Biomechanics of Pharyngeal Deglutitive Function following Total Laryngectomy

Functional Oral Intake in Primary Versus Salvage Laryngectomy

OBJECTIVE

Advanced-stage laryngeal squamous cell carcinoma is treated with primary surgery or chemoradiation. We aim to determine if there are differences in postoperative functional oral intake in primary (PL) versus salvage laryngectomees (SL).

STUDY DESIGN

Retrospective cohort study.

SETTING

Patients who underwent laryngectomy between 2011 and 2021.

METHODS

We examined demographic, diagnostic, treatment, and swallow function data pre- and postoperatively. A follow-up survey was distributed to assess current swallow status.

RESULTS

One hundred twenty-five patients were included. Preoperatively, 68.8% of patients reported dysphagia. Median functional oral intake score (FOIS) was 4.0 [interquartile range, IQR: 1.0-6.75]. The SL group had lower preop FOIS [2.0; IQR: 1.0-4.75] that did not reach significance compared to the PL group [4.5; IQR: 1.0-7.0] (P = .052). 73.4% of patients had a feeding tube. The PL group was more likely to have the tube removed [odds ratio, OR: 2.4; confidence interval, CI: 1.0-5.7]. The SL group was more likely to require feeding tube placement more than 6 months postop [OR: 6.9; CI: 1.65-32.6]. SL FOIS scores improved by 3 months postop to 5 (SL ΔFOIS = 3, P = .0150). PL scores improved to 7 [PL ΔFOIS = 2, P = .0005] at 12 to 15 months. Sixty-nine patients were contacted for a follow-up survey and 16 completed this survey. 30.4% patients reported dietary restrictions (mean 4.4 years postop).

CONCLUSION

Patients undergoing SL appear to obtain similar swallow outcomes compared to PL at 3 to 6 months postlaryngectomy, but plateau. The PL group continues to improve up to 1 year postoperatively. Fifty percent of patients report on-going dysphagia after 5 years.

Swallowing after total laryngectomy surgery: where are we after 150 years?

Purpose of review

Recent findings

Dysphagia is a common sequela following total laryngectomy surgery; however, there is significant variability in its assessment and management. Manometry enables an accurate understanding of the underlying mechanism of dysphagia and precise assessment of any oesophageal dysfunction. EndoFLIP is a useful tool to better understand dysfunction of the upper oesophageal sphincter particularly to detect stricture.

Summary

Following total laryngectomy surgery, dysphagia is common; clinicians need to be alert to early indicators of dysfunction and understand the tools to comprehensively characterize swallow function. Accurate diagnosis of a stricture is important, as this aspect of dysfunction can be modified, and may alleviate surrogate problems such as a leaking voice prosthesis. Clinicians should have a low threshold to examine patients for oesophageal dysfunction due to the high prevalence of dysmotility following a laryngectomy.

Dysphagia After Total Laryngectomy: An Exploratory Study and Clinical Phase II Rehabilitation Trial with the Novel Swallowing Exercise Aid (SEA 2.0)

The aims of this exploratory study and clinical phase II trial were to assess the specific nature and extent of dysphagia in laryngectomized patients with self-reported dysphagia, and its rehabilitation potential using the novel Swallowing Exercise Aid (SEA 2.0). Twenty laryngectomized patients participated in a six-week exercise program with the SEA 2.0. Exercises consisted of Chin Tuck Against Resistance (CTAR), Jaw Opening Against Resistance (JOAR), and Effortful Swallow Against Resistance, conducted three times per day. Swallowing was assessed at baseline (T0), six (T1) and 14 (T2) weeks, consisting of patient-reported outcomes, BMI, videofluoroscopy, swallowing capacity, and muscle strength measurements. Dysphagia significantly impacts quality of life, with impaired swallowing speed and bolus propulsion as main reported issues. Subjective dysphagia parameters, swallowing capacity, and pharyngeal residue clearance were reduced, but BMI was normal. Muscle and tongue strength were within normal ranges. All participants managed to use the SEA 2.0. Adherence was 95%. At T1, subjective swallowing parameters (MDADI and EAT-10) showed clinically relevant improvements. Objectively, CTAR and JOAR strength increased with 27.4 and 20.1 Newton, respectively. Also, swallowing capacity (from 2.4 g/s to 3.8 g/s) and pharyngeal residue clearance improved. At T2, results were slightly lower than at T1, but still better than at baseline. Dysphagia in laryngectomized patients affects quality of life, but swallowing can be improved with a six-week rehabilitation program using the novel SEA 2.0. Adherence was excellent and several subjective and objective swallowing parameters improved.

