A survey of assessment and management of velopharyngeal incompetence (VPI) in the UK and Ireland

Magnetic Resonance Imaging for Assessing Velopharyngeal Function: Current Applications, Barriers, and Potential for Future Clinical Translation in the United States

OBJECTIVE

The use of magnetic resonance imaging (MRI) in the assessment process for children with cleft/craniofacial conditions remains uncommon, particularly for velopharyngeal assessments. The purpose of this study was to analyze the perceived clinical utility of MRI for cleft/craniofacial providers and identify barriers that exist for clinical translation of this imaging modality to this population of patients.

METHODS

A 38-item survey was disseminated to craniofacial team providers. Workplace context and demographics, MRI as a research and clinical tool, access and barriers for use of MRI, and needs for successfully establishing MRI protocols at clinical sites were investigated. Descriptive statistics were used to identify differences in the clinical use of MRI across disciplines. Chi-square analyses were conducted to determine how different specialties perceived potential barriers.

RESULTS

Respondents reported that MRI is likely to be beneficial for clinical assessments (93.5%) and that this imaging modality is available for use (83.8%). However, only 11.8% of providers indicated the use of MRI in their clinical assessments. This discrepancy highlights a potential disconnect between perceived use and implementation of this imaging methodology on cleft and craniofacial teams. A number of barriers were identified by providers. Challenges and opportunities for clinical translation of MRI protocols were highlighted.

CONCLUSION

Results may guide the development for improved clinical feasibility and implementation of MRI for clinical planning in this population of patients. Reported barriers highlight additional areas for translational research and the potential for the development of clinical tools related to MRI assessment and protocol implementation.

Tissue adjuncts in primary cleft palate reconstruction: A systematic review

BACKGROUND

Tissue adjunct is non-palatal tissue used to manage tension at the defect site by providing additional coverage. This review aimed to compare outcomes of various adjuncts employed in primary palatoplasty.

METHODS

A literature search was conducted of MEDLINE, EMBASE, and Cochrane Library with keywords cleft palate, palatoplasty, surgical flaps, and allografts. Data extracted included demographics, cleft severity, primary/adjunctive techniques, outcomes, and follow-up periods. Logistic regression analyses and chi-squared tests were performed to investigate associations among variables.

RESULTS

A total of 1332 patients (aged 3 months-5 years) with follow-up of 1 month to 21 years were included. Cleft severity included submucous cleft (1.7%), Veau I/II (33.3%), Veau III (46.3%), and Veau IV (15.1%). Most reported techniques were Furlow (52%) and intravelar veloplasty (14.3%) for soft palate, Bardach (27.2%), and V-Y Pushback (11.1%) for hard palate. Buccal myomucosal flap (BMMF) was performed in 45.4% of cases, followed by buccal fat pad flap/graft (BFP) in 40.8% and acellular dermal matrix (ADM) in 14%. Severe clefts (Veau III/IV) were repaired more frequently with BMMF compared with ADM (p = 0.003) and BFP (p = 0.01). Oronasal fistula occurred in 3.1% of patients, and velopharyngeal insufficiency (VPI) in 4%, both associated with Veau IV (fistula: p = 0.002, VPI: p = 0.0002). No significant differences were found in fistula (p = 0.79) or VPI (p = 0.14) rates between adjuncts. In severe clefts (Veau III/IV), ADM was associated with fistula formation (p = 0.03).

CONCLUSIONS

Adjuncts in primary palatoplasty may mitigate unfavorable outcomes associated with severe clefts. BMMF is superior, given its inherent tissue properties, whereas BFP is effective in reducing fistula formation.

Surgery for Velopharyngeal Insufficiency Following Cleft Palate Repair: An Audit of Contemporary Practice and Proposed Schema of Techniques and Variations

OBJECTIVE

Surgical treatment of velopharyngeal insufficiency (VPI) includes a wide array of procedures. The purpose of this study was to develop a classification for VPI procedures and to describe variations in how they are performed.Design/participants/setting/outcomes: We completed an in-depth review of the literature to develop a preliminary schema that encompassed existing VPI procedures. Forty-one cleft surgeons from twelve hospitals across the USA and Canada reviewed the schema and either confirmed that it encompassed all VPI procedures they performed or requested additions. Two surgeons then observed the conduct of the procedures by surgeons at each hospital. Standardized reports were completed with each visit to further explore the literature, refine the schema, and delineate the common and unique aspects of each surgeon's technique.

