Neuroimaging in epilepsy.

Neuroimaging techniques have improved the understanding, diagnosis, and management of epilepsy. By providing excellent structural information, MRI is the technique of choice in evaluating patients with epilepsy. Functional imaging techniques, including MR spectroscopy, functional MRI, positron emission tomography, and single photon emission CT, permit noninvasive assessment of the epileptic substrate, its functional status, and neuroreceptors. The MRI-based techniques will potentially assume a greater role in the cost-effective workup of the patient. Currently, newer techniques such as magnetoencephalography, magnetic source imaging, and optical imaging are research tools.

Neurosyphilis in patients with AIDS.

Syphilis has become much more prevalent because of the dramatic increase in immunocompromised patients. The increase in immunocompromised patients is mainly secondary to AIDS. This article is put forth to refamiliarize the reader with syphilis, specifically neurosyphilis. The neurologic symptomatology and neuroimaging characteristics are presented so that one can recognize the findings and consider the diagnosis of neurosyphilis when confronted with a patient with AIDS.

Malignant supratentorial glial-neuronal neoplasms: report of two cases and review of the literature.

OBJECTIVE: Malignant neoplasms exhibiting mixed populations of neuronal and glial cells occurring in the cerebral hemispheres of young adults and children are well recognized, but rare. A confusing array of diagnostic terms has arisen. We describe two patients with such tumors and review the literature concerning these interesting cases. PATIENTS: A 21-year-old man and a 5-year-old girl presented with large, cystic, intracerebral lesions on magnetic resonance images, which proved to be composite neoplasms exhibiting malignant neurons and astrocytes. RESULTS: The 21-year-old man had a frontal lobe mass with enhancing and nonenhancing regions, which corresponded to cerebral neuroblastoma and anaplastic astrocytoma, respectively. The presence of occasional microtubules and rare primitive presynaptic processes, accompanied by antisynaptophysin immunoreactivity, established the neuronal nature of the cells in the enhancing region. The nonenhancing region was composed of a moderately cellular neoplasm of fibrillar astrocytes that were mitotically active. The 5-year-old girl presented with a left parietal lobe neoplasm, which histologically was composed of lobular proliferations of neuroblasts and glia. The neuroblastic populations exhibited evidence of maturation with small anaplastic cells, spindle-shaped cells, and large dysmorphic ganglion cells. The glial tumor showed both well-differentiated fibrillary astrocytes with microcysts and anaplastic populations with central necrosis and pseudopalisading. CONCLUSIONS: Present classification systems devised to describe mixed neuronal and glial tumors do not adequately encompass the diversity of morphologies presented by these two cases. We conclude that the terms cerebral neuroblastoma-anaplastic astrocytoma for case 1 and cerebral ganglioneuroblastoma-glioblastoma for case 2 are preferred because they convey useful clinical information by reflecting concepts already encompassed by the World Health Organization's classification system of tumors of the central nervous system.

The limbic system. An overview of the anatomy and its development.

The limbic system has a pivotal role in attention, memory, and the emotions. The limbic lobe comprises four C-shaped arches stretching from the medial surface of the frontal lobe to the temporal pole. The anatomic relationships are elegantly demonstrated by MR imaging. This article provides an overview of the development and complex anatomy of the limbic system.

Hippocampus. Normal magnetic resonance imaging anatomy with volumetric studies.

MR imaging sections of the hippocampus in different orthogonal planes are illustrated. Matching coronal slices in T2-weighted and gradient echo sequences allow a comparative evaluation of the intricate structure of the hippocampus and its relationship with adjacent structures. Techniques in volumetric assessment of the hippocampus are discussed in light of recent advancement in MR imaging.

Hippocampal pathology.

Medial temporal sclerosis of the hippocampus and other lesions in the adjacent temporal lobe that can cause epilepsy are discussed in this article. The technical factors to consider to optimally image the hippocampus and criteria to diagnose medial temporal sclerosis are emphasized.

