Peculiar CADASIL phenotype in monozygotic twins carrying a novel NOTCH3 pathogenetic variant

BACKGROUND

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an autosomal dominantly inherited cerebral small vessel disease caused by Neurogenic locus notch homolog protein 3 (NOTCH3) gene mutations. The main clinical features include migraine with aura, recurrent ischemic strokes and dementia. Brain MRI typically shows multiple small lacunar infarcts and severe, diffuse, symmetrical white matter hyperintensities (WMHs), with characteristic involvement of the anterior temporal pole, external capsule, and superior frontal gyrus. Reports of twins with CADASIL are scarce. Herein we describe a pair of monozygotic twins with peculiar CADASIL phenotype, carrying a new NOTCH3 variant.

CASE PRESENTATION

Twin A was a 45-year-old male suffering from migraine, obesity, arterial hypertension, and polycythemia (with negative genetic analysis), who complained of a transient, short-lasting (~ 5 minutes) episode of speech difficulties. Brain MRI showed diffuse, symmetrical, confluent periventricular WMHs involving frontal, parietal, and temporal lobes and external capsules, with sparing of anterior temporal poles. Genetic analysis of NOTCH3 gene demonstrated the presence of missense c.3329G>A, p.(Cys1110Tyr) variant, confirming CADASIL diagnosis. Twin B, affected by migraine and polycythemia, as well as his monozygotic twin, presented with a 2-month history of trigeminal neuralgia. Brain MRI demonstrated diffuse WMHs with a pattern of distribution like his twin. Genetic analysis revealed the same NOTCH3 pathogenic variant.

CONCLUSIONS

Our monozygotic twins have a strikingly similar neuroimaging picture with sparing of anterior temporal poles. They also have a peculiar phenotype, both presenting polycythemia without genetically confirmed cause. Twin B had trigeminal neuralgia, that is unusual in CADASIL. The possible association of the peculiar findings with the newly reported NOTCH3 variant needs to be confirmed with further observations.

MRI measures of corpus callosum iron and myelin in early Huntington's disease

Increased iron in subcortical gray matter (GM) structures of patients with Huntington's disease (HD) has been suggested as a causal factor in neuronal degeneration. But how iron content is related to white matter (WM) changes in HD is still unknown. For example, it is not clear whether WM changes share the same physiopathology (i.e. iron accumulation) with GM or whether there is a different mechanism. The present study used MRI to examine iron content in premanifest gene carriers (PreHD, n = 25) and in early HD patients (n = 25) compared with healthy controls (n = 50). 3T MRI acquisitions included high resolution 3D T1, EPI sequences for diffusion tensor imaging (DTI) as an indirect measure of tissue integrity, and T2*-weighted gradient echo-planar imaging for MR-based relaxometry (R2*), which provides an indirect measure of ferritin/iron deposition in the brain. Myelin breakdown starts in the PreHD stage, but there is no difference in iron content values. Iron content reduction manifests later, in the early HD stage, in which we found a lower R2* parameter value in the isthmus. The WM iron reduction in HD is temporally well-defined (no iron differences in PreHD subjects and iron differences only in early HD patients). Iron level in callosal WM may be regarded as a marker of disease state, as iron does not differentiate PreHD subjects from controls but distinguishes between PreHD and HD.

The Corticospinal Tract in Huntington's Disease

Huntington's disease (HD) is characterized by progressive motor impairment. Therefore, the connectivity of the corticospinal tract (CST), which is the main white matter (WM) pathway that conducts motor impulses from the primary motor cortex to the spinal cord, merits particular attention. WM abnormalities have already been shown in presymptomatic (Pre-HD) and symptomatic HD subjects using magnetic resonance imaging (MRI). In the present study, we examined CST microstructure using diffusion tensor imaging (DTI)-based tractography in 30-direction DTI data collected from 100 subjects: Pre-HD subjects (n = 25), HD patients (n = 25) and control subjects (n = 50), and T2*-weighted (iron sensitive) imaging. Results show decreased fractional anisotropy (FA) and increased axial (AD), and radial diffusivity (RD) in the bilateral CST of HD patients. Pre-HD subjects had elevated iron in the left CST, regionally localized between the brainstem and thalamus. CAG repeat length in conjunction with age, as well as motor (UHDRS) assessment were correlated with CST FA, AD, and RD both in Pre-HD and HD. In the presymptomatic phase, increased iron in the inferior portion supports the "dying back" hypothesis that axonal damage advances in a retrograde fashion. Furthermore, early iron alteration may cause a high level of toxicity, which may contribute to further damage.

