Gary A. Press

Leptomeningeal metastasis A comparison of gadolinium‐enhanced MR and contrast‐enhanced CT of the brain

We evaluated 14 consecutive patients with leptomeningeal metastasis prospectively, using both T1-weighted (T1W) gadolinium-DTPA-enhanced MR (Gd-MR) and contrast-enhanced CT (CE-CT). Thirteen had positive CSF cytology; the remaining patient had an atypical CSF lymphocytosis and primary CNS lymphoma. The patients (8M/6F) ranged in age from 8 to 70 years (median, 42 years). Tumor histology included 3 systemic and 2 primary CNS lymphomas, 3 breast carcinomas, 2 leukemias, 1 malignant schwannoma, 1 small cell lung cancer, 1 prostate cancer, and 1 melanoma. Both imaging methods demonstrated parenchymal volume loss equally well in all patients. Gd-MR revealed abnormal enhancement of meninges or parenchyma in 10 patients, including all 5 patients with positive CE-CT. Neither technique revealed any foci of abnormal enhancement in 4 patients. Gd-MR was superior to CE-CT in demonstrating and quantifying enhancing subarachnoid and parenchymal nodules in 6 patients and in demonstrating sulcal, dural, cisternal, tentorial, and ependymal enhancement. Our findings indicate that T1W Gd-MR is the preferred imaging modality in leptomeningeal metastasis and suggest that CE-CT is unnecessary.

Contribution of the cerebellum to neuropsychological functioning: evidence from a case of cerebellar degenerative disorder.

A detailed neuropsychological evaluation was performed on a patient with an idiopathic cerebellar degenerative disorder. Significant deficits were found in verbal and nonverbal intelligence, verbal associative learning, and visuospatial skills. These deficits were not readily explained by motor control difficulties. In contrast to the patients moderately impaired language abilities, he was severely impaired on a test of verbal fluency and demonstrated mild naming deficits. Severe cerebellar parenchymal volume loss was demonstrated by magnetic resonance examination. Supratentorial structures showed only minimal posterior parietal and occipital sulcal prominence. On neurological examination, this patient had signs of severe involvement of the cerebellar systems and mild-to-moderate dysfunction of the corticospinal tract. As is characteristic of patients with cerebellar degeneration, there was neurophysiological evidence of subclinical involvement of auditory and somatosensory pathways at the level of the brain stem. Since relatively little cerebral cortical atrophy was noted in this patient, these findings suggest that an intact cerebellum is important for normal cognitive functions.

Description of brain injury in the amnesic patient N.A. based on magnetic resonance imaging.

N.A. has been amnesic since 1960 when at the age of 22 years he sustained a penetrating brain injury with a miniature fencing foil. The amnesia primarily affects verbal material and occurs in the absence of other detectable cognitive deficits. Previous CT scans demonstrated a lucency in the region of the left mediodorsal thalamic nucleus, but no additional damage was revealed. Beginning in 1986 when he was 48 years old, N.A. was evaluated with a series of magnetic resonance imaging (MR) studies. Three major areas of damage were identified. In the left thalamus there is a prominent 3- to 4-mm-wide linear lesion that approximates the position and orientation of the internal medullary lamina. The defect extends for approximately 20 mm anteroposteriorly and likely involves the rostral group of intralaminar nuclei (central medial, paracentral, central lateral, rhomboid, and reuniens nuclei), the caudal group of intralaminar nuclei (centrum medianum and parafascicular nuclei), the ventral aspect of the mediodorsal nucleus, and the ventral lateral and ventral anterior nuclei. It also likely interrupts the trajectories of the mammillothalamic tract and postcommissural fornix. The posterior hypothalamus is markedly disrupted and the mammillary nuclei appear to be missing bilaterally. Finally, the right anterior temporal lobe is damaged for a distance of about 3.5 cm from the pole to midway through the amygdaloid complex. This damage probably occurred during exploratory neurosurgery done at the time of N.A.s injury. The hippocampal formation appears intact on both sides. A comparison of these findings with those from other patients with diencephalic amnesia suggests that amnesia can result when several diencephalic structures are damaged conjointly, including the internal medullary lamina, the intralaminar nuclei, the mediodorsal nucleus, and the mammillothalamic tract. Whether amnesia as severe as N.A.s would result from selective damage to any one of these structures remains to be determined.

