Compensated Hypogonadism Identified in Males with Cluster Headache: A Prospective Case-Controlled Study

OBJECTIVE

Androgens have been hypothesized to be involved in the pathophysiology of cluster headache due to the male predominance, but whether androgens are altered in patients with cluster headache remains unclear.

METHODS

We performed a prospective, case-controlled study in adult males with cluster headache. Sera were measured for hormones including testosterone, luteinizing hormone (LH), and sex hormone-binding globulin in 60 participants with episodic cluster headache (during a bout and in remission), 60 participants with chronic cluster headache, and 60 age- and sex-matched healthy controls. Free testosterone (fT) was calculated according to the Vermeulen equation. Shared genetic risk variants were assessed between cluster headache and testosterone concentrations.

RESULTS

The mean fT/LH ratio was reduced by 35% (95% confidence interval [CI]: 21%-47%, p < 0.0001) in patients with chronic cluster headache and by 24% (95% CI: 9%-37%, p = 0.004) in patients with episodic cluster headache compared to controls after adjusting for age, sleep duration, and use of acute medication. Androgen concentrations did not differ between bouts and remissions. Furthermore, a shared genetic risk allele, rs112572874 (located in the intron of the microtubule associated protein tau (MAPT) gene on chromosome 17), between fT and cluster headache was identified.

INTERPRETATION

Our results demonstrate that the male endocrine system is altered in patients with cluster headache to a state of compensated hypogonadism, and this is not an epiphenomenon associated with sleep or the use of acute medication. Together with the identified shared genetic risk allele, this may suggest a pathophysiological link between cluster headache and fT. ANN NEUROL 2024;95:1149-1161.

Reduced plasma calcitonin gene-related peptide level identified in cluster headache: A prospective and controlled study

BACKGROUND

The role of calcitonin gene-related peptide (CGRP) in the cyclic pattern of cluster headache is unclear. To acquire biological insight and to comprehend why only episodic cluster headache responds to CGRP monoclonal antibodies, we examined whether plasma CGRP changes between disease states (i.e. bout, remission and chronic) and controls.

METHODS

The present study is a prospective case-control study. Participants with episodic cluster headache were sampled twice (bout and remission). Participants with chronic cluster headache and controls were sampled once. CGRP concentrations were measured in plasma with a validated radioimmunoassay.

RESULTS

Plasma was collected from 201 participants diagnosed with cluster headache according to the International Classification of Headache Disorders, 3rd edition, and from 100 age- and sex-matched controls. Overall, plasma CGRP levels were significantly lower in participants with cluster headache compared to controls (p < 0.05). In episodic cluster headache, CGRP levels were higher in bout than in remission (mean difference: 17.1 pmol/L, 95% confidence interval = 9.8-24.3, p < 0.0001). CGRP levels in bout were not different from chronic cluster headache (p = 0.266).

CONCLUSIONS

Plasma CGRP is unsuitable as a diagnostic biomarker of cluster headache or its disease states. The identified reduced CGRP levels suggest that CGRPs role in cluster headache is highly complex and future investigations are needed into the modulation of CGRP and its receptors.

Overexpression of VEGFα as a biomarker of endothelial dysfunction in aortic tissue of α-GAL-Tg/KO mice and its upregulation in the serum of patients with Fabry's disease

Introduction

Fabry's disease is an X-linked lysosomal storage disorder caused by reduced activity of α-galactosidase A (GAL), leading to premature death on account of renal, cardiac, and vascular organ failure. Accumulation of the GAL substrate globotriaosylceramide (Gb3) in endothelial and smooth muscle cells is associated with early vascular cell damage, suggesting endothelial dysfunction as a driver of cardiorenal organ failure. Here, we studied the vascular expression of the key angiogenic factors, VEGFα and its antagonist angiostatin, in Fabry α-GAL-Tg/KO mice and determined circulating VEGFα and angiostatin serum levels in patients with Fabry's disease and healthy controls.

Methods

Cryopreserved aortic vessels from six α-GAL-Tg/KO and six wild-type (WT) mice were obtained and VEGFα and angiostatin levels were determined by performing Western blot analysis. VEGFα expression was visualized by an immunohistochemical staining of paraffin aortic rings. In addition, VEGFα and angiostatin serum levels were measured by using an enzyme-linked immunosorbent assay in 48 patients with genetically verified Fabry's disease (50% male) and 22 healthy controls and correlated with disease severity markers such as lyso-Gb3, albuminuria, NTproBNP, high-sensitive troponin T (hsTNT), and myocardial wall thickness.

Results

It was found that there was a significant increase in VEGFα protein expression (1.66 ± 0.35 vs. 0.62 ± 0.16, p = 0.0009) and a decrease in angiostatin expression (0.024 ± 0.007 vs. 0.053 ± 0.02, p = 0.038) in aortic lysates from α-GAL-Tg/KO compared with that from WT mice. Immunohistochemical staining revealed an adventitial VEGFα signal in α-GAL-Tg/KO mice, whereas no VEGFα signal could be detected in WT mice aortas. No differences in aortic angiostatin expression between α-GAL-Tg/KO- and WT mice could be visualized. The serum levels of VEGFα were significantly upregulated in patients with Fabry's disease compared with that in healthy controls (708.5 ± 426.3 vs. 458.5 ± 181.5 pg/ml, p = 0.048) and positively associated with albuminuria (r = 0.82, p < 0.0001) and elevated NTproBNP (r = 0.87, p < 0.0001) and hsTNT values (r = 0.41, p = 0.048) in male patients with Fabry's disease. For angiostatin, no significant difference was found between patients with Fabry's disease and healthy controls (747.6 ± 390.3 vs. 858.8 ± 599.3 pg/ml).

Discussion

In conclusion, an overexpression of VEGFα and downregulation of its counter player angiostatin in aortic tissue of α-GAL-Tg/KO mice support the hypothesis of an underlying vasculopathy in Fabry's disease. Elevated VEGFα serum levels were also observed in patients with Fabry's disease and were positively associated with elevated markers of organ manifestation in males. These findings suggest that angiogenetic markers, such as VEGFα, may be potentially useful biomarkers for the detection of endothelial dysfunction in classical Fabry's disease.

Cluster Headache Genomewide Association Study and Meta-Analysis Identifies Eight Loci and Implicates Smoking as Causal Risk Factor

OBJECTIVE

The objective of this study was to aggregate data for the first genomewide association study meta-analysis of cluster headache, to identify genetic risk variants, and gain biological insights.