Effect of levodopa on both verbal and motor representations of action in Parkinson's disease: a fMRI study

Previous studies have demonstrated that non-demented Parkinson's disease (PD) patients have a specific impairment of verb production compared with noun generation. One interpretation of this deficit suggested the influence of striato-frontal dysfunction on action-related verb processing. The aim of our study was to investigate cerebral changes after motor improvement due to dopaminergic medication on the neural circuitry supporting action representation in the brain as mediated by verb generation and motor imagery in PD patients. Functional magnetic resonance imaging on 8 PD patients in "ON" dopaminergic treatment state (DTS) and in "OFF" DTS was used to explore the brain activity during three different tasks: Object Naming (ObjN), Generation of Action Verbs (GenA) in which patients were asked to overtly say an action associated with a picture and mental simulation of action (MSoA) was investigated by asking subjects to mentally simulate an action related to a depicted object. The distribution of brain activities associated with these tasks whatever DTS was very similar to results of previous studies. The results showed that brain activity related to semantics of action is modified by dopaminergic treatment in PD patients. This cerebral reorganisation concerns mainly motor and premotor cortex suggesting an involvement of the putaminal motor loop according to the "motor" theory of verb processing.

Multimodal MRI analysis of the corpus callosum reveals white matter differences in presymptomatic and early Huntington's disease

Recent magnetic resonance imaging (MRI) studies suggest that abnormalities in Huntington's disease (HD) extend to white matter (WM) tracts in early HD and even in presymptomatic stages. Thus, changes of the corpus callosum (CC) may reflect various aspects of HD pathogenesis. We recruited 17 HD patients, 17 pre-HD subjects, and 34 healthy age-matched controls. Three-dimensional anatomical MRI and diffusion tensor images of the brain were acquired on a 3T scanner. Combining region-of-interest analyses, voxel-based morphometry, and tract-based spatial statistics, we investigated callosal thickness, WM density, fractional anisotropy, and radial and axial diffusivities. Compared with controls, pre-HD subjects showed reductions of the isthmus, likely due to myelin damage. Compared with pre-HD subjects, HD patients showed reductions of isthmus and body, with axonal damage confined to the body. Compared with controls, HD patients had significantly decreased callosal measures in extended regions across almost the entire CC. At this disease stage, both myelin and axonal damage are detectable. Supplementary multiple regression analyses revealed that WM reduction density in the isthmus as well as Disease Burden scores allowed to predict the "HD development" index. While callosal changes seem to proceed in a posterior-to-anterior direction as the diseases progresses, this observation requires validation in future longitudinal investigations.

Developmental topographical disorientation in a healthy subject

We present the case of F.G., a healthy, normally developed 22-year-old male subject affected by a pervasive disorder in environmental orientation and navigation who presents no history of neurological or psychiatric disease. A neuro-radiological examination showed no evidence of anatomical or structural alterations to the brain. We submitted the subject for a comprehensive neuropsychological assessment of the different cognitive processes involved in topographical orientation to evaluate his ability to navigate the spatial environment. The results confirmed a severe developmental topographical disorder and deficits in a number of specific cognitive processes directly or indirectly involved in navigation. The results are discussed with reference to the sole previously described case of developmental topographical disorientation (Pt1; Iaria et al., 2009). F.G. differs from the former case due to the following: the greater severity of his disorder, his complete lack of navigational skills, the failure to develop compensatory strategies, and the presence of a specific deficit in processing the spatial relationships between the parts of a whole. The present case not only confirms the existence of developmental topographical-skill disorders, but also sheds light on the architecture of topographical processes and their development in human beings.

Infratentorial lesion volume correlates with sensory functional system in multiple sclerosis patients: a 3.0-Tesla MRI study

PURPOSE

This study sought to correlate lesion volume in infratentorial areas using 3.0-T proton-density (PD)-weighted images with disability scales and appropriate functional system scores in patients with multiple sclerosis (MS).