Tissue plasminogen activator-mediated thrombolysis of cerebral emboli and its effect on hemorrhagic infarction in rabbits.

Tissue plasminogen activator (tPA) dissolves intravascular thrombus and restores blood flow after throm-boembolic vascular occlusion. The utility of this agent for treatment of stroke in humans may be limited by post-reperfusion hemorrhagic complications. We studied tPA-mediated thrombolysis in an animal model of cerebrovascular occlusion in order to determine what factors, if any, predispose tPA-treated animals to suffer hemorrhage. Small blood clot emboli were injected into the internal carotid arteries of rabbits. Angiograms confirmed occlusion of the middle cerebral artery or internal carotid artery in 100% of subjects. tPA or saline was administered as a 30-minute infusion at various times after embolization. Hemorrhage rates were similar in all groups regardless of treatment. tPA increased the prothrombin time and the thrombin time but not the partial thromboplastin time. There was no correlation between these changes in blood coagulation and the finding of cerebral hemorrhage. We observed a significant association between stroke severity and cerebral hemorrhage. We conclude that tPA treatment successfully causes thrombolysis of cerebral emboli without causing an increase in the incidence of cerebral hemorrhage in rabbits.

Rhinocerebral mucormycosis: Results of aggressive surgical debridement and amphotericin B

Rhinocerebral mucormycosis is a fulminant, devastating fungal disease. The use of amphotericin B, combined with aggressive surgical debridement, has increased survival rates from approximately 20% to 70%.

Spinal cord tumors: gadolinium-DTPA-enhanced MR imaging

SummaryTo assess the utility of gadolinium-DTPA (Gd) and of MR imaging in the evaluation of spinal cord tumors, ten consecutive patients were prospectively evaluated. T1-proton density-, and T2-weighted images were obtained in sagittal or axial planes. T1-weighted images were obtained before and after intravenous administration. Five tumors were within the cervical spinal cord; 3 neoplasms were within the thoracic cord; 1 neoplasm extended from the cervical to the thoracic cord and 1 neoplasm extended from the cervical cord to the conus medullaris. Four tumors were ependymomas; 3 were astrocytomas; 1 was an hemangioblastoma, and 1 was a metastatic malignant peripheral nerve sheath tumor. The remaining patient died prior to spinal surgery and no autopsy was obtained. Of theprecontrast sequences, tumors were best evaluated using T1-weighted images. Abnormal findings included cord widening, presence of a tumor mass, intratumoral or other associated cyst(s), and hemorrhage. Nevertheless, T1-weighted images obtainedfollowing the administration of GD were superior relative to all other pre- and post-contrast sequences for defining tumor margins, characterizing cyst(s) and delineating tumor masses. Based primarily on their appearance on post-contrast T1-weighted images, tumor-associated cysts could be subcategorized into 3 types: intratumoral cysts (foundwithin the contrast-enhancing soft tissue mass); nonenhancing extratumoral cysts (found either rostral or caudal to the enhancing tumor mass); and enhancing extratumoral cysts (having an enhancing wall or containing an enhancing nodule). Our results indicate that T1-weighted MR images obtained both before and after administration of Gd are sufficient for characterizing the varying components of intramedullary spinal cord tumors. This information assists in treatment planning and follow-up of patients with these tumors.