METHODS

A total of 4,777 cases (3,348 men and 1,429 women) with clinically diagnosed cluster headache were recruited from 10 European and 1 East Asian cohorts. We first performed an inverse-variance genomewide association meta-analysis of 4,043 cases and 21,729 controls of European ancestry. In a secondary trans-ancestry meta-analysis, we included 734 cases and 9,846 controls of East Asian ancestry. Candidate causal genes were prioritized by 5 complementary methods: expression quantitative trait loci, transcriptome-wide association, fine-mapping of causal gene sets, genetically driven DNA methylation, and effects on protein structure. Gene set and tissue enrichment analyses, genetic correlation, genetic risk score analysis, and Mendelian randomization were part of the downstream analyses.

RESULTS

The estimated single nucleotide polymorphism (SNP)-based heritability of cluster headache was 14.5%. We identified 9 independent signals in 7 genomewide significant loci in the primary meta-analysis, and one additional locus in the trans-ethnic meta-analysis. Five of the loci were previously known. The 20 genes prioritized as potentially causal for cluster headache showed enrichment to artery and brain tissue. Cluster headache was genetically correlated with cigarette smoking, risk-taking behavior, attention deficit hyperactivity disorder (ADHD), depression, and musculoskeletal pain. Mendelian randomization analysis indicated a causal effect of cigarette smoking intensity on cluster headache. Three of the identified loci were shared with migraine.

INTERPRETATION

This first genomewide association study meta-analysis gives clues to the biological basis of cluster headache and indicates that smoking is a causal risk factor. ANN NEUROL 2023;94:713-726.

Cluster headache polygenetic risk and known functional variants of CYP3A4 are not associated with treatment response

BACKGROUND AND PURPOSE

The response to cluster headache treatments has a high interindividual variation. To date, treatment response has only been assessed by a candidate gene approach and no investigations into metabolic pathways have been performed. Our aim was to investigate the association between the polygenetic risk of cluster headache and treatment response to first-line cluster headache treatments as well as known functional variants of CYP3A4 and the response to verapamil. Further, it was aimed to replicate previous single nucleotide polymorphisms found to be associated with treatment response in cluster headache and/or migraine.

METHODS

In, 508 cluster headache patients diagnosed according to the International Classification of Headache Disorders were genotyped and participated in a semi-structured interview to evaluate treatment response. Polygenetic risk scores were calculated by the effect retrieved from a meta-analysis of the latest two genome-wide association studies on cluster headache.

RESULTS

Inferior treatment response to oxygen, triptans and verapamil is associated with chronicity of cluster headache were confirmed but no evidence was found that a response could be predicted by a high genetic risk of cluster headache. Likewise, verapamil response was not associated with functional variants of CYP3A4. No support of the genetic variants previously reported to be associated with treatment response to triptans or verapamil was found.

CONCLUSION

The clinically relevant variation in treatment response for cluster headache was not influenced by genetic factors in the present study.

Transition of cluster headache phenotype: An interview-based study

Background Cluster headache exists diagnostically in a chronic and episodic variant between which patients can convert. We aimed to describe how many patients change phenotype, elucidate possible factors associated with this transition and identify differences in clinical features between primary and secondary phenotypes.Methods 540 well-defined cluster headache patients according to current ICHD-criteria completed a cross-sectional semi-structured interview.Results Total transition-incidence for the cohort was 20.7%. Conversion from chronic to episodic was reported by 6.3% and transition from episodic to chronic by 14.4% with attack side shift as a possible predictor (p = 0.007). Compared to primary chronic patients, secondary chronic patients had more frequent (60 vs 34 per month, p = 0.0487), but shorter (60 vs 90 minutes, p = 0.041) attacks. Secondary episodic patients experienced shorter remission periods than primary episodic patients (6 vs 11 months, p = 0.010). Treatment response was poor in all groups and only one third had effective prevention.Conclusion Cluster headache is a fluctuating disorder with a fifth of our cohort having experienced at least one phenotype change during course of disease. Apart from attack side shifts, no predictors for transition were identified. Severity differed between primary and secondary subtypes. Overall, there is an urgent need for better understanding of cluster headache.

The economic and personal burden of cluster headache: a controlled cross-sectional study

Background

Cluster headache is a less-prevalent primary headache disorder but is overrepresented with regards to use of health care and social services. More insight into the socioeconomic impact is required.

Methods

We investigated both the personal and societal disease burden and cost in 400 patients with well-classified cluster headache according to the ICHD-criteria and 200 sex- and age matched controls. All participants completed a cross sectional questionnaire and semi-structured interview.

Results

Patients with chronic cluster headache constituted 146 out of 400 (37%). Overall, restriction in personal and/or professional life was reported by 94% of patients during attack periods. Even in remission, nine times as many episodic patients rated their health as poor/very poor compared to controls (9% vs 1%, p = 0.002). For chronic patients, the odds of rating health as good/very good were ten times lower compared to controls (OR:10.10, 95%CI:5.29–18.79. p < 0.001) and three times lower compared to episodic patients in remission (OR:3.22, 95%CI:1.90–5.47, p < 0.001). Additionally, chronic cluster headache patients were 5 times more likely to receive disability pension compared to episodic (OR:5.0, 95%CI:2.3–10.9, p < 0.001). The mean direct annual costs amounted to 9,158€ and 2,763€ for chronic and episodic patients, respectively (p < 0.001). We identified a substantial loss of productivity due to absence from work resulting in a higher indirect cost of 11,809 €/year/patient in the chronic population and 3,558 €/year/patient in the episodic population. Presenteeism could not be quantified but productivity was reduced in patients by 65% in periods with attacks compared to controls.

Conclusion

Cluster headache has a major negative impact on personal life, self-perceived health, and societal cost. Patients with the chronic variant are vastly more burdened. Patients with the episodic form were still markedly affected during the remission period. This study highlights the need for more effective therapy to lighten the burden on patients and society.

Very-high-frequency oscillations in the main peak of a magnetar giant flare

Magnetars are strongly magnetized, isolated neutron stars^1-3 with magnetic fields up to around 10¹⁵ gauss, luminosities of approximately 10³¹-10³⁶ ergs per second and rotation periods of about 0.3-12.0 s. Very energetic giant flares from galactic magnetars (peak luminosities of 10⁴⁴-10⁴⁷ ergs per second, lasting approximately 0.1 s) have been detected in hard X-rays and soft γ-rays⁴, and only one has been detected from outside our galaxy⁵. During such giant flares, quasi-periodic oscillations (QPOs) with low (less than 150 hertz) and high (greater than 500 hertz) frequencies have been observed^6-9, but their statistical significance has been questioned¹⁰. High-frequency QPOs have been seen only during the tail phase of the flare⁹. Here we report the observation of two broad QPOs at approximately 2,132 hertz and 4,250 hertz in the main peak of a giant γ-ray flare¹¹ in the direction of the NGC 253 galaxy^12-17, disappearing after 3.5 milliseconds. The flare was detected on 15 April 2020 by the Atmosphere-Space Interactions Monitor instrument^18,19 aboard the International Space Station, which was the only instrument that recorded the main burst phase (0.8-3.2 milliseconds) in the full energy range (50 × 10³ to 40 × 10⁶ electronvolts) without suffering from saturation effects such as deadtime and pile-up. Along with sudden spectral variations, these extremely high-frequency oscillations in the burst peak are a crucial component that will aid our understanding of magnetar giant flares.

