Denis Melanson

Early childhood prolonged febrile convulsions, atrophy and sclerosis of mesial structures, and temporal lobe epilepsy An MRI volumetric study

We performed MRI volumetric measurements of the amygdala (AM) and hippocampal formation (HF) in a group of 43 patients with temporal lobe epilepsy not controlled by optimal drug treatment. Fifteen patients (35%) had a history of prolonged febrile convulsions (PFC) in early childhood; 30 patients underwent surgery, and histopathology was available in twenty-four. The mean values of AM and HF volumes ipsilateral to the EEG focus were significantly smaller than those of normal controls. The volumetric measurements showed a more pronounced atrophy of the AM in patients with a history of PFC, although the HF volumes were also smaller in this group. Patients with a history of PFC had a higher proportion of more severe mesial temporal sclerosis (MTS) compared with those with no PFC. These findings confirm a correlation between early childhood PFC, the severity of atrophy of mesial structures, and MTS.

Diagnosis of subtle focal dysplastic lesions: curvilinear reformatting from three-dimensional magnetic resonance imaging

Focal cortical dysplasia is a frequent cause of medically intractable partial epilepsy. These lesions are being increasingly identified by high quality images provided by magnetic resonance imaging (MRI), resulting in improved seizure control of surgically treated patients. Small dysplastic lesions are often missed by conventional MRI methods. The identification of subtle structural abnormalities by rectilinear slices is often limited by the complex convolutional pattern of the brain. We developed a method of curvilinear reformatting of three‐dimensional MRI data that improves the anatomical display of the gyral structure of the hemispheric convexities. It also reduces the asymmetric sampling of gray–white matter that may lead to false‐positive results. We present 5 patients in whom conventional two‐dimensional and three‐dimensional MRI with multiplanar reformatting was initially considered normal. Subsequent studies using curvilinear reformatting identified lesions in all. Four patients underwent surgery with histological diagnosis of focal cortical dysplasia. Three patients are seizure‐free and 1 had significant improvement in seizure control. These results indicate that an increase in the detection of subtle focal dysplastic lesions may be accomplished when one improves the anatomical display of the brain gyral structure by performing curvilinear reformatting. Ann Neurol 1999;46:88–94

Mri of Amygdala and Hippocampus in Temporal Lobe Epilepsy

In this study we compared the results of qualitative visual analysis of MRI with volumetric studies of the amygdala (AM) and hippocampal formation (HF) in a group of 31 patients. Twenty-six patients with temporal lobe epilepsy (TLE) and six with non-TLE had MRI studies using a 1.5 T Gyroscan following a specific protocol for scan acquisition. The MR images were interpreted by two blinded radiologists and by a third if discrepancy arose. Volumetric studies were carried out by one or two raters. The volumetric measurements of AM and HF were accurate in lateralizing the epileptogenic area in patients with TLE, concordant with the EEG in 92%; there was no false lateralization. In those patients who underwent surgery, there was a correlation between the degree of mesial temporal sclerosis demonstrated by histopathology, the amount of volume reduction, and the asymmetry. In patients with non-TLE, there was no volume asymmetry of AM or HF. The MR qualitative assessment yielded positive lateralization in patients with TLE in 56%, conflicting lateralization in 20%, and lateralization contralateral to the focus in 12%. A hyperintense signal in mesial structures was found ipsilateral to the focus in 40% and contralateral in 12% of patients with TLE. Volumetric study improves the diagnostic yield of MRI evaluation in patients with TLE not related to gross structural lesions. The interrater variability is low and the data are accurate and reproducible. Because they are quantitative, volumetric studies permit better comparison of results in different subgroups of patients with TLE.

Prolonged focal cerebral edema associated with partial status epilepticus.

Summary: Following several days of partial status epilepticus, three patients developed striking focal cerebral edema as demonstrated by computed axial tomography (CT) scan. An angiogram done in one patient showed a capillary blush and early cortical draining veins in the corresponding area. All patients developed severe focal neurological deficit which resolved as the edema improved, and this was demonstrated on serial CT scans (at 6 months, 1 month, and 2 months, respectively). In the first patient, an underlying tumor, and in the second and third, vascular occlusions, were suspected because we were not aware that edema due to status epilepticus could produce changes of such intensity and duration. The neurological disability after the partial status was long‐lasting but reversed completely in our patients. Maximal radiological changes occurred in the area of maximal epileptic discharge. Minimal atrophic changes persisted in two of the three patients. The clinical, CT scan, and angiographic findings suggest that partial status epilepticus can be associated with abnormal vascular permeability leading to prolonged focal cerebral edema. Similar pathophysiology of lesser intensity may be responsible for shorter postictal neurological deficits. Awareness of this clinical and radiological entity should avoid misdiagnosis of cerebral tumor or infarction.

