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Featured researches published by Duck Sun Ahn.


Annals of Plastic Surgery | 2000

A prospective study of the anatomic variations of the median nerve in the carpal tunnel in asians

Duck Sun Ahn; Eul Sik Yoon; Sang Hwan Koo; Seung Ha Park

&NA; A prospective study of anatomic variations of the median nerve and its relationship to the surrounding structures was performed of 354 consecutive operations in 192 patients with carpal tunnel syndrome at Korea University Anam Hospital from July 1995 to September 1997. A total of 184 patients were women and 8 patients were men. A total of 162 patients were bilateral and 30 were unilateral. Regarding the course of the motor branch, the extraligamentous type was most common (96.1%, 340 patients). A total of 81.1% of patients (N = 287) had the origin of the motor branch at the radial side of the median nerve (or radial one third), and 17.2% of patients (N = 61) had the origin of the motor branch at the anterior portion of the median nerve. Of these 61 patients, 30 patients (49.1%) were of the preligamentous type. Only one motor nerve branch was found in 89.5% of patients (N = 317), and multiple branches were found in 10.5% of patients. As a result of the comparison between two hands when both hands were operated, the origin and number of motor branches and their courses were identical in most patients (>60%). Hypertrophy of the flexor pollicis brevis was found in 8.5% of patients (N = 30), hypertrophy of the palmaris brevis was found in 4.2% of patients (N = 15), absence of the palmaris longus was discovered in 0.6% of patients (N = 2), existence of the median artery was found in 0.6% of patients (N = 2), and high division of the median nerve rejoining with the thenar motor nerve was found in 0.3% of patients (N = 1). Clearly, the anatomy of the carpal tunnel in Koreans is somewhat different, in part, from the results obtained from studies of whites, but overall results are not significantly different. These results can help obtain a better surgical outcome and complete decompression of the median nerve during operation while preventing inappropriate or inadvertent injury to the motor branch of the median nerve in Koreans. Ahn DS, Yoon ES, Koo SH, Park SH. A prospective study of the anatomic variations of the median nerve in the carpal tunnel in Asians. Ann Plast Surg 2000;44:282‐287


Medical Education | 2009

Developing a Korean communication skills attitude scale: comparing attitudes between Korea and the West

Sowon Ahn; Yeong Houn Yi; Duck Sun Ahn

Objectives  We aimed to develop a Korean version of the Communication Skills Attitude Scale (CSAS) created by Rees et al. in order to elucidate the positive and negative aspects of Korean pre‐medical and medical students’ attitudes towards communication skills (CS) learning.


Aesthetic Plastic Surgery | 2001

Laser punch-out for acne scars.

Sang Hwan Koo; Eul Sik Yoon; Duck Sun Ahn; Seung Ha Park

Abstract. Patients with acne scars want smooth facial skin. However, achieving this is difficult with dermabrasion or chemical peeling. Nor can acne scars be covered with cosmetics, due to their ice-picked or cobblestone appearance. Laser resurfacing is more effective and safer than other conventional methods due to its precision with depth control and variable methods of surface cutting. Even depth resurfacing with a laser shows unsatisfactory results, therefore, for the deep-sited acne scar the cutting methods have to be changed according to the depth and pattern of the scar. For 2 years, starting in January 1996, we treated 71 patients with a high-powered CO2 laser (Ultrapulse). Different resurfacing methods were applied according to the depth and pattern of the scars. For mild depressed scars, even depth resurfacing was done. For moderate-depth acne scars, the shoulder technique was also used. For the deepest and ice-picked scars, the laser punch-out was combined. Laser resurfacing was carried out at 300–500 mJ, with two to five passes. Laser punch-out was done at 500 mJ, with three to seven continuous passes on the ice-picked scar. From the pathologic findings of acne scars showing that there was thick intradermal scar, we knew that laser punch-out was necessary for improvement of acne scars. Depth-wide, the ice-picked scars improved by over 80% and the sharp demarcated margin of the acne scar faded out. Most of the patients with acne scars were satisfied with laser resurfacing. Only six patients had a second laser treatment, with an interval of 12 months. There were no hypertrophic scars after laser resurfacing, but erythema lasted for 3–12 months. Patients taking oral retinoic acid were not contraindicated for laser resurfacing but required special caution because they had atrophic skin and delayed wound healing. Laser resurfacing is the most versatile method for acne scars, with a high-powered CO2 laser. The laser punch-out method is better than even depth resurfacing for improving deep acne scars and can be combined with the shoulder technique or even depth resurfacing according to the type of acne scar.


Plastic and Reconstructive Surgery | 1999

Report of phenol peel for Asians.