MATERIALS AND METHODS

We examined 20 consecutive patients (13 women and 7 men) with a median age of 47 years (range 26-70). Neurological examination included the Expanded Disability Status Scale and its functional systems, the Barthel Index (BI) and the Rivermead Mobility Index (RMI). MRI scans were performed on a system operating at 3.0 T using a quadrature birdcage head coil. Acquired images imported as Digital Imaging and Communication in Medicine (DICOM) files, and the region of interest (ROI) files were converted to Neuroimaging Informatics Technology Initiative (NIfTI) format and normalised to the Montreal Neurological Institute (MNI) standard template. An automated segmentation algorithm was used to distinguish between supratentorial and infratentorial areas. Normalisation to the magnetisation-prepared rapid acquisition with gradient echo (MPRAGE) T1-weighted sequence allowed lesion volume estimation in the different anatomical areas.

RESULTS

A significant correlation was found between infratentorial lesion volume and the sensory functional system score (rho=0.76, p=0.002). No significant correlation was found between supratentorial lesion volume and Expanded Disability Status Scale (EDSS), RMI and BI scores.

CONCLUSIONS

The described method, by means of anatomical assignment of MS lesions, allows detection of significant correlation coefficients between clinical and MRI lesion burden in MS patients at the infratentorial level.

Imaging nervous pathways with MR tractography

This paper describes the state of the art of tractography, a technique which enables the virtual reconstruction of axon bundles of the central nervous system using diffusion-weighted magnetic resonance images. This technique has raised enthusiasm and expectations among specialists because it is the only non-invasive method for studying the three-dimensional architecture of axonal fibres in vivo. Tractography is a new technique used to assess the anatomy of the central nervous system, and it will be available for routine clinical use in the future. Understanding its potential applications and limitations is therefore important.

Turbo-Proton Echo Planar Spectroscopic Imaging (t-PEPSI) MR technique in the detection of diffuse axonal damage in brain injury. Comparison with Gradient-Recalled Echo (GRE) sequence

PURPOSE

Diffuse axonal injury (DAI) is a common type of primary neuronal injury in patients with severe traumatic brain injury, and is frequently accompanied by tissue tear haemorrhage. The T2*-weighted gradient-recalled echo (GRE) sequences are more sensitive than T2-weighted spin-echo images for detection of haemorrhage. This study was undertaken to determine whether turbo-PEPSI, an extremely fast multi-echo-planar-imaging sequence, can be used as an alternative to the GRE sequence for detection of DAI.

MATERIALS AND METHODS

Nineteen patients (mean age 24,5 year) with severe traumatic brain injury (TBI), occurred at least 3 months earlier, underwent a brain MRI study on a 1.5-Tesla scanner. A qualitative evaluation of the turbo-PEPSI sequences was performed by identifying the optimal echo time and in-plane resolution. The number and size of DAI lesions, as well as the signal intensity contrast ratio (SI CR), were computed for each set of GRE and turbo-PEPSI images, and divided according to their anatomic location into lobar and/or deep brain.

RESULTS

There was no significant difference between GRE and turbo-PEPSI sequences in the total number of DAI lesions detected (283 vs 225 lesions, respectively). The GRE sequence identified a greater number of hypointense lesions in the temporal lobe compared to the t-PEPSI sequence (72 vs 35, p<0.003), while no significant differences were found for the other brain regions. The SI CR was significantly better (i.e. lower) for the turbo-PEPSI than for the GRE sequence (p<0.00001).

CONCLUSIONS

Owing to its very short scan time and high sensitivity to the haemorrhage foci, the turbo-PEPSI sequence can be used as an alternative to the GRE to assess brain DAI in severe TBI patients, especially if uncooperative and medically unstable.

