Biomedical subjects

D Melanson

Publications and source records attributed to D Melanson.

At least 19 recordsLinked to original sources

PubMed1992

Dysplastic gangliocytoma (Lhermitte-Duclos disease): CT and MR imaging.

Dysplastic gangliocytoma (Lhermitte-Duclos disease) is a rare entity. Usually presenting as a posterior fossa mass, dysplastic gangliocytoma is not a true neoplasm but a hard-to-characterize lesion that may represent an abnormality of cell migration or a phacomatosis. Previous reports of CT findings are rare in the radiologic literature, and high-field (1.5 Tesla) MR images have never been described in the pediatric age group. We present a case of dysplastic gangliocytoma in a one-year-old boy with CT and MR findings.

Cerebellar Neoplasms↗

PubMed1992

Anatomic basis of amygdaloid and hippocampal volume measurement by magnetic resonance imaging.

Both the amygdala and the hippocampus are involved in the pathogenesis of a number of neurologic conditions, including temporal lobe epilepsy, postanoxic amnesia, and Alzheimer's disease. To enhance the investigation and management of patients with these disorders, we developed a protocol to measure the volumes of the amygdala and as much of the hippocampus as possible (approximately 90 to 95%) using high-resolution MRI. We present the anatomic basis of these two protocols and our results in normal control subjects. These volumetric studies of the amygdala may clarify the role of this structure in the pathogenesis of temporal lobe epilepsy.

Adult↗

PubMed1991

Hippocampal sclerosis in temporal lobe epilepsy demonstrated by magnetic resonance imaging.

The value of magnetic resonance imaging in the detection of hippocampal sclerosis has been controversial. We studied 10 patients aged 22.5 +/- 6.0 years with intractable temporal lobe epilepsy selected because of a history of a prolonged childhood convulsion, which is characteristic of a group of patients in whom hippocampal sclerosis is a constant finding. All 10 patients showed reduction in size of one hippocampus associated with increased signal intensity on T2-weighted magnetic resonance images. These changes were reliably detected on coronal spin-echo images, perpendicular to the long axis of the hippocampus. Appreciation of the normal imaging anatomy of the hippocampus allowed correct interpretation of the relative changes in signal intensities of the hippocampus and adjacent temporal horn on sequential echo images. The side of the abnormal hippocampus on magnetic resonance imaging accorded with the electroencephalographic localization in all 10 patients, and with the lateralization of the early convulsions in all 6 patients where this was known. Temporal lobectomy was performed in all 10 patients. Hippocampal sclerosis was confirmed in the 3 patients in whom hippocampal tissue was available for histological examination. The value of this technique was reinforced by the excellent postoperative results, with 80% being seizure free at a mean follow-up time of 33 +/- 4 months.

Adolescent↗

PubMed1991

Percutaneous aspiration biopsy in cervical spine lytic lesions. Indications and technique.

We describe the technique and the results of the percutaneous aspiration biopsy (PAB) in a series of 9 patients presenting with neck pain and different degrees of myelopathy, in whom the cervical spine X-ray demonstrated lytic lesions of unknown origin. PAB is a useful, relatively safe technique, and leads to histological diagnosis between metastatic and inflammatory processes. Furthermore, in inflammatory lesions with negative hemoculture. PAB may help in detecting the micro-organism responsible and therefore allow a better antibiotic treatment.

Adult↗

PubMed1991

Neuronal migration disorders: a contribution of modern neuroimaging to the etiologic diagnosis of epilepsy.

Computed tomography and magnetic resonance imaging enable the identification of neuronal migration disorders during life. Several specific syndromes have been identified and early diagnosis of previously unrecognized entities is now possible. We report 51 patients with imaging. Thirty-two had a single widespread cortical dysplastic lesion. Twenty-eight had focal corticectomies. From a pathological standpoint, these encompassed focal cortical dysplasia (14 cases) and forme fruste of tuberous sclerosis (10 cases). These two groups of patients were indistinguishable from the clinical and radiological standpoint. In only two was the MRI examination normal. In addition, there were 10 with bilateral perisylvian dysplasia, four with diffuse cortical dysplasia or the "double cortex" syndrome, three with hemimegalencephaly, one with megalencephaly, and one with nodular neuronal heterotopia. The electroclinical and imaging findings led to the development of specific surgical strategies for the alleviation of the intractable seizures in each of these radiologically-defined syndromes.

