PubMed Health⌕ Search

Biomedical subjects

J M Mercader

Publications and source records attributed to J M Mercader.

At least 19 recordsLinked to original sources
PubMed2006

Abnormal orbitofrontal development due to prematurity.

OBJECTIVE: To investigate the effects of prematurity on sulcal formation. METHODS: We evaluated the depth and volume of the primary olfactory sulcus (developed at 16 weeks' gestation) and the secondary orbital sulci (which start to develop at 28 weeks' gestation) in a sample of 22 adolescents with history of very-preterm birth (VPTB). We compared this preterm sample with a sample of subjects born at term and matched by age, gender, and sociocultural status. The Anatomist/BrainVISA 3.0.1 package was used to identify and quantify the sulci. In addition, voxel-based morphometry (VBM) was used to analyze possible reductions of gray and white matter in the orbitofrontal area. RESULTS: Compared with controls, we found a significant reduction in the secondary sulci depth but not in the primary sulcus in the VPTB. VBM analysis showed reduced gray-matter volume in VPTB in the orbital region. CONCLUSIONS: Premature birth affects cerebral gyrification, and this impairment is not reversible during childhood. Identification of the specific factors involved in abnormal brain maturation may lead to effective interventions.

Adolescent↗
PubMed2006

Increased cerebral activity in Parkinson's disease patients carrying the DRD2 TaqIA A1 allele during a demanding motor task: a compensatory mechanism?

Previous studies suggest that neuroimaging techniques are useful for detecting the effects of functional genetic polymorphisms on brain function in healthy subjects or in patients presenting with psychiatric or neurodegenerative conditions. Former evidence showed that individuals carrying risk alleles displayed broader patterns of brain activity during behavioural and cognitive tasks, despite being clinically comparable to non-carriers. This suggests the presence of compensatory brain mechanisms. In the present study, we investigated this effect in Parkinson's disease (PD) patients carrying the DRD2 TaqIA A1 allelic variant. This variant may confer an increased risk of developing the disease and/or influence the clinical presentation. During a complex sequential motor task, we evidenced by functional magnetic resonance imaging that A1 allele carriers activated a larger network of bilateral cerebral areas than non-carriers, including cerebellar and premotor regions. Both groups had similar clinical and demographic measures. In addition, their motor performance during the functional magnetic resonance experiment was comparable. Therefore, our conclusions, pending replication in a larger sample, seem to reflect the recruitment of compensatory cerebral resources during motor processing in PD patients carrying the A1 allele.

Adaptation, Physiological↗
PubMed2005

Cerebral correlates of declarative memory dysfunctions in early traumatic brain injury.

We investigated residual brain damage in subjects who suffered severe traumatic brain injury (TBI) in childhood, and its relationship with declarative memory impairment. Magnetic resonance imaging (MRI) volumetric data and memory performance were compared between 16 adolescents with antecedents of severe TBI and 16 matched normal controls. Volumes of grey matter, white matter, cerebrospinal fluid (CSF), hippocampus, and caudate nuclei were measured. Verbal memory was assessed by the Rey's Auditory Verbal Learning test and visual memory by the Rey's Complex Figure. TBI patients performed significantly worse than controls in both verbal and visual memory. Patients presented decreased white matter volume and increased CSF. The hippocampus was reduced, but not the caudate nuclei. Memory performance correlated with CSF. Plasticity is incomplete for structural and functional deficits in children with TBI. Hippocampal atrophy, white matter loss, and memory impairment remain until adolescence. Memory sequelae are related more to diffuse brain injury, as reflected by MRI findings of increased CSF, than to hippocampal injury.

Adolescent↗
PubMed2002

Apolipoproteins E and C1 and brain morphology in memory impaired elders.