Reference programme: diagnosis and treatment of headache disorders and facial pain. Danish Headache Society, 3rd edition, 2020

Headache and facial pain are among the most common, disabling and costly diseases in Europe, which demands for high quality health care on all levels within the health system. The role of the Danish Headache Society is to educate and advocate for the needs of patients with headache and facial pain. Therefore, the Danish Headache Society has launched a third version of the guideline for the diagnosis, organization and treatment of the most common types of headaches and facial pain in Denmark. The second edition was published in Danish in 2010 and has been a great success, but as new knowledge and treatments have emerged it was timely to revise the guideline. The recommendations for the primary headaches and facial pain are largely in accordance with the European guidelines produced by the European Academy of Neurology. The guideline should be used a practical tool for use in daily clinical practice for primary care physicians, neurologists with a common interest in headache, as well as other health-care professionals treating headache patients. The guideline first describes how to examine and diagnose the headache patient and how headache treatment is organized in Denmark. This description is followed by sections on the characteristics, diagnosis and treatment of each of the most common primary and secondary headache disorders and trigeminal neuralgia. The guideline includes many tables to facilitate a quick overview. Finally, the particular challenges regarding migraine and female hormones as well as headache in children are addressed.

Real-life treatment of cluster headache in a tertiary headache center - results from the Danish Cluster Headache Survey

BACKGROUND

Pharmacological treatment of cluster headache constitutes the core of clinical management, but evidence is sparse. We aimed to generate insight in the existing treatment and identify associations between clinical features and treatment response.

METHODS

Patients aged 18-65 diagnosed with cluster headache according to the ICHD-2 completed a questionnaire followed by a structured interview. Multiple logistic regression was used to identify associations.

RESULTS

The population consisted of 400 patients with an episodic: chronic ratio of 1.7:1. Episodic patients were more likely to respond to triptans (odds ratio = 1.77, confidence interval: 1.08-2.91, p = 0.023) and oxygen (odds ratio = 1.64, confidence interval: 1.05-2.57, p = 0.031) than chronic. Oxygen response was less likely if pain intensity was very severe (odds ratio = 0.53, confidence interval: 0.33-2.57, p = 0.006) and the risk of a poor response increased with disease duration (odds ratio = 0.79, confidence interval: 0.65-0.96, p = 0.016). Among current users of sumatriptan injection and oxygen, the proportion achieving 100% relief was higher with sumatriptan injection (p > 0.001) than with oxygen. No associations were identified regarding verapamil. Only 57% of current users of preventive medication responded at a 50% level.

CONCLUSION

Episodic cluster headache is more responsive to acute therapy than chronic. Further, sumatriptan injection was more effective than oxygen and the responder-rate was limited with verapamil. More effective acute and preventive therapies are needed for cluster headache patients.

Early BCG Vaccination, Hospitalizations, and Hospital Deaths: Analysis of a Secondary Outcome in 3 Randomized Trials from Guinea-Bissau

Background

This study was performed to examine the effects of early BCG vaccination on the risk, cause, and severity of infant hospitalizations. The analysis included 3 trials randomizing low-weight neonates to early BCG vaccination (intervention) versus no BCG vaccination (usual practice in low-weight neonates, control), with hospitalizations as secondary outcome.

Methods

Hospitalization data were collected at the pediatric ward of the National Hospital. Effects of BCG vaccination on hospitalization risk were assessed in Cox models providing overall and major disease-group incidence rate ratios (IRRs). Severity was assessed by means of in-hospital case-fatality rates and compared by group as cohort study risk ratios (RRs).

Results

Among 6583 infants (3297 in BCG group, 3286 controls), there were 908 infant hospitalizations (450 BCG, 458 controls) and 135 in-hospital deaths (56 BCG, 79 controls). The neonatal (28 days), 6-week, and infant (1-year) BCG versus control hospitalization IRRs were 0.97 (95% confidence interval [CI], .72-1.31), 0.95 (.73-1.24), and 0.96 (.84-1.10). Corresponding BCG versus control case-fatality rate RRs were 0.58 (95% CI, .35-.94), 0.56 (.35-.90), and 0.72 (.53-.99). BCG vaccination tended to reduce neonatal and infant sepsis hospitalization rates (IRR, 0.75 [95% CI, .50-1.13] and 0.78 [.55-1.11], respectively), and it reduced the neonatal in-hospital sepsis mortality rate (RR, 0.46; 95% CI, .22-.98). There were no confirmed hospitalizations for tuberculosis.

Conclusions

BCG vaccination did not affect hospitalization rates but reduced in-hospital mortality rates significantly, primarily by preventing fatal cases of sepsis. The observed beneficial effects of BCG on the in-hospital mortality rate were entirely nonspecific.

Clinical Trials Registration

NCT00146302, NCT00168610, and NCT00625482.

More precise phenotyping of cluster headache using prospective attack reports

BACKGROUND AND PURPOSE

The clinical characteristics of cluster headache (CH) are based mainly on retrospective attack descriptions of 'usual' attacks, but whether these reports are reliable is uncertain. The aim was to compare retrospective and prospective attack descriptions and describe the within- and between-patient variability of attacks.

METHOD

Fifty-seven CH patients underwent a semi-structured interview obtaining a retrospective account of usual CH attacks. Patients thereafter prospectively recorded the clinical characteristics of up to 10 attacks per patient in a headache diary. Four different attack characteristics were investigated: (i) severity, (ii) duration, (iii) number of autonomic symptoms and (iv) number of migrainous symptoms. Retrospective and prospective data were compared. Within- and between-patient variability of attacks was assessed.

RESULTS

Retrospective attack descriptions (n = 57) were significantly longer (P = 0.046) and more severe (P < 0.0001) for untreated attacks compared with prospective reports (n = 500). The number of autonomic symptoms was significantly higher in the retrospective reports compared to the prospective reports (P < 0.0001). Within-patient variability for attack duration, pain severity and number of autonomic and migrainous symptoms was low. Compared to men, more women reported longer (P = 0.026) and more severe (P = 0.028) attacks with more migrainous symptoms (P = 0.033).

CONCLUSIONS

Important differences were found between prospectively and retrospectively reported attacks with duration and severity of untreated attacks overestimated in retrospective attack descriptions. CH attacks display low within-patient variability, but the presentation of CH attacks varies between patients. The high prevalence of symptoms typically associated with migraine should raise more diagnostic awareness for CH, especially in women who are more often misdiagnosed as having migraine.

Genetics of cluster headache

BACKGROUND

Cluster headache is the most severe primary headache disorder. A genetic basis has long been suggested by family and twin studies; however, little is understood about the genetic variants that contribute to cluster headache susceptibility.

