High-field (3T) magnetic resonance defecography with functional assessment of the evacuation phase : a pictorial essay : P10

Purpose: Dynamic high-field magnetic resonance (MR) defecography including the evacuation phase is a promising tool for the assessment of functional pelvic disorders, nowadays seen with increasing frequency in elderly women in particular. Learning objectives: 1. To describe the adequate technique of dynamic high-field MRI (3T) in assessing pelvic floor disorders. 2. To provide an overview of the most common pathologies occurring during the evacuation phase, especially in comparison with results of conventional defecography. Methods and materials: After description of the ideal technical parameters of MR defecography performed in supine position after gel rectal filling with a 3 Tesla unit and including the evacuation phase we stress the importance of using a standardized evaluation system for the exact assessment of pelvic floor pathophysiology. Results: The typical pelvic floor disorders occurring before and/or during the evacuation phase, such as sphincter insufficiency, vaginal vault and/or uterine prolapse, cystourethrocele, peritoneo-/ entero-/ sigmoïdocele or rectal prolapse, are demonstrated. The difference between the terms "pelvic floor descent" and "pelvic floor relaxation" are pictorially outlined. MR results are compared with these of conventional defecography. Conclusion: Exact knowledge about the correct technique including the evacuation phase and the use of a standardized evaluation system in assessing pelvic floor disorders by dynamic high-field MRI is mandatory for accurate and reproducible diagnosis.

Effects of a dual inhibitor of angiotensin converting enzyme and neutral endopeptidase, MDL 100,240, on endocrine and renal functions in healthy volunteers.

OBJECTIVE: To investigate the endocrine and renal effects of the dual inhibitor of angiotensin converting enzyme and neutral endopeptidase, MDL 100,240. DESIGN: A randomized, placebo-controlled, crossover study was performed in 12 healthy volunteers. METHODS: MDL 100,240 was administered intravenously over 20 min at single doses of 6.25 and 25 mg in subjects with a sodium intake of 280 (n = 6) or 80 (n = 6) mmol/day. Measurements were taken of supine and standing blood pressure, plasma angiotensin converting enzyme activity, angiotensin II, atrial natriuretic peptide, urinary atrial natriuretic peptide and cyclic GMP excretion, effective renal plasma flow and the glomerular filtration rate as p-aminohippurate and inulin clearances, electrolytes and segmental tubular function by endogenous lithium clearance. RESULTS: Supine systolic blood pressure was consistently decreased by MDL 100,240, particularly after the high dose and during the low-salt intake. Diastolic blood pressure and heart rate did not change. Plasma angiotensin converting enzyme activity decreased rapidly and dose-dependently. In both the high- and the low-salt treatment groups, plasma angiotensin II levels fell and renin activity rose accordingly, while plasma atrial natriuretic peptide levels remained unchanged. In contrast, urinary atrial natriuretic peptide excretion increased dose-dependently under both diets, as did urinary cyclic GMP excretion. Effective renal plasma flow and the glomerular filtration rate did not change. The urinary flow rate increased markedly during the first 2 h following administration of either dose of MDL 100,240 (P < 0.001) and, similarly, sodium excretion tended to increase from 0 to 4 h after the dose (P = 0.07). Potassium excretion remained stable. Proximal and distal fractional sodium reabsorption were not significantly altered by the treatment. Uric acid excretion was increased. The safety and clinical tolerance of MDL 100,240 were good. CONCLUSIONS: The increased fall in blood pressure in normal volunteers together with the preservation of renal hemodynamics and the increased urinary volume, atrial natriuretic peptide and cyclic GMP excretion distinguish MDL 100,240 as a double-enzyme inhibitor from inhibitors of the angiotensin converting enzyme alone. The differences appear to be due, at least in part, to increased renal exposure to atrial natriuretic peptide following neutral endopeptidase blockade.

Major impact of body position on arterial stiffness indices derived from radial applanation tonometry in pregnant and nonpregnant women.

