Biomedical subjects

A K Osumi

Publications and source records attributed to A K Osumi.

13 recordsLinked to original sources

PubMed1995

Utility of MR imaging in pediatric spinal cord injury.

We evaluated the utility of MR imaging in pediatric patients with acute and subacute spinal cord injuries. MR imaging of 22 pediatric patients with suspected traumatic spinal cord injuries was reviewed. MR findings were correlated with physical examination and compared to available radiographs and CT examinations performed at time of presentation. Twelve patients had abnormalities on MR imaging. Seven had spinal cord contusions; five contusions were hemorrhagic. Five of seven patients with cord contusion had normal radiographs and CT exams. Six patients with normal radiographs and CT examinations had abnormal MR studies revealing cord contusion, ligamentous injury, disc herniation, and epidural hematoma. MR is useful in initial evaluation of pediatric patients with spinal cord injuries and in prognosis of future neurologic function. In the setting of spinal cord symptomatology and negative radiographic studies, MR imaging should be performed. Surgically correctable causes of cord compression demonstrated by MR imaging include disc herniation, epidural hematoma, and retropulsed fracture fragments. The entity of spinal cord injury without radiographic abnormality is a diagnosis of exclusion which should only be made after radiologic investigation with radiographs, high-resolution thin-section CT, and MR imaging.

Adolescent↗

PubMed1995

Fast spin-echo, magnetic resonance imaging-measured hippocampal volume: correlation with neuronal density in anterior temporal lobectomy patients.

To assess the value of magnetic resonance imaging (MRI)-measured hippocampal volume in the detection of hippocampal sclerosis, we studied 28 patients undergoing anterior temporal lobectomy for medically intractable mesial temporal lobe epilepsy. Hippocampal volumetry and visual analysis of T2 signal change were performed using fast spin-echo T2-weighed MRI. Quantitative neuronal density measurements were performed in the resected hippocampal specimens. There was a significant correlation between MRI-measured absolute hippocampal volume (AHV) and neuronal density in CA1, CA2, and CA3 subfields (p < 0.0001, p < 0.01, and p < 0.05, respectively). Differential hippocampal volume (side-to-side volume difference) failed to detect bilateral atrophy in three patients, but the bilateral hippocampal atrophy was recognized by considering AHV in these patients. This study suggests that MRI-measured AHV can be of value in elevating patients with mesial temporal lobe epilepsy, especially when there is no side-to-side difference in hippocampal volumetry.

Adolescent↗

PubMed1995

Fast spin-echo MR in hippocampal sclerosis: correlation with pathology and surgery.

PURPOSE: To identify the extent of hippocampal sclerosis in temporal lobe epilepsy with fast spin-echo MR and correlate it with histopathologic findings and surgical outcome. METHODS: MR images of 30 patients with temporal lobe epilepsy and pathologically proved hippocampal sclerosis and 30 control subjects were obtained using a fast spin-echo technique with 4000/100/4 (repetition time/echo time/excitations), 16 echo train, 2- to 3-mm section thickness with interleave, 256 x 256 matrix, and 18-cm field of view. Criteria for MR diagnosis of hippocampal sclerosis included hippocampal atrophy diagnosed with MR volumetry and/or T2-weighted signal change. Hippocampal sectional areas were plotted, and T2 signal changes were topographically evaluated to identify the extent of hippocampal sclerosis, which was subsequently correlated with histopathologic findings and surgical outcome. RESULTS: Hippocampal sclerosis was diffuse, involving both hippocampal head and body, in 96.7% of patients (29 of 30 patients). One patient had normal MR findings. Focal hippocampal sclerosis was not seen. Histopathologic findings of hippocampal sclerosis were present in all 29 patients who had abnormal MR findings. Eighty-six percent of patients (18 of 21 patients), who were followed for at least 1 year after temporal lobectomy, were seizure free (81%, 17 of 21 patients) or significantly improved (5%, 1 of 21 patients). CONCLUSION: Fast spin-echo MR enables accurate definition of the extent of hippocampal sclerosis in patients with temporal lobe epilepsy. All cases of hippocampal sclerosis identified in this study involved the hippocampus diffusely. However, leaving the posterior portion of the hippocampus during surgery does not seem to be a major factor influencing surgical outcome.

Adolescent↗

PubMed1995

Cerebral amyloid angiopathy presenting as a brain mass.

The MR images of a patient with cerebral amyloid angiopathy (a localized vascular deposition of amyloid without evidence of systemic amyloidosis) showed an extensive right temporoparietal lobe mass with frontal lobe extension that was slightly hypointense on T1-weighted images and heterogeneously hyperintense on T2-weighted images. No contrast enhancement was identified on MR imaging.

Brain Neoplasms↗

PubMed1995

Cerebral phaeohyphomycosis complicated with brain abscess: a case report.

