical management of lumbar disk disease and stenosis.

Adipose Tissue↗
PubMed1989

Hepaticodochojejunostomy with afferent limb: CT anatomy.

Hepaticodochojejunostomy with an afferent limb constructed to provide a permanent access route for retrograde biliary dilation has been described. The computed tomographic (CT) scans of 12 patients who had undergone this procedure were reviewed. The appearance of the afferent limb from its position within the subcutaneous tissues to its anastomosis with the biliary tree is described and illustrated. Recognition of the limb as a surgical pathway is important because familiarity with its anatomy will avoid errors in CT interpretation and aid in successful transjejunal catheterization of the bile ducts.

Adult↗
PubMed1989

Acquired spinal subarachnoid cysts: evaluation with MR, CT myelography, and intraoperative sonography.

Fifteen patients with acquired spinal subarachnoid cysts (14 surgically proved, one presumed) were evaluated preoperatively with immediate and/or delayed CT myelography (seven patients), MR (11 patients), or both (three patients). CT myelography separated subarachnoid cyst from myelomalacia and/or intramedullary cysts in four cases but failed to diagnose them in three, while MR accurately diagnosed subarachnoid cyst in all 10 cases that were also surgically proved. The results of these preoperative examinations were evaluated to determine the efficacy of each study in diagnosing subarachnoid cysts, ascertaining their extent and internal architecture, and detecting associated abnormalities of the spinal cord. In addition, during surgery these cysts were studied with sonography to gain an understanding of the pathophysiological mechanisms involved in their formation and propagation and to guide the surgeon in their decompression. On the basis of our experience, MR appears to be the most efficient preoperative study in diagnosing and characterizing acquired subarachnoid cyst and associated abnormalities. Intraoperative sonography provides a reliable means of ensuring adequate decompression of these cysts.

Adult↗
PubMed1988

Spinal infection: evaluation with MR imaging and intraoperative US.

Magnetic resonance (MR) images of the spine and/or intraoperative spinal ultrasound (US) in 24 patients with spinal infections were reviewed and correlated with clinical and pathologic data to determine their diagnostic value. In disk space infection with osteomyelitis and in retrospinal abscess, MR images showed characteristic findings, whereas in myelitis, MR images demonstrated nonspecific abnormalities. The appearance on MR images of epidural abscesses ranged from clearly identifiable extradural masses with high-intensity signal on spin-echo T2-weighted images to extensive inhomogeneous collections of mixed signal intensities, difficult to distinguish from adjacent meningitis. Myelography with high-resolution computed tomography (CT) and intraoperative spinal US was superior to MR imaging in demonstrating epidural abscesses when there was concomitant meningitis. With intraoperative spinal US, epidural abscesses could be located and their decompression monitored. MR imaging is recommended as the initial screening procedure in spinal infection; in those few patients with nondiagnostic MR images, myelography with high-resolution CT should be the supplementary study. If surgery is planned, intraoperative spinal US should be used.

Abscess↗
PubMed1988

Syringomyelia as a consequence of compressive extramedullary lesions: postoperative clinical and radiological manifestations.

MR imaging was performed to determine the cause of the onset of new neurologic symptoms in five patients who had previously undergone surgical excision of extramedullary masses. Syringomyelia and the absence of recurrent or residual lesions were documented in all cases. Three patients showed long cysts (multiseptated in two and smooth in one) with low signal intensity on both T1- and T2-weighted images. The flow-void phenomenon related to fluid motion in these three cysts, which were enlarging clinically, was responsible for the hypointensity on the T2-weighted images. In two patients the fluid within the lesions behaved similarly to normal nonpulsatile CSF and may have represented syrinx cavities in a state of "arrested growth." Three patients had surgical decompression under real-time intraoperative sonographic control, which showed the presence of intramedullary cyst-fluid pulsations in two cases and the absence of cyst-fluid pulsations in one case. These sonographic observations correlated with the MR findings. We postulate that these syrinx cavities form as a result both of the effect that the original extramedullary lesion had upon the underlying spinal cord and the subsequent postoperative alterations in the CSF dynamics at the level of prior surgery. Syringomyelia should be considered in patients with recurrent or new symptoms who previously had surgery for extramedullary lesions.

Adult↗
PubMed1988

Prophylactic indomethacin for prevention of intraventricular hemorrhage in premature infants.

