Leandro Tavares Lucato

Diffusion Tensor Imaging in Children with Periventricular Leukomalacia: Variability of Injuries to White Matter Tracts

BACKGROUND AND PURPOSE: Conventional MR imaging shows evidence of brain injury and/or maldevelopment in 70%–90% of children with cerebral palsy (CP), though its capability to identify specific white matter tract injury is limited. The great variability of white matter lesions in CP already demonstrated by postmortem studies is thought to be one of the reasons why response to treatment is so variable. Our hypothesis is that diffusion tensor imaging (DTI) is a suitable technique to provide in vivo characterization of specific white matter tract lesions in children with CP associated with periventricular leukomalacia (PVL). MATERIALS AND METHODS: In this study, 24 children with CP associated with PVL and 35 healthy controls were evaluated with DTI. Criteria for identification of 26 white matter tracts on the basis of 2D DTI color-coded maps were established, and a qualitative scoring system, based on visual inspection of the tracts in comparison with age-matched controls, was used to grade the severity of abnormalities. An ordinal grading system (0 = normal, 1 = abnormal, 2 = severely abnormal or absent) was used to score each white matter tract. RESULTS: There was marked variability in white matter injury pattern in patients with PVL, with the most frequent injury to the retrolenticular part of the internal capsule, posterior thalamic radiation, superior corona radiata, and commissural fibers. CONCLUSION: DTI is a suitable technique for in vivo assessment of specific white matter lesions in patients with PVL and, thus, a potentially valuable diagnostic tool. The tract-specific evaluation revealed a family of tracts that are highly susceptible in PVL, important information that can potentially be used to tailor treatment options in the future.

Acute Toxic Leukoencephalopathy: Potential for Reversibility Clinically and on MRI With Diffusion-Weighted and FLAIR Imaging

OBJECTIVE Toxic leukoencephalopathy may present acutely or subacutely with symmetrically reduced diffusion in the periventricular and supraventricular white matter, hereafter referred to as periventricular white matter. This entity may reverse both on imaging and clinically. However, a gathering together of the heterogeneous causes of this disorder as seen on MRI with diffusion-weighted imaging (DWI) and an analysis of their likelihood to reverse has not yet been performed. Our goals were to gather causes of acute or subacute toxic leukoencephalopathy that can present with reduced diffusion of periventricular white matter in order to promote recognition of this entity, to evaluate whether DWI with apparent diffusion coefficient (ADC) values can predict the extent of chronic FLAIR abnormality (imaging reversibility), and to evaluate whether DWI can predict the clinical outcome (clinical reversibility). MATERIALS AND METHODS Two neuroradiologists retrospectively reviewed the MRI examinations of 39 patients with acute symptoms and reduced diffusion of periventricular white matter. The reviewers then scored the extent of abnormality on DWI and FLAIR. ADC ratios of affected white matter versus the unaffected periventricular white matter were obtained. Each patients clinical records were reviewed to determine the cause and clinical outcome. Histology findings were available in three patients. Correlations were calculated between the initial MRI markers and both the clinical course and the follow-up extent on FLAIR using Spearmans correlation coefficient. RESULTS Of the initial 39 patients, seven were excluded because of a nontoxic cause (hypoxic-ischemic encephalopathy [HIE] or congenital genetic disorders) or because of technical errors. In the remaining 32 patients, no correlation was noted between any of the initial MRI markers (percentage of ADC reduction, DWI extent, or FLAIR extent) with the clinical outcome. Three patients had histologic correlation. However, moderate correlation was seen between the extent of abnormality on initial FLAIR and the extent on follow-up FLAIR (r = 0.441, p = 0.047). Of the 13 patients who underwent repeat MRI at 21 days or longer, the reduced diffusion resolved in all but one. Significant differences were noted between ADC values in affected white matter versus unaffected periventricular white matter on initial (p < 0.0001) but not on follow-up MRI (p = 0.13), and in affected white matter on initial versus follow-up (p = 0.0014) in those individuals who underwent repeat imaging on the same magnet (n = 9), confirming resolution of the DWI abnormalities. CONCLUSION Acute toxic leukoencephalopathy with reduced diffusion may be clinically reversible and radiologically reversible on DWI, and may also be reversible, but to a lesser degree, on FLAIR MRI. None of the imaging markers measured in this study appears to correlate with clinical outcome, which underscores the necessity for prompt recognition of this entity. Alerting the clinician to this potentially reversible syndrome can facilitate treatment and removal of the offending agent in the early stages.

