Chieh-Han John Tzou

Comparison of three-dimensional surface-imaging systems

BACKGROUND In recent decades, three-dimensional (3D) surface-imaging technologies have gained popularity worldwide, but because most published articles that mention them are technical, clinicians often have difficulties gaining a proper understanding of them. This article aims to provide the reader with relevant information on 3D surface-imaging systems. In it, we compare the most recent technologies to reveal their differences. METHODS We have accessed five international companies with the latest technologies in 3D surface-imaging systems: 3dMD, Axisthree, Canfield, Crisalix and Dimensional Imaging (Di3D; in alphabetical order). We evaluated their technical equipment, independent validation studies and corporate backgrounds. RESULTS The fastest capturing devices are the 3dMD and Di3D systems, capable of capturing images within 1.5 and 1 ms, respectively. All companies provide software for tissue modifications. Additionally, 3dMD, Canfield and Di3D can fuse computed tomography (CT)/cone-beam computed tomography (CBCT) images into their 3D surface-imaging data. 3dMD and Di3D provide 4D capture systems, which allow capturing the movement of a 3D surface over time. Crisalix greatly differs from the other four systems as it is purely web based and realised via cloud computing. CONCLUSION 3D surface-imaging systems are becoming important in todays plastic surgical set-ups, taking surgeons to a new level of communication with patients, surgical planning and outcome evaluation. Technologies used in 3D surface-imaging systems and their intended field of application vary within the companies evaluated. Potential users should define their requirements and assignment of 3D surface-imaging systems in their clinical as research environment before making the final decision for purchase.

Dynamic reconstruction of eye closure by muscle transposition or functional muscle transplantation in facial palsy.

For patients with facial palsy, lagophthalmus is often a more serious problem than the inability to smile. Dynamic reconstruction of eye closure by muscle transposition or by free functional muscle transplantation offers a good solution for regaining near-normal eye protection without the need for implants. This is the first quantitative study of three-dimensional preoperative and postoperative lid movements in patients treated for facial paralysis. Between February of 1998 and April of 2002, 44 patients were treated for facial palsy, including reconstruction of eye closure. Temporalis muscle transposition to the eye was used in 34 cases, and a regionally differentiated part of a free gracilis muscle transplant after double cross-face nerve grafting was used in 10 cases. Patients’ facial movements were documented by a three-dimensional video analysis system preoperatively and 6, 12, 18, and 24 months postoperatively. For this comparative study, only the data of patients with preoperative and 12-month postoperative measurements were included. In the 27 patients with a final result after temporalis muscle transposition for eye closure, the distance between the upper and lower eyelid points during eye closing (as for sleep) was reduced from 10.33 ± 2.43 mm (mean ± SD) preoperatively to 5.84 ± 4.34 mm postoperatively on the paralyzed side, compared with 0.0 ± 0.0 mm preoperatively and postoperatively on the contralateral healthy side. In the resting position, preoperative values for the paralyzed side changed from 15.11 ± 1.92 mm preoperatively to 13.46 ± 1.94 mm postoperatively, compared with 12.17 ± 2.02 mm preoperatively and 12.05 ± 1.95 mm postoperatively on the healthy side. In the nine patients with a final result after surgery using a part of the free gracilis muscle transplant reinnervated by a zygomatic branch of the contralateral healthy side through a cross-face nerve graft, eyelid closure changed from 10.21 ± 2.72 mm to 1.68 ± 1.35 mm, compared with 13.70 ± 1.56 mm to 6.63 ± 1.51 mm preoperatively. The average closure for the healthy side was from 11.20 ± 3.11 mm to 0.0 ± 0.0 mm preoperatively and from 12.70 ± 1.95 mm to 0.0 ± 0.0 mm postoperatively. In three cases, the resting tonus of the part of the gracilis muscle transplant around the eye had increased to an extent that muscle weakening became necessary. Temporalis muscle transposition and free functional muscle transplantation for reanimation of the eye and mouth at the same time are reliable methods for reconstructing eye closure, with clinically adequate results. Detailed analysis of the resulting facial movements led to an important improvement of the authors’ operative techniques within the last few years. Thus, the number of secondary operative corrections could be significantly reduced. These qualitative and quantitative studies of the reconstructed lid movements by three-dimensional video analysis support the authors’ clinical concept of temporalis muscle transposition being the first-choice method in adult patients with facial palsy. In children, free muscle transplantation is preferred for eye closure, so as not to interfere with the growth of the face by transposition of a masticatory muscle. In addition, a higher degree of central plasticity in children might be expected.

Three-dimensional video analysis of the paralyzed face reanimated by cross-face nerve grafting and free gracilis muscle transplantation: quantification of the functional outcome.