Temporal lobe ganglioglioma in refractory epilepsy: CT and MR in three cases

Abstract Three patients (ages 5, 16 and 21 years) with chronic, refractory, partial epilepsy and temporal lobe ganglioglioma were evaluated for surgical treatment. Noncontrast CT revealed a low attenuation, cystic temporal lesion in 2 patients. One neoplasm demonstrated focal calcification and temporal altrophy, while the other had mass effect and surrounding edema. Contrast enhancement of the mass was seen in one instance. Non-contrast and post-contrast CT were completely normal in the remaining patient.MR was abnormal in both patients in which it was performed (including the patient with a normal CT examination). Lesions were hyperintense on T2W inmages and iso-to-hypointense on T1W images when compared to normal parenchyma. Regions of calcification were missed on standard spin-echo sequences.Continuous video EEG monitoring captured habitual partial seizures in all patients; focal onset correlated with tumor location in each instance. Intraoperative electrocorticography corroborated the EEG results. Two of three patients underwent gross total resection. Pathologic features were characteristic of ganglioglioma in all instances. All patients have been seizure-free postoperatively [mean follow-up: 16 months (range 13–18 months)] and without evidence of tumor recurrence.Although ganglioglioma is an unusual cause of refractory temporal lobe epilepsy, our short term follow-up suggests excellent outcome with both partial and gross total resection.

Neonatal schizencephaly: Comparison of brain imaging

Schizencephaly is a regional disturbance of cerebral hemisphere formation occurring at 3-5 months gestation; neonatal presentation is uncommon. Three neonates with schizencephaly were evaluated with cranial ultrasonography (US), unenhanced computed tomography (CT), and magnetic resonance imaging (MRI) examinations. Common findings in US, CT, and MRI include parasylvian and midline clefts, size asymmetries of the basal ganglia and thalamus, cerebral parenchymal volume loss, ventriculomegaly, ventricular diverticula, and absence of the septum pellucidum. MRI and CT were superior to US in detecting calcification, gyral and sulcal abnormalities, and parasylvian clefts. MRI alone demonstrated homolateral absence of the sylvian vasculature, small medullary pyramids, low position of the fornix, and the thinning of the corpus callosum. Although US appears adequate as a screening test, MRI best defines the precise pathoanatomic findings of neonatal schizencephaly and allows for the prediction of neurologic outcomes in affected newborns.

Magnetic Resonance Imaging in the Evaluation of Vitreoretinal Disease in Eyes with Intraocular Silicone Oil

Media opacification in eyes filled with silicone oil makes the evaluation of recurrent retinal detachment difficult. Ultrasonography through silicone oil is subject to significant imaging artifacts. We performed magnetic resonance imaging on six patients with unilateral intravitreal silicone oil to determine if the technique would detect detached retina and subretinal oil. All patients had undergone pars plana vitrectomy with silicone oil injection for proliferative vitreoretinopathy; five patients had encircling solid silicone scleral buckles. In five patients the media were clear, and ophthalmoscopic findings were correlated with magnetic resonance findings. Four patients had recurrence of inferior retinal detachment; magnetic resonance imaging demonstrated subretinal oil in three of these patients. One patient had a concentric, shallow, anterior retinal detachment; magnetic resonance scanning demonstrated a globular hyperintensity suggestive of subretinal oil. In the sixth patient, who had an opaque cornea, magnetic resonance imaging suggested that the retina was attached preoperatively; this was confirmed at subsequent surgery. A chemical shift artifact was helpful in defining the contour of retinal detachments and the presence of subretinal oil by outlining the silicone oil within the eye.

The ferret as an animal model in cerebrovascular research.

Clinical and pathologic observations have suggested analogies between the developing nervous system of ferrets (Mustela putorius furo) and those of more traditional animal models employed in stroke research. Experimental work has demonstrated advantages of the ferret as a model of visual development. We performed in vivo cerebral angiography and postmortem neurovascular dissection of latex-injected specimens of adult ferrets. The great vessels include a cervical arterial trunk that gives rise to both carotid arteries. The anatomy of the cranial arteries is similar to that of rabbits. No carotid rete mirabile is present. There are no intracranial anastomoses between the external and internal carotid systems. We present in vivo cerebral angiograms with pathologic correlation that demonstrate that ferrets may provide the same anatomic advantages as a rabbit model for the experimental study of cerebrovascular disease, with the additional advantage of a long extracranial cervical segment of the carotid artery, affording easier access to the intracranial vasculature.