Changes in brain size during the menstrual cycle

Background

There is increasing evidence for hormone-dependent modification of function and behavior during the menstrual cycle, but little is known about associated short-term structural alterations of the brain. Preliminary studies suggest that a hormone-dependent decline in brain volume occurs in postmenopausal, or women receiving antiestrogens, long term. Advances in serial MR-volumetry have allowed for the accurate detection of small volume changes of the brain. Recently, activity-induced short-term structural plasticity of the brain was demonstrated, challenging the view that the brain is as rigid as formerly believed.

Methodology/Principal Findings

We used MR-volumetry to investigate short-term brain volume changes across the menstrual cycle in women or a parallel 4 week period in men, respectively. We found a significant grey matter volume peak and CSF loss at the time of ovulation in females. This volume peak did not correlate with estradiol or progesterone hormone levels. Men did not show any significant brain volume alterations.

Conclusions/Significance

These data give evidence of short-term hormone-dependent structural brain changes during the menstrual cycle, which need to be correlated with functional states and have to be considered in structure-associated functional brain research.

A comparison of different treatment techniques for posterior crossbite in the mixed dentition

In this retrospective investigation, the changes occurring during the treatment of patients with posterior crossbite in the mixed dentition with the use of expansion plate and quad-helix appliances were evaluated and compared with those resulting from growth and development occurring in a control group of patients of similar age and type of malocclusion. The expansion plate group consisted of 13 patients, the quad-helix group of 14 patients, and the control group consisted of 10 children with transverse posterior crossbites in the mixed dentition. The research material was formed from orthodontic models and lateral and frontal cephalometric radiographs from 37 children. It was observed in this investigation that transverse expansion is achieved by both the expansion plate and quad-helix appliances. However, the average period of treatment was 1.2 years for the expansion plate, and 0.6 years for the quad-helix appliance. Although posterior crossbite was corrected in a fairly short period of time, the quad helix appliance caused considerable buccal tipping of the maxillary first permanent molars.

Olfactory impairment in monozygotic twins discordant for schizophrenia

OBJECTIVE

Several studies demonstrated olfactory dysfunction in patients with schizophrenia, some reported deficient olfaction in unaffected relatives of schizophrenics as well. This study differentially assessed olfactory acuity as well as smell identification and smell discrimination in monozygotic twins discordant for schizophrenia and healthy, monozygotic control twins, to determine the genetic basis of different olfactory modalities and their association to schizophrenia.

METHOD

The Sniffin'Sticks test,a comprehensive and standardized olfactory test, was employed to assess the olfactory function of 10 monozygotic twin pairs discordant for schizophrenia versus 10 age- and sexmatched healthy,monozygotic twin pairs.

RESULTS

Olfaction of affected monozygotic twins was globally impaired. Partial olfactory impairment of their unaffected co-twins may point to a genetic cause of olfactory impairment in schizophrenia. The influence of genetic factors was most evident for olfactory acuity and least evident for smell identification. All olfactory functions declined with duration of illness. Side of stimulus presentation did not influence olfactory performance.

CONCLUSIONS

Genetic factors associated with olfactory dysfunction may contribute to schizophrenia. The degree of the genetic influence on olfaction depends on the olfactory domain under examination.

Recurrent posterior reversible encephalopathy syndrome (PRES)

Posterior reversible encephalopathy syndrome is a proposed cliniconeuroradiological entity characterized by headache, altered mental status, cortical blindness, seizures, and other focal neurological signs, and a diagnostic magnetic resonance imaging picture. A variety of different etiologies have been reported like hypertension, pre-eclampsia/eclampsia, cyclosporin A or tacrolimus neurotoxicity, uraemia and porphyria. With early diagnosis and prompt treatment, the syndrome is usually fully reversible. We report a case of recurrent PRES of unknown aetiology following intensive care unit treatment and only moderately elevated blood pressure. Clinicians as well as radiologists must be familiar with this clinically frightening, underdiagnosed condition to assure timely diagnosis and treatment to prevent persistent deficits.

The mechanisms of taurine mediated protection against cell damage induced by hypoxia and reoxygenation

Taurine administered during hypoxia markedly reduced the cell damage due to O2 deficiency and reoxygenation. Different mechanisms are responsible for the improved survival of the renal cell cultures. Taurine markedly reduces the osmoregulatory deterioration during hypoxia and reoxygenation. Calcium homeostasis was markedly improved. Ca2+ efflux during hypoxia as well as Ca2+ overload during reoxygenation was significantly reduced by the amino acid. The effect of taurine was partly comparable to the effect induced by Ca2+ channel blockers. One of the effects mainly responsible for cellular protection seems to be the taurine-induced acceleration of cellular growth processes in spite of hypoxia and reoxygenation. The spectrum of cytoprotective effects of taurine predisposes this substance to be a physiological protective agent responsible for cellular homeostasis or enantiostasis.

Positional brain deformation visualized with magnetic resonance morphometry

OBJECTIVE

To assess and visualize gravitational effects on brain morphology and the position of the brain within the skull by magnetic resonance (MR) morphometry in order to identify confounding effects and possible sources of error for accurate planning of neurosurgical interventions.