RESULTS

Procedures were divided into three groups: palate-based surgery; pharynx-based surgery; and augmentation. Palate-based operations included straight line mucosal incision with intravelar veloplasty, double-opposing Z-plasty, and palate lengthening with buccal myomucosal flaps. Many surgeons blended maneuvers from these three techniques, so a more descriptive schema was developed classifying the maneuvers employed on the oral mucosa, nasal mucosa, and muscle. Pharynx-based surgery included pharyngeal flap and sphincter pharyngoplasty, with variations in design for each. Augmentation procedures included palate and posterior wall augmentation.

CONCLUSIONS

A comprehensive schema for VPI procedures was developed incorporating intentional adaptations in technique. There was substantial variation amongst surgeons in how each procedure was performed. The schema may enable more specific evaluations of surgical outcomes and exploration of the mechanisms through which these procedures improve speech.

A segmentation-informed deep learning framework to register dynamic two-dimensional magnetic resonance images of the vocal tract during speech

Objective

Dynamic magnetic resonance (MR) imaging enables visualisation of articulators during speech. There is growing interest in quantifying articulator motion in two-dimensional MR images of the vocal tract, to better understand speech production and potentially inform patient management decisions. Image registration is an established way to achieve this quantification. Recently, segmentation-informed deformable registration frameworks have been developed and have achieved state-of-the-art accuracy. This work aims to adapt such a framework and optimise it for estimating displacement fields between dynamic two-dimensional MR images of the vocal tract during speech.

Methods

A deep-learning-based registration framework was developed and compared with current state-of-the-art registration methods and frameworks (two traditional methods and three deep-learning-based frameworks, two of which are segmentation informed). The accuracy of the methods and frameworks was evaluated using the Dice coefficient (DSC), average surface distance (ASD) and a metric based on velopharyngeal closure. The metric evaluated if the fields captured a clinically relevant and quantifiable aspect of articulator motion.

Results

The segmentation-informed frameworks achieved higher DSCs and lower ASDs and captured more velopharyngeal closures than the traditional methods and the framework that was not segmentation informed. All segmentation-informed frameworks achieved similar DSCs and ASDs. However, the proposed framework captured the most velopharyngeal closures.

Conclusions

A framework was successfully developed and found to more accurately estimate articulator motion than five current state-of-the-art methods and frameworks.

Significance

The first deep-learning-based framework specifically for registering dynamic two-dimensional MR images of the vocal tract during speech has been developed and evaluated.

The case for the pharyngeal flap pharyngoplasty in the management of velopharyngeal dysfunction

Velopharyngeal dysfunction (VPD) occurs when there is inadequate closure of the velopharyngeal sphincter during speech. An incompetent velopharyngeal sphincter may require surgical intervention to create a functional seal between the oropharynx and the nasopharynx during speech. To date, no single pharyngoplasty procedure has emerged as superior to another, and the comparison of results between studies has been limited by variation in outcomes reporting. Here, we use the newly defined Core Outcome Set for VPD (COS-VPD) to report a consecutive series of 109 patients managed with a midline pharyngeal flap and simultaneous dissection and repositioning of the velar muscles. The overall 30-day postoperative complication rate was 3.6% (4 out of 109 patients). At 12-month follow-up, 79.3% of patients experienced a statistically significant improvement in hypernasality. Seven patients (6.4%) developed obstructive sleep apnoea (OSA) postoperatively, and this was confirmed with polysomnography, with four (3.6%) patients requiring takedown of the pharyngeal flap. Seven patients in total (7.3%) required takedown of the pharyngeal flap and sphincter pharyngoplasty because of insufficient improvement of their VPD following the initial procedure. Patient-reported outcomes were investigated using the Velopharyngeal Effects on Life Outcome (VELO) instrument, and a mean total score of 74.5 out of 100 was recorded. We conclude that cleft surgeons should not be dissuaded by historical concerns about high rates of perioperative complications and OSA and should consider including the pharyngeal flap in their armamentarium when managing patients with VPD.