Abnormal Motor Preparation in Severe Traumatic Brain Injury with Good Recovery

Movement-related cortical potentials (MRCPs) were examined in seven patients with severe traumatic brain injury (TBI) and 12 matched control subjects. All patients had clinically established good recovery by the time of testing. Flexion movements of the index finger of the left or right hand were recorded in two (alternating and repetitive) self-paced conditions and in one externally triggered condition. In control subjects, the bereitschaftspotential (BP) component of MRCP was detected approximately 2000 msec prior to movement onset in the self-paced conditions and was larger and earlier in the alternating compared to the repetitive condition. The BP component was absent in the externally triggered condition. In TBI patients, the BP was greatly reduced and no difference between the alternating-repetitive conditions was detected; in contrast, only small differences were present in the controls for the negative slope (NS) and MP components and no difference for the reafferent positivity (RAP) component. A dipole analysis indicated the supplementary motor area and the premotor area as the likely generators of BP and NS' components, respectively. Gradientrecalled echo magnetic resonance imaging allowed the detection of a number of small hypointense lesions primarily located in the frontal lobes, as in diffuse axonal injury. This pattern of results indicates a selective deficit in motor preparation and a relatively spared pattern of activation during and following movement in these patients. Imaging data appear generally consistent with the pattern of MRCPs observed in the patient group. Implications of these results for the problem of slowness in TBI patients are discussed.

Atypical multiple sclerosis: MRI findings and differential diagnosis

In the past few years, magnetic resonance imaging (MRI) has become increasingly relevant in the diagnosis of multiple sclerosis (MS). Yet, the specificity of MR is limited. Atypical forms of MS and other diseases of the central nervous system may show similar patterns in MR. We briefly discuss the MR findings of the main MS-like diseases. Correct differential diagnosis can be carried out by combining the MR findings with clinical and laboratory findings.

Diffusion of water in large demyelinating lesions: a follow-up study

We studied five patients with multiple sclerosis with one plaque of demyelination more than 2 cm in diameter, using conventional and diffusion-weighted MRI, soon after the onset of symptoms and over 1-36 months. The orientationally averaged diffusion coefficient <D> was increased in all the acute lesions, and increased further during follow-up in three. There was a strong correlation between <D> and the degree of low signal on T1-weighted images. The quantitative information provided by <D> allowed delineation of different diffusion patterns in large MS lesions, that may reflect heterogeneity of the anatomical substrate.

Diazepam effects on the cerebral responses to tonic pain: a SPET study

RATIONALE

Pain is a complex phenomenon with a strong affective-emotional component in addition to a sensory-discriminative one. This causes the activation of multiple brain areas, which process different aspects of pain simultaneously.

OBJECTIVES

We investigated the effects of diazepam (DZ) on a well-known pattern of brain regions activated by cold, tonic pain stimuli.

METHODS

Quantitative cerebral blood flow (CBF) was assessed by single photon emission tomography (SPET) and the Xe-133 inhalatory method, at rest and during tonic pain activation in eight normal, right-handed, male volunteers. The cold pressor test (CPT) was performed by immersion of the left hand in cold water twice, first during CPT alone, and again 30 min after intravenous administration of diazepam (CPT+DZ).

RESULTS

During CPT we observed a significant CBF increase in the right thalamus, primary sensory-motor cortex (S1/M1), frontal and temporal regions, and in the left temporal region and anterior cingulate cortex (ACC). During CPT+DZ, the average CBF was significantly lower than during the CPT state (-11%, P<0.05). After normalisation, during CPT+DZ we again observed a significant CBF increase in the right thalamus, S1/M1 and frontal regions, and in the left ACC, though not in the temporal regions. DZ administration first causes a global reduction in CBF, then modifies the pattern of brain activation.

CONCLUSIONS

During CPT, activation of the temporal regions has been interpreted as part of the affective-emotional component of pain response. DZ seems to affect the "pain-related" pattern of activation by abolishing the CBF increase in the temporal regions, without, however, modifying the pain perception or determining a sedating effect.

Demyelinating plaques in relapsing-remitting and secondary-progressive multiple sclerosis: assessment with diffusion MR imaging

BACKGROUND AND PURPOSE

Conventional MR imaging does not provide specific information that can be reliably associated with the pathologic substrate and clinical status of patients with multiple sclerosis (MS). Our goals were 1) to determine whether the orientationally averaged water diffusion coefficient (<D>) can be used to distinguish between plaques of different severity in these patients and 2) to assess possible correlations between <D> values and disease duration, Expanded Disability Status Scale (EDSS) score, and signal intensity on T1-weighted MR images.