Cerebral phaeohyphomycosis is used to describe the rare clinical syndrome of cerebral infection caused by dematiaceous (i.e. pigmented olivaceous-brown) fungi. It usually presents as brain abscess. In view of the rarity of this fungal infection and its clinical importance, we report a case of cerebral phaeohyphomycosis caused by Xylohypha bantiana. The patient presented with a seizure attack. The MRI study revealed a ring-enhancing lesion with marked perifocal edema in right high frontoparietal junction of the brain. He underwent an initial craniotomy for removal of the lesion and a second craniotomy for recurrence of the lesion 3 months later. The diagnosis was based on successful cultivation of X. bantiana from the surgical specimen and on histopathology. The patient received antifungal drug therapy of 5-flucytosine and itraconazole. He has done well without any symptoms. We think complete surgical removal of the brain abscess combined with antifungal drug therapy is the best management for this rare fungal disease.

Brain Abscess↗

PubMed1995

Clinical significance of asymmetry of the fornix and mamillary body on MR in hippocampal sclerosis.

PURPOSE: To investigate the clinical significance of MR-defined asymmetry of the fornix and mamillary body for presurgical determination of the side of hippocampal sclerosis in patients with temporal lobe epilepsy. METHODS: Fast spin-echo MR images were evaluated for evidence of an asymmetrically small fornix and mamillary body in 33 patients with pathologically proved hippocampal sclerosis (presurgical hippocampal sclerosis group), 7 patients who had undergone anterior temporal lobectomy (mean, 3 years from surgery) because of hippocampal sclerosis (postsurgical hippocampal sclerosis group), and 34 healthy subjects (control group). Fast spin-echo hippocampal volumetry was performed in each patient. RESULTS: In the control group, 6% (2 of 34) of subjects had MR evidence of asymmetrically small fornix and none (0 of 34) of the subjects had asymmetrically small mamillary body. In the patient population, an asymmetrically small fornix was seen in 42% of presurgical hippocampal sclerosis group, 39% (13 of 33) ipsilateral, and 3% (1 of 33) contralateral, and in 71% of the postsurgical hippocampal sclerosis group (5 of 7), all ipsilateral. In the presurgical hippocampal sclerosis group, hippocampal atrophy measured with MR was more severe in patients with an ipsilaterally small fornix than in patients without. An asymmetrically small mamillary body was found ipsilaterally in 3% (1 of 33) of the presurgical hippocampal sclerosis group and in 57% (4 of 7) of the postsurgical hippocampal sclerosis group; all patients with an asymmetrically small mamillary body in the postsurgical hippocampal sclerosis group also had an asymmetrically small fornix on the same side. CONCLUSION: In presurgical hippocampal sclerosis patients, an asymmetrically small fornix can be seen ipsilaterally on the side of the hippocampal sclerosis; however, its low frequency, its association with severe hippocampal atrophy only, and the possibility of false-positive results limit its clinical usefulness in determining the side of the seizure focus. An asymmetrically small mamillary body is too rare to be used for presurgical location of hippocampal sclerosis. However, an asymmetrically small fornix and mamillary body are frequently seen on MR images after temporal lobectomy.

Adolescent↗

PubMed1994

MR measurements of the hippocampus for lateralization of temporal lobe epilepsy: value of measurements of the body vs the whole structure.

OBJECTIVE: Measurements of the volume of the hippocampus have been used preoperatively to determine the side of the hippocampus involved in patients with intractable temporal lobe epilepsy. However, the method used is time consuming and requires special training. The purpose of this study was to determine the validity of using measurements of the volume of the hippocampal body as a substitute for measurements of the volume of the whole hippocampus in patients with temporal lobe epilepsy. SUBJECTS AND METHODS: The study group consisted of 33 patients with intractable temporal lobe epilepsy due to presumed hippocampal sclerosis and 30 control subjects. Of the 33 patients with intractable temporal lobe epilepsy, 30 had hippocampal sclerosis and three had normal findings on pathologic examination of the hippocampus. T2-weighted fast spin-echo images were used to determine hippocampal volumes. Volumes were calculated by summing the sectional areas of the entire hippocampus and of the hippocampal body. Correlation between the volume of the hippocampal body and the volume of the whole hippocampus was determined. The sensitivity and specificity of measurement of the volume of the hippocampal body for lateralizing the foci responsible for seizures in patients with presumed hippocampal sclerosis were compared with those of measurement of the volume of the whole hippocampus. RESULTS: Significant linear relationships were noted between volumes of the hippocampal body and volumes of the whole hippocampus (p < .001). The sensitivity and specificity of measurements of volumes of the hippocampal body were identical to those of measurements of volumes of the whole hippocampus (87% and 100%, respectively). CONCLUSIONS: Our results show that segmental MR measurements of the body of the hippocampus are as accurate as measurements of the whole hippocampus for lateralizing temporal lobe epilepsy before surgery. Because segmental measurements are less time consuming and require less experience to perform, they are considered the procedure of choice.

Adolescent↗

PubMed1994

Terminal syringohydromyelia and occult spinal dysraphism.