Speech Outcomes Following Orticochea Pharyngoplasty in Patients With History of Cleft Palate and Noncleft Velopharyngeal Dysfunction

OBJECTIVE

To report speech outcomes following Orticochea pharyngoplasty in 43 patients with cleft palate and noncleft velopharyngeal dysfunction.

DESIGN

A retrospective surgical audit of patients undergoing Orticochea pharyngoplasty between 2004 and 2012, with speech as a primary outcome measure.

SETTING

Patients known to a regional UK cleft center.

METHODS

Forty-three patients underwent Orticochea pharyngoplasty by a single surgeon in a UK regional cleft center. Twenty-one patients had undergone a prior procedure for velopharyngeal dysfunction. Pre- and postoperative speech samples were assessed blindly using the Cleft Audit Protocol for Speech-Augmented by a specialist cleft speech and language therapist, external to the team. Speech samples were rated on the following parameters: hypernasality, hyponasality, audible nasal emission, nasal, turbulence, and passive cleft speech characteristics. Statistical differences in pre- and postoperative speech scores were tested using the Wilcoxon matched-pairs signed-ranks test. Inter- and intrareliability scores were calculated using weighted Cohen κ.

RESULTS

Whole group: A statistically significant difference in pre- and postoperative scores for hypernasality (P < .001), hyponasality (P < .05), nasal emission (P < .01), and passive cleft speech characteristics (P < .01) were reported. Patients with cleft diagnoses: A statistically significant difference in scores for hypernasality (P < .001), nasal emission (P < .01), and passive cleft speech characteristics (P < .01) were reported for this group of patients. Patients with noncleft diagnoses: The only parameter to demonstrate a statistically significant difference was hypernasality (P < .01) in this group.

CONCLUSIONS

Orticochea pharyngoplasty is a successful surgical procedure in treating velopharyngeal dysfunction in both the cleft and noncleft populations.

Management of cleft lip and palate in Egypt: A National survey

Background:

Variable protocols for the management of cleft lip and/or palate (CLP) patients are currently used. However, to our knowledge, there are no previously published data about cleft management and practice in Egypt.

Materials and Methods:

One-hundred questionnaires were distributed to cleft surgeons attending the annual meeting of the Egyptian Society of Plastic and Reconstructive Surgeons in March 2016 to investigate timing, techniques and complications of cleft surgery. Seventy-two colleagues returned the questionnaire, and the data were analysed using Microsoft Excel software.

Results:

The majority of cleft lip cases are repaired between 3 and 6 months. Millard and Tennison repairs for unilateral cleft lip, while Millard and Manchester techniques for bilateral cleft lip are the most commonly performed. Cleft palate is usually repaired between 9 and 12 months with the two-flap push-back technique being the most commonly used. The average palatal fistula rate is 20%. Pharyngeal flap is the method of choice to correct velopharyngeal incompetence. Polyglactin 910 is the most commonly used suture material in cleft surgery in the country. Multidisciplinary cleft management is reported only by 16.5% of participants.

Conclusion:

Management of CLP in Egypt is mainly dependent on personal preference, not on constitutional protocols. There is a lack of multidisciplinary approach and patients’ registration systems in the majority of centres. The establishment of cleft teams from the concerned medical specialties is highly recommended for a more efficient care of cleft patients.

Application of radial GRAPPA techniques to single- and multislice dynamic speech MRI using a 16-channel neurovascular coil

PURPOSE

To investigate: (1) the feasibility of using through-time radial GeneRalized Autocalibrating Partially Parallel Acquisitions (rGRAPPA) and hybrid radial GRAPPA (h-rGRAPPA) in single- and multislice dynamic speech MRI; (2) whether single-slice dynamic speech MRI at a rate of 15 frames per second (fps) or higher and with adequate image quality can be achieved using these radial GRAPPA techniques.

METHODS

Seven healthy adult volunteers were imaged at 3T using a 16-channel neurovascular coil and 2 spoiled gradient echo sequences (radial trajectory, field of view = 192 × 192 mm² , acquired pixel size = 2.4 × 2.4 mm² ). One sequence imaged a single slice at 16.8 fps, the other imaged 2 interleaved slices at 7.8 fps per slice. Image sets were reconstructed using rGRAPPA and h-rGRAPPA, and their image quality was compared using the root mean square error, structural similarity index, and visual assessments.