Adolescent↗

PubMed1991

Computed tomography and magnetic resonance imaging of an infiltrative lesion of the anterior visual pathways.

Infiltrative lesions of the optic chiasm and optic nerves are uncommon. The authors report such a case and discuss the differential diagnosis, paying particular attention to imaging. In the reported case high-resolution computed tomography and magnetic resonance imaging revealed thickening of the optic chiasm and intracranial optic nerves, a pattern characteristic of an inflammatory or neoplastic process.

Diagnosis, Differential↗

PubMed1991

Wilson's disease: computed tomography and magnetic resonance imaging findings.

The condition of a patient with Wilson's disease was evaluated by magnetic resonance imaging (MRI) on initial presentation of the illness. The examination revealed mild atrophy of the superior vermis. Symmetric areas of increased signal intensity on T2-weighted images were detected in the anterior thalami, mesencephalic tectum and tegmentum. Marked symmetric hypointensities appeared in the head of caudate, pallida, substantia nigra and red nuclei. The histopathology of Wilson's disease suggests that these hypointensities may be secondary to the presence of protein-bound copper.

Adult↗

PubMed1989

Generalized cortical dysplasia manifested by diffusely thick cerebral cortex.

Unilateral or bilateral rolandic macrogyria has been described as a cause of epilepsy and, in some cases, retardation. Tissue from the periphery of these lesions shows the changes of focal cortical dysplasia. Evidence reported herein suggests that cortical dysplasia may also be generalized. Two patients with intractable epilepsy and mental retardation had diffusely abnormal, thick cortex, shallow gyri, and poor demarcation of gray and white matter. One patient had an anterior callosotomy that led to considerable improvement of the epilepsy. Cortical layers 5 and 6 could not be differentiated on biopsy material. The white matter was poorly myelinated and contained clusters of heterotopic neurons. This syndrome, a congenital disorder of neuronal migration, with prolonged survival, represents a mild form of lissencephaly. It can be diagnosed during life by computed tomography or magnetic resonance scanning.

Adolescent↗

PubMed1989

Bilateral central macrogyria: epilepsy, pseudobulbar palsy, and mental retardation--a recognizable neuronal migration disorder.

The neuronal migration disorders comprise several morphological entities that are recognizable during life using current imaging techniques. We studied 4 patients who had a characteristic bilateral central rolandic and sylvian macrogyria. The patients had pseudobulbar palsy with oromotor incoordination and developmental delay and were mildly retarded. Minor seizures developed between the ages of 8 and 9 years. Subsequently, atonic drop attacks became the predominant epileptic pattern. Epileptogenic electrographic abnormalities were secondary generalized or multifocal. The lesions were detected by computed tomography and magnetic resonance imaging in all patients. Bilateral symmetrical areas of thick cortex surrounding a large sulcus were seen. This syndrome consists of specific clinical, imaging, electroencephalographic, and epileptic features. It can be suspected clinically and confirmed by imaging studies. Callosotomy in two patients helped the intractable seizures.

Adolescent↗

PubMed1989

Partially sequestered fourth ventricle: CT and MR diagnosis of an unusual entity.

Encystment of the fourth ventricle, due to occlusion of the aqueduct as well as the foramina of Magendie and Luschka has been described previously. Partial sequestration such as that encountered in two cases described is a less common entity. In these two cases, the aqueduct of Sylvius was occluded, but the basal foramina (Magendie and Luschka) were patent. We discuss this partial sequestration or communicating hydrocephalus of the fourth ventricle on the basis of MR and CT scan findings. Although computed tomography following water soluble cisternography did diagnose the entity indirectly MRI proved to be a superior tool. It permitted direct visualization of the basal foramina noninvasively.

Adult↗

PubMed1989

MR of deep cerebral venous thrombosis.

Two cases of deep cerebral venous thrombosis are presented with specific reference to the CT and MR findings. The MR findings are discussed, with comparison to the findings of superficial cerebral sino-venous occlusion.

Adult↗

PubMed1988

Focal cortical myoclonus and rolandic cortical dysplasia: clarification by magnetic resonance imaging.