Toward a robust swallowing detection for an implantable active artificial larynx: a survey

Total laryngectomy consists in the removal of the larynx and is intended as a curative treatment for laryngeal cancer, but it leaves the patient with no possibility to breathe, talk, and swallow normally anymore. A tracheostomy is created to restore breathing through the throat, but the aero-digestive tracts are permanently separated and the air no longer passes through the nasal tracts, which allowed filtration, warming, humidification, olfaction, and acceleration of the air for better tissue oxygenation. As for phonation restoration, various techniques allow the patient to talk again. The main one consists of a tracheo-esophageal valve prosthesis that makes the air passes from the esophagus to the pharynx, and makes the air vibrate to allow speech through articulation. Finally, swallowing is possible through the original tract as it is now isolated from the trachea. Yet, many methods exist to detect and assess a swallowing, but none is intended as a definitive restoration technique of the natural airway, which would permanently close the tracheostomy and avoid its adverse effects. In addition, these methods are non-invasive and lack detection accuracy. The feasibility of an effective early detection of swallowing would allow to further develop an implantable active artificial larynx and therefore restore the aero-digestive tracts. A previous attempt has been made on an artificial larynx implanted in 2012, but no active detection was included and the system was completely mechanic. This led to residues in the airway because of the imperfect sealing of the mechanism. An active swallowing detection coupled with indwelling measurements would thus likely add a significant reliability on such a system as it would allow to actively close an artificial larynx. So, after a brief explanation of the swallowing mechanism, this survey intends to first provide a detailed consideration of the anatomical region involved in swallowing, with a detection perspective. Second, the swallowing mechanism following total laryngectomy surgery is detailed. Third, the current non-invasive swallowing detection technique and their limitations are discussed. Finally, the previous points are explored with regard to the inherent requirements for the feasibility of an effective swallowing detection for an artificial larynx. Graphical Abstract.

Neopharyngeal Stricture following Laryngectomy

Stricture formation is a serious complication following pharyngeal reconstruction. These strictures can be life-threatening and can severely impact quality of life. In this article, the existing literature on surgical risk factors linked to neopharyngeal stricture formation is reviewed. Intraoperative preventative measures reconstructive surgeons should consider are also discussed. Finally, this article will describe the evaluation and management of pharyngoesophageal strictures, including the challenges and options when dealing with refractory strictures.

Using high resolution manometry impedance to diagnose upper esophageal sphincter and pharyngeal motor disorders

BACKGROUND

Oro-pharyngeal pathophysiology, including upper esophageal sphincter (UES) and pharyngeal disorders, can be assessed by pharyngeal high-resolution manometry impedance (P-HRM-I). We aimed to establish methodology to diagnose disorders utilizing P-HRM-I, hypothesizing that the objective measures could be used to diagnose disordered deglutition evidenced by greater aspiration scores.

METHODS

Patients (n = 509, 18-91 years) were compared to controls (n = 120, 20-94 years). Variables measuring UES relaxation, UES opening extent, intrabolus pressure, and pharyngeal contractile strength were derived for 10 ml liquid swallows. Three associated pharyngeal pressurization patterns, which may be indicative of obstructed flow, were characterized: pan-pressurization (Type 1), distal compartmentalized pressurization (Type 2), and transient pressurization (Type 3). Deglutitive aspiration was determined from video fluoroscopy.

RESULTS

UES relaxation pressure was best able to differentiate patients from controls (T 6.528, p < 0.0001). Patients with abnormal relaxation pressure (>8 mmHg) more frequently exhibited pharyngeal pressurization patterns and had adjunct evidence of reduced luminal distensibility (high intrabolus pressure and/or reduced UES opening). Utilizing this information, a diagnostic scheme was devised identifying 138 patients with UES disorder. A further 96 patients without evidence of UES disorder had abnormally weak pharyngeal pressures, confirming propulsive disorder. Amongst a sub-sample of 320 patients undergoing video fluoroscopy, those with pharyngeal pressurizations and adjunct evidence of reduced UES relaxation and/or distensibility had higher aspiration scores (Chi-square 60.169, p < 0.0001).