Previous research has shown that polymorphisms of the apolipoproteins E ( APOE) and APOC1 represent genetic risk factors for dementia and for cognitive impairment in the elderly. The brain mechanisms by which these genetic variations affect behavior or clinical severity are poorly understood. We studied the effect of APOE and APOC1 genes on magnetic resonance imaging measures in a sample of 50 subjects with age-associated memory impairment. The APOE E4 allele was associated with reduced left hippocampal volumes and APOE*E3 status was associated with greater frontal lobe white matter volumes. However, no APOE effects were observed when analyses accounted for other potential confounding variables. The effects of APOC1 on hippocampal volumes appeared to be more robust than those of the APOE polymorphism. However, no modulatory effects on brain morphology outside the medial temporal lobe region were observed when demographic variables, clinical status, and other anatomical brain measurements were taken into consideration. Our results suggest that the role of the APOC1 polymorphism in brain morphology of the cognitively impaired elderly should be examined in further studies.

Aged↗
PubMed2001

(1)H-MR spectroscopy is sensitive to subtle effects of perinatal asphyxia.

The authors performed neuropsychological and (1)H-MRS studies in 18 subclinical patients with antecedents of perinatal asphyxia (PA) and in 18 matched control subjects. Patients with PA showed reduced values of N-acetylaspartate (NAA) in both the basal ganglia and the midtemporal region (MTR) and reduced NAA/choline values in the MTR. Neuropsychological testing showed group differences in tasks related to attention and memory. These results indicate persistent dysfunctions in cerebral structures vulnerable to hypoxia and demonstrate the utility of MRS for the long-term evaluation of cerebral sequelae of neonatal asphyxia.

Adolescent↗
PubMed2001

Correlation of atrophy measures on MRI with neuropsychological sequelae in children and adolescents with traumatic brain injury.

To examine the relationship between neuropsychological sequelae and atrophy parameters from magnetic resonance imaging (MRI) following paediatric moderate-to-severe traumatic brain injury (TBI), 19 head injured children and adolescents were studied at least 6 years after injury. Three-dimensional MRI scans were obtained. A semi-automatic computerized method was used to estimate ventricular volumes and the corpus callosum area. Tests of intellectual, memory, visuospatial, frontal lobe, and motor speed functioning were administered to all patients and to 19 matched normal control subjects. Patients' performance significantly differed from controls in general intellectual function, visual memory, visuospatial and frontal lobe tests. The corpus callosum area correlated strongly with several measures involving processing speed and visuospatial function. Ventricular enlargement was less related to neuropsychological outcome. In conclusion, quantitative measurement of the corpus callosum on MRI reflects neuropsychological outcome better than ventricular dilation in paediatric patients.

Adolescent↗
PubMed2001

MRI atrophy parameters related to cognitive and motor impairment in Parkinson's disease.

BACKGROUND: Patients with Parkinson's disease (PD) show specific neuropsychological deficits in attention, memory, visuospatial or frontal lobe functions, which can arise from degeneration of different cerebral structures. OBJECTIVE: The aim of the present study was to analyze the role of focal degeneration (basal ganglia and substantia nigra) and diffuse cerebral atrophy (ventricular enlargement) in motor/cognitive impairment in PD. PATIENTS AND METHODS: We administered to 14 patients with advanced PD the following tests: Purdue Pegboard, Rey's Auditory-Verbal Learning test (RAVLT), Benton's Line Orientation, Trail Making, phonemic verbal fluency and Stroop test. Ventricular system, caudate and putamen nuclei and pars compacta of the substantia nigra were quantitatively measured by magnetic resonance imaging. Correlation analyses were carried out. RESULTS: The results showed that ventricular enlargement is negatively correlated with the performance on RAVLT and Stroop test. No relationship was found between caudate atrophy and cognitive deficits. Degeneration of putamen nucleus was found to be associated with motor deficits. CONCLUSION: Memory and frontal impairment are related to diffuse cerebral degeneration and the motor deficit is related to degeneration of the putamen nucleus.

Aged↗
PubMed2000

Neuroradiological and clinical findings in rhombencephalosynapsis.

Rhombencephalosynapsis is an unusual disorder characterised by maldevelopment of the rhombencephalon, sometimes with supratentorial midline anomalies. We report MRI findings in a 39-year-old woman, the oldest in the literature. MRI demonstrated hypoplasia of the cerebellar vermis, with fusion of the cerebellar hemispheres and abnormally oriented folia. Supratentorial anomalies were also seen.

