Marcus Belke

Men and women are different: Diffusion tensor imaging reveals sexual dimorphism in the microstructure of the thalamus, corpus callosum and cingulum

INTRODUCTION Numerous magnetic resonance imaging (MRI) studies have addressed the question of morphological differences of the brain of men and women, reporting conflicting results regarding brain size and the ratio of gray and white matter. In the present study, we used diffusion tensor imaging (DTI) to delineate sex differences of brain white matter. METHODS We investigated brain microstructure in 25 male and 25 female healthy subjects using a 3T MRI scanner. Whole-head DTI scans were analyzed without a-priori hypothesis using Tract-Based Spatial Statistics (TBSS) calculating maps of fractional anisotropy (FA), radial diffusivity (RD, a potential marker of glial alteration and changes in myelination) and axial diffusivity (AD, a potential marker of axonal changes). RESULTS DTI revealed regional microstructural differences between the brains of male and female subjects. Those were prominent in the thalamus, corpus callosum and cingulum. Men showed significantly (p<0.0001) higher values of fractional anisotropy and lower radial diffusivity in these areas, suggesting that the observed differences are mainly due to differences in myelination. DISCUSSION As a novel finding we showed widespread differences in thalamic microstructure that have not been described previously. Additionally, the present study confirmed earlier DTI studies focusing on sexual dimorphism in the corpus callosum and cingulum. All changes appear to be based on differences in myelination. The sex differences in thalamic microstructure call for further studies on the underlying cause and the behavioral correlates of this sexual dimorphism. Future DTI group studies may carefully control for gender to avoid confounding.

In vivo demonstration of microstructural brain pathology in progressive supranuclear palsy: A DTI study using TBSS

We investigated DTI changes, potentially indicating alterations of microstructure and brain tissue integrity in 13 patients with probable progressive supranuclear palsy (PSP, Richardson syndrome) at stage III or less and 10 age‐matched controls using a whole brain analysis of diffusion tensor imaging (DTI) data. DTI images were analyzed using tract‐based spatial statistics, a hypothesis‐free technique. Fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD) were determined. In patients with PSP, significant increases in FA (P < 0.0001), an unspecific measure of microstructural tissue integrity, were found in the cerebellum and in the superior cerebellar peduncle bilaterally, in the fornix, the body of the corpus callosum and the olfactory region, when compared with age‐matched healthy controls. Further, regional reductions in AD (P < 0.0001), an indicator of altered axonal integrity, were observed in the pons, the right substantia nigra and the cerebellar white matter bilaterally. Significant increases in RD (P < 0.0001), a potential measure of altered myelin integrity, occurred bilaterally in the superior cerebellar peduncle, the cerebellar white matter, the vermis of the cerebellum, the fornix, the body of the corpus callosum, and the olfactory region. RD values in the superior cerebellar peduncle discriminated patients with PSP and controls with high sensitivity (0.92) and specificity (1.0). The findings are supported by neuropathological studies. Our data suggest the usefulness of this clinically available new technique as a possible tool for differential diagnosis.

Intravenous initiation and maintenance of ketogenic diet: Proof of concept in super-refractory status epilepticus

Super-refractory status epilepticus (SE) is characterized by unresponsiveness to initial anaesthetic therapy. This definition encompasses a SE that continues or recurs 24 h or more after the onset of anaesthetic therapy and includes those cases in which SE recurs on the reduction or withdrawal of anaesthesia. Treatment is difficult due to the failure of firstand second-line therapy. As no controlled or randomized studies are available on this phenomenon, further therapeutic management is based on clinical reports and expert opinion. The ketogenic diet (KD) is a high-fat, low-carbohydrate and adequate protein diet that has been an established, effective nonpharmacological treatment in the management of refractory epilepsy and severe childhood encephalopathies since the early 1920s. The KD alters the primary cerebral energy metabolism from glucose to ketone bodies and probably has multiple mechanisms of antiepileptic action. Emergency use of KD has been reported predominantly in children with SE. In adults only five case reports on prolonged SE have been published. The KD should probably be tried in all severe cases of super-refractory SE. Patients usually receive a commercial enteral KD preparation (4:1 or 3:1 ketogenic ratio: grams of fat to protein and carbohydrates combined), which is usually administered via a gastric or gastrostomy tube, provided the patient tolerates tube feeds well.

