Taiwanese Clinical Experience with Noninvasive Prenatal Testing for DiGeorge Syndrome.

OBJECTIVE: DiGeorge syndrome (DGS) is associated with microdeletions of chromosome 22q11. It is the second most common cause of congenital heart disease and is an important consideration whenever a conotruncal cardiac anomaly is identified. The availability of noninvasive prenatal testing (NIPT) is altering the practice of prenatal genetics and maternal-fetal medicine, resulting in a decline in invasive testing. Antenatal ultrasound and other biomarkers have their own limitation. NIPT was proposed to screen DGS with cell-free DNA in Taiwan. Here, we present our experience of prenatal diagnosis of DGS in our center. METHODS: This was a retrospective study between November 1, 2019, and August 31, 2020, in Taiwan. Data were collected from 7,826 pregnant women self-referred for DGS screening with massive parallel shotgun sequencing-based NIPT. High-risk cases subsequently received amniocentesis for array comparative genomic hybridization (aCGH) to confirm the diagnosis. Characteristics of pregnancies were documented when participants received the test. Report of NIPT was completed 2 weeks after the test. Follow-up on high-risk cases was completed by telephone interview on January 30, 2021. RESULTS: Thirteen cases showed high risk by NIPT, and 7 cases were confirmed by aCGH. The sensitivity and specificity were 100% (95% confidence interval [CI] 64.57-100.00%) and 99.92% (95% CI 99.83-99.96%). The prevalence of DGS was 1 in 1,118 pregnancies. The positive predictive rate was 53.85% (95% CI 29.14-76.79%). One true positive (TP) showed US anomaly, and 5 TPs selected termination. DISCUSSION/CONCLUSION: NIPT demonstrated good performance in DGS screening. Detection of 22q11.2 deletion could be combined with routine screening to facilitate proper intervention.

Mycoplasma pneumoniae and Chlamydia pneumoniae Coinfection with Acute Respiratory Distress Syndrome: A Case Report.

Community-acquired pneumonia caused by Mycoplasma pneumoniae or Chlamydia pneumoniae is usually mild. Mycoplasma pneumoniae-related and C. pneumoniae-related acute respiratory distress syndromes (ARDSs) are rare. Moreover, to our knowledge, there are no published reports on ARDS caused by M. pneumoniae and C. pneumoniae coinfection. Here, we report a case of an immunocompetent young woman who was co-infected with M. pneumoniae and C. pneumoniae and was started on treatment with piperacillin and clarithromycin. Two days later, she developed ARDS. She recovered rapidly following a change of antibiotic treatment to levofloxacin and was discharged on day 12. We conducted exome sequencing followed by alternative filtering to search for candidate ARDS-related genes. We identified an intronic variant of unknown significance within leucine-rich repeat-containing 16A (LRRC16A), a gene previously identified as a significant locus for platelet count with a possible role in ARDS. This is a rare case of ARDS in a young adult caused by M. pneumoniae and C. pneumoniae coinfection. This case suggests that ARDS in young adults may be correlated with variants in LRRC16A. This requires confirmation by further case reports.

A comparison of ultrasound-guided rotator interval and posterior glenohumeral injection techniques for MR shoulder arthrography.

PURPOSE: The aim of this prospective, randomized study was to compare the performance of a rotator interval approach with the posterior glenohumeral approach for ultrasound-guided contrast injection prior to MR shoulder arthrography. METHOD: This study was approved by the institutional review board. One hundred and twenty consecutive patients referred for MR shoulder arthrography were randomized into four groups: rotator interval approach in-plane (n = 30); rotator interval approach out-of-plane (n = 30); posterior approach in-plane (n = 30); and posterior approach out-of plane (n = 30). Outcome measures included procedure time, number of injection attempts, patient-reported pain score (0-10), and radiologist-reported technical difficulty (0-10). MR arthrograms were assessed for adequacy of joint distension, diagnostic utility, and extra-capsular contrast leakage. RESULTS: All 120 patients had a successful ultrasound-guided injection with adequate joint distension and diagnostic utility for MR arthrography. In-plane needle guidance was less technically demanding, quicker, required fewer injection attempts, and had a lower frequency of contrast leakage than out-of-plane needle guidance. The posterior glenohumeral approach was less technically demanding though had a higher frequency of contrast leakage and caused more patient discomfort than the rotator interval approach. CONCLUSION: For ultrasound-guided shoulder joint injection, an in-plane approach is preferable. The posterior glenohumeral approach is less technically demanding though causes more patients discomfort than the rotator interval approach possibly due to the longer needle path.