Adult↗
PubMed2000

Cortical laminar necrosis caused by immunosuppressive therapy and chemotherapy.

We report three patients in whom neurologic symptoms and cortical laminar necrosis developed after immunosuppressive treatment (cyclosporin A and FK 506) and polychemotherapy (vincristine and methotrexate). Initial neuroradiologic studies showed cortical and white matter involvement. Follow-up studies showed cortical hyper-intense lesions on T1-weighted MR images, consistent with cortical laminar necrosis. The clinical and radiologic data indicate that a transient hypoxic-ischemic process could have been responsible for the encephalic lesions in these three patients.

Adolescent↗
PubMed1999

Cognitive and behavioral changes after unilateral posteroventral pallidotomy: relationship with lesional data from MRI.

We investigated cognitive and behavioral changes after unilateral posteroventral pallidotomy, and their relationship with lesion size and location as identified in magnetic resonance image quantitative analysis. Fifteen consecutive patients with Parkinson's disease were assessed neuropsychologically before and after unilateral posteroventral pallidotomy (five right and 10 left). Immediate postsurgery evaluation (1 week) demonstrated significant worsening of memory, motor learning, motor speed, and verbal fluency. In the 3-month follow up, learning, memory, and speed returned to the presurgical level, but verbal fluency remained below the baseline. Significant improvements were observed in visuospatial functions and obsessive-compulsive behavior. Lesional volume did not correlate with neuropsychologic changes. Left lesions produced more impairment in verbal fluency than right-sided lesions. Regression analysis identified two lesional areas in the pallidum mediale internum. These regions accounted for 68% of the variance in the visuospatial changes.

Aged↗
PubMed1999

Magnetic resonance imaging in myelofibrosis and essential thrombocythaemia: contribution to differential diagnosis.

To ascertain the value of magnetic resonance (MR) imaging in the differential diagnosis between myelofibrosis (MF) and essential thrombocythaemia (ET), 38 patients were analysed. 20 patients had MF (idiopathic myelofibrosis, 15 cases; post-ET myelofibrosis, four cases; post-polycythaemic MF, one case) and 18 ET. Mean age was 61.5 years (range 30-89) for patients with MF and 60.9 years (range 26-83) for ET patients. MR imaging was performed in the dorsal vertebrae in all cases, and also in both femurs in 2 5 of the patients. In most ET cases the MR signal of the dorsal vertebrae was not modified, whereas it was markedly reduced in MF (P=0.0000001). With regard to femoral marrow, it was usually fatty in ET, with an absent to moderate degree of reconversion seen in the 14 cases analysed, contrasting with the marked degree of reconversion noted in 10/11 patients with MF (P=0.000007). An inverse correlation was demonstrated between the vertebral signal and the degree of femoral reconversion. These differences were due to the fact that in ET the bone marrow adipose tissue is grossly preserved, whereas in MF it is usually markedly decreased or absent. The above results indicate that MR imaging is a useful tool for the differential diagnosis of ET and MF, with the usefulness of this technique increasing when vertebral and femoral bone marrow studies are combined.

Adult↗
PubMed1998

[Contribution of magnetic resonance to the differential diagnosis of a collapsed vertebra in a patient with multiple myeloma].

The only safe method to determine whether or not patients diagnosed of smoldering myeloma will progress to symptomatic multiple myeloma (MM) is periodic follow-up. In the last years, several studies have emphasized the efficacy of magnetic resonance imaging (MRI) to detect bone marrow involvement in these patients. However, the detection of a focal spinal lesion in elderly patients raises a diagnostic problem, sometimes difficult to solve, between a benign or malignant origin. We present the case of an elderly women with marked osteoporosis and smoldering myeloma who suddenly complained of pain in dorsal spine. MRI showed focal lesions in two dorsal vertebra consistent with myeloma involvement. However, there were no other signs of progression, the lesions were considered secondary to osteoporosis and calcitonin was administered. This resulted in the disappearance of the pain and the MRI abnormalities, which confirmed its benign etiology. The role and limitations of MRI to detect bone marrow involvement by MM in the evaluation of these patients is reviewed.