RESULTS

Image quality deteriorated when fewer than 170 calibration frames were used in the rGRAPPA reconstruction. rGRAPPA image sets demonstrated: (1) in 97% of cases, a similar image quality to h-rGRAPPA image sets reconstructed using a k-space segment size of 4, (2) in 98% of cases, a better image quality than h-rGRAPPA image sets reconstructed using a k-space segment size of 32.

CONCLUSION

This study confirmed: (1) the feasibility of using rGRAPPA and h-rGRAPPA in single- and multislice dynamic speech MRI, (2) that single-slice speech imaging at a frame rate higher than 15 fps and with adequate image quality can be achieved using these radial GRAPPA techniques.

Acquired Velopharyngeal Dysfunction: Survey, Literature Review, and Clinical Recommendations

PURPOSE

The aim of this study was to describe the clinical assessment recommendations for acquired velopharyngeal dysfunction (AVPD) and, through a literature review and online survey, summarize current practice patterns for evaluation and treatment pathway determination for this target population.

METHOD

An online survey to query current assessment procedures and treatment pathway recommendations for AVPD was developed. Following survey results, a literature review was completed to determine evidence-based recommendations for assessment procedures and intervention recommendations based on assessment findings. Literature search terms included the following: acquired velopharyngeal dysfunction, hypernasality, non-cleft velopharyngeal dysfunction, velopharyngeal dysfunction, velopharyngeal dysfunction AND iatrogenic, velopharyngeal dysfunction AND neurogenic, velopharyngeal dysfunction AND assessment OR evaluation, velopharyngeal dysfunction AND treatment OR intervention, velopharyngeal dysfunction AND practice patterns OR clinical guidelines, velopharyngeal insufficiency. Inclusion criteria were limited to practice patterns/recommendations for assessment and/or treatment recommendations for AVPD, English language articles published between 2000 and 2017, and peer-reviewed journals. Studies regarding solely congenital or cleft palate velopharyngeal dysfunction and intervention outcome studies were excluded. Forty articles met inclusionary criteria.

RESULTS

The online survey results indicated lack of consensus for AVPD assessment and treatment recommendation protocols, with 93% of respondents indicating the need for a clinical guide for developing treatment recommendations. The majority of recommendations were filtered into an algorithm for clinical decision making.

CONCLUSIONS

Clinical uncertainty among speech-language pathologists surveyed and the paucity of published clinical guidelines for assessing individuals with AVPD indicate the need for additional clinical research for this disorder, one that is heterogeneous and distinct from those with congenital velopharyngeal dysfunction. The proposed evidence-based clinical worksheet may assist in determining management for patients with AVPD and may serve as a starting place for validation of a clinical guideline.

Palatal Protective Stents Prevent Oro-Nasal Fistulas after Surgery for Velopharyngeal Insufficiency: A Preliminary Report

Background: One of the potential complications of surgery for velopharyngeal insufficiency (VPI) is postoperative oral-nasal fistula (ONF). Reported rates vary from 0 to 60%. Several factors are on account of these disproportionate rates. Objective: The purpose of this study was to describe the use of a palatal protective stent (PPS) to preserve the VPI repair surgical site and to study its effectiveness for decreasing the incidence of postoperative ONF. Materials and Methods: A retrospective study was carried out. All patients undergoing surgery for VPI with complete preoperative and postoperative evaluations including at least one year follow up after surgery from 2012 to 2016 were studied. Some of the patients were operated on using a pre-molded palatal protective stent (PPS). Twenty-seven patients were included in the study group. Most of the patients underwent a customized pharyngeal flap according to findings of imaging procedures. The remaining cases underwent a Furlow palatoplasty. Twelve patients were operated on using PPS. Results: There were no surgical complications during the procedures. ONF was detected in four of the patients operated on without PPS. None of the patients undergoing surgery using PPS demonstrated ONF. All fistulas were located at the soft/hard palate junction. VPI was corrected in 92% of the cases. Conclusion: Although only a reduced number of cases were studied, these preliminary results suggest that using PPS during surgical procedures for correcting VPI is a safe and reliable tool for preventing ONF.