METHODS

We conducted a literature search of the MEDLINE database using the PubMed search engine to identify all human genetic studies for cluster headache. In this article we provide a review of those genetic studies, along with an overview of the pathophysiology of cluster headache and a brief review of migraine genetics, which have both been significant drivers of cluster headache candidate gene selection.

RESULTS

The investigation of cluster headache genetic etiology has been dominated by candidate gene studies. Candidate selection has largely been driven by the pathophysiology, such as the striking rhythmic nature of the attacks, which spurred close examination of the circadian rhythm genes CLOCK and HCRTR2. More recently, unbiased genetic approaches such as genome-wide association studies (GWAS) have yielded new genetic avenues of interest including ADCYAP1R1 and MME.

CONCLUSIONS

The majority of candidate genes studied for cluster headache suffer from poor reproducibility. Broader genetic interrogation through larger unbiased GWAS, exome, and whole genome studies may provide more robust candidates, and in turn provide a clearer understanding of the causes of cluster headache.

Cluster headache beyond the pain phase: A prospective study of 500 attacks

OBJECTIVE

To describe the nature, prevalence, and duration of symptoms in the preictal, ictal, and postictal phases of cluster headache (CH) attacks.

METHODS

Fifty-seven patients with episodic or chronic CH participated in this prospective, observational study. In a questionnaire concerning 33 CH and migraine-related symptoms, patients reported the clinical features of up to 10 CH attacks/patient. The questionnaire was divided into 3 sections: a preictal phase, ictal phase, and postictal phase. For each phase, patients documented whether the given symptom was present, and if possible estimated the duration of the symptom.

RESULTS

In total, 500 CH attack descriptions were obtained. In the preictal phase, general symptoms (most frequently concentration difficulties, restlessness, and mood changes) occurred 20 minutes prior to 46.0% of attacks. Local painful and autonomic symptoms were observed 10 minutes prior to 54.6% and 35% of attacks, respectively. Postictally, pain and autonomic symptoms resolved over 20 minutes, leaving patients with fatigue (36.2%), decreased energy (39.0%), and concentration difficulties (27.6%), lasting a median of 60 minutes.

CONCLUSIONS

Preictal and postictal symptoms are very frequent in CH, demonstrating that CH attacks are not composed of a pain phase alone. Since the origin of CH attacks is unresolved, studies of preictal and postictal symptoms could contribute to the understanding of CH pathophysiology and, potentially, early, abortive treatment strategies.

Cluster headache is associated with unhealthy lifestyle and lifestyle-related comorbid diseases: Results from the Danish Cluster Headache Survey

AIM

To compare the prevalence of unhealthy lifestyle factors and comorbid disorders in cluster headache patients with headache-free controls, in order to discuss pathophysiology and possible consequences.

METHODS

Cluster headache patients from the Danish cluster headache survey aged 18-65 years, diagnosed according to ICHD-II, were compared to sex- and age-matched headache-free controls. Participants completed questionnaires and structured interviews.

RESULTS

A total of 400 cluster headache patients and 200 controls participated. Patients had a more unhealthy lifestyle compared with controls in the form of current and current/former smoking (48.3% vs. 9.0%, p < 0.001 and 74.5% vs. 30.0%, p < 0.001, respectively), higher average alcohol intake per week (98.2 grams vs. 77.9 grams, p = 0.033) and BMI (26.1 vs. 24.2 kg/m², p < 0.001), whereas coffee and energy drink consumption was equally distributed. Further, lifestyle-related, psychiatric and pain-related diseases were much more prevalent in patients compared with controls, except for diabetes. Sub-group analyses revealed that current/former smokers had a worse clinical presentation than never smokers.

CONCLUSION

Unhealthy lifestyle factors and lifestyle-related diseases were more prevalent in cluster headache patients compared to controls. As lifestyle-related diseases might have serious consequences in the management of cluster headache, it is key to inform patients at an early time point about the possible risks of their lifestyle choices.

Changes in medication cost observed in chronic cluster headache patients treated with sphenopalatine ganglion (SPG) stimulation: Analysis based on 1-year data from the Pathway R-1 Registry

Background On-demand stimulation of the sphenopalatine ganglion (SPG) by means of an implantable neurostimulation system has been shown to be a safe and effective therapy for treatment-refractory cluster headache patients. Our objective was to estimate changes in cluster headache medication cost observed in SPG-treated chronic patients. Methods Detailed patient-level data of 71 chronic patients treated with the Pulsante® SPG Microstimulator System were available from the Pathway R-1 Registry through 12 months' follow-up. We used utilization data of preventive and acute medications reported at baseline, 3, 6, 9, and 12 months to estimate annualized drug costs for SPG-treated patients and compared it to baseline. Cost estimates for all drug/dosage combinations were developed based on German medication prices for 2016. Results In the base case analysis, mean annual acute and preventive medication costs decreased from €14,178 to €6924 (-€7254; -51%), and €559 to €328 (-€231; -41%), respectively, leading to total estimated annual drug cost savings of €7484, 97% of which were attributable to acute medications. Conclusions Our analysis suggests that SPG stimulation for the treatment of chronic cluster headache is associated with pronounced reductions in cluster headache medication usage that might lead to sizable annual savings in medication costs.

Pre-attack signs and symptoms in cluster headache: Characteristics and time profile

Introduction In contrast to the premonitory phase of migraine, little is known about the pre-attack (prodromal) phase of a cluster headache. We aimed to describe the nature, prevalence, and duration of pre-attack symptoms in cluster headache. Methods Eighty patients with episodic cluster headache or chronic cluster headache, according to ICHD-3 beta criteria, were invited to participate. In this observational study, patients underwent a semi-structured interview where they were asked about the presence of 31 symptoms/signs in relation to a typical cluster headache attack. Symptoms included previously reported cluster headache pre-attack symptoms, premonitory migraine symptoms and accompanying symptoms of migraine and cluster headache. Results Pre-attack symptoms were reported by 83.3% of patients, with an average of 4.25 (SD 3.9) per patient. Local and painful symptoms, occurring with a median of 10 minutes before attack, were reported by 70%. Local and painless symptoms and signs, occurring with a median of 10 minutes before attack, were reported by 43.8% and general symptoms, occurring with a median of 20 minutes before attack, were reported by 62.5% of patients. Apart from a dull/aching sensation in the attack area being significantly ( p < 0.05) more frequent among men and episodic patients, compared with women and chronic patients respectively, no other differences in the prevalence of pre-attack symptoms were identified between groups. Conclusion Pre-attack symptoms are frequent in cluster headache. Since the origin of cluster headache attacks is still unresolved, studies of pre-attack symptoms could contribute to the understanding of cluster headache pathophysiology. Furthermore, identification and recognition of pre-attack symptoms could potentially allow earlier abortive treatment.