Aged↗
PubMed1997

Hepatoerythropoietic porphyria: neuroimaging findings.

CT and MR findings in two patients with hepatoerythropoietic porphyria are presented. CT scans showed atrophy and cortical mineralization at the same level. MR examination performed in one of the two patients showed mainly frontal cortical atrophy and punctate bright signal on T1- and T2-weighted sequences.

Adult↗
PubMed1996

[Occult involvement of bone marrow in Hodgkin's disease: detection with magnetic resonance].

Although bone marrow biopsy is considered the best procedure to detect bone marrow involvement by Hodgkin's disease (HD), in recent years several studies have emphasized the value of magnetic resonance imaging (MRI). We present the case of a patient with HD apparently localized in a laterocervical lymph node, who also referred disestasiae at a region corresponding to D10 metamera. Bone marrow biopsy, vertebral TC and 67-Ga scintigraphy were all normal. However, a node of 1 cm in diameter was detected by MRI in the tenth dorsal vertebra. Because of the topographic coincidence between the patient's symptomatology and the MRI findings, the HD was considered to be in advanced stage and CMOPP/ABV chemotherapy was administered, this resulting in a rapid improvement of symptoms and disappearance of the MRI abnormalities. Since in the present case, the MRI determined a change in disease stage and treatment, the role of MRI as a complementary exploration of bone marrow biopsy to detect marrow involvement by HD is reviewed.

Adult↗
PubMed1996

[Magnetic resonance of the spinal cord: a densitometric analysis].

BACKGROUND: Images obtained by magnetic resonance can present changes in a variety of haematologic disorders. The vertebral magnetic resonance signal depends chiefly on the relationship between fatty and cellular components of the haemopoietic bone marrow. A quantitative analysis of signal can be performed either during the magnetic resonance examination or on the computer-stored images. In this work, a densitometric grey-scale method is presented allowing to analyze the signal intensity on printed magnetic resonance images for those cases in which the computer-stored information is lacking. PATIENTS AND METHODS: A comparative study between magnetic resonance signal and the result of the densitometric analysis was carried out in 29 patients with different haematologic disorders. In order to achieve a suitable standardization, an internal control in both measures was used, i.e., the magnetic resonance signal intensity and the grey intensity of an area of spinal cord, respectively, yielding two ratios: magnetic resonance ratio and grey ratio. RESULTS: The precision analysis of the densitometric method gave the following results: within-batch coefficient of variation was 1.78%, between-batch coefficient of variation was 1.94% and overall reproducibility 6.4%. The correlation between magnetic resonance ratio and grey ratio was very high, i.e., 0.98 (p < 0.001). Moreover, the regression line displayed on ideal location since it originated in the point 0 and showed a slope of 45 degrees. CONCLUSION: The densitometric method presented in this paper can be useful for the quantitative analysis of the magnetic resonance signal intensity generated by the haemopoietic bone marrow, for those cases in which the computer-stored information is lacking.

Data Interpretation, Statistical↗
PubMed1996

[Vertebral hemangioma and quiescent myeloma: association of therapeutic significance].

Smouldering myeloma is a monoclonal gammopathy in which the M component is higher than 30 g/l and the proportion of plasma cells in the bone marrow is higher than 10% with no anemia, renal failure, hypercalcemia, osteolysis or other features due to the monoclonal gammopathy. The recognition of this clinical variant of myeloma resides in the fact that treatment should be deferred until there are clinical or biologic data indicating evident disease progression. Vertebral hemangioma is a relatively frequent benign tumor in the general population which, although usually asymptomatic, may cause local or radicular bone pain. A patient who fulfilled the criteria of myeloma and who complained of localized bone pain in the spinal column is herein presented. Following a study of the dorsolumbar column by computerized tomography and magnetic resonance, bone lesions with radiologic images characteristic of vertebral hemangioma, clearly different from those observed in myelomatous lesions, were identified. This finding conditioned the treatment, which included radiotherapy for the vertebral hemangioma and no treatment for the smouldering myeloma.

Diagnosis, Differential↗