MRI of the Carpal Tunnel 3 and 12 Months After Endoscopic Carpal Tunnel Release.

OBJECTIVE. The purpose of this study was to study changes in the median nerve, retinaculum, and carpal tunnel on MRI after successful endoscopic carpal tunnel release (ECTR). SUBJECTS AND METHODS. In this prospective study, 35 wrists in 32 patients (five men, 27 women; mean age, 56.7 ± 6.8 [SD] years) with nerve conduction test-confirmed primary carpal tunnel syndrome were evaluated from May 2013 to September 2016. Clinical scores ranging from 0 to 4 (no improvement to symptoms completely resolved) and MRI morphologic features of median nerve and carpal tunnel were evaluated at baseline and 3 and 12 months after ECTR. The paired t test was used to compare MRI parameters before and after ECTR and their relationships to clinical improvement scores. RESULTS. All patients' conditions improved after ECTR with mean clinical improvement scores of 2.94 ± 1.0 at 3 months and 3.49 ± 0.56 at 12 months. Although median nerve swelling did decrease proximally, the nerve remained swollen (> 15 mm2) and flattened in all areas, even 12 months after ECTR. Additional changes occurred in median nerve caliber-change ratio, relative signal intensity, and carpal tunnel cross-sectional area. A retinacular gap was present in 33 (94%) wrists 3 months and six (17%) wrists 12 months after ECTR, and increased retinacular bowing persisted. CONCLUSION. After ECTR, undue swelling and flattening of the median nerve persist as long as 12 months after surgery, even in patients with a good surgical outcome. One should be wary of using these MRI findings as signs of persistent neural compression. The retinaculum reforms in most patients within 12 months of surgery but with a more bowed configuration.

Inadvertent arterial & venous injury by bone marrow biopsy needle: case report on rescue embolization techniques.

BACKGROUND: Bone marrow biopsy is a common medical procedure for diagnosis and characterization of haematological diseases. It is generally regarded as a safe procedure with low rate of major complications. Inadvertent vascular injury is however an uncommon but important complication of bone marrow biopsy procedure. The knowledge of a safe and effective embolization method is crucial for interventional radiologists to reduce significant patient morbidity and mortality, shall such inadvertent vascular injury occurs. CASE PRESENTATION: Bedside bone marrow biopsy was performed for an elderly gentleman to evaluate for his underlying acute leukaemia. Biopsy needle inadvertently injured the internal iliac artery and vein during the procedure. Coil embolization was carefully performed across injured arterial segment via the culprit biopsy needle until contrast cessation. Concomitant venous injury was subsequently confirmed on angiography when the needle was withdrawn for a short distance from the iliac artery. This venous injury was tackled by further withdrawing the biopsy needle to distal end of the bone marrow tract for tract embolization with coils and gelatin sponges. High caution was made to avoid coil dislodgement into the iliac vein, to prevent pulmonary embolism. Patient was clinically stable throughout the procedure. Post-procedure contrast CT shows no pelvic haematoma or contrast extravasation. CONCLUSIONS: This case illustrates rescue embolization techniques for rare life-threatening concomitant internal iliac arterial and venous injuries by a bone marrow biopsy needle. Interventional radiologists can play an important role in carrying out precise embolization to avoid significant patient morbidity and mortality in the case of life-threatening haemorrhage.

Detection of copy number variants with chromosomal microarray in 10 377 pregnancies at a single laboratory.