Familial Cerebral Aneurysms: A Study of 13 Families

Despite the recent interest in familial cerebral aneurysms, the epidemiology, natural history, pattern of inheritance, screening of asymptomatic relatives, and the search for a biochemical marker remain problematic. To assess these issues, we report the results of our prospective study of 30 patients with 38 aneurysms (27 ruptured) and of the angiographic screening of asymptomatic relatives, all from 13 families seen consecutively since 1986. Women were over-represented (77%), and patients with multiple aneurysms (17%) were under-represented, compared with sporadic cases. Only 16% of the aneurysms were at the anterior communicating artery. Aneurysms occurred at the same or at the mirror site in 10 of 16 siblings (62%) and in 50% of mother-daughter pairs versus 20% for randomly selected, sporadic aneurysm patients. Rupture occurred in the same decade in 10 of 12 siblings (83%) versus the expected 21% for randomly selected, sporadic aneurysms. The average age at rupture was 47.2 years, and 60% of patients with a ruptured aneurysm were 50 years of age or younger. Seventy percent of patients died or were disabled from aneurysmal rupture. Screening of 41 individuals, including 2 dizygous twins, identified 1 aneurysm and 2 infundibula. A specific pattern of inheritance could not be ascertained from the pedigrees. The presence of an aneurysm was not associated with a specific human leukocyte antigen haplotype or antigen, and collagen Type III was qualitatively and quantitatively normal. Until a biological marker is identified, angiographic screening by intra-arterial digital subtraction or magnetic resonance angiography remains the only way to identify patients at risk of harboring a familial cerebral aneurysm.

Intracerebral cavernous angiomas.

We studied 31 patients with histologically verified intracerebral cavernous angiomas. Twenty-two patients were symptomatic; nine were asymptomatic. All 22 symptomatic patients had seizures, three had intracranial hemorrhage, and one had signs of a space-occupying lesion. Twenty-seven lesions were located in the neocortex, three in the brainstem, and one in the cerebellum; all exhibited characteristic gross and microscopic features of cavernous angiomas. CT identified the location and extent of the lesion in 16 of 27 cases. Six of seven lesions demonstrated contrast enhancement, and ten of 27 scans harbored densities consistent with intracerebral calcium. Angiography was performed in 17 cases and was completely normal in eight. MRI revealed mixed signal intensity centrally with a ring of decreased signal intensity peripherally on T2-weighted images and was diagnostic in five cases. Surgical treatment offers an excellent prognosis for seizure control in patients with such lesions.

Occult encephaloceles and temporal lobe epilepsy: developmental and acquired lesions in the middle fossa.

Three patients with medically refractory partial complex seizures were shown to have small and initially unsuspected encephaloceles of the middle fossa. All had bitemporal, independent, interictal epileptogenic abnormalities, and the side of origin of the seizures could not be determined by surface EEG alone. The encephaloceles were missed on the initial radiologic studies and were found retrospectively in two patients; the third was found at operation and was not demonstrable radiologically, even in retrospect. One was the sequel of remote mastoid surgery, another was neoplasm-related, and the third, developmental. In all, bony defects of the middle cranial fossa were associated with temporal lobe herniation. The patients were treated surgically and have had no further partial complex seizures since operation.

SPINAL ANGIOLIPOMAS : CT AND MR ASPECTS

Spinal angiolipomas are rare benign tumors containing vascular and mature adipose elements. In greater than 90% of the cases they are located in the epidural space. The clinical symptomatology is nonspecific, but CT and particularly MR studies allow for a precise diagnosis. Computed tomography (four cases in the literature plus one explored in our department) showed a hypodense lesion in 80% of the cases. In one case the angiolipoma was isodense to the cord. Magnetic resonance (three cases in the literature plus two explored in our department) showed a more or less homogeneous mass with a signal in T1- and T2-weighted images close to that of the subcutaneous fat. The infusion of gadolinium (one case in the literature plus one of ours) is helpful as an indicator to the degree of vascularization of the angiolipoma.

Embolization with temporary balloon occlusion of the internal carotid or vertebral arteries

SummaryFunctional vascular anastomoses at the base of the brain allow for temporary occlusion of the carotid or vertebral arteries. Six embolizations with temporary balloon occlusion of the internal carotid or vertebral artery are reported. Polyvinyl alcohol was the embolic material in all cases and all procedures were performed using digital angiography. The size of the embolic particles and the positioning of the balloon related to the branches of the occluded vessel is discussed.

Familial Cerebral Aneurysms

Despite the recent interest in familial cerebral aneurysms, the epidemiology, natural history, pattern of inheritance, screening of asymptomatic relatives, and the search for a biochemical marker remain problematic. To assess these issues, we report the results of our prospective study of 30 patients with 38 aneurysms (27 ruptured) and of the angiographic screening of asymptomatic relatives, all from 13 families seen consecutively since 1986. Women were over-represented (77%), and patients with multiple aneurysms (17%) were under-represented, compared with sporadic cases. Only 16% of the aneurysms were at the anterior communicating artery. Aneurysms occurred at the same or at the mirror site in 10 of 16 siblings (62%) and in 50% of mother-daughter pairs versus 20% for randomly selected, sporadic aneurysm patients. Rupture occurred in the same decade in 10 of 12 siblings (83%) versus the expected 21% for randomly selected, sporadic aneurysms. The average age at rupture was 47.2 years, and 60% of patients with a ruptured aneurysm were 50 years of age or younger. Seventy percent of patients died or were disabled from aneurysmal rupture. Screening of 41 individuals, including 2 dizygous twins, identified 1 aneurysm and 2 infundibula. A specific pattern of inheritance could not be ascertained from the pedigrees. The presence of an aneurysm was not associated with a specific human leukocyte antigen haplotype or antigen, and collagen Type III was qualitatively and quantitatively normal. Until a biological marker is identified, angiographic screening by intra-arterial digital subtraction or magnetic resonance angiography remains the only way to identify patients at risk of harboring a familial cerebral aneurysm.