[Value of colour Doppler ultrasonography in relation to clinical pretest probability in giant cell (temporal) arteritis]

BACKGROUND

Colour Doppler sonography (CDS) is an established technique in the diagnosis of giant-cell (temporal) arteritis (GCA). The predictive value of its diagnostic criteria for GCA (halo sign or stenosis) is related to the pretest probability (PTP), a measure of probability of presence of a target disease before the result of a diagnostic test is known.

PATIENTS AND METHODS

A total of 182 (average age 69 years, 69% women) patients of the Rheumatology Center Baden-Württemberg were investigated. Based on the diagnostic criteria of the American College of Rheumatology (ACR) they were assigned to one of three groups, before a CDS was performed: group 1 (n= 139) patients with "isolated" polymyalgia rheumatica (PMR) and a low PTP for GCA; group 2 (n=19) patients with intermediate PTP and nonspecific headache and fewer than three ACR criteria for GCA); and group 3 (n=224) patients with a high PTP and new headache loclized to the temporal artery and at least three ACR criteria for GCA.

RESULTS

The halo sign (periluminal dark halo) of more than 0.3 mm was present in 26% of group 1. 42% of those in group 2 and 83% of those in group 3. A stenosis or occlusion of the temporal artery was present in 3.5% (group 1), 5% (group 2) and 46% (group 3), respectively. 3 of 24 patients of group 3 also had a stenosis of the axillary or brachial artery. Concordance between clinical criteria and CDS (normal CDS in patients with PMR but no headache or abnormal CDS and clinically suspected BCA was found in 123 of 182 patients (67.5%). In these patients biopsy of the temporal artery ("gold standard" for the diagnosis of GCA) was not recommended. Temporal artery biopsy was, however, recommended in all patients with discordant findings (abnormal CDS with PMR but no headache or normal CDS with clinically suspected GCA, and also those with intermediary PTP (32%). A biopsy was performed in 42 of these patients after informed consent had been obtained. This demonstrated vasculitis in 11 of 25 patients with PMR (PPV in group 1: 0.44). But biopsies were negative in all four patients with clinically suspected GCA and normal CDS (NPV in group 3:1). In the intermediary group biopsy demonstrated vasculitits in 5 of 6 patients with an abnormal CDS (PPV 0.63), while 4 of 5 patients with a normal CDS had a normal biopsy (NPV 0.8).

CONCLUSION

Taking into account pretest probability, an RCA can be accurately diagnosed or excluded by CDS in two thirds of patients without biopsy. When performed by an experienced investigator CDS is a basic part in the diagnosis of CDA.

Randomized study of darbepoetin alfa as modifier of radiotherapy in patients with primary squamous cell carcinoma of the head and neck (HNSCC): Final outcome of the DAHANCA 10 trial

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Background: The study aimed to evaluate if correction of low hemoglobin (Hb) levels by means of the erythropoietin stimulating agent: darbepoetin alpha (Aranesp) during radiotherapy (RT) improves outcome in patients with HNSCC. Following a planned interim analysis which showed inferiority of the experimental treatment, the trial was stopped in November 2006. Methods: Pts with HNSCC eligible for primary RT alone and with Hb values below 14.0 g/dl were randomized to receive Aranesp together with accelerated fractionated RT. Pts. were stratified according to gender, T and N staging, tumor site, and institution. Aranesp was given subcutaneously in a dose of 150 micrograms weekly during RT, or stopped earlier if the Hb exceeded 15.5 g/dl. Results: In total, 522 patients (of a planned intake of 600) were included at the time of the interim analysis. Of these 514 pts were eligible for analysis (255 pts treated with Aranesp and 259 pts in the control group) with a median follow up of 49 months. Among these, 201 developed a loco-regional failure (primary endpoint). There have been 238 deaths of which 176 are due to HNSCC. The patients were evenly distributed according to the stratification parameters (gender, T and N staging, tumor site, institution).Aranesp resulted in the expected increase in Hb in more than 81% of the patients. The compliance to Aranesp was good with no significant difference in serious (cardiovascular) adverse events (3% vs. 1%). Overall, the results showed a poorer outcome in 5-year loco-regional control (59% vs. 68% (p = 0.04, RR: 1.47 [1.14–1.94]) for the Aranesp vs. control arm. This was also seen for the endpoint of disease-free survival (37% vs. 47%, p = 0.02, RR: 1.32 [1.04–1.68]), whereas there was no significant difference in overall survival (40% vs. 51%, p = 0.16, RR: 1.20 [0.93–1.55]). There were no differences in radiation related morbidity. All univariate analyses were confirmed in a multivariate setting. Conclusions: Correction of the Hb level with Aranesp in patients with HNSCC resulted in a significantly poorer tumor control after radiotherapy. The treatment principle was abandoned and the difference in outcome is being subjected to further examination.