The impact of early prophylactic use of intravenous indomethacin on the incidence and severity of periventricular-intraventricular hemorrhage and patent ductus arteriosus in 199 oxygen-requiring premature infants (less than or equal to 1300 g birth weight) was prospectively investigated. The trial was controlled, the infants were randomized, and the investigators were unaware of the group assignments. Patients with minimal (grade I) or no periventricular-intraventricular hemorrhage determined by prestudy echoencephalography were randomized within two birth weight subgroups (500 to 899 and 900 to 1300 g) to receive either prophylactic indomethacin (n = 99) or an equal volume of saline-vehicle placebo (n = 100). The first dose (0.2 mg/kg) was given within 12 hours of delivery and two subsequent doses (0.1 mg/kg) were administered at 12 hourly intervals. Prophylactic indomethacin significantly reduced the incidence of grades II to IV periventricular-intraventricular hemorrhage. Intraventricular hemorrhage was half as common in infants given prophylactic indomethacin as in control infants (23% v 46%, P less than .002). The reduction was manifested in both birth weight subgroups. Results of this study also confirmed a lower incidence of clinically significant patent ductus arteriosus in infants who received prophylactic indomethacin in contrast to those who received placebo (11% v 42%, P less than .001). No significant differences were found between treatment and control groups in the duration of oxygen therapy, mechanical ventilation, or hospitalization or in the incidence of pneumothorax, chronic lung disease, sepsis, necrotizing enterocolitis, retinopathy of prematurity, or death. Early prophylactic indomethacin initiated within 12 hours of delivery is effective in reducing the incidence of intraventricular hemorrhage as well as clinically significant patent ductus arteriosus in very low birth weight premature infants.

Birth Weight↗
PubMed1987

Intraoperative sonography in spinal dysraphism and syringohydromyelia.

The use of intraoperative sonography was analyzed in 24 patients with spinal dysraphism and syringohydromyelia in order to determine the role of real-time sonography in the surgical management of these patients. Specific diagnoses included tethered cord (nine), syringohydromyelia (seven), congenital tumor unassociated with a tethered cord (four), diastematomyelia (three), and occult sacral meningocele (one). Intraoperative sonography determined the exact relationship of congenital tumors to the cord before opening the dura, which allowed a more precise approach to the mass. Intraoperative sonography identified the lower end of the syrinx cavities, which allowed optimal catheter placement. Fibroglial scar tissue, which may compartmentalize these syrinx cavities, was clearly shown, and the efficacy of shunt catheter placement was immediately determined. In diastematomyelia, intraoperative sonography identified the relationship of the hemicords to bony, cartilaginous, and/or fibrous septa and demonstrated the effect on the tethered hemicords of removing these septa and constructing a single dural sac from the two dural sacs that had enclosed the hemicords. Since significant surgical decisions are based on these sonographic observations, the authors urge widespread use of intraoperative sonography in patients with spinal dysraphism and syringohydromyelia.

Humans↗
PubMed1987

Intramedullary spinal cord metastases, mainly of nonneurogenic origin.

The clinical data and imaging studies of 12 patients with intramedullary metastases were reviewed retrospectively to see if these lesions had a typical radiographic appearance and to determine the sensitivity of the various radiologic examinations. The lesions were identified antemortem by either myelography, CT, MR, and/or intraoperative spinal sonography (IOSS). Final diagnosis was based on biopsy material from either the spinal cord lesion, another metastatic site, and/or the primary tumor. Ten patients had primary tumors located outside the central nervous system, while only two patients had primary brain tumors. Metrizamide myelography and CT demonstrated a definite intramedullary mass in nine of 11 patients. In five patients the mass was relatively small, well-defined, single, and resembled a primary spinal cord neoplasm. In the other four patients, longer and sometimes several segments of the cord were involved. These appeared irregular and nodular and were often associated with intradural lesions at separate sites. MR detected not only enlargement and abnormal signal in the cord but also clinically unsuspected brain lesions. IOSS localized lesions for biopsy and monitored tumor resection. These various imaging procedures showed that cord metastases were often more extensive than anticipated clinically. Spread of tumor into the spinal and intracranial subarachnoid space was common. Imaging of the entire spinal canal and brain, preferably with MR, is therefore recommended to aid in diagnosis, prognosis, and treatment.

Adult↗
PubMed1986

Intraoperative cranial sonography.

The use of real time ultrasound in the neurosurgical operating room can enhance the ability to localize intracerebral masses, allow accurate needle biopsies, diminish the amount of potential damage to normal brain tissue, show the results of tumor resection, and help in the placement of ventricular and cyst shunts. The end result makes the surgical procedure faster, safer, and more accurate.

Adult↗