OBJECTIVE: To evaluate the impact of body position on the arterial stiffness indices provided by radial applanation tonometry in pregnant and nonpregnant women. METHODS: Twenty-four young women (18-30 years) in the third trimester of a normal pregnancy and 20 healthy nonpregnant women of the same age were enrolled. In each, applanation tonometry was carried out in the sitting and supine position. The following stiffness indices were analyzed: systolic augmentation index (sAix), sAix adjusted for heart rate (sAix@75) and diastolic augmentation index (dAix), all expressed in % of central aortic pulse pressure. RESULTS: The sAix was apparently not influenced by body position, but the transition from seated to supine was associated with a substantial decrease in heart rate. When correcting for this confounder by calculating the sAix@75, systolic augmentation was substantially lower when individuals were supine (mean ± SD: nonpregnant 3.0 ± 14.4%, pregnant 8.8 ± 9.7%) than when they were sitting (nonpregnant 5.7 ± 13.0%, pregnant 11.1 ± 83%, P = 0.005 supine vs. seated in both study groups, P > 0.2 for pregnant vs. nonpregnant). The influence of body position on the dAix went in the opposite direction (supine: nonpregnant 9.7 ± 6.6%, pregnant 4.4 ± 3.5%; seated: nonpregnant 7.7 ± 5.8%, pregnant 3.3 ± 2.4%, P < 0.00001 supine vs. seated in both study groups, P = 0.001 for pregnant vs. nonpregnant). CONCLUSION: Body position has a major impact on the pattern of central aortic pressure augmentation by reflected waves in healthy young women examined either during third trimester pregnancy or in the nonpregnant state.

Late outcome of spinal cord stimulation for unreconstructable and limb-threatening lower limb ischemia.

OBJECTIVES: To determine whether the initial benefits of spinal cord stimulation (SCS) treatment for critical limb ischemia (CLI) persist over years. DESIGN: Analysis of data prospectively collected for every CLI patient receiving permanent SCS. Follow-up range 12 to 98 months (mean 46+/-23, median 50 months). POPULATION: 87 patients (28% stage III, 72%stage IV) with unreconstructable CLI due (83%) or not (17%) to atherosclerosis and with an initial sitting/supine transcutaneous pO2 gradient >15 mmHg. METHODS: Assessment of actuarial patient survival (PS), limb salvage (LS) and amputation-free patient survival (AFPS). Analysis of the impact of 15 risk factors on long-term outcomes using the Fischer's exact test for categorical variables and the t test for continuous variables. RESULTS: Follow-up was complete for patient and limb survival. A single non-atherosclerotic patient died during follow-up. Among atherosclerotic patients PS decreased from 88% at 1y, to 76% at 3y, 64% at 5y and 57% at 7y. LS reached 84% at 1y, 78% at 2y, 75% at 3y and remained stable thereafter. Diabetes was found to affect LS (p<0.05) and heart disease to reduce PS (p<0.01). AFPS was reduced in heart patients (p<0.01), diabetics (p<0.05) and in patients with previous stroke (p<0.05). CONCLUSIONS: In CLI patients the beneficial effects of SCS persist far beyond the first year of treatment and major amputation becomes infrequent after the second year.

Superiority of prone position in free-breathing 3D coronary MRA in patients with coronary disease.

Navigator-gated and corrected 3D coronary MR angiography (MRA) allows submillimeter image acquisition during free breathing. However, cranial diaphragmatic drift and relative phase shifts of chest-wall motion are limiting factors for image quality and scanning duration. We hypothesized that image acquisition in the prone position would minimize artifacts related to chest-wall motion and suppress diaphragmatic drift. Twelve patients with radiographically-confirmed coronary artery disease and six healthy adult volunteers were studied in both the prone and the supine position during free-breathing navigator-gated and corrected 3D coronary MRA. Image quality and the diaphragmatic positions were objectively compared. In the prone position, there was a 36% improvement in signal-to-noise ratio (SNR; 15.5 +/- 2.7 vs. 11.4 +/- 2.6; P < 0.01) and a 34% improvement in CNR (12.5 +/- 3.3 vs. 9.3 +/- 2.5, P < 0.01). The prone position also resulted in a 17% improvement in coronary vessel definition (P < 0.01). Cranial end-expiratory diaphragmatic drift occurred less frequently in the prone position (23% +/- 17% vs. 40% +/- 26% supine; P <0.05), and navigator efficiency was higher. Prone coronary MRA results in improved SNR and CNR with enhanced coronary vessel definition. Cranial end-expiratory diaphragmatic drift also was reduced, and navigator efficiency was enhanced. When feasible, prone imaging is recommended for free-breathing coronary MRA.