No significant financial relationships to disclose.

Virtual reality training for radiotherapy becomes a reality

A report in 2007 to the UK Government identified a crisis in England for training staff and students for the radiotherapy treatment of cancer. The Hull authors have developed an immersive life size virtual environment of a radiotherapy treatment room, known as VERT, to address this problem. VERT provides the trainee with models, simulation, enhanced visualization and training aids for treatment of virtual patients in a virtual treatment room. In 2007 immersive VERT systems for radiotherapy training were established for training purposes at the University Aarhus Hospital (Denmark) and the Birmingham City University (UK). This paper reports on early evaluations of VERT by these two institutions.

The PLPp-specific T-cell population promoted by pertussis toxin is characterized by high frequencies of IL-17-producing cells

Experimental autoimmune encephalomyelitis (EAE) is commonly regarded as an animal model of the human disease multiple sclerosis (MS). Pertussis toxin (PTX) is routinely used for EAE induction in mice. Besides opening the blood-brain barrier, it acts as an adjuvant causing strong expansion of antigen-specific cells after coinjection with neuroantigens in IFA. Using an IL-17 ELISPOT assay we developed previously, we investigated the capability of PTX to induce proteolipid protein peptide 139-151(PLPp)-specific Th-17 cells in the immune periphery and in the thymus after coinjection with PLPp/IFA. PTX was found to induce peripheral PLPp-specific Th-17 cells in the draining lymph node and in the spleen, but not in the thymus. Our study indicates a new mechanism by which microbial agents can initiate or maintain autoimmune reactions and supports the growing role in particular for Th-17 cells in organ-specific autoimmune diseases like multiple sclerosis or EAE.

Mismatch negativity impairment associated with alcohol consumption in chronic alcoholics: A scalp current density study

Previous studies, based on amplitude and latency measurements of auditory event-related brain potentials, yielded inconclusive results about the status of mismatch negativity (MMN) in chronic alcoholics. The present study explores scalp current density (SCD) dynamics during MMN latency range in alcoholics, and correlates electrical SCD results with clinical data of the patients. SCD was computed from 30 electrodes in 16 abstinent chronic alcoholics and 16 healthy control volunteers in a paradigm on MMN elicited by duration changes. Reduced activity was observed in left frontal and right anterior and posterior temporal areas during MMN in alcoholics. Alcohol consumption correlated negatively with SCD intensity in these regions. Delayed activation was observed in the left posterior temporal area in the patients. Alcohol abstinence duration correlated positively with SCD intensity in this region. These results point to an impairment of automatic brain processing mechanisms associated with auditory change detection in chronic alcoholism. The present results suggest a reorganization of the computational neurodynamics of automatic auditory change detection linked to the amount of alcohol consumed in abstinent chronic alcoholics.