INTRODUCTION: Invasive prenatal testing with chromosomal microarray analysis may be a relevant option for all pregnant women, but there is only moderate-quality evidence for such an offer. We intended to study the prevalence of copy number variants (CNVs) in prenatal samples using a single SNP-array platform stratified by indication. MATERIAL AND METHODS: A cross-sectional study was performed based on a cohort. From January 2015 to December 2017, a total of 10 377 prenatal samples were received for prenatal single nucleotide polymorphism (SNP)-array in the laboratory of the Genetics Generation Advancement Corporation. Indications for chromosomal microarray analysis studies included the confirmation of an abnormal karyotype, ultrasound abnormalities, advanced maternal age and parental anxiety. CNVs and region of homozygosity identified by the SNP-array were analyzed. RESULTS: Of 10 377 cases, 689 had ultrasound abnormalities and 9688 were ascertained to have other indications. The overall prevalence of CNVs was 2.1% (n = 223/10 377, 95% confidence interval [CI] 1.9-2.4), but the prevalence was 4.4% (95% CI 3.0-6.1) for cases referred with abnormal ultrasound findings and 2.0% (95% CI 1.7-2.3) for other indications. Of the 223 CNVs detected, 42/10 377 were pathogenic (0.4%, 95% CI 0.3-0.6), 84 were susceptibility CNV (0.8%, 95% CI 0.6-1.0) and 97 were variants of uncertain significance (0.9%, 95% CI 0.8-1.1). Using an SNP-based platform allowed for the detection of paternal uniparental disomy of chromosome 14 in a fetus with ultrasound abnormality. CONCLUSIONS: With an indication of advanced maternal age but normal ultrasound scans, the prevalence of pathogenic CNVs was 0.4% and that of susceptibility CNV 0.7%. As CNVs are independent of maternal age, the prevalence is likely the same for younger women. Thus, this study provides further evidence that chromosomal microarray analysis should be available for all women who wish to receive diagnostic testing, as this risk is above the cut-off of 1:300 for Down syndrome, leading to the suggestion of invasive testing. A chromosomal microarray analysis based on SNP-array platform is preferable, as it can also detect uniparental disomy in addition to copy number variants.

Percutaneous Portal Vein Embolization Using a Simplified Sheathless 18-Gauge Trocar Needle Approach: Review of Efficacy and Safety.

PURPOSE: Portal vein (PV) embolization (PVE) is traditionally performed via a PV sheath with selective embolization of PV branches. Here, the efficacy and safety of PVE with the use of only an 18-gauge needle is reported. MATERIALS AND METHODS: Consecutive patients who underwent PVE from 2009 through 2017 were retrospectively reviewed. Forty-five patients (mean age, 60 y ± 7.6; 38 men) underwent 45 PVE procedures. Hepatocellular carcinoma, cholangiocarcinoma, and metastases accounted for 26 (58%), 13 (29%), and 6 (13%) patients, respectively. PVE was performed by puncturing a branch of right PV with an 18-gauge needle under US guidance. Via the same needle, direct portography was performed, followed by PVE with an N-butyl cyanoacrylate/Lipiodol mixture. Percentage increase of future liver remnant (FLR) volume and increase in ratio of FLR to total liver volume were estimated as measures of efficacy. Complications were reported according to Society of Interventional Radiology classification. Fluoroscopy time, procedure time, and dose-area product (DAP) were recorded. RESULTS: Technical success rate was 100%. The median DAP, fluoroscopy time, and procedure time were 74,387 mGy·cm2 (IQR, 90,349 mGy·cm2), 3.5 min (IQR, 2.10 min), and 24 min (IQR, 10.5 min). Among the 23 patients with complete CT volumetry data, mean increase in the ratio of FLR to total liver volume and percentage increase of FLR volume were 12.5% ± 7.7 and 50% ± 33, respectively. There were 3 minor complications (asymptomatic nonocclusive emboli in FLR) and 3 major complications (1 hepatic vein emboli, 1 subphrenic collection, and 1 hepatic infarct). CONCLUSIONS: PVE via a sheathless 18-gauge needle approach is feasible, with satisfactory FLR hypertrophy.

CT brain artefact due to air bubbles in the oil cooling system: characteristic band-like configuration on sagittal reformatted image.

PURPOSE: To retrospectively review the imaging characteristics of CT artefacts due to air bubbles within the oil cooling system of the X-ray tube housing. MATERIALS AND METHODS: Air bubbles were introduced into the oil cooling system of the X-ray tube housing during tube replacement in one of the CT scanners in the authors' institution. All 126 CT brain studies performed in this period were retrospectively reviewed. One hundred and four studies were negative for artefacts. Artefacts were confirmed in 5 and considered probable in 17 studies, respectively. The imaging characteristics of artefacts in these 22 cases were analysed. RESULTS: All artefacts manifested as ill-defined hypoattenuations in the periventricular/subcortical white matter of bilateral cerebral hemispheres with/without involvement of the internal capsule and basal ganglia. The posterior fossa was also involved in two (40%) confirmed and four (24%) probable studies. A band-like configuration of hypoattenuations on sagittal images was observed in five (100%) confirmed and eight (47%) probable studies. CONCLUSION: Air bubble artefacts manifested as hypoattenuations in the periventricular/subcortical white matter of the supratentorial brain. A characteristic band-like configuration was observed in the sagittal reformatted image, which is useful for differentiating it from periventricular small vessel disease.