Chronobiology differs between men and women with cluster headache, clinical phenotype does not

Objective:

To describe differences between the sexes in the phenotype of cluster headache (CH) in a large, well-characterized clinical CH population.

Methods:

Patients from the Danish CH survey aged 18–65 years, diagnosed with CH according to International Classification of Headache Disorders, second edition, completed questionnaires and structured interviews.

Results:

A total of 351 patients with CH participated, with a male:female ratio of 2:1. The diurnal variation of attacks showed moments of peak prominence in men’s attack cycle to be advanced by 1 hour compared to women’s, despite no difference in self-reported bedtime or chronotype (p = 0.31). The onset of CH decreased with increasing age for both sexes. Diagnostic delay was numerically longer for men vs women (6.56 vs 5.50 years, p = 0.21); however, more women had previously been misdiagnosed (61.1% vs 45.5%, p < 0.01) and received the correct diagnosis at a tertiary headache center (38.8% vs 20.9%, p < 0.001). Only minor sex differences in clinical characteristics were found but chronic CH was more prevalent in women compared to men (44.0% vs 31.9%, p < 0.05).

Conclusions:

Despite a similar clinical phenotype, diurnal attack cycle is advanced by 1 hour in men with CH compared to women. Rhythmicity is a defining characteristic of CH and these findings suggest differences in the hypothalamus’ influence on attack occurrence between the sexes. In addition, women were more often misdiagnosed and diagnosis in the primary or secondary sector more often failed. Furthermore, women had chronic CH more frequently than men. A long diagnostic delay and frequent misdiagnosis emphasize the need for increased awareness of CH in both sexes.

Campaigns with oral polio vaccine may lower mortality and create unexpected results

Three studies from Guinea-Bissau found conflicting effects of OPV-at-birth (OPV0) on child survival. One study from 2004 suggested excess male mortality among children receiving OPV0 compared with children receiving NoOPV0 during a period of shortage of OPV. However, two subsequent studies showed beneficial effects of OPV0. In 2004, two national OPV-campaigns had been conducted in Guinea-Bissau. In a reanalysis of the 2004-study, in a survival analysis the age-adjusted mortality rate of study participants was 67% (95% CI=42-81%) lower after the OPV-campaigns than before the campaigns. In the OPV0 group only 22% (655/3031 person-years (pyrs)) of follow-up time was "after" the OPV-campaigns whereas 55% (473/859 pyrs) of the time in the NoOPV0 group was post-campaign (p<0.0001, Chi²). Censoring for OPV-campaigns in the original study removed excess male mortality and made the three studies more homogeneous. Overall, there is now considerable evidence that OPV, like other live vaccines, has important beneficial non-specific effects.

Sclerostin does not play a major role in the pathogenesis of skeletal complications in type 2 diabetes mellitus

In contrast to previously reported elevations in serum sclerostin levels in diabetic patients, the present study shows that the impaired bone microarchitecture and cellular turnover associated with type 2 diabetes mellitus (T2DM)-like conditions in ZDF rats are not correlated with changes in serum and bone sclerostin expression.

INTRODUCTION

T2DM is associated with impaired skeletal structure and a higher prevalence of bone fractures. Sclerostin, a negative regulator of bone formation, is elevated in serum of diabetic patients. We aimed to relate changes in bone architecture and cellular activities to sclerostin production in the Zucker diabetic fatty (ZDF) rat.

METHODS

Bone density and architecture were measured by micro-CT and bone remodelling by histomorphometry in tibiae and femurs of 14-week-old male ZDF rats and lean Zucker controls (n = 6/group).

RESULTS

ZDF rats showed lower trabecular bone mineral density and bone mass compared to controls, due to decreases in bone volume and thickness, along with impaired bone connectivity and cortical bone geometry. Bone remodelling was impaired in diabetic rats, demonstrated by decreased bone formation rate and increased percentage of tartrate-resistant acid phosphatase-positive osteoclastic surfaces. Serum sclerostin levels (ELISA) were higher in ZDF compared to lean rats at 9 weeks (+40 %, p < 0.01), but this difference disappeared as their glucose control deteriorated and by week 14, ZDF rats had lower sclerostin levels than control rats (-44 %, p < 0.0001). Bone sclerostin mRNA (qPCR) and protein (immunohistochemistry) were similar in ZDF, and lean rats at 14 weeks and genotype did not affect the number of empty osteocytic lacunae in cortical and trabecular bone.

CONCLUSION

T2DM results in impaired skeletal architecture through altered remodelling pathways, but despite altered serum levels, it does not appear that sclerostin contributes to the deleterious effect of T2DM in rat bone.

Uterine artery embolization of symptomatic uterine fibroids: Initial success and short-term results

Purpose: To evaluate reduction in fibroid volume, the effect on clinical symptoms, adverse events and complications after percutaneous uterine artery embolization (UAE) as primary invasive treatment for symptomatic uterine fibroids.

Material and Methods: Sixty-two patients entered the study. Indications for treatment were fibroid-induced menorrhagia, bulk symptoms, pain, and/or large fibroid size. The first 50 patients were evaluated by clinical examination and ultrasonography with measurement of fibroid volume before treament and 1, 6 and 12 months after UAE. The remaining 12 patients were followed 3 and 12 months after treatment. Embolization with microparticles was performed percutaneously in local analgesia by selective catheterization of both uterine arteries.

Results: A primary technical success with bilateral UAE was achieved in 60/62 (97%) of the patients. They were treated for postprocedural pain lasting up to 24 h. In 30 of the 62 patients with 6 months follow-up, the mean fibroid volume was reduced 68% 6 months after treatment. Twenty-nine (96%) of the patients experienced reduced bleeding, 21 (70%) reduced pain, and 18 (61%) reduced bulk symptoms at follow-up.

Conclusion: UAE is a method with a high technical success rate. The treatment has good effect on fibroid volume reduction and clinical symptoms. Severe post-procedural pain occurs generally in successful bilateral embolizations, but complications and adverse events are otherwise few and minor. UAE represents a promising new method for treating uterine fibroid-related symptoms.

Sleep and chronobiology in cluster headache

BACKGROUND AND AIM

Cluster headache (CH) is the headache disorder with the strongest chronobiological traits. The severe attacks of pain occur with diurnal and annual rhythmicity but the precise rhythm and involvement of potential zeitgebers is unknown. Patients complain of poor sleep quality yet this has never been studied. We investigated triggers, rhythms, sleep quality and chronotypes in CH.

METHODS

Patients and controls completed questionnaires and structured interviews composed of new and previously validated parts including the Pittsburgh Sleep Quality Index (PSQI) and Morningness-Eveningness Questionnaire (MEQ). Patients were characterized by a CH index, a unified measure of headache burden.