Terminal syringohydromyelia is a cystic dilatation of the lower third of the spinal cord. The authors describe its incidence and characteristics, its frequent association with occult spinal dysraphism, and its clinical significance and need for surgical treatment. All 143 cases of occult spinal dysraphism treated at the Duke University Medical Center between 1972 and 1992 were reviewed. A terminal syrinx was found in 24 (27%) of the 90 cases that were evaluated by magnetic resonance (MR) imaging. In contrast three (6.2%) of 48 cases evaluated by myelography and postmyelographic computerized tomography had a syrinx documented. The relative radiographic severity of the different syringes was estimated by using measurements of the syrinx and spinal cord on the MR images, classifying the cysts into large and small. Large syringes were frequently symptomatic, commonly presenting with pain, motor and sensory deficits of the lower extremities, scoliosis, and bowel and bladder dysfunction. Terminal syringohydromyelia with occult spinal dysraphic lesions was most often associated with tethered spinal cord from a tight filum terminale in the presence of an anorectal anomaly (67% of cases), meningocele manqué (54%), and diastematomyelia (38%). An infrequent association was seen with other spinal cord anomalies. The results of surgical management of terminal syringohydromyelia were analyzed, highlighting the necessity and effectiveness of shunting the large cysts, especially in the setting of a progressive symptomatology. Of the 11 patients with shunts who underwent MR imaging, 10 showed either complete or significant resolution of the syrinx; all five patients who had presented with pain (mainly back pain) showed complete resolution of the pain after shunting; finally, one-third of patients with shunt placement had significant postoperative improvement in their neurological examination, whereas none worsened. It is stressed that terminal syringohydromyelia is an important pathological entity that should be considered in patients with occult spinal dysraphism, and treated surgically when clinically or radiographically significant.

Adolescent↗

PubMed1993

Complex partial seizures and mesial temporal sclerosis: evaluation with fast spin-echo MR imaging.

PURPOSE: This study was performed to determine the sensitivity and specificity of fast spin-echo (FSE) magnetic resonance (MR) imaging in detecting mesial temporal sclerosis. MATERIALS AND METHODS: Twenty-one patients with a diagnosis of complex partial seizures were studied. Criteria for abnormality included visual detection of hippocampal MR signal abnormality and atrophy or significantly decreased hippocampal volume determined by using MR morphometric techniques. RESULTS: The overall sensitivity and specificity of MR imaging in demonstrating correct lateralization of seizure focus were both 100%. The positive predictive value of FSE MR imaging was 100%. The negative predictive value was 50%. CONCLUSION: The authors recommend FSE MR imaging of the hippocampus as the imaging technique of choice in the evaluation of patients with complex partial seizures for mesial temporal sclerosis.

Adult↗

PubMed1993

Herpesvirus infections of the CNS: MR findings.

Herpesvirus infections of the CNS are prevalent in all segments of the population, and are an important health care issue. The family of herpesviruses consists of a large group of double-stranded DNA viruses that includes herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2), cytomegalovirus, Epstein-Barr virus, varicella-zoster virus, B virus, herpesvirus 6, and herpesvirus 7. In addition to producing infection when the host initially acquires the virus, an important property shared by these viruses is the ability to produce latent infection and to be reactivated.

Central Nervous System↗

PubMed1993

The dementias: correlation of clinical features, pathophysiology, and neuroradiology.

Current methods of neuroimaging have revolutionized the examination of patients with dementia. Clinical examination of these patients has identified cortical and subcortical patterns of dementia. Each of these patterns can be caused by various diseases. Mixed patterns also occur and also have several possible causes. Neuroimaging can be quite useful in confirming the clinical assessment of the pattern of dementia and in further refining the diagnosis. We review the pathophysiologic basis of and the clinical and neuroimaging findings in dementia, both cortical and subcortical. The roles of neuroimaging in diagnosis, prognostic assessment, and treatment evaluation are discussed.

Adult↗

PubMedDate not supplied

Muslin-induced optic arachnoiditis ("gauzoma"): findings on CT and MR.

We report a case with a paraophthalmic aneurysm that was wrapped with muslin because it was unclippable. Six months after wrapping, the patient developed gradual vision loss involving the ipsilateral eye. Both CT and MR studies demonstrated a loculated fluid collection with marked surrounding enhancement in the region of the previous surgery. Craniotomy revealed an abscess centered in the region of the aneurysmal wrapping. Pathological diagnosis was consistent with a foreign-body reaction with acute and chronic inflammation. Postoperatively the patient showed improvement in vision. We describe the MR findings in this case of muslin-induced optic arachnoiditis ("gauzoma").

Abscess↗

PubMedDate not supplied

Well differentiated astrocytoma occurring nine years after radiation therapy for medulloblastoma.

Conventional treatment for medulloblastoma includes surgical resection followed by craniospinal irradiation, with the potential risk of subsequent radiotherapy-induced secondary neoplasms. We report a 23-year-old woman previously irradiated nine years earlier for a cerebellar medulloblastoma who developed a new enhancing lesion in the primary radiation field four weeks following completion of high dose chemotherapy with bone marrow transplantation for recurrent disease. Resection of this lesion revealed a low grade glioma with no evidence of recurrent medulloblastoma.

Adult↗