Anatomy and pathology of the septal region.

Comprising the septal area and the subcortical nuclei, the septal region is gray matter structures with widespread projection systems and different neurotransmitters. Although their function is poorly understood, lesions of the septal nuclei result in a syndrome of hyper-reactivity, amnesia, and hypersexuality. The pathologic processes affecting the septal region are discussed.

Limbic circuits and neuropsychiatric disorders. Functional anatomy and neuroimaging findings.

The limbic system seems to be involved in the pathophysiology of neuropsychiatric disorders, including dementia, schizophrenia, affective disorders, and amnestic disorders. These findings are subtle and largely went undetected until the advent of modern neuroimaging. This article discusses some of the neuroimaging findings in these disorders.

Gliomatosis cerebri presenting with optic nerve involvement: MRI.

Gliomatosis cerebri is a rare form of astrocytoma characterized by extreme infiltration of the brain structure in conjunction with a relative paucity of clinical findings. We describe the MRI findings in a patient with gliomatosis cerebri widely infiltrating the brain who presented with symptoms related to involvement of the optic nerves and chiasm. Contrast-enhanced MRI showed enlargement of the optic nerves and chiasm with pathological enhancement; T2-weighted images showed extensive infiltration of the brain by tumor. Histopathologic examination of the biopsy specimen showed anaplastic astrocytoma with gemistocytic predominance and a diagnosis of gliomatosis cerebri was reached.

Single-voxel proton brain spectroscopy exam (PROBE/SV) in patients with primary brain tumors.

OBJECTIVE: The Single-Voxel Proton Brain Exam (PROBE/SV) is an automated MR spectroscopic technique. The purpose of this study was to investigate the use of PROBE/SV as a diagnostic tool in patients with primary brain tumors and to compare our findings with the known information obtained from conventional nonautomated MR spectroscopic techniques. SUBJECTS AND METHODS: We used PROBE/SV to image 10 normal adults and 46 patients with primary brain tumors: 29 glioblastoma multiformes (GBMs), five anaplastic astrocytomas, and 12 low-grade astrocytomas. All studied were performed on a 1.5-T Signa unit. Average voxel sizes were 6-8 cm3. A corresponding point-resolved spectroscopy spectrum was obtained from normal-appearing brain parenchyma in each patient for comparison with the spectra from known areas of pathology. RESULTS: In patients with low-grade gliomas (grades 1 and 2), we observed decreased N-acetylaspartate (12 of 12) and slightly increased choline (11 of 12) when we compared these metabolites with those in the spectra of patients' normal brains. This comparison in patients with GBM yielded markedly decreased N-acetylaspartate (29 of 29) and prominently increased choline (27 of 29). In the short TE spectra, we frequently saw lipid signal in high-grade tumors, especially in GBMs (12 of 20). We identified lactate peaks in high-grade tumors (anaplastic astrocytoma and GBM, 29 of 34) and also in low-grade tumors (four of 12). The creatine signal in all gliomas was slightly less than that of healthy brain tissue. The lowest N-acetylaspartate, choline, and creatinine levels in conjunction with the highest lactate levels were usually found in necrotic portions of high-grade tumors. CONCLUSION: PROBE/SV is a simplified MR spectroscopy technique that reduces setup time and provides automatic on-line data processing and display. The voxel location can be selected to focus on the area of interest and to minimize voxel contamination from unwanted tissue. The results from our experimentation with PROBE/SV in patients with brain tumors generally concur with published reports of tumor spectra obtained by conventional MR spectroscopic techniques. The ease and accuracy of this new technique make it a useful clinical tool in differentiating human brain tumor grades.

Intrathecal 131I-labeled antitenascin monoclonal antibody 81C6 treatment of patients with leptomeningeal neoplasms or primary brain tumor resection cavities with subarachnoid communication: phase I trial results.

