The effect of pulse width and contact configuration on paresthesia coverage in spinal cord stimulation.

BACKGROUND: In spinal cord stimulation for the management of chronic, intractable pain, a satisfactory analgesic effect can be obtained only when the stimulation-induced paresthesias cover all painful body areas completely or partially. OBJECTIVE: To investigate the effect of stimulus pulse width (PW) and contact configuration (CC) on the area of paresthesia (PA), perception threshold (VPT), discomfort threshold (VDT), and usage range (UR) in spinal cord stimulation. METHODS: Chronic pain patients were tested during a follow-up visit. They were stimulated monopolarly and with the CC giving each patient the best analgesia. VPT, VDT, and UR were determined for PWs of 90, 210, and 450 microseconds. The paresthesia contours at VDT were drawn on a body map and digitized; PA was calculated; and its anatomic composition was described. The effects of PW and CC on PA, VPT, VDT, and UR were tested statistically. RESULTS: Twenty-four of 31 tests with low thoracic stimulation and 8 of 9 tests with cervical stimulation gave a significant extension of PA at increasing PW. In 14 of 18 tests (low thoracic), a caudal extension was obtained (primarily in L5-S2). In cervical stimulation the extension was predominantly caudal as well. In contrast to VPT and VDT, UR is not significantly different when stimulating with any CC. CONCLUSION: PA extends caudally with increasing PW. The mechanism includes that the larger and smaller dorsal column fibers have a different mediolateral distribution and that smaller dorsal column fibers have a smaller UR and can be activated only when PW is sufficiently large. A similar effect of CC on PA is unlikely as long as electrodes with a large intercontact distance are applied.

Risk of spontaneous abortion in singleton and twin pregnancies after IVF/ICSI.

BACKGROUND: The risk of spontaneous first trimester abortion is estimated to be between 10 and 20%. Although it is common knowledge that the incidence of abortion decreases as pregnancy progresses, exact data in relation to the duration of pregnancy are scarce. METHODS: We reviewed 1597 clinical IVF/ICSI pregnancies with known outcome and tabulated the number of miscarriages or fetal demise per intervals of 2 weeks. We furthermore compared the outcome in terms of fetal survival of 1200 singleton pregnancies with that of 397 twin pregnancies. RESULTS: The overall incidence of non-ongoing singleton pregnancies was 21.7%. Fetal death, after positive heart activity had been recorded, occurred in 12.2% of singleton pregnancies. The overall incidence of spontaneous abortion in twin pregnancies was 17.1% (12.1% vanishing twins and 5.0% complete miscarriages). The incidence of miscarriage in the twin pregnancies, expressed per gestational sac, was 11.1%. Once fetal heart activity was present, the risk of abortion (per gestational sac) was 7.3%, which is significantly lower than that in singleton pregnancies. CONCLUSIONS: Our data give an estimate of the probability of miscarriage or fetal demise at any given period of the first trimester both for singleton and twin pregnancies. Twin pregnancies after IVF have a better potential for survival than singleton pregnancies.

Poor response after hormonal stimulation for in vitro fertilization is not related to ovarian aging.

OBJECTIVE: To investigate whether the diminished efficacy of ART in young poor responders compared to young normal responders is due to a quantitative or a qualitative oocyte factor. DESIGN: Retrospective comparative analysis. SETTING: University-based infertility center. PATIENT(S): Nine thousand six hundred forty-four patients who underwent ART procedures at our hospital from 1993 until 2001. INTERVENTION(S): Controlled ovarian hyperstimulation, ultrasonographic monitoring of the ovarian response, oocyte retrieval, ART procedure, embryo transfer, and follow-up of pregnant patients until 12 weeks of amenorrhea. MAIN OUTCOME MEASURES: Clinical rates of pregnancy and miscarriage. RESULT(S): Nine thousand six hundred forty-four ART cycles were analyzed. The pregnancy rate for poor responders was significantly lower than for normal responders (17% vs. 35%). In cycles in which two good-quality embryos were transferred, the pregnancy rate was similar in poor responders and normal responders (33% vs. 42%). The rate of miscarriage was no higher in poor responders than normal responders. CONCLUSION(S): Young poor responders have a lower pregnancy rate than young normal responders because they have fewer oocytes, which leads to fewer good-quality embryos to choose from for transfer. The quality of their oocytes and embryos is not inferior to that of normal responders.

Effects of electrical stimulation or lesion in nucleus accumbens on the behaviour of rats in a T-maze after administration of 8-OH-DPAT or vehicle.