Ultrasound-guided suprascapular nerve block, description of a novel supraclavicular approach.

BACKGROUND AND OBJECTIVES: The suprascapular nerve (SSN) block is frequently performed for different shoulder pain conditions and for perioperative and postoperative pain control after shoulder surgery. Blind and image-guided techniques have been described, all of which target the nerve within the supraspinous fossa or at the suprascapular notch. This classic target point is not always ideal when ultrasound (US) is used because it is located deep under the muscles, and hence the nerve is not always visible. Blocking the nerve in the supraclavicular region, where it passes underneath the omohyoid muscle, could be an attractive alternative. METHODS: In the first step, 60 volunteers were scanned with US, both in the supraclavicular and the classic target area. The visibility of the SSN in both regions was compared. In the second step, 20 needles were placed into or immediately next to the SSN in the supraclavicular region of 10 cadavers. The accuracy of needle placement was determined by injection of dye and following dissection. RESULTS: In the supraclavicular region of volunteers, the nerve was identified in 81% of examinations (95% confidence interval [CI], 74%-88%) and located at a median depth of 8 mm (interquartile range, 6-9 mm). Near the suprascapular notch (supraspinous fossa), the nerve was unambiguously identified in 36% of examinations (95% CI, 28%-44%) (P < 0.001) and located at a median depth of 35 mm (interquartile range, 31-38 mm; P < 0.001). In the cadaver investigation, the rate of correct needle placement of the supraclavicular approach was 95% (95% CI, 86%-100%). CONCLUSIONS: Visualization of the SSN with US is better in the supraclavicular region as compared with the supraspinous fossa. The anatomic dissections confirmed that our novel supraclavicular SSN block technique is accurate.

Estimation of time of death in relation to gastric contents

Introduction: Estimation of the time since death based on the gastric content is still a controversy subject. Many studies have been achieved leaving the same incertitude: the intra- and inter-individual variability. Aim: After a homicidal case where a specialized gastroenterologist was cited to estimate the time of death based on the gastric contents and his experience in clinical practice. Consequently we decided to make a review of the scientific literature to see if that method was more reliable nowadays. Material and methods: We chose articles from 1979 that describe the estimation of the gastric emptying rate according to several factors and the forensic articles about the estimation of the time of death in relation with the gastric content. Results: Most of the articles cited by the specialized gastroenterologist were studies about living healthy people and the effects of several factors (medication, supine versus upside-down position, body mass index or different type of food). Forensic articles frequently concluded that the estimation of the time since death by analyzing the gastric content can be used but not as the unique method. Conclusion: Estimation of the time since death by analyze of the gastric contents is a method that can be used nowadays. But it cannot be the only method as the inter- and intra-individual variability remains an important bias.

Effects of MDL 100,240, a dual inhibitor of angiotensin-converting enzyme and neutral endopeptidase on the vasopressor response to exogenous angiotensin I and angiotensin II challenges in healthy volunteers.

MDL 100,240, a dual inhibitor of angiotensin-converting enzyme (ACE) and neutral endopeptidase (NEP), was administered intravenously to two panels of four healthy males in a four-period, dose-increasing (0, 1.56, 6.25, and 25 mg, and 0, 3.13, 12.5, and 50 mg, respectively) double-blind, placebo-controlled study. Plasma ACE activity and blood-pressure response to exogenous angiotensin I and angiotensin II i.v. challenges and safety and tolerance were assessed over a 24-h period. MDL 100,240 induced a rapid, dose-related, and sustained inhibition of ACE (>70% over 24 h at doses > or =12.5 mg). The time integral of ACE inhibition was related to the dose but with near-maximal values already attained at doses > or =12.5 mg. Systolic and diastolic blood-pressure responses to exogenous angiotensin I challenges were inhibited in a dose-dependent fashion, whereas the effects of angiotensin II remained unaffected. Mean supine blood pressure decreased transiently (3 h) at doses > or =3.125 mg and < or =24 h with the 25- and 50-mg doses, but not significantly. MDL 100,240 was well tolerated. In healthy subjects, MDL 100,240 exerts a dose-dependent and long-lasting ACE-blocking activity, also expressed by the inhibition of the pressor responses to exogenous angiotensin I challenges. The baroreceptor reflex, assessed by the response to exogenous angiotensin II challenge, remains unaltered.