METHODS

Twenty patients (10 with relapsing-remitting MS and 10 with secondary-progressive MS) and 11 healthy volunteers underwent a combined conventional and diffusion-weighted MR study of the brain. <D>, a parameter that is proportional to the trace of the diffusion tensor, was computed by averaging the apparent diffusion coefficients measured in the x, y, and z directions. <D> measurements were obtained for selected areas of white matter plaques. Differences in <D> among the three groups were tested using analysis of variance.

RESULTS

<D> was significantly higher (1.445 +/- 0.129 x 10(-3) mm2/s) in secondary-progressive lesions than in relapsing-remitting lesions (0.951 +/- 0.08), and both values were higher than <D> in normal white matter (0.732 +/- 0.02). There was a significant negative correlation between <D> and the degree of hypointensity on T1-weighted images, and a positive correlation between <D> and both EDSS score and disease duration.

CONCLUSION

Our findings suggest that <D> is useful for distinguishing MS lesions of different severities, which are associated with different degrees of clinical disability.

Cortical motor reorganization in akinetic patients with Parkinson's disease: a functional MRI study

Using functional MRI (fMRI), we have studied the changes induced by the performance of a complex sequential motor task in the cortical areas of six akinetic patients with Parkinson's disease and six normal subjects. Compared with the normal subjects, the patients with Parkinson's disease exhibited a relatively decreased fMRI signal in the rostral part of the supplementary motor area (SMA) and in the right dorsolateral prefrontal cortex, as previously shown in PET studies. Concomitantly, the same patients exhibited a significant bilateral relative increase in fMRI signal in the primary sensorimotor cortex, lateral premotor cortex, inferior parietal cortex, caudal part of the SMA and anterior cingulate cortex. These fMRI data confirm that the frontal hypoactivation observed in patients with Parkinson's disease is restricted to the rostral part of the SMA and to the dorsolateral prefrontal cortex. These results also show that, apart from the lateral premotor and parietal cortices, increased fMRI signals can be found in other cortical motor areas of these patients, including the posterior SMA, the anterior cingulate cortex and the primary sensorimotor cortices, which are then likely to participate in the same putative attempt by the dopamine-denervated brain to recruit parallel motor circuits in order to overcome the functional deficit of the striatocortical motor loops.

Use of Bacille Calmette-Guèrin (BCG) in multiple sclerosis

We studied the effect of Bacille Calmette-Guerin (BCG) vaccine as an immunomodulator in MS. According to the guidelines for clinical trials in MS, a single crossover, MRI-monitored trial was performed in 14 patients with relapsing-remitting MS. After treatment, MRI activity was significantly reduced. No major adverse effects were reported. Adjuvant therapy with BCG vaccine was safe and merits study in MS.

Normal frontal perfusion in patients with frozen gait

We have studied the frontal perfusion in the resting condition of two groups of patients with frozen gait: 10 patients with the syndrome of "isolated gait ignition failure" (IGIF) and 8 patients with idiopathic Parkinson's disease (PD) and severe "off" freezing. These patients were compared with two other groups: one including 20 age-matched volunteers as normal control subjects and the other one including 12 patients with progressive supranuclear palsy (PSP) as a positive control with expected frontal hypoperfusion. Frontal perfusion was assessed using single photon emission computed tomography (SPECT) regional cerebral blood flow measurement with intravenous 133Xenon. A significant frontal hypoperfusion was only present in the PSP group but not in the three others. These results do not support the hypothesis that start hesitations and freezing when walking are related to a frontal lobe dysfunction. However, it is possible that frontal neuronal dysfunction occurs without measurable cerebral blood flow changes in the resting condition.