Functional neural dynamics underlying auditory event-related N1 and N1 suppression response

Presenting tone triplets of identical stimuli preceded by silent intervals of 30 s produces a series of three N1 averaged event-related potentials (ERPs), the first being of greater amplitude (non-suppressed N1) than the second and third ones (suppressed N1). Maximal statistically independent components (ICs) of single-trial multi-electrode scalp EEG responses to triplets were obtained by ICA algorithm, and then each IC was searched for underlying brain structures by LORETA inverse solution, and for oscillatory contributions by time-frequency analysis. Non-suppressed N1 cortical mechanisms were broken down into five ICs, grouped in two time-windows (early-onset and late-onset) involving the participation of temporal, frontal and parietal structures, and sub-serving EEG oscillatory contributions of power enhancement and putative phase concentration of mainly theta, alpha and low beta bands. Suppressed N1 was due to the modulation of two above-mentioned early-onset ICs, involving temporal structures only, and mainly sub-serving oscillatory contributions of phase concentration of theta and alpha. Present results, showing quantifiable changes of IC descriptors - i.e. time window of activation, implied structures and oscillatory contributions - extracted from two distinct brain functional situations (non-suppressed versus suppressed N1), give support to the view that ICA is not merely a statistical "latent variables" model when applied to ERPs, but could help to capture underlying specific function subunits of brain dynamics.

Location of brain rhythms and their modulation by preparatory attention estimated by current density

To test the hypothesis that there is a functional modulation of conventional EEG bands associated with preparatory attention, putative changes in the spontaneous brain rhythms and their associated cerebral sources were addressed. The goals of the present report were, first, to find the brain areas with maximal rhythmic activity before warning and imperative stimuli in a classic contingent negative variation (CNV) paradigm, and, second, to study the modulation of the EEG rhythms of these areas during the preparatory attention interval which precedes the S2 (imperative) stimulus. Trial by trial LORETA analysis found similar brain rhythm generators during both pre-S1 and pre-S2 intervals. Each theta, alpha and beta traditional EEG rhythm originates in several anatomically distinct brain structures. Preparatory attention is associated with a decrease in power in alpha (right and left occipital and temporal areas) and low-beta (left frontal, bilateral occipital and middle frontal areas) EEG bands. In these structures power changes associated with preparatory attention modulated either a dominant or a non-dominant oscillatory band, suggesting that non-dominant rhythms of a cerebral area have some functional relevance. Our results imply distributed regional sources for brain rhythms and support the view that during preparatory attention there is a modulation of the brain sources generating alpha and beta brain rhythms. Moreover, the proposed combined approach makes it possible to explore the definition of a given brain area not only anatomically, but also by the frequency content and the functional reactivity of the electrical rhythms that it generates.

Modulation of spectral power and of phase resetting of EEG contributes differentially to the generation of auditory event-related potentials

Nowadays, the mechanisms involved in the genesis of event-related potentials (ERPs) are a matter of debate among neuroscientists. Specifically, the debate lies in whether ERPs arise due to the contribution of a fixed-polarity and fixed-latency superimposed neuronal activity to background electroencephalographic oscillations (evoked model) and/or due to a partial phase synchronization of the ongoing EEG (oscillatory model). The participation of the two mechanisms can be explored by the spectral power modulation and phase coherence of scalp EEG rhythms, respectively. However, an important limitation underlies their measurement: the fact that an added neural activity will be relatively phase-locked to stimulus, thus enhancing both spectral power and phase synchrony measures and making the contribution of each mechanism less clear-cut. This would not be relevant in the case that an increase in phase concentration was not accompanied by any concurrent spectral power modulation, thus opening the way to an oscillatory-based explanation. We computed event-related spectral power modulations and phase coherence to an auditory repeated-stimulus presentation paradigm with tone intensity far from threshold (90 dB SPL), in which N1 decreases its amplitude (N1 gating) as an attenuation brain process. Our data indicate that evoked and oscillatory activity could contribute together to the non-attenuated N1, while N1 to repeated stimuli could be explained by partial phase concentration of scalp EEG activity without concurrent power increase. Therefore, our results show that both increased spectral power and partial phase resetting contribute differentially to different ERPs. Moreover, they show that certain ERPs could arise through reorganization of the phase of ongoing scalp EEG activity only.