Functional mapping of the pelvic floor and sphincter muscles from high-density surface EMG recordings

Introduction and hypothesis

Knowledge of the innervation of pelvic floor and sphincter muscles is of great importance to understanding the pathophysiology of female pelvic floor dysfunctions. This report presents our high-density intravaginal and intrarectal electromyography (EMG) probes and a comprehensive innervation zone (IZ) imaging technique based on high-density EMG readings to characterize the IZ distribution.

Methods

Both intravaginal and intrarectal probes are covered with a high-density surface electromyography electrode grid (8?×?8). Surface EMG signals were acquired in ten healthy women performing maximum voluntary contractions of their pelvic floor. EMG decomposition was performed to separate motor-unit action potentials (MUAPs) and then localize their IZs.

Results

High-density surface EMG signals were successfully acquired over the vaginal and rectal surfaces. The propagation patterns of muscle activity were clearly visualized for multiple muscle groups of the pelvic floor and anal sphincter. During each contraction, up to 218 and 456 repetitions of motor units were detected by the vaginal and rectal probes, respectively. MUAPs were separated with their IZs identified at various orientations and depths.

Conclusions

The proposed probes are capable of providing a comprehensive mapping of IZs of the pelvic floor and sphincter muscles. They can be employed as diagnostic and preventative tools in clinical practices.

     

1,25‐Dihydroxyvitamin D Alone Improves Skeletal Growth,Microarchitecture, and Strength in a Murine Model of XLH,Despite Enhanced FGF23 Expression

X‐linked hypophosphatemia (XLH) is characterized by impaired renal tubular reabsorption of phosphate owing to increased circulating FGF23 levels, resulting in rickets in growing children and impaired bone mineralization. Increased FGF23 decreases renal brush border membrane sodium‐dependent phosphate transporter IIa (Npt2a) causing renal phosphate wasting, impairs 1‐α hydroxylation of 25‐hydroxyvitamin D, and induces the vitamin D 24‐hydroxylase, leading to inappropriately low circulating levels of 1,25‐dihydroxyvitamin D (1,25D). The goal of therapy is prevention of rickets and improvement of growth in children by phosphate and 1,25D supplementation. However, this therapy is often complicated by hypercalcemia and nephrocalcinosis and does not always prevent hyperparathyroidism. To determine if 1,25D or blocking FGF23 action can improve the skeletal phenotype without phosphate supplementation, mice with XLH (Hyp) were treated with daily 1,25D repletion, FGF23 antibodies (FGF23Ab), or biweekly high‐dose 1,25D from d2 to d75 without supplemental phosphate. All treatments maintained normocalcemia, increased serum phosphate, and normalized parathyroid hormone levels. They also prevented the loss of Npt2a, α‐Klotho, and pERK1/2 immunoreactivity observed in the kidneys of untreated Hyp mice. Daily treatment with 1,25D decreased urine phosphate losses despite a marked increase in bone FGF23 mRNA and in circulating FGF23 levels. Daily 1,25D was more effective than other treatments in normalizing the growth plate and metaphyseal organization. In addition to being the only therapy that normalized lumbar vertebral height and body weight, daily 1,25D therapy normalized bone geometry and was more effective than FGF23Ab in improving trabecular bone structure. Daily 1,25D and FGF23Ab improved cortical microarchitecture and whole‐bone biomechanical properties more so than biweekly 1,25D. Thus, monotherapy with 1,25D improves growth, skeletal microarchitecture, and bone strength in the absence of phosphate supplementation despite enhancing FGF23 expression, demonstrating that 1,25D has direct beneficial effects on the skeleton in XLH, independent of its role in phosphate homeostasis. © 2016 American Society for Bone and Mineral Research.     