RESULTS

A total of 275 CH patients and 145 matched controls were included. The most common trigger was sleep (80%) and a relationship between clusters and daylight was identified. Of the patients, 82.2% reported diurnal and 56% annual rhythmicity. Patients reported impaired sleep quality (PSQI) (p < 0.0001) and an inverse relationship between time passed since last attack and sleep quality was identified (p < 0.0001). The CH index was positively related to the PSQI (p < 0.0001).

CONCLUSION

Diurnally, CH exhibits a relationship with night-time and annually with daylight hours. Patients' sleep quality is reduced compared with controls. Results suggest a complex relationship as sleep quality improves between clusters, but remains pathological.

Reduced CSF hypocretin-1 levels are associated with cluster headache

Background

Cluster headache (CH) is a debilitating disorder characterized by unilateral, severe pain attacks with accompanying autonomic symptoms, often waking the patient from sleep. As it exhibits strong chronobiological traits and genetic studies have suggested a link with the hypocretin (HCRT) system, the objective of this study was to investigate HCRT-1 in CH patients.

Methods

Cerebrospinal fluid HCRT-1 concentration was measured in 12 chronic and 14 episodic CH patients during an active bout, and in 27 healthy controls. The patients were well characterized and clinical features compared to the HCRT concentration.

Results

We found significantly lower HCRT levels both in chronic ( p = 0.0221) and episodic CH ( p = 0.0005) patients compared with controls. No significant relationship was found with other clinical features.

Conclusions

This is the first report of significantly reduced HCRT concentrations in CH patients. We speculate that decreased HCRT may reflect insufficient antinociceptive activity of the hypothalamus. The mechanism of the antinociceptive effect of HCRT is not known and requires further investigation. This study supports the hypothesis of a connection between arousal regulation and CH.

Epidemiology of concurrent headache and sleep problems in Denmark

AIMS

There are no previous epidemiologic studies on concurrent headache and sleep problems (HSP). This cross-sectional study aimed to determine the prevalence of HSP in Denmark, broadly characterize those with HSP, and examine associations between HSP and socioeconomic/lifestyle factors.

METHODS

A total of 129,150 randomly selected individuals were invited to participate in the Danish National Health Survey 2010. Respondents were asked about headache, sleep problems, depression and anxiety in the last two weeks, health-related lifestyle and quality of life (SF-12). Socioeconomic data were retrieved from national registers. Prevalence proportions were adjusted for stratified sampling and non-response. Regression analyses examined associations between HSP and socioeconomic/lifestyle factors.

RESULTS

Of 68,518 respondents, 16.3% reported only headache, 21.1% only sleep problems, and 18.1% HSP with 2.6% being severely affected. Prevalence was higher among women and the middle-aged. Severe HSP was associated with low socioeconomic position, non-Western ethnicity, unhealthy lifestyle, high stress and anxiety/depression. Those with HSP had substantially reduced quality of life; more so than those having only headache or only sleep problems.

CONCLUSIONS

HSP is a highly prevalent condition. Lifestyle modification, stress reduction, and screening for concurrent depression and anxiety may play important roles in management. The high prevalence of HSP suggests a common pathophysiological mechanism.

Sleep in trigeminal autonomic cephalagias: a review

PURPOSE OF REVIEW

Sleep and cluster headache (CH) are believed to be interconnected but the precise relation to the other trigeminal autonomic cephalalgias (TACs) is uncertain and complex. A better understanding of these relations may eventually lead to a clarification of the underlying mechanisms and eventually to more effective therapeutic regimens. This review aims to evaluate the existing literature on the subject of TACs and sleep. An association between episodic CH and distinct macrostructural sleep phases, especially the relation to rapid eye movement (REM) sleep, has been described in some older studies but could not be confirmed in other, more recent studies. Investigations into the microstructure of sleep in these patients are lacking. Only a few case reports exist on the relation between sleep and other TACs.

SUMMARY

Recent studies do not find an association between CH and REM sleep. One older study suggests chronic paroxysmal hemicranias may be locked to REM sleep but otherwise the relation is unknown. Reports indicate that CH and obstructive sleep apnoea are associated in some individuals but results are diverging. Single cases show improvement of CH upon treatment of sleep apnoea, but the causal relationship remains in question. Other TACs are probably not connected to sleep and strictly nocturnal attacks should prompt investigations for secondary causes. The relation between CH and sleep is, however, fascinating and detailed sleep studies in carefully diagnosed patients are warranted.

Achieving a clinically relevant composite outcome of an HbA1c of <7% without weight gain or hypoglycaemia in type 2 diabetes: a meta-analysis of the liraglutide clinical trial programme

AIM

Effective type 2 diabetes management requires a multifactorial approach extending beyond glycaemic control. Clinical practice guidelines suggest targets for HbA1c, blood pressure and lipids, and emphasize weight reduction and avoiding hypoglycaemia. The phase 3 clinical trial programme for liraglutide, a human glucagon-like peptide 1 analogue, showed significant improvements in HbA1c and weight with a low risk of hypoglycaemia compared to other diabetes therapies. In this context, we performed a meta-analysis of data from these trials evaluating the proportion of patients achieving a clinically relevant composite measure of diabetes control consisting of an HbA1c <7% without weight gain or hypoglycaemia.

METHODS

A prespecified meta-analysis was performed on 26-week patient-level data from seven trials (N = 4625) evaluating liraglutide with commonly used therapies for type 2 diabetes: glimepiride, rosiglitazone, glargine, exenatide, sitagliptin or placebo, adjusting for baseline HbA1c and weight, for a composite outcome of HbA1c <7.0%, no weight gain and no hypoglycaemic events.

RESULTS

At 26 weeks, 40% of the liraglutide 1.8 mg group, 32% of the liraglutide 1.2 mg group and 6-25% of comparators (6% rosiglitazone, 8% glimepiride, 15% glargine, 25% exenatide, 11% sitagliptin, 8% placebo) achieved this composite outcome. Odds ratios favoured liraglutide 1.8 mg by 2.0- to 10.5-fold over comparators.

CONCLUSIONS

As assessed by the composite outcome of HbA1c <7%, no hypoglycaemia and no weight gain, liraglutide was clearly superior to the other commonly used therapies. However, the long-term clinical impact of this observation remains to be shown.

No morphine sparing effect of ketamine added to morphine for patient-controlled intravenous analgesia after uterine artery embolization

BACKGROUND

Pain following embolization of the uterine arteries (UAEs) is variable and may be very severe requiring large doses of parenteral opioids for relief. The present study tested the hypothesis that the addition of ketamine to i.v. patient-controlled morphine reduces the amount of morphine required for pain-control during the first 24 h after UAE embolization.