Diffusion tensor imaging in episodic cluster headache.

Background.— Cluster headache (CH) is a rare headache disorder with severe unilateral headache bouts and autonomic symptoms. The pathophysiology of CH is not completely understood. Using a voxel‐based morphometric paradigm or functional imaging, a key role of the hypothalamus and the pain matrix could be demonstrated during CH episodes. However, there are no diffusion tensor imaging (DTI) data investigating the white matter microstructure of the brain in patients with CH. Therefore, we used DTI to delineate microstructural changes in patients with CH in a headache‐free state.

DTI reveals hypothalamic and brainstem white matter lesions in patients with idiopathic narcolepsy

BACKGROUND Symptomatic narcolepsy is often related to hypothalamic, pontine, or mesencephalic lesions. Despite evidence of disturbances of the hypothalamic hypocretin system in patients with idiopathic narcolepsy, neuroimaging in patients with idiopathic narcolepsy revealed conflicting results and there is limited data on possible structural brain changes that might be associated with this disorder. METHODS We investigated with diffusion tensor imaging (DTI) whether microstructural abnormalities in the brain of eight patients with idiopathic narcolepsy with cataplexy are detectable compared to 12 healthy controls using a 1.5T MRI scanner. Whole-head DTI scans were analyzed without an a priori hypothesis. Voxelwise statistical analysis of fractional anisotropy (FA) data was performed using Tract-Based Spatial Statistics (TBSS), a non-linear analysis approach. RESULTS Patients with narcolepsy showed microstructural white matter changes in the right hypothalamus as well as in the left mesencephalon, pons, and medulla oblongata. Additionally, areas in the left temporal lobe, the pre- and postcentral gyrus, the frontal and parietal white matter, the corona radiata, the right internal capsule, and the caudate nucleus had altered microstructure in patients with narcolepsy. CONCLUSIONS Our study shows widespread microstructural white matter changes that are not visible on conventional MRI scans in patients with idiopathic narcolepsy. In support of the evidence from patients with symptomatic narcolepsy, we found microstructural changes in the hypothalamus, mesencephalon, pons, and medulla oblongata. Changes are in accordance with disturbances of the hypothalamic hypocretin system and its projections to mesencephalic and pontine areas regulating REM sleep.

Sustained seizure remission on perampanel in progressive myoclonic epilepsy (Lafora disease).

Aim The aim of this report is to provide initial evidence that add-on treatment with perampanel might be highly effective in progressive myoclonic epilepsy such as Lafora disease. Case report We report on a 21-year-old woman suffering from persistent myoclonus and generalized tonic–clonic seizures for more than seven years. Additionally, ataxia, a disturbance in speech and gait, as well as a cognitive decline were rapidly progressing. Subsequently, the diagnosis of Lafora disease was confirmed by the identification of a novel homozygous missense mutation in exon 3 of the EPM2A gene (c.538C>G; p.L180V). Adjunctive therapy with perampanel was started in this patient with advanced Lafora disease and was titrated up to 8 mg/day. A sustained and reproducible remission of myoclonus and GTCS could be achieved for a follow-up of three months. After dosage reduction to 6 mg/day, seizures recurred; however, on increasing the daily dose to 10 mg, seizures stopped for another three months. The patient also regained her ability to walk with help and the aid of a walker. Conclusions Perampanel is a selective, noncompetitive antagonist of AMPA-type glutamate receptors and recently licensed as adjunctive therapy for the treatment of refractory focal onset seizures. There is evidence for its effectiveness in generalized epilepsies, and phase III studies for this indication are on the way. Our case illustrates the possibility that perampanel might be a valuable option for treatment in PME. Considering its impressive efficacy in this case, we suggest a prospective, multicenter study evaluating perampanel in PME.