Neonatal adaptation of energy and protein metabolism

During the last decade, the development of "bedside" investigative methods, including indirect calorimetry, nutritional balance and stable isotope techniques, have given a new insight into energy and protein metabolism in the neonates. Neonates and premature infants especially, create an unusual opportunity to study the metabolic adaptation to extrauterine life because their physical environment can be controlled, their energy intake and energy expenditure can be measured and the link between their protein metabolism and the energetics of their postnatal growth can be assessed with accuracy. Thus, relatively abstract physiological concepts such as the postnatal timecourse of heat production, energy cost of growth, energy cost of physical activity, thermogenic effect of feeding, efficiency of protein gain, metabolic cost of protein gain and protein turnover have been quantified. These results show that energy expenditure and heat production rates increase postnatally from average values of 40 kcal/kgxday during the first week to 60 kcal/kgxday in the third week. This increase parellels nutritional intakes as well as the rate of weight gain. The thermogenic effect of feeding and the physical activity are relatively low and account only for an average of 5% each of the total heat production. The cost of protein turnover is the highest energy demanding process. The fact that nitrogen balance becomes positive within 72 hours after birth places the newborn in a transitional situation of dissociated balance between energy and protein metabolism: dry body mass and fat decrease while there is a gain in protein and increase in supine length. This particular situation ends during the second postnatal week and soon thereafter the rate of weight gain matches the statural growth. The goals of the following review are to summarize recent data on the physiological aspects of energy and protein metabolism directly related to the extrauterine adaptation, to describe experimental approaches which recently were adapted to the newborns in order to get "bedside results" and to discuss how far these results can help everyday's neonatal practice.

Pulse wave analysis of aortic pressure: diastole should also be considered.

BACKGROUND: : The systolic augmentation index (sAix), calculated from the central aortic pulse wave (reconstructed from the noninvasive recording of the radial pulse with applanation tonometry), is widely used as a simple index of central arterial stiffness, but has the disadvantage of also being influenced by the timing of the reflected with respect to the forward pressure wave, as shown by its inverse dependence on heart rate (HR). During diastole, the central aortic pulse also contains reflected waves, but their relationship to arterial stiffness and HR has not been studied. METHODS: : In 48 men and 45 women, all healthy, with ages ranging from 19 to 70 years, we measured pulse wave velocity (PWV, patients supine), a standard evaluator of arterial stiffness, and carried out radial applanation tonometry (patients sitting and supine). The impact of reflected waves on the diastolic part of the aortic pressure waveform was quantified in the form of a diastolic augmentation index (dAix). RESULTS: : Across ages, sexes, and body position, there was an inverse relationship between the sAix and the dAix. When PWV and HR were added as covariates to a prediction model including age, sex and body position as main factors, the sAix was directly related to PWV (P < 0.0001) and inversely to HR (P < 0.0001). With the same analysis, the dAix was inversely related to PWV (P < 0.0001) and independent of HR (P = 0.52). CONCLUSION: : The dAix has the same degree of linkage to arterial stiffness as the more conventional sAix, while being immune to the confounding effect of HR. The quantification of diastolic aortic pressure augmentation by reflected waves could be a useful adjunct to pulse wave analysis.

Circadian variations of renal sodium handling in patients with orthostatic hypotension.