METHODS

Fifty-six patients undergoing UAE embolization for treatment of symptomatic uterine leiomyomata were randomized to receive either 2 mg/ml of morphine (Control group, n=30) or 2 mg/ml of both morphine and ketamine (Ketamine group, n=26) by i.v. patient-controlled analgesia (IV-PCA). Pump settings were bolus dose 1 ml, lockout 10 min, no background infusion. In addition, all patients received diclofenac and acetaminophen for pain relief. Pain scores, morphine consumption and adverse events like nausea, vomiting, itching, visual disturbances, anxiety, dreaming and hallucinations, if any, were recorded for 24 h after embolization.

RESULTS

The mean +/- SD 24-h consumption of patient-controlled morphine was 38.3 +/- 21.0 mg in the Ketamine group vs. 33.3 +/- 18.3 mg in the Control group (NS). The difference between the means was 5.0 mg (95% confidence interval: -5.7; 15.6). One patient in the Ketamine group vs. none in the Control group experienced auditory hallucinations.

CONCLUSION

Studying an unselected group of patients undergoing embolization of the UAEs for treatment of symptomatic uterine leiomyomata under conditions of basal analgesia with acetaminophen and diclofenac, we failed to demonstrate any morphine-sparing effect of IV-PCA ketamine and morphine compared with IV-PCA morphine alone.

Compact sources as the origin of the soft γ-ray emission of the Milky Way

The Milky Way is known to be an abundant source of gamma-ray photons, now determined to be mainly diffuse in nature and resulting from interstellar processes. In the soft gamma-ray domain, point sources are expected to dominate, but the lack of sensitive high-resolution observations did not allow for a clear estimate of the contribution from such sources. Even the best imaging experiment revealed only a few point sources, accounting for about 50% of the total Galactic flux. Theoretical studies were unable to explain the remaining intense diffuse emission. Investigating the origin of the soft gamma-rays is therefore necessary to determine the dominant particle acceleration processes and to gain insights into the physical and chemical equilibrium of the interstellar medium. Here we report observations in the soft gamma-ray domain that reveal numerous compact sources. We show that these sources account for the entirety of the Milky Way's emission in soft gamma-rays, leaving at most a minor role for diffuse processes.

Alternative treatment for symptomatic fibroids

The present review discusses treatment options for symptomatic fibroids. Although the standard treatment of fibroids has been surgical hysterectomy, an increasing number of reports indicate that uterine artery embolization with preservation of the uterus is a promising alternative. Other surgical and medical approaches reported during the past year are also addressed. The review summarizes patient selection, contraindications, results, complications and future considerations. Complications following uterine artery embolization treatment for symptomatic fibroids have been minor in comparison with those following hysterectomy. Although patient satisfaction is good, none of the studies included control individuals and further studies are needed to optimize patient selection and to evaluate long-term results of treatment.

[Endovascular treatment of uterine fibromas]

Uterine artery embolisation represents a promising new method of treating fibroid-related menorrhagia and pelvic pain. The procedure is performed under local analgesia and intravenous sedation. Both uterine arteries are selectively catheterised under fluoroscopic control. Microparticles suspended in contrast medium are used to embolise the uterine vascular bed. Ischaemic pain during the first day is treated with intravenous morphine. Patients treated with embolisation can expect excellent results with respect to menorrhagia, pelvic pain, and reduction in the fibroid tumour volume. Women undergoing uterine embolisation retain their potential for future pregnancies. The procedure is well tolerated by patients, and possesses the advantages of shorter hospitalisation and recovery time, as compared to hysterectomy.

Beneficial effect of glycoprotein IIb/IIIa inhibitor (AZ-1) on endothelium in Escherichia coli endotoxin-induced shock

OBJECTIVE

To investigate the effects of AZ-1, a murine monoclonal antiglycoprotein-IIb/IIIa antibody, on endothelium and on hemostasis in a rabbit endotoxic shock model.

DESIGN

Prospective laboratory study.

SETTING

University laboratory.

SUBJECTS

Thirty-five male New-Zealand rabbits.

INTERVENTIONS

In vitro vascular reactivity, endothelium CD31-PECAM1 immunohistochemistry, plasma coagulation factors, and monocyte tissue factor determination were performed 1 day and/or 5 days after onset of endotoxic shock (0.5 mg/kg, intravenous bolus,Escherichia coli lipopolysaccharide) with or without treatment by AZ-1 (0.5 mg/kg intravenously) given 1 hr after lipopolysaccharide injection.

MEASUREMENTS AND MAIN RESULTS

Metabolic acidosis and coagulation activation confirmed the presence of shock. AZ-1 treatment improved endothelial-dependent relaxation at 1 day (maximal effect = 87.2 +/- 4.0% vs. 60.9 +/- 5.2% in the nontreated group, p <.05) and at 5 days (maximal effect = 84.5 +/- 3.5% vs. 56.6 +/- 8.2% in the nontreated group, p <.05). Endotoxin-induced endothelial injury was decreased significantly by AZ-1 at 1 day (6.4 +/- 1.9% vs. 10.3 +/- 0.8% in the nontreated group, p <.05) and at 5 days (6.3 +/- 2.0% vs. 20.2 +/- 1.2% in the nontreated group, p <.05). Monocyte tissue factor expression was significantly reduced at 5 days.

CONCLUSIONS

These data indicate that potent inhibition of platelet function via antiglycoprotein-IIb/IIIa receptor blockade can inhibit coagulation activation and protect against endothelial dysfunction and histologic injury in endotoxin-induced shock.

Uterine artery embolization of symptomatic uterine fibroida . Initial success and short-term results

PURPOSE

To evaluate reduction in fibroid volume, the effect on clinical symptoms, adverse events and complications after percutaneous uterine artery embolization (UAE) as primary invasive treatment for symptomatic uterine fibroids.

MATERIAL AND METHODS

Sixty-two patients entered the study. Indications for treatment were fibroid-induced menorrhagia, bulk symptoms, pain, and/or large fibroid size. The first 50 patients were evaluated by clinical examination and ultrasonography with measurement of fibroid volume before treament and 1, 6 and 12 months after UAE. The remaining 12 patients were followed 3 and 12 months after treatment. Embolization with microparticles was performed percutaneously in local analgesia by selective catheterization of both uterine arteries.

RESULTS

A primary technical success with bilateral UAE was achieved in 60/62 (97%) of the patients. They were treated for postprocedural pain lasting up to 24 h. In 30 of the 62 patients with 6 months follow-up, the mean fibroid volume was reduced 68% 6 months after treatment. Twenty-nine (96%) of the patients experienced reduced bleeding, 21 (70%) reduced pain, and 18 (61%) reduced bulk symptoms at follow-up.

CONCLUSION

UAE is a method with a high technical success rate. The treatment has good effect on fibroid volume reduction and clinical symptoms. Severe post-procedural pain occurs generally in successful bilateral embolizations, but complications and adverse events are otherwise few and minor. UAE represents a promising new method for treating uterine fibroid-related symptoms.