Application of non-invasive prenatal testing in late gestation in a pregnancy associated with intrauterine growth restriction and trisomy 22 confined placental mosaicism.

OBJECTIVE: We present the application of non-invasive prenatal testing (NIPT) in late gestation in a pregnancy associated with intrauterine growth restriction (IUGR) and trisomy 22 confined placental mosaicism (CPM). CASE REPORT: A 35-year-old pregnant woman underwent chorionic villus sampling (CVS) at 12 weeks of gestation. The pregnancy was conceived by in vitro fertilization and intracytoplasmic sperm injection. CVS revealed a karyotype of 47,XY,+22 in all of 15 cultured chorionic villi cells. Array comparative genomic hybridization analysis on uncultured chorionic villi revealed a result consistent with trisomy 22. The woman underwent amniocentesis at 17 weeks of gestation. Amniocentesis revealed a karyotype of 46,XY in all 20 colonies of cultured amniocytes. Additional polymorphic DNA marker analysis excluded uniparental disomy 22. The parental karyotypes were normal. Prenatal ultrasound at 23 weeks of gestation revealed fetal retrognathia, IUGR and a calcified placenta. NIPT at 27 weeks of gestation using maternal plasma cell-free DNA analysis showed a chromosome Z-score of 5.74 for chromosome 22 (the Z-score for each pair of chromosomes is defined as "increased" if >3), indicating an abnormal placenta with trisomy 22 CPM leading to IUGR in the fetus. At 36 weeks of gestation, a 1754-g male fetus was delivered with cleft palate and imperforate anus but no other phenotypic abnormalities. The cord blood had a karyotype of 46,XY (40/40 cells), the umbilical cord had a karyotype of 47,XY,+22[9]/46,XY[31], and the placental tissues had a karyotype of 47,XY,+22[15]/46,XY[25]. CONCLUSION: NIPT in late gestation is useful in detection of placental abnormality associated with CPM and IUGR but a normal karyotype at amniocentesis.

Noninvasive prenatal testing for whole fetal chromosomal aneuploidies: a multicenter prospective cohort trial in Taiwan.

OBJECTIVE: To evaluate the performance of noninvasive prenatal testing for all fetal chromosomal aneuploidies in an extremely high-risk group undergoing first trimester combined Down syndrome screening. METHOD: A multicenter cohort prospective study in Taiwan was performed between June and December 2012. Maternal plasma was collected and shotgun massive parallel sequencing was performed on each fetal chromosome. 201 Taiwanese pregnant women at >12 weeks' gestation from 11 medical centers were enrolled in this trial. The extremely high-risk group was defined as a Down syndrome risk cutoff >1:30 or nuchal translucency >3.0 mm (n = 100), while the low-risk group was defined as a Down syndrome cutoff <1:1,500 (n = 101). Amniocentesis confirmation was performed and birth outcome was also recorded. RESULTS: There were 11 cases of trisomy 21, 8 cases of trisomy 18, 3 cases of trisomy 13, 1 case of trisomy 16, 3 cases of 45,X, and 1 case of 47,XYY detected prenatally in 100 extremely high-risk gravidas [n = 27/100 (27%)]. The overall autosomal or sex chromosome aneuploidy detection rate was 96% (27/28) because of an insufficient amount maternal plasma for one fetus with Turner syndrome. In the low-risk group, no chromosomal abnormalities were detected (specificity = 100%). There were no false-positive cases in this study. CONCLUSIONS: This first trial in Taiwan shows that noninvasive prenatal testing for whole chromosome aneuploidies can be efficiently applied in extremely high- and low-risk populations.

Human application of ex vivo expanded umbilical cord-derived mesenchymal stem cells: enhance hematopoiesis after cord blood transplantation.