Outcome of Palate Re-repair with Radical Repositioning of the Levator Muscle Sling as a First-Line Strategy in Postpalatoplasty Velopharyngeal Incompetence Management Protocol

BACKGROUND

Palatal re-repair aims to improve velar function by retropositioning the levator muscles. Although it has become a popular procedure, very few studies document its efficacy. To date, this is the largest series reported to clarify its indications and efficacy.

METHODS

One hundred eighty-three consecutive cleft patients presenting with velopharyngeal incompetence and evidence of abnormally oriented levator muscles underwent palate re-repair (regardless of the gap size) performed by a single surgeon from 2000 to 2015. Perceptual speech assessment was performed using the Pittsburgh Weighted Speech Score. Other patients' demographic data were collected.

RESULTS

Complete records of 111 patients were available. Eighteen cases were syndromic (18.9 percent). Postoperatively, there was highly significant improvement (p < 0.001) in nasal emission (from 2.24 to 0.64), nasality (from 3.44 to 1.27), articulation (from 5.32 to 2.01), and total score (from 11.29 to 4.11). Speech became normal/borderline normal, improved or did not improve in 66.7, 24.3, and 9 percent of patients, respectively. An initial diagnosis of isolated cleft palate, Caucasians, intravelar veloplasty in the primary repair, older patients, and nonsyndromic cases were associated with better outcome. There were no reported cases of postoperative fistula or new obstructive sleep apnea.

CONCLUSIONS

This large series study provides confirmatory evidence of the effectiveness and safety of the re-repair procedure. It is recommended as a first-line procedure in all velopharyngeal incompetence cases with abnormally oriented levator muscles regardless of gap size, even if the primary operation included prior muscle dissection. The pharyngoplasty rate could be significantly reduced with the current protocol.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Time course of improvement after re-repair procedure for VPI management

OBJECTIVES

Palatal re-repair aims to improve velar function by retro-positioning the levator veli palatini muscles. The surgery includes extensive dissection, leading to tissue edema and scar formation which may need time to remodel. Together with the change of muscle orientation and tension, it is expected that a period of time is needed to reach the final functional performance. This study attempts to determine how much time is required to reach the optimum performance of the palate after re-repair.

METHODS

A retrospective chart review identified consecutive cleft patients with VPI who underwent palate re-repair procedure by a single surgeon from 2000 to 2015 and achieved normal or borderline normal VP function. Only patients who had regular postoperative follow-up visits for speech assessments until resolution of speech abnormalities were included. The percent of patients cured at each time point following surgery was recorded.

RESULTS

Forty-five patients met the inclusion criteria. The mean age at surgery was 6.6 ± 3.2 years. Speech abnormalities had resolved in 44.5% of patients within the first 6 months after surgery, 62.2% after up to 1 year, 75.6% after up to 2 years and 88.9% after up to 3 years post re-repair palatoplasty. The remaining 11.1% continued to improve after 3 years up to 6 years.

CONCLUSIONS

Re-repair procedures may take a longer time than previously thought for the final outcome to manifest. Close monitoring of improvement with continued speech therapy is recommended before deciding to move to the next surgical step in management.

What We Do: The Hynes Pharyngoplasty-Deep Prevertebrae Stitch

The Hynes pharyngoplasty is the second most often performed procedure for velopharyngeal insufficiency in the United Kingdom and Ireland. A crucial step of the procedure is reliable fixation of the flaps onto the posterior pharynx wall. We prefer to fix the flaps to the prevertebral fascia. By using a manually straightened needle and a skin hook, in our hands, placement of this stitch can be made easier and faster.

A Treatment Protocol for Velopharyngeal Insufficiency and the Outcome

BACKGROUND

A simple algorithm is applied to treat velopharyngeal insufficiency. The purpose of this study was to assess its success rate and complications.

METHODS

The diagnosis includes speech perceptual assessment and nasopharyngoscopy, focusing on velopharyngeal closure ratio. The treatment is composed of a double-opposing Z-plasty for marginal velopharyngeal insufficiency or a pharyngeal flap for moderate to severe velopharyngeal insufficiency. A retrospective chart review was conducted for 84 consecutive nonsyndromic postpalatoplasty patients undergoing velopharyngeal insufficiency surgery from August of 2007 to December of 2014. The demographic, perioperative, and follow-up data were collected. Statistical analyses were performed.