CONCLUSION

P-HRM-I can provide evidence for UES disorder based on pharyngeal pressurization patterns and abnormal findings for UES relaxation pressure, UES opening, and intrabolus pressure. Measuring pharyngeal contractility requires further optimization.

Transient hypopharyngeal intrabolus pressurization patterns: Clinically relevant or normal variant?

INTRODUCTION

In oropharyngeal dysphagia, impaired pharyngoesophageal junction (PEJ) opening is reflected by an elevated hypopharyngeal intrabolus pressure (IBP), quantifiable using pharyngeal high-resolution manometry with impedance (P-HRM-I). Transient intrabolus pressurization (TP) phenomena are not sustained and last for only a brief period. We hypothesized that TP patterns reflect impaired coordination between timing of hypopharyngeal bolus arrival and PEJ relaxation.

METHODS

A retrospective audit was conducted of P-HRM-I datasets; 93 asymptomatic Controls and 214 Patients with differing etiological/clinical backgrounds were included. TP patterns were examined during 10ml liquid swallows. TP was defined by a simultaneous, non-sustained, pressurization wave spanning from the velo-/meso-pharynx to PEJ. The coordination between deglutitive pharyngeal bolus distension and PEJ relaxation timing was assessed using timing variables; (i) Distention-Contraction Latency (DCL, s) and (ii) PEJ Relaxation Time (RT, s). Resultant flow resistance was quantified (IBP, mmHg).

RESULTS

TP swallows were observed in 87 (28%) cases. DCL was not significantly different in relation to TP, while PEJ relaxation time was shorter, and IBP was higher during TP swallows. In Patients RT-DCL time difference correlated with IBP (r -0.368, p < 0.01).

CONCLUSION

Bolus distension and PEJ relaxation were miss-timed during TP swallows, impeding bolus flow and leading to a brief period of pressurization of the pharyngeal chamber by muscular propulsive forces. While TP swallows were identified in both Controls and Patients, increased IBPs were most apparent for Patient swallows indicating that the extent of IBP increase may differentiate pathological TP swallows.

Fluoroscopic Swallowing Examination: Radiologic Findings and Analysis of Their Causes and Pathophysiologic Mechanisms

Dysphagia is a common symptom in the general population, and its prevalence increases with patient age. The deterioration of swallowing function has many acute and chronic causes, including cerebrovascular and neuromuscular diseases, radiation, and surgery. In an elderly population, diagnosis and treatment of swallowing abnormalities is a high priority because it improves the patient's quality of life and helps them to avoid medical complications. Fluoroscopic swallowing examinations and modified barium swallow studies are the most used and most reliable diagnostic procedures to evaluate swallowing disorders. Functional anomalies include disturbances of the oral preparatory, oral propulsory, and pharyngeal phases of swallowing as premature spillage from the mouth, nasal regurgitation, delayed initiation of pharyngeal swallowing, incomplete displacement of the hyolaryngeal complex, abnormal epiglottic tilt, incomplete laryngeal closure, and pharyngeal dysmotilities. Anatomic abnormalities of the pharynx include diverticula, benign strictures, and tumors. The abnormalities diagnosed on the basis of fluoroscopic examination have a variety of treatment strategies, and the choice of treatment depends on the cause of the anomaly and its pathophysiologic characteristics. The radiologist's interpretation of these characteristics is crucial to therapeutic decision making and achieving the best patient outcomes. Online supplemental material is available for this article. ^©RSNA, 2021.

Biomechanics of the tongue during swallowing after total laryngectomy: an integrative review

PURPOSE

To synthesize the state of scientific knowledge about biomechanics of the tongue during swallowing after total laryngectomy.

RESEARCH STRATEGY

The PICO question and combinations of descriptors and single terms were formulated in the PubMed/Medline, EMBASE, LILACS, and SciELO databases.

SELECTION CRITERIA

Articles in Portuguese, English, or Spanish were included, without time limit, with results on the biomechanics of the tongue during swallowing and total laryngectomy, and studies on randomized or non-randomized clinical trials, cohort, case control, cross-sectional, case series, and case studies.

DATA ANALYSIS

year, country, population, objective, study design, assessment methods, main outcomes, and methodological quality were analyzed.