Delayed hematopoietic reconstitution after cord blood (CB) transplantation (CBT) needs to be overcome. Bone marrow-derived mesenchymal stem cells (BMMSCs) have been found to enhance engraftment after hematopoietic stem cell transplantation. However, getting BMMSCs involves an invasive procedure. In this study, umbilical cord-derived mesenchymal stem cells (UCMSCs) were isolated from Wharton's jelly and cryopreserved in the UCMSCs bank. Compared with BMMSCs, we found that UCMSCs had superior proliferative potential. We found that NOD/SCID mice cotransplanted with CB and UCMSCs demonstrated significant human CD45(+) cell engraftment compared with those transplanted with CB alone. Then, 20 patients with high-risk leukemia were prospectively randomized to either receive cotransplantation of CB and ex vivo expanded banked UCMSCs or to receive CBT alone. No serious adverse events were observed in the patients receiving UCMSC infusion. The time to undergo neutrophil engraftment and platelet engraftment was significantly shorter in the eight patients receiving cotransplantation than that in the 12 patients receiving CBT alone (p=0.003 and p=0.004, respectively). Thus, application of ex vivo expanded banked UCMSCs in humans appears to be feasible and safe. UCMSCs can enhance engraftment after CBT, but further studies are warranted.

Cotransplantation of umbilical cord-derived mesenchymal stem cells promote hematopoietic engraftment in cord blood transplantation: a pilot study.

BACKGROUND: Delayed hematopoietic reconstitution after cord blood transplantation (CBT) may lead to increased risk of complications and longer hospitalization. Bone marrow-derived mesenchymal stem cells (MSCs) have been found to promote engraftment after hematopoietic stem cell transplantation. However, harvesting MSCs from bone marrow involves an invasive procedure. Then again, MSCs can be easily obtained from umbilical cords without harm to the donors. METHODS: Umbilical cord-derived MSCs (UCMSCs) were isolated from Wharton's jelly and then ex vivo cultured. After showing normal karyotype and negative for infectious contamination, culture-expanded UCMSCs were intravenously infused into the recipients on the day of CBT. The control patients were those receiving CBT alone. Adverse effects and efficacy of intravenous UCMSCs were evaluated. RESULTS: A total of five patients received cotransplantation of UCMSCs at the time of CBT. No serious adverse events were observed. The time to achieve neutrophil engraftment ranged from 7 to 13 days (median, 11 days) and platelet engraftment ranged from 22 to 41 days (median, 32 days). Compared with the nine patients receiving CBT alone, patients receiving cotransplantation of UCMSCs had significantly faster hematopoietic recovery of neutrophils and platelets (P=0.02 and 0.01, respectively). CONCLUSIONS: This pilot study is the first report of cotransplantation of UCMSCs in CBT. Intravenous infusion of UCMSCs appeared to be a feasible and safe modality to enhance hematopoietic engraftment in patients receiving CBT. Further studies were warranted.

Umbilical cord-derived mesenchymal stem cells for hematopoietic stem cell transplantation.

Hematopoietic stem cell transplantation (HSCT) is becoming an effective therapeutic modality for a variety of diseases. Mesenchymal stem cells (MSCs) can be used to enhance hematopoietic engraftment, accelerate lymphocyte recovery, reduce the risk of graft failure, prevent and treat graft-versus-host disease, and repair tissue damage in patients receiving HSCT. Till now, most MSCs for human clinical application have been derived from bone marrow. However, acquiring bone-marrow-derived MSCs involves an invasive procedure. Umbilical cord is rich with MSCs. Compared to bone-marrow-derived MSCs, umbilical cord-derived MSCs (UCMSCs) are easier to obtain without harm to the donor and can proliferate faster. No severe adverse effects were noted in our previous clinical application of UCMSCs in HSCT. Accordingly, application of UCMSCs in humans appears to be feasible and safe. Further studies are warranted.

Effective treatment of severe steroid-resistant acute graft-versus-host disease with umbilical cord-derived mesenchymal stem cells.