CT and MR in non-neonatal hypoxic-ischemic encephalopathy: radiological findings with pathophysiological correlations.

Non-neonatal hypoxic–ischemic encephalopathy is a clinical condition often related to cardiopulmonary arrest that demands critical management and treatment decisions. Management depends mainly on the degree of neurological impairment and prognostic considerations. Computed tomography (CT) is often used to exclude associated or mimicking pathology. If any, only nonspecific signs such as cerebral edema, sulci effacement, and decreased gray matter (GM)/white matter (WM) differentiation are evident. Pseudosubarachnoid hemorrhage, a GM/WM attenuation ratio <1.18, and inverted GM attenuation are associated with a poor prognosis. Magnetic resonance (MR) imaging is more sensitive than CT in assessing brain damage in hypoxic–ischemic encephalopathy. Some MR findings have similarities to those seen pathologically, based on spatial distribution and time scale, such as lesions distributed in watershed regions and selective injury to GM structures. In the acute phase, lesions are better depicted using diffusion-weighted imaging (DWI) because of the presence of cytotoxic edema, which, on T2-weighted images, only become apparent later in the early subacute phase. In the late subacute phase, postanoxic leukoencephalopathy and contrast enhancement could be observed. In the chronic phase, atrophic changes predominate over tissue signal changes. MR can be useful for estimating prognosis when other tests are inconclusive. Some findings, such as the extent of lesions on DWI and presence of a lactate peak and depleted N-acetyl aspartate peak on MR spectroscopy, seem to have prognostic value.

ABNORMAL SENSORY INTEGRATION AFFECTS BALANCE CONTROL IN HEMIPARETIC PATIENTS WITHIN THE FIRST YEAR AFTER STROKE

OBJECTIVE: Impairments in balance can be a consequence of changes in the motor, sensory, and integrative aspects of motor control. Abnormal sensory reweighting, i.e., the ability to select the most appropriate sensory information to achieve postural stability, may contribute to balance impairment. The Sensory Organization Test is a component of Computerized Dynamic Posturography that evaluates the impact of visual, vestibular, and somatosensory inputs, as well as sensory reweighting, under conditions of sensory conflict. The aim of this study is to compare balance control in hemiparetic patients during the first year post-stroke and in age-matched neurologically normal subjects using the Berg Balance Scale and Computerized Dynamic Posturography. METHODS: We compared the Berg Balance Scale and Sensory Organization Test scores in 21 patients with hemiparesis after first-ever ischemic stroke and in 21 age-matched, neurologically normal subjects. An equilibrium score was defined for each Sensory Organization Test condition. RESULTS: Berg Balance Scale scores were significantly lower in the patients than in the neurologically normal subjects. Equilibrium scores were significantly lower in the patients than in the neurologically normal subjects for those Sensory Organization Test conditions that did not provide appropriate somatosensory information and under conditions of sensory conflict. A history of falls was more frequent in patients with lower equilibrium scores. CONCLUSION: During the first year after a stroke, defective sensory reweighting significantly impacts balance control in hemiparetic patients. These results are important for the planning of effective rehabilitation interventions.