RESULTS

There were four studies in the United States, one in Australia, and one in Brazil, all published between 1986 and 2014. In all studies, the biomechanics of the tongue was the secondary outcome. Most articles had low methodological quality, small samples, predominance of the male gender, and a prevalent cross-sectional design. The assessment instruments were fluoroscopy, manometry, accelerometer or a device to capture tongue pressure. Main results indicated a higher propulsion force of the tongue base to overcome the high resistance of the neopharynx to the bolus flow, reduced contact and pressure between the base of the tongue and the posterior pharyngeal wall, residues in the tongue base after swallowing, increased pressure, and reduced resistance of the oral tongue.

CONCLUSION

There are indications of compensatory tongue movements during swallowing after total laryngectomy; however, the scientific evidence is insufficient.

European white paper: oropharyngeal dysphagia in head and neck cancer

PURPOSE

To develop a European White Paper document on oropharyngeal dysphagia (OD) in head and neck cancer (HNC). There are wide variations in the management of OD associated with HNC across Europe.

METHODS

Experts in the management of specific aspects of OD in HNC across Europe were delegated by their professional medical and multidisciplinary societies to contribute to this document. Evidence is based on systematic reviews, consensus-based position statements, and expert opinion.

RESULTS

Twenty-four sections on HNC-specific OD topics.

CONCLUSION

This European White Paper summarizes current best practice on management of OD in HNC, providing recommendations to support patients and health professionals. The body of literature and its level of evidence on diagnostics and treatment for OD in HNC remain poor. This is in the context of an expected increase in the prevalence of OD due to HNC in the near future. Contributing factors to increased prevalence include aging of our European population (including HNC patients) and an increase in human papillomavirus (HPV) related cancer, despite the introduction of HPV vaccination in various countries. We recommend timely implementation of OD screening in HNC patients while emphasizing the need for robust scientific research on the treatment of OD in HNC. Meanwhile, its management remains a challenge for European professional associations and policymakers.

Comparison of Pharyngoesophageal Segment Biomechanics Between Persons with Total Laryngectomy With and Without Dysphagia Using sEMG: A Multicentric Swallow Study

Total laryngectomy (TL) is the surgical treatment option for advanced stage of laryngeal cancer, involving the removal of larynx along with several muscles attached to it. Several anatomical changes occur following the surgery which will in turn affect the swallowing mechanism. The severing of the cricopharyngeus muscle, which is an important muscle of the pharyngoesophageal segment (PES), may lead to dysphagia. Several other causes have also been explained in the literature. Several invasive instruments have been used to identify dysphagia in this population. The present study aimed to identify the differences in the biomechanics of the PES during dry and wet swallow tasks in persons with TL with and without dysphagia. Amplitude and duration of movement of PES was analysed using a non-invasive instrumental method surface electromyography. The results indicate that amplitude of PES movement was significantly higher in dysphagic group for solids and semisolids. A significantly longer duration was observed for solid consistency for dysphagic group when compared to non-dysphagic group. sEMG evidences suggestive of differences in amplitude and duration between the TL with and without dysphagia groups. Findings also revealed that TL with dysphagia group require more effort to swallow solids and semisolid consistencies when compared to the effort exerted by them during liquid and dry swallow.

The relationship between biomechanics of pharyngoesophageal segment and tracheoesophageal phonation

This study examined the relationship between biomechanical features of the pharyngoesophageal (PE) segment, acoustic characteristics of tracheoesophageal (TE) phonation, and patients’ satisfaction with TE phonation. Fifteen patients using TE phonation after total laryngectomy completed the Voice Symptom Scale (VoiSS) and underwent acoustic voice analysis for cepstral peak prominence (CPP) and relative intensity. High resolution manometry (HRM) combined with videofluoroscopy was used to evaluate PE segment pressure and calculate the pressure gradient (ΔP), which was the pressure difference between the upper oesophagus and a point two centimetres above the vibrating PE segment. The upper oesophageal sphincter (UOS) minimal diameters were measured by Endolumenal Functional Lumen Imaging Probe (EndoFLIP). HRM detected rapid pressure changes at the level of the 4th – 6th cervical vertebra. CPP, relative intensity, and ΔP were significant predictors of satisfactory TE phonation. ΔP was a significant predictor of CPP and intensity. Minimal UOS diameter was a significant predictor of relative intensity of TE phonation. In two patients with unsuccessful TE phonation, endoscopic dilatation subsequently restored TE phonation. These findings suggest that sufficient ΔP and large UOS diameter are required for satisfactory TE phonation. Endoscopic dilatation increasing UOS diameter may provide a new approach to treat unsuccessful TE phonation.