Background: Surgeons have found it difficult to quantify facial paralysis and its improvement by reconstructive surgery. This article presents the results achieved by free functional muscle transplantation for reconstruction of the paralyzed face, registered by three-dimensional video analysis of facial movements. Methods: Of patients treated consecutively between 1997 and 2006, two groups were constituted: group 1 comprised 22 patients with reinnervation completed after a single cross-face nerve graft and a free gracilis muscle graft for reconstruction of the smile; group 2 comprised nine patients treated with two cross-face nerve grafts followed by a territorially differentiated gracilis muscle transplant for reconstruction of the smile and eye closure. Smiling with showing teeth, maximal showing of teeth, and closing the eyes as in sleep were analyzed in detail. Results: In group 1, static asymmetry was reduced from 12.19 ± 8.73 mm preoperatively to −1.84 ± 7.67 mm at 18 months postoperatively. Smile amplitude increased from 9 to 60 percent of that on the healthy side in 10 incomplete facial palsies of this group, and from 0 to 62 percent in eight functionally successful muscle grafts among 11 patients with complete lesions. In group 2, static asymmetry improved from 7.24 ± 12.64 mm to −5.36 ± 9.07 mm; the overcorrection was intentional. Movement was improved in eight cases. Smile amplitude reached 68 ± 43 percent of that on the normal side. Lagophthalmus improved from 7.21 ± 3.59 mm to 1.38 ± 2.49 mm. All improvements were statistically significant (p ≤ 0.05). Conclusions: Three-dimensional video analysis provided an exact quantitative documentation of the degree of facial palsy preoperatively and the reconstructed movements. The value of free functional gracilis muscle transplantation was demonstrated for both variations of the technique.

Evolution of the 3-dimensional video system for facial motion analysis: ten years' experiences and recent developments.

AbstractSince the implementation of the computer-aided system for assessing facial palsy in 1999 by Frey et al (Plast Reconstr Surg. 1999;104:2032–2039), no similar system that can make an objective, three-dimensional, quantitative analysis of facial movements has been marketed.This system has been in routine use since its launch, and it has proven to be reliable, clinically applicable, and therapeutically accurate. With the cooperation of international partners, more than 200 patients were analyzed. Recent developments in computer vision—mostly in the area of generative face models, applying active-appearance models (and extensions), optical flow, and video-tracking—have been successfully incorporated to automate the prototype system.Further market-ready development and a business partner will be needed to enable the production of this system to enhance clinical methodology in diagnostic and prognostic accuracy as a personalized therapy concept, leading to better results and higher quality of life for patients with impaired facial function.

The combination of muscle transpositions and static procedures for reconstruction in the paralyzed face of the patient with limited life expectancy or who is not a candidate for free muscle transfer.

Background: In long-standing complete and irreversible facial palsy where reconstruction by nerve grafting alone is no longer sufficient, reconstruction by dynamic procedures such as muscle transplantation or muscle transposition is required. The authors present the results obtained by regional muscle transposition for reconstruction of eye closure and smile in patients with irreversible facial palsy. Methods: Twenty-nine patients treated by temporalis transposition for the eye and eight patients treated by masseter transposition for the mouth are presented. Assessment of outcome was based on clinical examination and analysis of facial movements by three-dimensional video analysis. Results: Preoperatively, the paretic eye fissure was on average 2.30 ± 2.17 mm wider than the healthy one. The difference was reduced postoperatively to 0.95 ± 1.89 mm. Paralytic lagophthalmus during closure of the eyes was 9.59 ± 3.03 mm preoperatively and was reduced postoperatively to 4.33 ± 2.68 mm. Ocular tearing and desiccation were reduced drastically in all patients. Static asymmetry of the mouth corner improved from 14.17 ± 5.26 mm preoperatively to 5.38 ± 3.23 mm postoperatively. The index of dynamic symmetry improved from −0.17 ± 0.25 preoperatively to 0.18 ± 0.19 postoperatively. This means that, postoperatively, the amplitude of motion on the reconstructed side reached 18 ± 19 percent that of the amplitude on the healthy side, whereas preoperatively a shift of the paralyzed mouth corner toward the healthy side occurred. Conclusions: Muscle transposition improves static symmetry and provides dynamic activity to a certain degree. It is therefore a valuable concept for patients with limited life expectancy.

Evaluation of facial reconstructive surgery on patients with facial palsy using optical strain

We explore marker-less tracking methods for the purpose of evaluating the efficacy of facial re-constructive surgery on patients with facial palsies. After experimenting with several optical flow methods, we choose an approach that results in less than 2 pixels in tracking error for 15 markers tracked on the face. A novel method is presented that utilizes the non-rigid deformation observed on facial skin tissue to visualize the severity of facial paralysis. Results are given on a dataset that contains three videos of an individual recorded using a standard definition camera both before and after undergoing facial reconstructive surgery over a period of three years.