Cortical motor overactivation in parkinsonian patients with L-dopa-induced peak-dose dyskinesia

We have studied the regional cerebral blood flow (rCBF) changes induced by the execution of a finger-to-thumb opposition motor task in the supplementary and primary motor cortex of two groups of parkinsonian patients on L-dopa medication, the first one without L-dopa induced dyskinesia (n = 23) and the other with moderate peak-dose dyskinesia (n = 15), and of a group of 14 normal subjects. Single photon emission tomography with i.v. 133Xe was used to measure the rCBF changes. The dyskinetic parkinsonian patients exhibited a pattern of response which was markedly different from those of the normal subjects and non-dyskinetic parkinsonian patients, with a significant overactivation in the supplementary motor area and the ipsi- and contralateral primary motor areas. These results are compatible with the hypothesis that an hyperkinetic abnormal involuntary movement, like L-dopa-induced peak dose dyskinesia, is due to a disinhibition of the primary and associated motor cortex secondary to an excessive outflow of the pallidothalamocortical motor loop.

The ipsilateral cerebellar hemisphere is overactive during hand movements in akinetic parkinsonian patients

We compared the rCBF changes induced by the execution of a finger-to-thumb opposition motor task in the cerebellar hemispheres of 12 normal subjects, 12 parkinsonian patients whose medication had been withheld for at least 18 h and 16 parkinsonian patients on medication using single photon emission tomography and i.v. 133Xe. The normal subjects and parkinsonian patients on medication exhibited the same pattern of response, with a significant increase in rCBF in the contralateral primary motor cortex and in the supplementary motor areas. No significant rCBF change was detected in the cerebellum of these two groups; this finding was expected since our technique cannot detect cerebellar activation when the motor task is executed at a relatively low rate and small amplitude as it was in this study. The parkinsonian patients off medication exhibited a markedly different pattern of activation characterized by a significant overactivation in the ipsilateral cerebellar hemisphere and a significant underactivation in the supplementary motor areas. These results suggest that parkinsonian patients off medication may try to compensate for their basal ganglia-cortical loop's dysfunction using other motor pathways involving cerebellar relays.

Motor recovery after stroke. Morphological and functional brain alterations

The aim of this study was to evaluate the relationships of morphological and CBF patterns with both the severity and the evolution of the motor deficit in the late phase of stroke and, in particular, to identify morphological and/or functional brain alterations associated with a persistent severe motor deficit or a poor, delayed motor recovery. We analysed CT/MRI and single photon emission tomography (SPET) findings from 37 patients studied in the chronic phase of stroke (mean duration +/- SD = 3.6 +/- 1.6 months), whom we were able to follow clinically for a period of 3 months. The eventual degree of motor recovery correlated significantly (negatively) with the time since stroke at entry, but not with the severity of neurological impairment at entry. The volume, side and location (cortical or subcortical) of the infarct did not correlate with either the severity or the evolution of the motor deficit. Patients with a CT/MRI lesion of the parietal lobe (n = 8) showed a more severe motor deficit than those with other cortical locations. The severity of the motor deficit correlated significantly (negatively) with CBF values in the supplementary motor area (SMA) and parietal areas of the damaged hemisphere, and in the contralateral undamaged primary motor cortex. The degree of motor improvement correlated significantly (positively) with CBF values in the contralateral undamaged thalamus, lentiform and caudate nuclei, and premotor cortex. In the late phase of stroke, the severity of the motor deficit may be positively associated with the functional impairment of associative parietal and frontal areas of the damaged hemisphere. The functional impairment of the basal ganglia-frontal network in the undamaged hemisphere seems to be related to a poor, delayed motor recovery.

Involvement of the limbic system in multiple sclerosis patients with depressive disorders

This study investigates the relationship between depression and both anatomic and cerebral blood flow abnormalities in multiple sclerosis (MS) patients. Ten nondepressed MS patients were compared with 10 depressed MS patients matched for age, sex, and functional disability. Both groups were evaluated by means of neuropsychological tests, magnetic resonance imaging, and single-photon emission tomography imaging. There was no difference between the two groups with regard to the global cognitive score. Magnetic resonance imaging data showed no significant differences in the number, side, location, and area of the demyelinating lesions between the two groups; however, regional cerebral blood flow asymmetries in the limbic cortex did distinguish the two groups. Analysis of variance showed a significant effect of depression on the perfusion asymmetries in the limbic cortex. Finally, perfusion asymmetries in limbic cortex significantly correlated with depression test scores. Our findings suggest that depression in MS patients could be induced by a disconnection between subcortical and cortical areas involved in the function of the limbic system.