High-Resolution Pharyngeal Manometry and Impedance: Protocols and Metrics-Recommendations of a High-Resolution Pharyngeal Manometry International Working Group

High-resolution manometry has traditionally been utilized in gastroenterology diagnostic clinical and research applications. Recently, it is also finding new and important applications in speech pathology and laryngology practices. A High-Resolution Pharyngeal Manometry International Working Group was formed as a grass roots effort to establish a consensus on methodology, protocol, and outcome metrics for high-resolution pharyngeal manometry (HRPM) with consideration of impedance as an adjunct modality. The Working Group undertook three tasks (1) survey what experts were currently doing in their clinical and/or research practice; (2) perform a review of the literature underpinning the value of particular HRPM metrics for understanding swallowing physiology and pathophysiology; and (3) establish a core outcomes set of HRPM metrics via a Delphi consensus process. Expert survey results were used to create a recommended HRPM protocol addressing system configuration, catheter insertion, and bolus administration. Ninety two articles were included in the final literature review resulting in categorization of 22 HRPM-impedance metrics into three classes: pharyngeal lumen occlusive pressures, hypopharyngeal intrabolus pressures, and upper esophageal sphincter (UES) function. A stable Delphi consensus was achieved for 8 HRPM-Impedance metrics: pharyngeal contractile integral (CI), velopharyngeal CI, hypopharyngeal CI, hypopharyngeal pressure at nadir impedance, UES integrated relaxation pressure, relaxation time, and maximum admittance. While some important unanswered questions remain, our work represents the first step in standardization of high-resolution pharyngeal manometry acquisition, measurement, and reporting. This could potentially inform future proposals for an HRPM-based classification system specifically for pharyngeal swallowing disorders.

High-resolution manometry: what about the pharynx?

PURPOSE OF REVIEW

High-resolution pharyngeal manometry (HRPM) is a well tolerated, catheter-based, method for recording the pressures and bolus flow generated by the pharyngeal muscles during swallowing. Despite a body of published evidence and a critical mass of investigators in the field, there is a lack of consensus surrounding what biomechanical phenomena to measure. The purpose of this review is to provide some insights into the information on swallowing physiology that can be gathered using HRPM.

RECENT FINDINGS

HRPM literature has focused on measuring biomechanical phenomena that may be relevant to measure in relation to dysphagia research. This review focuses on the measurement of pharyngeal luminal occlusive forces, intrabolus distension pressure, bolus presence and bolus flow timing as key features of pharyngeal swallowing that require measurement and allow for derivation of the Swallow Risk Index, a global measure of swallow function indicative of swallowing functional reserve.

SUMMARY

HRPM allows objective derivation of measures of swallow function that may have value for diagnosis and research in relation to swallowing disorders. HRPM has demonstrated clinical applicability in specific patient populations and offers unique advantages that compliment current assessment methods.

A systematic review of current methodology of high resolution pharyngeal manometry with and without impedance

PURPOSE

This systematic review appraises and summaries methodology documented in studies using high resolution pharyngeal manometry (HRM) with and without impedance technology (HRIM) in adult populations.

METHODS

Four electronic databases CINAHL, EMBASE, MEDLINE, and Cochrane Library were searched up to, and including March 2017. Studies reporting pharyngeal HRM/HRIM for swallowing and/or phonatory assessment, published in peer-reviewed journals in English, German, or Spanish were assessed for the inclusion criteria. Of the selected studies, methodological aspects of data acquisition and analysis were extracted. Publications were graded based on their level of evidence and quality of methodological aspects was assessed.

RESULTS

Sixty-two articles were identified eligible, from which 50 studies reported the use of HRM and 12 studies used HRIM. Of all included manuscripts, the majority utilized the ManoScan™ system (64.5%), a catheter diameter of 4.2 mm was most prevalently documented (30.6%). Most publications reported the application of topical anesthesia (53.2%). For data analysis in studies using HRM, software intrinsic to the recording system was reported most frequently (56%). A minority of the studies using HRM provided data about measurement reliability (10%). This is higher for studies using HRIM (50%).