Focal cortical myoclonus is rare. Obvious causes include tumor or atrophy involving the motor strip, but in some cases no cause is apparent. We present 4 patients who started to have focal myoclonus in childhood. All had focal motor seizures as well, and one had recurrent focal motor status epilepticus. All 4 had a mild progressive hemiparesis. Electrographic investigations showed focal epileptic discharges in the contralateral rolandic areas. Radiological studies were unrevealing, but magnetic resonance showed rolandic lesions in 3 patients. At surgery, abnormally wide gyri were found in the distribution demonstrated by magnetic resonance. The pathological substrate was focal cortical dysplasia. All patients have improved considerably following surgery. These findings suggest that focal myoclonus may be due to a rolandic neuronal migration disorder. Visualization of these lesions by magnetic resonance permits development of a surgical strategy leading to optimal treatment of these medically intractable epileptic disorders.

Adolescent↗

PubMed1988

Hypothalamic hamartomas and ictal laughter: evolution of a characteristic epileptic syndrome and diagnostic value of magnetic resonance imaging.

Detailed study of 4 patients and review of the literature allowed us to delineate further the epileptic syndrome associated with hypothalamic hamartomas, which characteristically begins in infancy with laughing seizures. Because early childhood psychomotor development is usually normal, the condition appears benign and may not even be recognized. The episodes of laughter are brief, frequent, and mechanical in nature. These features distinguish it from other forms of epileptic laughter, particularly that which occurs in temporal lobe epilepsy. Subsequently, the seizures become longer, other seizure types appear, and between the ages of 4 and 10 years, the clinical and electroencephalographic features of secondary generalized epilepsy develop. Cognitive deterioration occurs and severe behavior problems are frequent. Prognosis for seizure control and social adjustment is poor. Cortical abnormality occurs in association with the hypothalamic hamartoma. The lesions are best detected by magnetic resonance imaging but may be difficult to identify by computed tomographic scanning.

Adolescent↗

PubMed1988

Magnetic resonance imaging of meningio-angiomatosis.

We report the case of a patient with meningio-angiomatosis, a rare disorder of the cerebral cortex often associated with Von Recklinghausen's neurofibromatosis. Previous reports have described a variety of radiological findings but in general they have been of little value in the diagnosis of this disorder. We describe the magnetic resonance image, which identified a well-defined lesion. The imaging techniques are reviewed.

Adolescent↗

PubMed1988

Cavernous hemangiomas of the spinal cord: MR imaging.

In three patients with histologically proved cavernous hemangiomas of the spinal cord, magnetic resonance (MR) imaging was superior to myelography, delayed computed tomography (CT) myelography, and contrast-enhanced CT in depicting the lesion. The presence of mixed subacute and chronic hemorrhage, suggested by mixed high- and low-signal-intensity components of these lesions on MR images, may be characteristic of this rare, intramedullary vascular malformation.

Adult↗

PubMed1988

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.

Adolescent↗

PubMed1988

Cavernous angiomas of the spinal cord.

Five cases of histologically verified cavernous angiomas of the spinal cord are reported. Acute lower-extremity sensory disturbance was the initial symptom in four patients, and one presented with weakness of the hand. Progressive neurological deficit occurred in all patients, but the clinical course and outcome were extremely variable. Myelography revealed an intramedullary lesion in two cases but was completely normal in three; magnetic resonance imaging was diagnostic in these patients. Subtotal removal was accomplished in two cases, and myelotomy and biopsy were carried out in three. Four of the cavernous angiomas were located in the cervicothoracic region, whereas one was found in the thoracolumbar cord. All of the patients exhibited characteristic gross and microscopic features as well as hemosiderin-laden macrophages indicating remote hemorrhage. The diagnostic, therapeutic, and prognostic implications of this rare condition are discussed.

Adult↗

PubMed1988

Metrizamide compared with iohexol for cervical myelography: a double-blind study.

A double-blind comparative study of iohexol and metrizamide for use in cervical myelography through lumbar puncture was carried out in a group of 30 patients. No difference was found in the quality of radiographic examinations of the cervical or lumbar regions nor in the postmyelographic computed tomographic examinations of the cervical spine. The overall incidence of side effects was significantly higher in the metrizamide group (93.4%) than in the iohexol group (40%) (p = 0.002). The differences in incidence of nausea (53% in the metrizamide group compared with 13% in the iohexol group) and vomiting (46.6% with metrizamide, 6.6% with iohexol) were also significant (p = 0.02). Pyramidal signs and seizures occurred only after metrizamide myelography.

Adult↗