Electrical brain stimulation may be a therapeutic alternative for irreversible lesions in treatment-resistant patients with obsessive-compulsive disorder (OCD). We compared the effects of electrical stimulation and lesion in the nucleus accumbens (n acc) on the behaviour of rats in a model for OCD. Rats were tested for spontaneous alternation behaviour (AB) in a T-maze and assigned to four groups: an electrode implant group with stimulation 'ON' (stimON) or 'OFF' (stimOFF), a lesion or a sham group. Postoperatively, the number of arm visits and AB were tested after 8-hydroxy-2-(di-n-propylamino)-tetralin hydrobromide (8-OH-DPAT; 2 mg/kg) or saline administration. After 8-OH-DPAT administration, more arm visits were counted in the stimON (92.2%) and lesion groups (79.3%) than in both control groups (stimOFF 54.2; sham 61.2%). AB was significantly decreased in the stimON (10.5%) and lesion groups (10.2%) relative to the sham (22.0%) but not to the stimOFF group (14.7%). After saline administration, rats performed more arm visits in the stimON (81.5% non-significant) and lesion groups (93.6% significant) relative to the stimOFF (70.8%) and the sham groups (74.5%). No significant differences, however, were observed for AB. In conclusion, both treatments resulted in a decreased AB after 8-OH-DPAT administration (modelling an increase in compulsions) and more arm visits.

FOXL2 and BPES: mutational hotspots, phenotypic variability, and revision of the genotype-phenotype correlation.

Blepharophimosis syndrome (BPES), an autosomal dominant syndrome in which an eyelid malformation is associated (type I) or not (type II) with premature ovarian failure (POF), has recently been ascribed to mutations in FOXL2, a putative forkhead transcription factor gene. We previously reported 22 FOXL2 mutations and suggested a preliminary genotype-phenotype correlation. Here, we describe 21 new FOXL2 mutations (16 novel ones) through sequencing of open reading frame, 5' untranslated region, putative core promoter, and fluorescence in situ hybridization analysis. Our study shows the existence of two mutational hotspots: 30% of FOXL2 mutations lead to polyalanine (poly-Ala) expansions, and 13% are a novel out-of-frame duplication. In addition, this is the first study to demonstrate intra- and interfamilial phenotypic variability (both BPES types caused by the same mutation). Furthermore, the present study allows a revision of the current genotype-phenotype correlation, since we found exceptions to it. We assume that for predicted proteins with a truncation before the poly-Ala tract, the risk for development of POF is high. For mutations leading to a truncated or extended protein containing an intact forkhead and poly-Ala tract, no predictions are possible, since some of these mutations lead to both types of BPES, even within the same family. Poly-Ala expansions may lead to BPES type II. For missense mutations, no correlations can be made yet. Microdeletions are associated with mental retardation. We conclude that molecular testing may be carefully used as a predictor for POF risk in a limited number of mutations.

A health-economic decision-analytic model comparing double with single embryo transfer in IVF/ICSI.

BACKGROUND: Single embryo transfer (SET) is the sole strategy with which to reduce the incidence of twins following assisted reproductive technology (ART), but SET may increase the number of ART cycles needed per live-born child. Its cost-effectiveness compared with double embryo transfer (DET) is therefore unknown. METHODS: A decision-analytic model comparing SET with DET was developed. Estimates were obtained from literature, national pregnancy registers and local hospital records. A sensitivity analysis was performed, using pregnancy rates from four published studies. The outcome measure was the cost per child born, calculated from IVF procedure-related, pregnancy-related and neonatal care costs. Neonatal mortality and long-term morbidity costs were not taken into account. RESULTS: Independently of the pregnancy rates used, the SET cost per child born was in all instances the same as with DET, varying from EURO= 9520 (SET) versus EURO= 9511 (DET) to EURO= 12254 (SET) versus EURO= 12934 (DET). CONCLUSIONS: More ART cycles are required to obtain the same numbers of children born following SET compared with DET. Because SET allows the avoidance of twins and thus diminishes pregnancy-related and neonatal care costs, there is no difference in the cost per child born between SET and DET. The real advantage of SET is the avoidance of the very high long-term costs resulting from the increased morbidity of twins after birth.

Adjuvant-induced arthritis in rats: a possible animal model of chronic pain.

Adjuvant-induced arthritic rats were observed clinically and behaviorally. The clinical disease has a duration of greater than 1 month and can be divided into a pre-clinical (1-10 days), an acute (15-30 days), postacute (30-50 days) and a late phase (greater than 50 days). Adjuvant arthritis induces significantly quantitatively changes in the rats' behaviour. Two types of behavioural change merit special attention: freezing (arresting) and scratching. Freezing is significantly increased in the acute and postacute phases; it is increased by morphine, this effect being blocked by naloxone. Scratching is significantly increased in the acute, postacute and late phases; it is decreased by morphine, this effect being blocked by naloxone. The chronic presence of scratching, and the effects of morphine and naloxone on it, allow us to consider it as a possible pain-rated behaviour and therefore as a possible parameter for the study of chronic pain in animals.