Eul Sik Yoon; Duck Sun Ahn

With the advancement of trichloroacetic acid peel technology and wound care, trichloroacetic acid peeling has become very successful in Korea. Its success has opened studies on the possibility of using phenol on Korean skin. Dr. Mees phenol formula (molding mask technique) was chosen for experiments on Korean skin because of the presumed safety of use on non-Caucasian skin. Between January of 1996 and January of 1998, 30 cases of significant small pox scars were treated with phenol at the Korea University Anam Hospital. The age range was from 43 to 60 years, with a mean of 49 years. The average follow-up period was 13 months, ranging from 1 month to 2 years. All of the procedures were performed in the operating room while the patient was under deep i.v. sedation. After the entire face was peeled, it was covered with an occlusive tape mask. During the recovery period, the patients underwent a post-peel skin care program. All 30 patients showed significant improvement of the severe pox marks with a marked rejuvenation effect. There was no sign of hypopigmentation or hyperpigmentation. As a complication, two patients developed hypertrophic scars on the perioral area, which responded well to steroid injections. Another pair of patients had herpetic infection, which left minimal scarring. Five patients developed cardiac arrhythmia with this rapid technique, but this was safely managed by an anesthesiologist during the procedure. Korean skin belongs to Fitzpatrick types IV and V and occasionally to type III or VI. It is common knowledge that performing chemical peeling on the latter types of skin is dangerous, but in this report, excellent results were obtained from all 30 patients, even though the peeling itself was very deep. With more knowledge and experience, phenol peel can be safely conducted on Asian skin.


Annals of Plastic Surgery | 2001

The outcome of the nonoperated contralateral hand in carpal tunnel syndrome.

Eul Sik Yoon; Hee Kyu Kwon; Hang Jae Lee; Duck Sun Ahn

It is not well known how the nonoperated contralateral hand behaves in bilateral carpal tunnel syndrome (CTS). The postoperative clinical course of the nonoperated contralateral hand in unilateral CTS is not well documented either. Of 324 CTS patients, the authors studied 37 who had carpal tunnel release on one hand only to evaluate the postoperative outcome of the nonoperated contralateral hand. The other 287 patients had operations on both hands. Seven patients were excluded because of missing data or because they could not be contacted. All 324 patients were subject to clinical and electrodiagnostic studies on both hands. The patients were divided into three groups. Group I was composed of patients who had bilateral CTS, diagnosed clinically and electrophysiologically, but who had surgery done only on the hand with the most pronounced symptoms. The patients in group II showed symptoms of CTS in one hand only. However, the opposite hand was diagnosed with subclinical CTS: Electrodiagnostic studies showed involvement of the median nerve, but without symptoms. Group III was composed of true unilateral CTS patients, diagnosed by symptoms and electrodiagnostic study. The results of the electrodiagnosis were categorized according to the severity of median nerve damage (mild, moderate, severe). The outcome and postoperative clinical course of the nonoperated contralateral hand were evaluated by electromyography and telephone survey. This method of survey was used because of the vast spread of patients throughout the country. Within 1 year, all 30 operated hands showed significant improvement, 20 of which belonged to group I. Regarding progress of the nonoperated contralateral hand, 10 patients showed improvement of one grade whereas 5 patients showed three grades of improvement. In another 5 patients there was no change whatsoever. In addition, from groups II and III there were 5 patients who showed no change in the nonoperated hand. The postoperative electromyographic findings of the nonoperated contralateral hand was not commensurate with the symptoms. However, regardless of electromyographic results, the nonoperated contralateral hand showed significant improvement (p < 0.0001). Patients with unilateral CTS did not experience any symptom development in the nonoperated contralateral hand.


Medical Teacher | 2006

The OSCE: a new challenge to the evaluation system in Korea

Young Mee Lee; Duck Sun Ahn

Introduced in Korea in 1994, the number of medical schools using Objective Structured Clinical Examination (OSCE) and standardized patients (SPs) has been steadily increasing. Although OSCE is accepted as an effective teaching and evaluation tool in Korea, many challenges in applying OSCE remain. These problems stem mainly from differences in the educational environment and infrastructure in medical schools between different countries. To reduce trial and error cost inefficiencies and to help accelerate the adaptation process, sharing experiences at all levels of applying OSCE to non-Western settings would be valuable. The authors describe how and to what extent the OSCE has been applied to the Korean medical education system. Additionally, the elements that should be in place for OSCE to successfully transform the national licensure examination into a high stakes examination are described.