Intranasal midazolam during presurgical epilepsy monitoring is well tolerated, delays seizure recurrence, and protects from generalized tonic–clonic seizures

To evaluate the tolerability and efficacy of the ictal and immediate postictal application of intranasal midazolam (in‐MDZ) in adolescents and adults during video–electroencephalography (EEG) monitoring.

DTI and VBM reveal white matter changes without associated gray matter changes in patients with idiopathic restless legs syndrome.

We evaluated cerebral white and gray matter changes in patients with iRLS in order to shed light on the pathophysiology of this disease.

Microstructural white matter changes and their relation to neuropsychological deficits in patients with juvenile myoclonic epilepsy

OBJECTIVE Juvenile myoclonic epilepsy (JME) is the most common idiopathic generalized epilepsy syndrome. Neuropsychological, electrophysiological, and neuroimaging studies have led to the hypothesis that JME is related to dysfunction of frontal brain regions and mainly frontal thalamocortical networks. METHODS We investigated possible microstructural white matter abnormalities of 20 patients with JME as compared with 20 healthy control subjects using diffusion tensor imaging (DTI). We analyzed whole-head DTI scans without an a-priori hypothesis using Tract-Based Spatial Statistics (TBSS). To analyze associated gray matter changes, we applied voxel-based morphometry (VBM) to a 3D T1 magnetization prepared rapid gradient echo (MPRAGE) sequence. Neuropsychological testing and personality trait tests were performed to bridge the gap between structure and function. RESULTS In patients, DTI revealed microstructural white matter changes in anterior parts of the Corpus callosum, anterior parts of the cingulate gyrus, and widespread frontal white matter bilaterally as well as in anterior parts of the right thalamus, which were not accompanied by gray matter changes in VBM. Microstructural changes in the cingulum correlated with personality traits. Neuropsychological test results showed impaired attention and executive functions and reduced short-term memory in the patient group. Also, there was a tendency toward alexithymia and significantly higher scores on depression. SIGNIFICANCE The present study results showed neuropsychological deficits including frontal lobe cognitive performance and a tendency toward alexithymia as well as accompanying microstructural neuroimaging changes in patients with JME, which all point to alterations in frontal brain regions and frontal thalamocortical networks in these patients.

Predictors of New Cerebral Microbleeds in Patients with Antiplatelet Drug Therapy

BACKGROUND Cerebral microbleeds (CMB) are associated with an increased risk for ischemic and especially hemorrhagic stroke. The aim of the present study is to identify patients at high risk for the development of new CMB after initiation of an antiplatelet drug therapy. METHODS Patients received magnetic resonance imaging (MRI) within 1 week after initiation of an antiplatelet drug treatment due to a first ischemic stroke (n = 58) and after a follow-up period of 6 months (n = 40). We documented the presence and the number of CMB at baseline and follow-up and analyzed the influence of possible risk factors including vascular risk factors, stroke etiology, and number of CMB at baseline using stepwise logistic regression and Spearmans correlation coefficient. We compared progression rates of CMB in relation to each risk factor using the Mann-Whitney U-test. RESULTS The logistic regression model could correctly predict the presence of CMB in 70.7% of patients at baseline and 80% at follow-up. The model correctly identified 85% of patients with new CMB. We observed progression of CMB in 40% of the patients. The overall progression rate was .8 CMB per patient. The progression rate was significantly influenced by age more than 70 years and atherothrombotic stroke. The number of new CMB correlated significantly with the number of CMB at baseline. CONCLUSIONS We found several predictors of CMB after initiation of antiplatelet drug therapy. The results help to identify patients who need closer monitoring and thorough control of risk factors in order to lower the risk of new CMB and associated complications.