Opportunistic Quantitative CT Bone Mineral Density Measurement at the Proximal Femur Using Routine Contrast‐Enhanced Scans: Direct Comparison With DXA in 355 Adults

For patients undergoing routine contrast‐enhanced CT examinations, an opportunity exists for concurrent osteoporosis screening without additional radiation exposure or patient time using proximal femur CT X‐ray absorptiometry (CTXA). We investigated the effect of i.v. contrast enhancement on femoral neck CTXA T‐score measurement compared with DXA. This cohort included 355 adults (277 female; mean age, 59.7 ± 13.3 years; range, 21 to 90 years) who underwent standard contrast‐enhanced CT assessment at 120 kV_p over an 8‐year interval, as well as DXA BMD assessment within 100 days of the CT study (mean 46 ± 30 days). Linear regression and a Bland‐Altman plot were performed to compare DXA and CTXA results. CTXA diagnostic sensitivity and specificity was evaluated with DXA as the reference standard. There was good correlation between DXA and CTXA (r² = 0.824 for both areal BMD and T‐scores) and the SD of the distribution of residuals was 0.063 g/cm² or 0.45 T‐score units. There was no trend in differences between the two measurements and a small bias was noted with DXA T‐score +0.18 units higher than CTXA. CTXA had a sensitivity for discriminating normal from low bone mineral density of 94.9% (95% CI, 90.6% to 97.4%). For opportunistic osteoporosis screening at routine post‐contrast abdominopelvic CT scans, CTXA produces T‐scores similar to DXA. Because femoral neck CTXA BMD measurement is now included in the WHO Fracture Risk Assessment Tool (FRAX) tool, this opportunistic method could help to increase osteoporosis screening because it can be applied regardless of the clinical indication for CT scanning. © 2016 American Society for Bone and Mineral Research.     

Validity of birth certificate‐derived maternal weight data in twin pregnancies

Birth certificates are an important source of pre‐pregnancy body mass index (BMI) and gestational weight gain (GWG) data for surveillance and aetiologic studies, but little is known about their validity in twin pregnancies. Twins experience high rates of adverse perinatal outcomes that have been associated with BMI and GWG in singletons. Our objective was to evaluate the accuracy of birth certificate‐derived pre‐pregnancy BMI and GWG compared with medical record‐derived data in a sample of 186 twin pregnancies at a teaching hospital in Pennsylvania (2003–2010). Twelve strata were created by simultaneous stratification on pre‐pregnancy BMI (underweight, normal weight/overweight, obese class 1, obese classes 2 and 3) and GWG (<20th, 20–80th, >80th percentile). The agreement of birth certificate‐derived pre‐pregnancy BMI category with medical record BMI category was lowest among underweight mothers [75% (95% confidence interval 51–91%) ] and highest among normal/overweight [97% (90–99%) ] and obese classes 2 and 3 mothers [97% (85–99%) ]. Agreement for GWG category from the birth certificate varied from 57% (41–70%) for GWG >80th percentile to 80% (65–91%) and 82% (72–89%) for GWG <20th and 20th–80th percentiles, respectively. The misclassification of BMI and GWG was primarily due to error in pre‐pregnancy weight rather than weight at delivery or height. Agreement proportions for twins were not meaningfully different from the proportions in a comparable sample of singleton pregnancies. These data suggest that birth certificate‐based BMI and GWG data are prone to error in twin pregnancies. Those who use these data should conduct internal validation studies and adjust their results using bias analyses.     

Opioid-Induced Androgen Deficiency (OPIAD): Diagnosis,Management, and Literature Review

Opioid-induced androgen deficiency (OPIAD) was initially recognized as a possible consequence of opioid use roughly four decades ago. Long-acting opioid use carries risks of addiction, tolerance, and systemic side effects including hypogonadotropic hypogonadism with consequent testosterone depletion leading to multiple central and peripheral effects. Hypogonadism is induced through direct inhibitory action of opioids on receptors within the hypothalamic-pituitary-gonadal (HPG) and hypothalamic-pituitary-adrenal (HPA) axes as well as testosterone production within the testes. Few studies have systematically investigated hormonal changes induced by long-term opioid administration or the effects of testosterone replacement therapy (TRT) in patients with OPIAD. Clomiphene citrate, a selective estrogen receptor modulator (SERM), is a testosterone enhancement treatment which upregulates endogenous hypothalamic function. This review will focus on the pathophysiology, diagnosis, and management of OPIAD, including summary of literature evaluating OPIAD treatment with TRT, and areas of future investigation.