Annals of Plastic Surgery | 2002

Correction of blepharoptosis in oculopharyngeal muscular dystrophy

Dong Hee Kang; Sang Hwan Koo; Duck Sun Ahn; Seung Ha Park; Eul Sik Yoon

Oculopharyngeal muscular dystrophy is a hereditary, autosomal dominant, slowly progressive disorder with onset that occurs during middle age. Major symptoms are ptosis and dysphagia resulting primarily from selectively involved levator palpebrae and the pharyngeal muscles. Progressive, usually symmetrical blepharoptosis, with or without dysphagia, appears during middle age. Muscular weakness in the limbs can be noted in some patients. The guidelines for surgery in myopathic ptosis are conservative in view of the increased risk of postoperative corneal complications. However, orbicularis function remains intact in oculopharyngeal muscular dystrophy; therefore, corrective surgery is performed in most patients. This report describes four cases of ptosis correction in patients with oculopharyngeal muscular dystrophy in one family. The frontalis action was very poor to qualify for frontalis transfer; therefore, the authors performed moderate to large levator resection in all patients. The follow-up results 5 years postoperatively are promising to date and all the patients are satisfied with the results.


Archives of Plastic Surgery | 2015

Stabilizing Morbidity and Predicting the Aesthetic Results of Radial Forearm Free Flap Donor Sites.

Tae Kyoung Yun; Eul Sik Yoon; Duck Sun Ahn; Seung Ha Park; Byung Il Lee; Hyon Surk Kim; Hi Jin You

Background The radial forearm flap is a versatile, widely used flap. However, the possibility of donor site complications has led to concern over its use. Some surgeons prefer using other flaps whose donor sites can be closed primarily with less morbidity, including avoiding unpleasant scarring. However, in our experience, donor site stability of the radial forearm flap can be reliably achieved by using well-implemented specific procedures. Here, we present a collection of donor site cases of the radial forearm flap and investigate factors that affect the aesthetic results as the basis for a reference for selecting a radial forearm flap. Methods In this retrospective study, we reviewed 171 cases in which a radial forearm flap was used for free tissue transfer after resecting head and neck cancer. We focused on donor site morbidity rates. Each operation involved a detailed procedure designed to minimize donor site morbidity. Moreover, statistical investigations were conducted for 22 cases to determine factors affecting the scar appearance. Results Only one case developed total skin graft necrosis as a major complication. Scar-related aesthetic results were acceptable, and the body-mass index, body weight, diabetes, and cardiac problems were significant factors related to the appearance of scars. Conclusions Performing the radial forearm flap using a well-implemented detailed technique helps achieve acceptable donor site morbidity results. The aesthetic results were more promising for patients without excess body weight, diabetes, or cardiac problems. Therefore, anxiety about donor site morbidity should not be a reason to avoid selecting the radial forearm flap in suitable patients.


Korean Journal of Medical Education | 1970

The Present Conditions of Clinical Clerkship Management in Korea

Sang Hyun Kim; Eun Bae Yang; Duck Sun Ahn; Woo Tack Jeon; Chuhl Joo Lyu

PURPOSE This study investigated the present conditions of clinical clerkship management in Korea to make recommendations for it. METHODS The data were collected between April 15 and May 30 in 2009 using questionnaires that were sent to the clerkship directors of 41 colleges of medicine and medical graduate schools. RESULTS The elective course system was established in 78% of the institutions; the 6 core specialties were found in all medical schools. The duration of clerkship was longest in internal medicine, followed by surgery, pediatrics, obstetrics and gynecology, psychiatry, and emergency medicine. There were differences between the planning and monitoring agencies. Preclinical courses existed in 92.7% of the institutions. However, much more remains to be done ie, with regard to the issues of student assessment in clinical clerkship, faculty development programs for the faculty and residents, incentive systems for educational involvement, provisions for yearly systematic clerkships, integration of basic-clinical science-medical humanities, and community-based education. CONCLUSION Because clinical clerkship education is very important as a core curriculum, curriculum planning and its management must be given adequate attention. The following measures are suggested: elective systems that allow students to choose by career planning; concerns over faculty development programs for residents as a teacher; consensus on the concept, objectives, duration, content, evaluation tools of pre-clinical clerkship and clinical clerkship, and student well-being; and emphasis on community-based education.


Journal of Educational Evaluation for Health Professions | 2007

Reconsidering the Cut Score of Korean National Medical Licensing Examination

Duck Sun Ahn; Sowon Ahn

After briefly reviewing theories of standard setting we analyzed the problems of the current cut scores. Then, we reported the results of need assessment on the standard setting among medical educators and psychometricians. Analyses of the standard setting methods of developed countries were reported as well. Based on these findings, we suggested the Bookmark and the modified Angoff methods as alternative methods for setting standard. Possible problems and challenges were discussed when these methods were applied to the National Medical Licensing Examination.

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Ock Joo Kim

Seoul National University

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