BACKGROUND: Sodium wasting during the night has been postulated as a potential pathophysiological mechanism in patients suffering from orthostatic hypotension due to severe autonomic deficiency. METHODS: In this study, the diurnal variations in creatinine clearance, sodium excretion and segmental renal tubular handling of sodium were evaluated in 18 healthy subjects and 20 young patients with orthostatic hypotension (OH). In addition, 24-hour ambulatory blood pressure and the neuro-hormonal response to changes in posture were determined. The patients and their controls were studied on a free sodium intake. In a second protocol, 10 controls and 10 patients were similarly investigated after one week of a high salt diet (regular diet + 6 g NaCl/day). RESULTS: Our results demonstrate that, in contrast to normal subjects in whom no significant changes in glomerular filtration, sodium excretion and segmental sodium reabsorption were observed throughout the day, patients with OH were characterized by a significant increase in glomerular filtration rate during the nighttime (P = 0.03) and significant increases in urinary lithium excretion (P < 0.05) and lithium clearance (P = 0.05) during the night, suggesting a decreased proximal reabsorption of sodium. On a high sodium diet, the symptoms of orthostatic hypotension and the circadian variations in sodium reabsorption were significantly blunted. CONCLUSIONS: These results suggest that, while the patient is in a supine position the effective blood volume of those with OH becomes excessive due to the increased venous return. Hence, the kidney responds with an increase in glomerular filtration and a relative escape of sodium from the proximal tubular segments. These circadian variations in renal sodium handling may contribute to the maintenance of the orthostatic syndrome.

Effect of an I.V. bolus of phenylephrine or ephedrine on skin blood flow during spinal anesthesia

Effet d'un bolus intraveineux de phénylephrine ou d'éphedríne sur le flux sanguin cutané lors d'une anesthésie rachidienne Introduction : La phénylephrine et l'éphedrine sont des substances vaso-actives utilisées de routine pour corriger des épisodes d'hypotension artérielle induits par l'anesthésie intrarachidienne. L'influence de ces deux vasopresseurs sur le flux sanguin cutané (FSC) dans ce contexte n'a jusqu'à maintenant pas été décrite. Cette étude évalue l'effet d'une injection intraveineuse de 75 µg de phénylephrine ou de 7.5 mg d'éphedrine sur le FSC mesuré par Laser Doppler, dans les zones concernées parle bloc sympathiqué induit par l'anesthésie intrarachidienne (membres inférieurs) et dans les zones non concernées (membres supérieurs). Méthode :Après acceptation par le Comité d'Éthique, et obtention de leur accord écrit, 20 patients devant subir une intervention chirurgicale élective en décubitus dorsal sous anesthésie. intrarachidienne ont été inclus dans cette étude randomisée en double insu. Le FSC a été mesuré en continu par deux sondes fixées l'une à la cuisse (zone avec bloc sympathique) et l'autre sur l'avantbras (zone sans bloc sympathique). Les valeurs de FSC ont été enregistrées après l'anesthésie rachidienne (valeur contrôle), puis après l'injection i.v. dè phénylephrine (10 patients) ou d'éphedrine (10 patients) pour corriger une hypotension définie comme une chute de 20 mmHg de la pression artérielle systolique. Les variations de FSC exprimées en pourcentage de la valeur contrôle moyenne (+/- écart type) ont été analysées par le test t de Student. Résultats :Les données démographiques des patients et le niveau sensitif induit par l'anesthésie rachidienne sont similaires dans les deux groupes. Aux doses utilisées, seule l'éphedrine restaure la pression artérielle aux valeurs précédant l'anesthésie rachidienne. La phénylephrine augmente le FSC de l'avant-bras de 44% (+/- 79%) et de la cuisse de 34% (+/-24%), alors que l'éphedrine diminue le débit sanguin cutané de l'avant-bras de 16% (+/- 15%) et de la cuisse de 22% (+/-11%). Conclusion : L'injection intraveineuse de phénylephrine et d'éphedrine ont des effets opposés sur le flux sanguin cutané, et cette réponse n'est pas modifiée par le bloc sympathique.. Cette différence peut s'expliquer par la distribution des sous-types de récepteurs adrénergiques alpha et leur prédominance relative dans les veines et les artères de différents diamètres perfusant le tissu sous-cutané et la peau. L'éphedrine, èn raison de sa meilleure efficacité pour traiter les épisodes d'hypotension artérielle après anesthésie intrarachidienne devrait être préféré à la phénylephrine, leurs effets opposés sur le flux sanguin cutané n'étant pas pertinents en pratique clinique. SUMMARY Background: Phenylephrine or ephedrine is routinely used to correct hypotensive episodes fallowing spinal anaesthesia (SA). The influence of these two vasopressors on skin blood flow (SBF) has not yet been described. We have therefore evaluated the effects of an i.v. bolus of 75 µg phenylephrine or 7.5 mg of ephedrine on SBF measured by laser Doppler flowmetry during sympathetic blockade induced by SA. Methods: With Ethical Committee approval and written consent, 20 patients scheduled for elective procedures in supine position under SA were enrolled in this double-blind randomized study. SBF was measured continuously by two probes fixed at the thigh (area with sympathic blockade) and forearm level (area without sympathic blockade) respectively. SBF values were recorded after SA (control values) and then after a bolus administration of phenylephriné (n=10) or ephedrine (n=10) when systolic blood pressure decreased by 20 mmHg. Changes were expressed as percentage of control SBF values and analysed by Student's paired t-test. Results: Patient characteristics and dermatomal sensory levels were similar in both groups. Phenylephrine increases mean SBF at the forearm level by 44% (79%) [mean (SD)j and at the thigh by 34% (24%). Ephedrine decreases SBF at the forearm level by 16% (15%) and at the thigh by 22% (il%). Ephedrine bolus restores arterial blood pressure to pre-anaesthesia values, whereas phenylephrine does not. Conclusion: Administratión of phenylephrine and ephedrine has opposite effects on skin blood flow and sympathetic blockade does not modify this response. These findings could be explained by the distribution of the alpha-adrenoréceptor subtypes and their relative predominance among veins and arteries of different size perfusing the subcutaneous tissue and the skin. Ephedrine, due to its better efficacy to correct hypotensive episodes following SA, should be preferred, to phenylephrine, their opposite effects on SBF being not relevant for clinical practice.