The Role of Conventional MR Imaging Sequences in the Evaluation of Neurocysticercosis: Impact on Characterization of the Scolex and Lesion Burden

BACKGROUND AND PURPOSE: There are few studies comparing the capacity of lesion detection of conventional MR imaging in neurocysticercosis (NCC). This study was designed to clarify its role in the evaluation of this disease, focusing on the total number of lesions identified and the characterization of the scolex. MATERIALS AND METHODS: MR images from 115 patients were prospectively collected during a 3-year interval, including axial spin-echo (SE) T1-weighted; axial fast SE T2-weighted; axial fluid-attenuated inversion recovery (FLAIR); and gadolinium-enhanced axial, coronal, and sagittal SE T1-weighted sequences. They were compared regarding the potential for detection of NCC lesions and specifically of the scolex. RESULTS: Comparing all sequences, we found that FLAIR images were more sensitive to the detection of the scolex (P < .003), whereas the last gadolinium-enhanced T1-weighted series (coronal or sagittal) identified the highest number of lesions (P < .001). CONCLUSION: When dealing with NCC, optimal MR imaging protocols should include FLAIR images to obtain maximal rates of scolex detection. Special attention should be paid to the last gadolinium-enhanced sequence, which maximizes the quantification of lesion load.

Inter- and intrareader variability in the interpretation of two radiographic classification systems for juvenile rheumatoid arthritis

ObjectiveTo evaluate the inter- and intrareader variability for interpretation of a modified Larsens radiographic classification system for juvenile rheumatoid arthritis (JRA) focused on osteochondral lesions and a conventional Larsens classification system, compared to a reference MR scoring system of corresponding images.Materials and methodsSeventy-five radiographs of 60 children with JRA, performed within a short interval of time from the MR examinations, were independently evaluated by three experienced radiologists, three diagnostic imaging residents and three rheumatologists, in two separate sessions, according to the two different classification methods, blinded to the corresponding MR images.ResultsThe inter- and intrareader concordance rates between the two radiographic classification systems and the MR-related radiographs were respectively poor and poor/moderate. The interobserver range of weighted kappa values for the conventional and the modified Larsens system respectively was 0.25–0.37 vs 0.19–0.39 for radiologists, 0.25–0.37 vs 0.18–0.30 for residents and 0.19–0.51 vs 0.17–0.29 for rheumatologists. The intrareader rate ranged from 0.17–0.55 for radiologists, 0.2–0.56 for residents, and 0.14–0.59 for rheumatologists.ConclusionAlthough the proposal of a new radiographic classification system for JRA focused on osteochondral abnormalities sounds promising, the low inter- and intrareader concordance rates with an MR-related radiographic system makes the clinical applicability of such a radiographic system less suitable.

Merosin-deficient congenital muscular dystrophy (CMD) : a study of 25 Brazilian patients using MRI

Background: Merosin-deficient congenital muscular dystrophy (CMD) is characterized clinically by hypotonia and muscular weakness and, on imaging studies, by white matter (WM) abnormality. Objective: To evaluate MRI findings in Brazilian patients with merosin-deficient CMD. Materials and methods: Twenty-five patients were evaluated using MRI. Three patients presented with partial merosin deficiency and 22 with total merosin deficiency. Follow-up examinations were done in 7 cases. T1- and T2-weighted images were performed in all examinations, and fluid-attenuated inversion recovery (FLAIR) was performed in 15. Enhanced images were done in 11 cases. The WM involvement was classified according to location and severity. Results: From 1991 to 2004, 32 MRI examinations were performed. Severe involvement was found in 23 patients in the frontal and temporal lobes, in 18 patients in the parietal lobes, and in 7 patients in the occipital lobes. The brain stem (n=5), cerebellum (n=6), internal capsules (n=1), and external capsules (n=5) were also affected. One patient had occipital pachygyria, and one had cerebellar vermian hypoplasia. No gadolinium enhancement was noted. Follow-up MRI showed no interval change (n=4), progression (n=1), or improvement of the findings (n=2). Conclusion: This series of patients demonstrated that there was no correlation between the extent of WM abnormality on MRI and the clinical status and degree of merosin deficiency (partial or total). Bilateral WM involvement was seen to be more prominent in the parietal, frontal, and temporal regions of the brain. The brain stem and internal and external capsules were less affected. Cerebellar WM involvement is rare. Changes on follow-up imaging studies did not correlate with the clinical status of the patient.