BACKGROUND: Severe steroid-resistant acute graft-versus-host disease (aGVHD) is associated with high mortality. Bone marrow-derived mesenchymal stem cells (BMMSC) have been found to be immunosuppressive, and intravenous infusion of BMMSC is an effective therapy for steroid-resistant aGVHD. However, acquiring BMMSC requires an invasive procedure. METHODS: We compared umbilical cord-derived mesenchymal stem cells (UCMSC) and BMMSC for morphology, surface markers expression, differentiation, proliferative potential, and their suppressive effects on peripheral blood mononuclear cell proliferation. After institutional review board approved, we intravenously infused ex vivo expanded third-party UCMSC into two patients with severe steroid-resistant aGVHD. Adverse effects and patient responses of UCMSC were monitored. All procedures for UCMSC processing complied with current good tissue practice requirements. RESULTS: We found that UCMSC had superior proliferative potential and more suppressive effects on peripheral blood mononuclear cell proliferation compared with BMMSC. The aGVHD improved dramatically after each of four infusions of UCMSC into the two patients. No adverse effects were noted. Both patients are doing well now. CONCLUSIONS. Considering that acquiring UCMSC is noninvasive, these cells would appear to be the ideal candidates for clinical cell-based therapies. This is the first report of UCMSC in a human clinical application, and this procedure seems both feasible and safe. These findings suggested that UCMSC were effective for treating aGVHD.

Carrier screening for spinal muscular atrophy (SMA) in 107,611 pregnant women during the period 2005-2009: a prospective population-based cohort study.

BACKGROUND: Spinal muscular atrophy (SMA) is the most common neuromuscular autosomal recessive disorder. The American College of Medical Genetics has recently recommended routine carrier screening for SMA because of the high carrier frequency (1 in 25-50) as well as the severity of that genetic disease. Large studies are needed to determine the feasibility, benefits, and costs of such a program. METHODS AND FINDINGS: This is a prospective population-based cohort study of 107,611 pregnant women from 25 counties in Taiwan conducted during the period January 2005 to June 2009. A three-stage screening program was used: (1) pregnant women were tested for SMA heterozygosity; (2) if the mother was determined to be heterozygous for SMA (carrier status), the paternal partner was then tested; (3) if both partners were SMA carriers, prenatal diagnostic testing was performed. During the study period, a total of 2,262 SMA carriers with one copy of the SMN1 gene were identified among the 107,611 pregnant women that were screened. The carrier rate was approximately 1 in 48 (2.10%). The negative predictive value of DHPLC coupled with MLPA was 99.87%. The combined method could detect approximately 94% of carriers because most of the cases resulted from a common single deletion event. In addition, 2,038 spouses were determined to be SMA carriers. Among those individuals, 47 couples were determined to be at high risk for having offspring with SMA. Prenatal diagnostic testing was performed in 43 pregnant women (91.49%) and SMA was diagnosed in 12 (27.91%) fetuses. The prevalence of SMA in our population was 1 in 8,968. CONCLUSION: The main benefit of SMA carrier screening is to reduce the burden associated with giving birth to an affected child. In this study, we determined the carrier frequency and genetic risk and provided carrier couples with genetic services, knowledge, and genetic counseling.

Areas of capsaicin-induced secondary hyperalgesia and allodynia are reduced by a single chiropractic adjustment: a preliminary study.

INTRODUCTION: The aim of the study was to investigate the hypoalgesic effects of a single spinal manipulation treatment on acute inflammatory reactions and pain induced by cutaneous application of capsaicin. METHODS: Twenty healthy subjects participated in the experiment, which consisted of 2 sessions. In both sessions, following control measurements, topical capsaicin was applied to the right or left forearm to induce cutaneous inflammatory reactions. The cream was removed after 20 minutes. Then subjects received either spinal manipulation treatment (SMT) or "nonspinal manipulation treatment" (N-SMT), respectively. In control as well as pretreatment and posttreatment intervals, the following tests were performed: measurement of the areas of mechanical hyperalgesia and stroking allodynia, assessment of spontaneous pain, and measurement of blood flow. RESULTS: The results confirmed that topical capsaicin induced inflammatory reactions based on occurrence of hyperalgesia and allodynia, augmented pain perception, and increased blood flow following capsaicin application compared with the control session. When compared with N-SMT, spontaneous pain was rated significantly lower post-SMT (P <.014). In addition, areas of both secondary hyperalgesia and allodynia decreased after SMT (hyperalgesia: P <.007; allodynia: P <.003). However, there was no significant treatment effect for local blood flow. CONCLUSION: These results suggest hypoalgesic effects following a single SMT. As local vascular parameter was not affected by the single SMT, the hypoalgesic effects appear to be due to central mechanisms.