Efficacy of the barbecue manoeuvre in benign paroxysmal vertigo of the horizontal canal

Five to ten percent of benign paroxysmal positional vertigo are caused by the horizontal semi-circular variant (h-BPPV). In this study, we reviewed the efficacy of the Barbecue repositioning manoeuvre in h-BPPV, and we assessed the possible effect of different factors on the outcome. Barbecue manoeuvre consists in turning the supine patient around his longitudinal axis toward the unaffected side until 360 degrees are accomplished. After every 90 degrees step the patient is maintained in the new position for 30 s. We reviewed 46 patients with h-BPPV, treated by barbecue rotation from 2003 to 2005. After the first Barbecue manoeuvre, the patients were followed-up at intervals of approximately 1 week and the rotation was repeated if h-BPPV persisted (up to three rotations). Factors assessed were age, gender, duration of symptoms before treatment and type of h-BPPV (canalolithiasis vs. cupulolithiasis). Fisher's exact test was used for the analysis. Results: 85% of patients (39/46) were cured after a maximum of 3 rotations. 74% (34/46) were cured after the first manoeuvre and 80% (37/46) after the second one. None of the evaluated factors did significantly affect the efficacy (P > 0.05). The Barbecue manoeuvre is an efficient treatment of h-BPPV demonstrating 85% cure rate after a maximum of three sessions. 74% of the patients are healed after one manoeuvre. The efficacy is not affected by the evaluated factors.

Single Subject Finger Somatotopy Mapping at 7T.