Fibroids treated by uterine artery embolization. A review

An increasing number of reports indicate that uterine fibroids can be successfully treated with uterine artery embolization (UAE). UAE seems to be a promising treatment for women who want to retain their uterus. This review summarizes the technical considerations and the results. UAE is a radiological procedure using angiography for visualization of the blood circulation. Subsequently, the flow through the uterine arteries is blocked resulting in infarction of fibroids. Success rates of 87% have been achieved with an average 57% reduction of fibroid volume. Complications have been few compared to hysterectomy and patient satisfaction is high. However, none of the reports include controls. Further studies are needed to optimize patient selection and to evaluate long-term results.

Effect of L-arginine on endothelial injury and hemostasis in rabbit endotoxin shock

To investigate whether impaired endothelial function was related to alteration of nitric oxide (NO) formation during endotoxic shock, we studied the effects of supplementation of L-arginine (L-Arg), D-arginine (D-Arg), and N(G)-nitro-L-arginine methyl ester (L-NAME), on endothelial function and structure in a rabbit model. Endotoxic shock was induced by a single lipopolysaccharide bolus (0.5 mg/kg i.v., Escherichia coli endotoxin). Coagulation factors and expression of monocyte tissue factor were determined by functional assays. Endothelium-dependent vascular relaxation was assessed by in vitro vascular reactivity. Immunohistochemical staining (CD31) was performed to assess damaged endothelial cell surface of the abdominal aorta. These parameters were studied 5 days after the onset of endotoxic shock and were compared under three conditions: in absence of treatment, with L-Arg or D-Arg supplementation, or with L-NAME. Both L-Arg and D-Arg significantly improved endothelium-dependent relaxation and endothelial morphological injury. L-NAME did not alter endothelial histological injury induced by lipopolysaccharide. These data indicate that arginine supplementation nonspecifically prevents endothelial dysfunction and histological injury in rabbit endotoxic shock. Moreover, L-Arg has no effect on coagulation activation and expression of monocyte tissue factor induced by endotoxic shock.

Assessment of tissue oxygenation in the critically-ill

It is hypothesized that tissue dysoxia and O2 debt are major factors in the development and the propagation of multiple organ failure in critically ill patients. Dysoxia is the result of an abnormal relationship between O2 supply (DO2) and O2 demand and translates into increased anaerobic metabolism and tissue and blood lactate concentration. First-line therapeutic strategies used to avoid the development of an O2 debt involve correction of cardiac output, haemoglobin, and O2 saturation in order to increase DO2 above its critical value. They are not sufficient, however, to ensure appropriate end-organ perfusion and oxygenation. The adequacy of cardiac output towards tissue metabolic requirements may be appreciated by venous-to-arterial and gut mucosal-to-arterial PCO2 differences. This review details these strategies and discusses their usefulness in current practice.

Photometry and spectroscopy of the GRB 970508 optical counterpart

An optical transient within the error box of the gamma ray burst GRB 970508 was imaged 4 hours after the event. It displayed a strong ultraviolet excess, and reached maximum brightness 2 days later. The optical spectra did not show any emission lines, and no variations on time scales of minutes were observed for 1 hour during the decline phase. According to the fireball and afterglow models, the intensity should rise monotonically before the observed optical maximum, but the data indicate that another physical mechanism may be responsible for the constant phase seen during the first hours after the burst.

pH heterogeneity in skeletal muscle extracellular fluid

Oxygen and carbon dioxide are known to be heterogeneously distributed in tissues. Extracellular skeletal muscle tissue pH (pHt) also exhibits a spatial variability in vitro, but this has not been examined in vivo. pHt distributions in resting skeletal muscle and the effect of the dispersion of pHt on ischemia and normoxic hypercarbia was therefore studied in an animal model with a multichannel pH microelectrode. Under resting conditions and spontaneous breathing, local pHt (from all animals, n = 10) was found to vary between 6.96 and 7.68 (range), and 70% of the values were within a pH of 7.00-7.32. In each animal the maximum pHt differences (maximum range between the 6 channels of the microelectrode) found were 0.32 +/- 0.11 pH units (mean +/- SD). During tissue acidosis, induced by ischemia, no significant change in the local pHt differences in each animal was seen. During normoxic hypercarbia a 2-fold increase in pHt variability within each animal was noticed (p < 0.01), which suggests that carbon dioxide and buffering effects of the blood are significant factors for the pHt distribution. The pHt distribution range found is of similar magnitude as previously described in in vitro studies on skeletal muscle. Locally varying pHt levels may be of importance as they will affect cellular H+ extrusion, membrane potential and volume control of different cell populations differently.

Autonomic modulation of heart rate variability during endotoxin shock in rabbits

OBJECTIVE

Gram-negative septic shock is associated with severe hypotension and autonomic cardiovascular dysfunction. We hypothesized that in an anesthetized rabbit model of endotoxin shock, autonomic modulation of cardiac activity, as measured by power spectral analysis of heart rate (HR) variability, would be decreased compared with the anesthetized control rabbits.

DESIGN

Experimental, comparative study.

SETTING

Laboratory of a university hospital.

SUBJECTS

Fourteen adult male New Zealand white rabbits (2.7 to 3.1 kg body weight) were studied under anesthesia.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We studied the absolute and temporal changes in HR power spectra and plasma catecholamine concentrations in eight experimental and six control New Zealand white rabbits during Escherichia coli endotoxin-induced shock. HR, respirations, arterial blood pressure (BP), HR power spectra, and plasma catecholamine concentrations were measured at 5- to 10-min intervals for 60 mins in control rabbits or until the mean arterial pressure (MAP) decreased by > or = 20 mm Hg in experimental rabbits. There were no differences in basal HR, respiratory rate, BP, HR power spectra, or catecholamine concentrations between groups. After endotoxin administration, MAP decreased (82 +/- 7 vs. 62 +/- 5 mm Hg; p < .05) as did log low-frequency HR power (-2.14 +/- 2.46 vs. -2.20 +/- 2.48 beats/min2; p < .05). Low-frequency HR power and MAP remained unchanged in control animals. Log high-frequency HR power decreased in control and experimental rabbits (-1.02 +/- 1.34 vs. -1.69 +/- 2.12 [control], p < .05; -1.53 +/- 2.19 vs. -2.19 +/- 2.85 beats/min2 [experimental], p < .05). While there was an inverse relationship between low- and high-frequency HR power and MAP, the direction of change was opposite in six of six rabbits in the control group and in six of eight rabbits in the experimental group. Plasma catecholamine concentrations did not change during the experiment in either group.

CONCLUSIONS

Sympathetic modulation of cardiac activity decreased, while the sympathomedullary response remained unchanged during endotoxin shock. We speculate that a concomitant decrease in low-frequency HR power as MAP decreases may prove to be an early marker for impending shock.