RESULTS

Mean age at velopharyngeal insufficiency surgery was 7.0 years. The overall improvement rate for patients was 86.9 percent. Nine patients in the double-opposing Z-plasty group and two patients in the pharyngeal flap group were refractory to velopharyngeal insufficiency surgery. The improvement rates for each surgical group were 80.4 percent for the double-opposing Z-plasty group and 94.7 percent for the pharyngeal flap group. There were no significant differences in postoperative velopharyngeal function between the coronal and noncoronal groups. Airway-associated complications were observed in nine patients (10.7 percent). The complications in the double-opposing Z-plasty group were observed in two patients (4.3 percent), and none of the patients presented obstructive sleep apnea. Seven patients (18.4 percent) in the pharyngeal flap group showed postoperative snoring, and one (2.6 percent) of them presented with obstructive sleep apnea.

CONCLUSION

The authors' algorithm is a simple patient- and surgeon-friendly strategy to obtain satisfactory improvement of velopharyngeal function for velopharyngeal insufficiency patients, with a low risk of airway complications.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Velopharyngeal videofluoroscopy: Providing useful clinical information in the era of reduced dose radiation and safety

BACKGROUND

The state of the art for correcting velopharyngeal insufficiency (VPI) is a surgical procedure which is customized according to findings on imaging procedures: multiplanar videofluoroscopy (MPVF) and flexible videonasopharyngoscopy (FVNP). Recently, the use of MPVF has been challenged because of the potential risk of using ionizing radiation, especially in children.

OBJECTIVE

To study whether using a protocol for performing MPVF can effectively decrease radiation dose in patients with VPI while providing useful information for planning surgical correction of VPI in combination with FVNP. The methodology used for performing the imaging procedures is described as well as the effectiveness of the surgical procedure.

MATERIAL AND METHODS

Eighty - nine patients (Age range = 3-17 years; median = 5.5 years) with VPI resulting from multiple etiologies were studied. All patients underwent MPVF and FVNP for planning surgical correction of VPI. Radiation dosage data in each case was recorded. Forty of the 89 patients also completed a postoperative evaluation. Eleven out of the remaining 49 patients have not completed a postoperative evaluation and 38 patients are still pending surgical correction.

RESULTS

Radiation dosage ranged from 1.00 to 8.75 miliSieverts (mSv); Mean = 2.88 mSv; SD = 1.575 mSv. Preoperative nasometry demonstrated mean nasalance ranging from 41%-95%; Mean = 72.30; SD = 4.54. Postoperatively mean nasalance was within normal limits in 36 (90%) out of 40 cases, ranging from 21% to 35%; Mean = 28.10; SD = 5.40. Nasal emission was eliminated postoperatively in all cases.

CONCLUSION

MPVF provides useful information for planning the surgical procedure aimed at correcting VPI. The combination of MPVF and FVNP is a reliable procedure for assessing velopharyngeal closure and to surgically correcting VPI with a highly successful outcome.

Profile of Patients Undergoing Gluteoplasty

BACKGROUND

Gluteal augmentation surgery has grown by 42 % per year; however, the epidemiological profile of patients who seek this treatment has never been studied.

OBJECTIVE

To establish the epidemiological profile of patients who have undergone gluteoplasty surgery, evaluating their level of satisfaction and the social impact caused by the surgery.

METHODS

Fifty patients, with ages ranging from 23 to 57 years replied to a specific questionnaire and the esthetic result of the surgery was evaluated. Thirty-seven patients were analyzed prospectively, using CT scans and gluteal reconstruction. The esthetic result was evaluated by eight plastic surgeon specialists from SBCP.

RESULTS

About satisfaction and quality of life, 98 % of the patients demonstrated improvement in some aspect of life. Analysis of the marital status of patients showed that 24 % of them have changed it. Therefore, all cases showed positive correlations between implant size and monthly income, age and satisfaction of patients. There has also been a positive correlation between implant size and recovery time. There was no statistically significant correlation between the esthetic result and the implant volume or the anthropometric measurements.

CONCLUSIONS

The epidemiological profile of patients undergoing gluteoplasty augmentation with implants is predominantly white skin, 36 years old, unrelated to the occupation or socioeconomic status. Augmentation gluteoplasty with implants is a surgery with a high level of satisfaction to patients, improving life in many aspects but, mainly, affectively. Its outcome produces a natural look and is hardly noticed by others.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.