METHODS

Three-dimensional MR imaging data sets of 13 healthy adults were acquired in different positions in the scanner. With a morphometric approach, data sets were evaluated by deformation field analysis and the brain boundary shift integral. Distortions of the brain were assessed comparing right versus left and prone versus supine positioning, respectively.

RESULTS

Two effects could be differentiated: 1) greatest brain deformation of up to 1.7 mm predominantly located around central brain structures in the lateral direction and a less pronounced change after position changes in posterior-anterior direction, and 2) the brain boundary shift integral depicted position-dependent brain shift relative to the inner skull.

CONCLUSION

Position-dependent effects on brain structure may undermine the accuracy of neuronavigational and other neurosurgical procedures. Furthermore, in longitudinal MR volumetric studies, gravitational effects should be kept in mind and the scanning position should be rigidly controlled for.

Tonotopy of the Auditory-Evoked Field Component N100m in Patients with Schizophrenia

Abstract A number of clinical studies on the auditory neuromagnetic evoked field (AEF) component N100m have reported an altered lateralization in schizophrenic patients. This study addresses the problem of a possible functional reorganization of the temporal cortex in schizophrenia by examining the tonotopic organization of the N100m. Thirty-two patients with schizophrenia and 33 healthy controls of both sexes took part. Two tone frequencies (1000 and 5000 Hz tone) were applied for auditory stimuli, and AEF were recorded over both hemispheres successively using a 31-channel biomagnetometer. The comparison of N100m dipole location and orientation between hemispheres revealed no alterations in male or female patients. Between tone frequencies highly significant differences were found for N100m peak latency, mean global field power, dipole orientation, and dipole location in the anterior-posterior direction. Although the main effects of frequency were found to be the same in patients and controls, the balance between hemispheres was altered in patients with schizophrenia, with respect to the dependence between frequency and dipole location in the anterior-posterior direction as well as between frequency and latency. In patients, the influence of frequency on these variables was more pronounced in the right hemisphere and less pronounced in the left, compared to controls.

Enlarged gamma band response of neuromagnetic auditory evoked fields in a visually impaired subject

Under acoustic stimulation a phase-locked response in the gamma band (near 40 Hz) in the latency range between 20 and 130 ms is evoked. We report on a considerably visually impaired woman with Grönblad-Strandberg syndrome which involves degeneration at the level of retina, but has no overt central nervous component to the degeneration. The subject exhibited an extraordinarily high power in the phase-locked gamma band response (GBR) which was found to be more than three, and sometimes more than four, standard deviations above the average of a group of 25 subjects with normal vision. Furthermore, the dipoles of her mismatch reaction and M200 were found to be located posteriorly to the dipoles of the M100. Overall, both enlarged GBR and changed cortical representation could be results of cortical plasticity related to visual impairment.

Psychosis following anti-obesity treatment with rimonabant

BACKGROUND

In this report, we present the case of a patient with a relapse of schizophrenia following an episode of depression and increased anxiety after antiobesity treatment with rimonabant, a cannabinoid type 1 receptor antagonist.

CASE REPORT

After 4 weeks of treatment the patient developed psychiatric symptoms, i.e. depressed mood and elevated anxiety. Four months after the discontinuation of rimonabant, the patient presented with psychotic symptoms fulfilling ICD-10 criteria of paranoid schizophrenia. Antipsychotic treatment with quetiapine was initialized. A stable recovery took further 4 weeks in which combined treatment with quetiapine and ziprasidone was given.

CONCLUSION

The course of the illness suggests that the continuous affective symptoms, which were most likely a side effect of rimonabant, may have triggered the psychosis analogous to the stress-diathesis model of schizophrenia. As a consequence, rimonabant may not be the first choice in obese patients with a history of schizophrenia due to a potentially increased risk of a relapse via an indirect mechanism.

Non-invasive measurement of thyroidal iodine content (TIC) by X-ray fluorescence analysis (XFA)

The determination of thyroidal iodine content by X-ray fluorescence analysis is based on the phenomenon that the gamma radiation of Americium-241 excites stable iodine atoms to emit a characteristic fluorescence radiation which is proportional to the amount of iodine present in the gland. To study this, a stationary system has been developed which consists of a 11.1 GBq Am-241 source and a high-purity Germanium detector with spectrum analysator. Lower limit of detectability of this system corresponds to 0.013 mg per ml of thyroid volume measured sonographically; in-vivo precision given as coefficient of variation of duplicate measurements amounts to 12%. The thyroid is exposed with a radiation dose of 60 microSvs per measurement (approximately 5 % of a Tc-99m scan). Studies carried out in 149 volunteers and 173 patients showed a mean iodine concentration of 0.325 +/- 0.134 mg/ml in healthy persons; decreased iodine concentrations were found in euthyroid goitre patients and hyperthyroid patients with focal functional autonomy or Graves' disease. Iodine concentrations correlated negatively with age and goitre volume. The method is well suited for individual follow-up studies exploring different treatment modalities because of its sensitivity, high reproducibility and low radiation exposure.