Introduction: The primary somatosensory cortex (SI) contains Brodmann areas (BA) 1, 2, 3a, and 3b. Research in non-human primates showed that BAs 3b, 1, and 2 each contain one full representation of the hand with separate representations for each finger. This research also showed that the finger representation in BA3b has larger and clearer finger somatotopy than BA1 and 2. Although several efforts to map finger somatotopy in SI by fMRI have been made at 1.5 and 3T these studies have yielded variable results and were not able to detect single subject finger somatotopy, probably due to the limited spatial extent of the cortical areas representing a digit (close to the resolution in most fMRI experiments), complications due to acquisition of consistent maps for individual subjects (Schweizer et al 2008), or inter-individual variability in sulcal anatomy impeding group studies. Here, we used 7T fMRI to investigate finger somatotopy in SI, some of its functional characteristics, and its reproducibility. Methods: Eight right-handed male subjects were scanned on a 7T scanner (Siemens Medical, Germany) with an 8-channel Tx/Rx rf-coil (Rapid Biomedical, Germany). 1.3x1.3x1.3mm3 resolution fMRI data were acquired using a sinusoidal readout EPI sequence (Speck et al, 2008) and FOV=210mm, TE/TR=27ms/2.5s, GRAPPA=2. Each volume contained 28 transverse slices covering SI. A single EPI volume with 64 slices was acquired to aid coregistration. 1x1x1mm3 anatomical data were acquire using the MP2RAGE sequence (Marques et al, 2009; TE/TR/TI1,2/TRmprage=2.63ms/7.2ms/0.9,3.2s/5s). Subjects were positioned supine in the scanner with their right arm comfortably against the magnet bore. An experimenter was positioned at the entrance of the bore where he could easily reach and stroke successively the two distal phalanxes of each digit. The order of stroked digit was D1 (thumb)-D3-D5-D2-D4, with 20s ON, 10s OFF alternated. This sequence was repeated four times per run and two functional runs were acquired per subject. Realignment, smoothing (FWHM 2 mm), coregistration of the anatomical to the fMRI data and calculation of t-statistics were done using SPM8. An SI mask was obtained via an F-contrast (p<0.001) over all digits. Within the mask, voxels were labeled with the number of the digit demonstrating the highest t-value for that particular voxel. Results: For all subjects, areas corresponding to the five digits were identified in contralateral SI. BA3b showed the most consistent somatotopic finger representation (see an example in Fig.1). The five digits were localized in a consecutive order in the cortex, with D1 most anterior, inferior and distal and D5, most posterior, superior and medial (mean distance between centres of mass of digit representations ±stderr: 4.2±0.7mm; see Fig. 2). The analysis of average beta values within each finger representation region revealed the specificity of the somatotopic region to the tactile input for each tested finger (except digit 4 and 5). Five of these subjects also presented an orderly and consecutive representation of the five digits in BA1 and 2. Conclusions: Our data reveal that the increased BOLD sensitivity at 7T and the high spatial resolution used in this study allow consistent somatotopic mapping using human touch as a stimulus and that human SI contains at least three separate regions that contain five separate representations of all single contralateral fingers. Moreover, adjacent fingers were represented at adjacent cortical regions across the three SI regions. The spatial organization of SI as reflected in individual subject topography corresponds well with previous electrophysiological data in non-human primates. The small distance between digit representations highlights the need for the high spatial resolution available at 7T.

Positional therapy for obstructive sleep apnea: an objective measurement of patients' usage and efficacy at home.

BACKGROUND: Positional therapy that prevents patients from sleeping supine has been used for many years to manage positional obstructive sleep apnea (OSA). However, patients' usage at home and the long term efficacy of this therapy have never been objectively assessed.¦METHODS: Sixteen patients with positional OSA who refused or could not tolerate continuous positive airway pressure (CPAP) were enrolled after a test night study (T0) to test the efficacy of the positional therapy device. The patients who had a successful test night were instructed to use the device every night for three months. Nightly usage was monitored by an actigraphic recorder placed inside the positional device. A follow-up night study (T3) was performed after three months of positional therapy.¦RESULTS: Patients used the device on average 73.7 ± 29.3% (mean ± SD) of the nights for 8.0 ± 2.0 h/night. 10/16 patients used the device more than 80% of the nights. Compared to the baseline (diagnostic) night, mean apnea-hypopnea index (AHI) decreased from 26.7 ± 17.5 to 6.0 ± 3.4 with the positional device (p<0.0001) during T0 night. Oxygen desaturation (3%) index also fell from 18.4 ± 11.1 to 7.1 ± 5.7 (p = 0.001). Time spent supine fell from 42.8 ± 26.2% to 5.8 ± 7.2% (p < 0.0001). At three months (T3), the benefits persisted with no difference in AHI (p = 0.58) or in time spent supine (p = 0.98) compared to T0 night. The Epworth sleepiness scale showed a significant decrease from 9.4 ± 4.5 to 6.6 ± 4.7 (p = 0.02) after three months.¦CONCLUSIONS: Selected patients with positional OSA can be effectively treated by a positional therapy with an objective compliance of 73.7% of the nights and a persistent efficacy after three months.