We aimed to determine the maximum tolerated dose (MTD) of 131I-labeled 81C6 in patients with leptomeningeal neoplasms or brain tumor resection cavities with subarachnoid communication and to identify any objective responses. 81C6 is a murine IgG monoclonal antibody that reacts with tenascin in gliomas/carcinomas but does not react with normal adult brain. 131I-labeled 81C6 delivers intrathecal (IT) radiation to these neoplasms. This study was a Phase I trial in which patients were treated with a single IT dose of 131I-labeled 81C6. Cohorts of three to six patients were treated with escalating doses of 131I (starting dose, 40 mCi; 20 mCi escalations) on 10 mg 81C6. MTD is defined as the highest dose resulting in serious toxicity in no more than two of six patients. Serious toxicity is defined as grade III/IV nonhematological toxicity or major hematological toxicity. We treated 31 patients (8 pediatric and 23 adult). Eighteen had glioblastoma multiforme. Patients were treated with 131I doses from 40 to 100 mCi. Hematological toxicity was dose limiting and correlated with the administered 131I dose. No grade III/IV nonhematological toxicities were encountered. A partial response occurred in 1 patient and disease stabilization occurred in 13 (42%) of 31 patients. Twelve patients are alive (median follow-up, > 320 days); five are progression free >409 days median posttreatment. The MTD of a single IT administration of 131I-labeled 81C6 in adults is 80 mCi 131I-labeled 81C6. The MTD in pediatric patients was not reached at 131I doses up to 40 mCi normalized for body surface area.

Chorea-ballismus with nonketotic hyperglycemia in primary diabetes mellitus.

PURPOSE: To describe the neuroimaging (Ct, MR, and single-photon emission CT [SPECT]) findings in a series of patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus and to correlate the imaging findings with the clinical presentation. METHODS: The neuroimaging and clinical data from 10 patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus were evaluated. Family and drug histories, as well as other causes of chorea, were excluded. All 10 patients had CT, 5 also had MR imaging, and 3 had SPECT examinations. Three had follow-up CT and MR imaging studies, and MR findings were correlated with CT findings in 5 cases. Two experienced neuroradiologists, aware of the diagnosis but blinded to the clinical status of the patients, evaluated all images and reached a consensus as to the final interpretation. RESULTS: CT studies in 9 of 10 patients showed a hyperdense putamen and/or caudate nucleus; in 1, the CT findings were normal. T1-weighted MR images in all 5 patients who had MR imaging (including the patient with a normal CT study) showed hyperintense lesions without significant T2 signal alternation at the basal ganglia. In all 3 of the patients who had SPECT studies of the brain, the scans revealed hypoperfusion at corresponding areas. All 3 follow-up studies depicted resolution of the lesions in the abnormal basal ganglia. Increased hypointensity on T2-weighted and gradient-echo T2*-weighted images was also observed in the sequential MR images. In all patients, the initial side of involvement correlated well with the neuroimaging findings. The chorea resolved within 2 days after treatment of the hyperglycemia in 9 patients. CONCLUSION: In patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus, CT and T1-weighted MR images show unilateral or bilateral lesions of the putamen and/or caudate. SPECT scans show hypoperfusion. These findings may be related to petechial hemorrhage and/or myelin destruction. Early recognition of these imaging characteristics may facilitate diagnosis of primary diabetes mellitus with hyperglycemia and prompt appropriate therapy.

MRI of papillary meningiomas in children.

We report two cases of papillary meningioma in children. The MRI appearance of this special type of meningioma is described for the first time. Both lesions were dura based and associated with cystic components. We review the literature pertaining to this type of meningioma and discuss the differential diagnosis of the MRI appearance. Because this is a malignant type of meningioma, early diagnosis and surgical intervention are important in the management of patients.

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.

Frontoethmoidal giant cell reparative granuloma.

We present a case of a giant cell reparative granuloma of the frontoethmoidal region that had a large intracranial extraaxial component and was studied with MR. Although rare, giant cell reparative granuloma can be suggested in the correct clinical setting and when MR features suggest a fibrous lesion.