Dissecção espontânea cervical carotídea e verbal: estudo de 48 pacientes

OBJECTIVE To report a Brazilian series of spontaneous cervical arterial dissections, risk factors, warning symptoms, clinical manifestations, diagnostic tests, treatment and prognosis. METHOD We performed the retrospective analysis of clinical and neuroradiological records (MRI, A-MRI and Angiography) of patients with this diagnosis who were evaluated in a tertiary hospital for the period of 1997-2003. RESULTS 48 patients (24 men) with median age 37.9 years: 26 patients with unilateral internal carotid dissection (ICAD), 15 with unilateral vertebral artery dissection (VAD) and 7 with multivessel dissections. All patients presented neurological deficits. Hypertension, smoking and dyslipidemia were the main risk factors. More than 80% of patients presented at least one initial symptom, most of them temporoparietal headache. 44% of patients with VAD and only 3.4% of patients with ICAD had neck pain. The median interval between the onset of symptom and the appearance of neurological deficit was 5.4 days for ICAD and 13.5 days for VAD. Five patients with ICAD presented preceding TIA. Angiography was performed in 93% of patients. In 42% of these patients, MRI and A-MRI were associated. In three patients the diagnosis was made just through cervical MRI. 75% of patients received anticoagulation. Two patients received intravenous thrombolytic therapy with no complications. Prognosis was good for all patients but two patients with bilateral ICAD died. CONCLUSION Our results are similar to the literature, except for the low frequency of neck pain in ICAD patients and predominance of temporoparietal headache in cervical artery dissection patients. Vascular risk factors were commonly found.

Spectrum of cognitive impairment in neurocysticercosis Differences according to disease phase

Objectives: Cognitive decline related to neurocysticercosis (NC) remains poorly characterized and underdiagnosed. In a cross-sectional study with a prospective phase, we evaluated cognitive decline in patients with strictly calcified form (C-NC), the epidemiologically largest subgroup of NC, and investigated whether there is a spectrum of cognitive abnormalities in the disease. Methods: Forty treatment-naive patients with C-NC aged 37.6 ± 11.3 years and fulfilling criteria for definitive C-NC were submitted to a comprehensive cognitive and functional evaluation and were compared with 40 patients with active NC (A-NC) and 40 healthy controls (HC) matched for age and education. Patients with dementia were reassessed after 24 months. Results: Patients with C-NC presented 9.4 ± 3.1 altered test scores out of the 30 from the cognitive battery when compared to HC. No patient with C-NC had dementia and 10 patients (25%) presented cognitive impairment–no dementia (CIND). The A-NC group had 5 patients (12.5%) with dementia and 11 patients (27.5%) with CIND. On follow-up, 3 out of 5 patients with A-NC with dementia previously still presented cystic lesions with scolex on MRI and still had dementia. One patient died and the remaining patient no longer fulfilled criteria for either dementia or CIND, presenting exclusively calcified lesions on neuroimaging. Conclusions: Independently of its phase, NC leads to a spectrum of cognitive abnormalities, ranging from impairment in a single domain, to CIND and, occasionally, to dementia. These findings are more conspicuous during active vesicular phase and less prominent in calcified stages.

Mania as the first manifestation of Wilson's disease.

BACKGROUND Although mental changes are frequent in Wilsons disease, severe psychiatric disorders occur uncommonly and usually accompany the neurological picture. There are few reports in the literature of Wilsons disease patients with typical bipolar affective disorder (BPAD). CASE REPORT The authors report the case of a patient with Wilsons disease whose initial manifestation was a manic episode followed by depression. Tremor in the upper limbs appeared one year after the onset of symptoms. The diagnosis of Wilsons disease was established three years after the first symptoms appeared, based on the neuropsychiatric picture, the detection of Kayser-Fleischer rings and the results of diagnostic tests indicating chronic liver disease and copper excess. ATP7B genotyping and magnetic resonance imaging of the brain with proton spectroscopy study were also performed. The patient became asymptomatic two years after starting treatment with penicillamine and remained non-symptomatic controlled during the eight-year follow-up period, without any specific treatment for the BPAD. CONCLUSIONS To our knowledge, this is a singular report of a case of Wilsons disease in which a manic episode preceded the onset of neurological symptoms. The association between Wilsons disease and bipolar disorder is discussed.