Bridging Peripheral Nerve Defects Using a Single-fascicle Nerve Graft

Background: The criterion standard of nerve reconstruction is an autologous nerve graft, identical in cross-section to the severed nerve stumps. This study investigates single-fascicle nerve transplantation to bridge nerve defects. Methods: Forty female Sprague-Dawley rats, each weighing approximately 225 g, were randomized into five groups. Groups A and B were the positive and negative control groups, respectively. In the experimental groups (groups C, D, and E), a nerve defect of 25 mm was created in the right sciatic nerve and reconstructed with a reversed sciatic nerve graft, a three-fascicle sural nerve graft, or a single-fascicle sural nerve graft, respectively. Results: Functional muscle evaluation of the triceps surae differed significantly among the reverse nerve (group C, n = 10; 600 ± 154.16 mN), triple-fascicle (group D, n = 10; 411 ± 262 mN), and single-fascicle (group E, n = 10; 324 ± 215.8 mN) graft groups (p < 0.05). The results of retrograde labeling of the reverse nerve group (group C, 518 ± 2) showed that there were twice as many motor neurons as in the three-fascicle nerve group (group D, 221 ± 19). In the single-fascicle nerve group, motor neurons were scarce and faintly labeled (group E, 180 ± 25). Conclusion: The results showed that single-fascicle nerve grafting has potential for good functional nerve regeneration.

Longitudinal Gliding of the Median Nerve in the Carpal Tunnel: Ultrasound Cadaveric Evaluation of Conventional and Novel Concepts of Nerve Mobilization

OBJECTIVE To evaluate median nerve excursion during conventional nerve gliding exercises and newly developed exercises, primarily comprising abduction and adduction of the fingers. DESIGN Descriptive study. SETTING Anatomical dissection facility. CADAVERS Random sample of upper extremities of fresh whole-body human cadavers (N=18). Cadavers with neuromuscular diseases in the medical record or anatomic variations were excluded. INTERVENTION Conventional and new nerve gliding exercises. MAIN OUTCOME MEASURES Distances between markers applied into the nerve and markers in the periosteum were visualized with ultrasound and measured. Comparisons of nerve excursions between different exercises were performed. RESULTS Conventional exercises led to substantial nerve gliding proximal to the carpal tunnel and between the head of the pronator teres (12 and 13.8mm, respectively), but it led to far less in the carpal tunnel (6.6mm). With our novel exercises, we achieved nerve gliding in the carpal tunnel of 13.8mm. No substantial marker movement could be detected during lateral flexion of the cervical spine. CONCLUSIONS Although conventional nerve gliding exercises only lead to minimal nerve excursions in the carpal tunnel, our novel exercises with the abduction and adduction of the fingers result in substantial longitudinal gliding throughout the arm. Clinical trials will have to deliver the clinical evidence.

Correlation of functional recovery with the course of electrophysiological parameters after free muscle transfer for reconstruction of the smile in irreversible facial palsy.

Introduction: The aim of this study was to determine whether processes of denervation and reinnervation, as measured by electrodiagnostic methods, correlate with clinical function, as measured by three‐dimensional (3D) video analysis and whether electrodiagnostic data can serve as a prognostic indicator. Methods: Eighteen patients with facial palsy were investigated by 3D video analysis, needle electromyography, and electrical muscle testing at 6, 12, and 18 months after free muscle transplantation for smile reconstruction. Results: Electrophysiological parameters determined 6 months postoperatively correlated significantly with the index of dynamic symmetry 12 and 18 months postoperatively. Conclusions: Processes of reinnervation can be detected earlier by electrophysiological analysis than by quantified clinical analysis. Pathological spontaneous activity alone and combined assessment with motor unit action potentials in the early postoperative stage are strong prognostic indicators. Muscle Nerve, 2011

Facial synkinesia before and after surgical reanimation of the paralyzed face.

Background: Facial synkinesia is a common sequela of facial palsy, affecting 15 to 20 percent of patients. The rate of postoperative synkinesia after facial reanimation is not clearly established. The severity and type of synkinesia determine the degree of clinical relevance. Methods: One hundred sixty-seven patients with facial palsy were included in this retrospective cohort study. Three-dimensional video analysis of facial movements was performed preoperatively and 18 months after facial reanimation. The severity of synkinesia was rated subjectively on a four-degree severity scale. Objective three-dimensional analysis of synkinesia was performed on patients with 18-month follow-up times. Results: Preoperatively, 84.4 percent of patients were not affected by synkinesia, 9 percent presented with mild synkinesia, 4.2 percent presented with moderate synkinesia, and 2.4 percent presented with severe synkinesia. Postoperatively, 51 percent of all patients presented with facial synkinesia (41.8 percent mild, 17.3 percent moderate, and 1 percent severe synkinesia; some patients had more than one type). Patients treated with territorially differentiated gracilis muscle transplantation were most frequently affected (69.8 percent), followed by patients treated with gracilis muscle transplantation in combination with temporalis muscle transposition to the eye (51.8 percent). Oculo-oral synkinesia was the most frequent form of synkinesia. Conclusions: After surgical reanimation of the paralyzed face, half of the patients presented with synkinesia. The majority of patients developed mild or moderate forms of synkinesia; therefore, the clinical relevance of synkinesia has to be seen in the context of total facial function. Because of the high prevalence of synkinesia, it should be documented and addressed in patients undergoing facial reanimation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.