CONCLUSIONS

Considerable methodological variability exists regarding data acquisition and analysis in published studies using HRM/HRIM. Lacking reports of methodology make study replications difficult and reduce the comparability across studies. More data regarding the impact of individual methodological aspects on study outcomes are further required for the development of methodological recommendations.

Diagnosis and treatment of oropharyngeal dysphagia after total laryngectomy with or without pharyngoesophageal reconstruction: Systematic review

Background

This systematic review qualitatively summarizes the current literature on diagnosis and treatment of oropharyngeal dysphagia (OD) after total laryngectomy (TLE).

Methods

Electronic databases PubMed, Embase, and the Cochrane Library were used. Two independent reviewers carried out the literature search and assessed the methodological quality of the included studies using a critical appraisal tool.

Results

Forty‐four articles met the inclusion criteria. Of these, 35 studies were on diagnosis, four on therapy, and five on both diagnosis and treatment of OD following TLE. Study aims, swallowing‐assessment methods, and main findings of the included studies were summarized and presented.

Conclusions

The reviewers found heterogeneous outcomes and serious methodological limitations, which prevented us from pooling data to identify trends that would assist in designing best clinical practice protocols for OD following TLE. Further research should focus on several remaining gaps in our knowledge on diagnosis and treatment interventions for OD following TLE.

Pathophysiology of swallowing following oropharyngeal surgery for obstructive sleep apnea syndrome

BACKGROUND

Uvulopalatopharyngoplasty (UPPP) and coblation channeling of the tongue (CCT) are oropharyngeal surgeries used to treat obstructive sleep apnea syndrome. The extent to which UPPP and CCT affect pharyngeal swallow has not been determined. We therefore conducted a novel case series study employing high-resolution impedance manometry (HRIM) to quantify the swallowing-related biomechanics following UPPP and/or CCT surgery.

METHODS

Twelve patients who underwent UPPP+CCT or CCT only were assessed an average 2.5 years postsurgery. Swallow function data were compared with ten healthy controls. All patients completed the Sydney swallow questionnaire (SSQ). Pharyngeal pressure-flow analysis of HRIM recordings captured key distension, contractility and pressure-flow timing swallow parameters testing 5, 10, and 20 mL volumes of thin and thick fluid consistencies.

KEY RESULTS

Postoperative patients had more dysphagia symptoms with five returning abnormal SSQ scores. Swallowing was biomechanically altered compared to controls, consistent with diminished swallowing reserve, largely driven by elevated hypopharyngeal intrabolus pressure due to a reduced capacity to open the upper esophageal sphincter to accommodate larger volumes.

CONCLUSIONS & INFERENCES

Patients who have undergone UPPP and/or CCT surgery appear to have a deficiency in normal modulation of the swallowing mechanism and a reduced swallowing functional reserve. We speculate that these changes may become relevant in later life with the onset of age-related stressors to the swallowing mechanism. This case series strikes a note of caution that further studies are needed to determine the role of preoperative swallow assessment in patients undergoing UPPP and/or CCT surgery.

Diagnosis of Swallowing Disorders: How We Interpret Pharyngeal Manometry

PURPOSE OF REVIEW

We provide an overview of the clinical application of novel pharyngeal high-resolution impedance manometry (HRIM) with pressure flow analysis (PFA) in our hands with example cases.

RECENT FINDINGS

In our Centre, we base our interpretation of HRIM recordings upon a qualitative assessment of pressure-impedance waveforms during individual swallows, as well as a quantitative assessment of averaged PFA swallow function variables. We provide a description of two global swallowing efficacy measures, the swallow risk index (SRI), reflecting global swallowing dysfunction (higher SRI = greater aspiration risk) and the post-swallow impedance ratio (PSIR) detecting significant post-swallow bolus residue. We describe a further eight swallow function variables specific to the hypopharynx and upper esophageal sphincter (UES), assessing hypo-pharyngeal distension pressure, contractility, bolus presence and flow timing, and UES basal tone, relaxation, opening and contractility. Pharyngeal HRIM has now come of age, being applicable for routine clinical practice to assess the biomechanics of oropharyngeal swallowing dysfunction. In the future, it may guide treatment strategies and allow more objective longitudinal follow-up on clinical outcomes.