Biomedical subjects

David Chwei-Chin Chuang

Publications and source records attributed to David Chwei-Chin Chuang.

9 recordsLinked to original sources

PubMed2006

Sensory reinnervation of a musculocutaneous flap: an experimental rabbit study.

Sensory neurotisation of a muscle (sensory nerve transfer to the motor nerve of a muscle) produces muscle sensibility, but not skin sensibility. How to achieve sensation of a musculocutaneous flap remains a challenge to reconstructive microsurgeons. The purpose of our study was to determine if multiple nerve grafts which were placed vertically between the neuromuscular entrance zone of a muscle and a target area of dermis on the overlying skin could improve sensation. Thirty-six gracilis musculocutaneous flaps (18 rabbits) were raised and divided into three groups: group 1 consisted of 12 sensory neurotised gracilis musculocutaneous flaps with five nerve grafts each; group 2 consisted of another 12 sensory neurotised gracilis flaps with 10 nerve grafts each; and the control group consisted of 12 sensory neurotised gracilis musculocutaneous flaps without any nerve grafts. All nerve grafts spanned the distance between the neuromuscular entrance zone of the gracilis muscle and a specified 3 cm diameter area of the skin island. The saphenous nerve (sensory) was coapted to the obturator nerve (motor nerve of the gracilis) in an effort to achieve improved sensation of the skin island in the musculocutaneous flaps. After 6 months, the flaps were individually evaluated using cortical somatosensory evoked potentials (CSSEP) using normal, painful, cold and hot stimuli. One unoperated rabbit was studied as the baseline CSEEP for comparison. Retrograde horseradish peroxidase (HRP) labelling was then performed to evaluate the possibility of newly established neural pathways. Results of the CSSEP testing revealed that flaps possessing 10 nerve grafts (group 2) demonstrated better sensation when compared to flaps possessing five nerve grafts (group 1) or no nerve grafts (control group). Furthermore, retrograde HRP labelling proved that a new neural pathway had been established from the skin island to the dorsal root ganglia of S1 and S2 via the interposed nerve grafts and the sensory neurotised gracilis muscle in groups 1 and 2 rabbits. The control group did not display any sensory regeneration.

Animals↗

PubMed2005

Nerve transfers in adult brachial plexus injuries: my methods.

The reconstructive strategies for avulsion in-juries vary from patient to patient and over time,continue to evolve depending on the surgeon's philosophy, available facilities and therapy, the elapsed time from injury to intervention, the severity of injury, and patient age and motivation. The author's results show that nerve transfer can obtain an average of 60 degrees (range, 20 degrees - 180 degrees) of shoulder elevation without shoulder arthrodesis, M3 to M4 muscle strength of elbow flexion, M2 to M4 elbow extension, and M3 finger flexion and sensation. Intrinsic hand function was obtained with help of dynamic splinting for interphalangeal joint extension and arthrodesis of thumb joints asa post for opposition.

Brachial Plexus↗

PubMed2005

Surgical strategy for infant obstetrical brachial plexus palsy: experiences at Chang Gung Memorial Hospital.

BACKGROUND: Strategies for management of infant obstetrical brachial plexus palsy remain controversial, including timing of surgery and treatment modalities. METHODS: The senior author (Chuang) performed surgical explorations on 78 infant obstetrical brachial plexus palsy patients from 1992 to 1999. Sixty-eight patients underwent brachial plexus operation during the infant period (2 to 11 months), and 10 patients underwent surgery beyond the infant period. RESULTS: For the ruptured upper and/or middle trunk injury (Erb's palsy), better shoulder and elbow function was observed in those who received numerous short grafts from C5 to the suprascapular and posterior division and from the C6 spinal nerve to the anterior division of the upper trunk. For the rupture injury associated with root avulsion (total palsy), nerve graft and transfer (intraplexus and extraplexus) provided a one-stage reconstruction for shoulder, elbow, and especially hand functions. The contralateral C7 or ipsilateral part of the ulnar nerve transfer was rarely used in infant obstetrical brachial plexus palsy, compared with adult brachial plexus injury. CONCLUSIONS: The operative results proved that earlier timing of nerve surgery (within 3 months) is strongly indicated in patients who have total palsy, and only relatively indicated in patients with isolated rupture of the upper plexus.

Birth Injuries↗

PubMed2004

Traumatic major muscle loss in the upper extremity: reconstruction using functioning free muscle transplantation.

Traumatic crushing injuries of the muscle compartments will occasionally cause major muscle or muscle-group loss with concomitant irreparable nerve injuries. Those cases with or without the availability of local muscle transfers form another indication for functioning free muscle transplantation (FFMT). The authors report their experience with 20 FFMTs in 14 patients with severe muscle loss from 1986 to 1996. They were selected because all their major muscle loss was primarily due to muscle avulsion, avascularity, and necrosis, but not secondarily due to nerve injury or ischemic injury. The motor nerves innervating these muscles were either disrupted after muscle debridement or avulsed from the neuromuscular junction concomitantly. The initial injury in this series was so severe that in many cases amputation was advised. Fractures were present in almost half the cases (6/14). Half the cases required revascularization due to rupture of major vessels (7/14), and the need for free-tissue transfer for soft-tissue coverage was demonstrated in over two-thirds (8/14). All FFMTs were innervated by the motor nerve which originally innervated the lost major muscle(s), and to replace palmar arm compartment (elbow flexors, 6 cases), palmar forearm compartment (finger flexors, 6 cases), and dorsal forearm compartment (finger extensors, 8 cases). Postoperative follow-up ranged from 3 to 12.5 years (average: 8.3 years). The success rate, i.e., achieving M4 muscle strength, was nearly 90 percent (18 of 20 FFMTs). Two cases with sub-optimal results were performed in the acute stage for the purpose of soft-tissue coverage and functional results. These reconstructions make the originally compromised limb useful for most activities of daily living. This type of injury should be recognized as providing a good prognosis after application of the FFMT, and arbitrary amputation should be avoided.

Adolescent↗

PubMed2004

Free proximal gracilis muscle and its skin paddle compound flap transplantation for complex facial paralysis.

Gracilis functioning free-muscle transplantation for the correction of pure facial paralysis has been a preferred method used by many reconstructive microsurgeons. However, for complex facial paralysis, the deficits include facial paralysis along with soft-tissue, mucosa, and/or skin defects. No adequate solution has been proposed. Treatment requests in those patients are not only for facial reanimation but also for correction of the defects. Of 161 patients with facial paralysis treated with gracilis functioning free-muscle transplantation from 1986 to 2002, eight patients (5 percent) presented with complex deficits requiring not only facial reanimation but also aesthetic correction of tissue defects. The tissue defects included an intraoral defect created following contracture release (one patient), infra-auricular radiation dermatitis with contour depression (one patient), temporal depression following a temporalis muscle-fascia transfer (one patient), ear deformity (two patients), and infra-auricular atrophic tissue with contour depression (three patients). A compound flap, consisting of a gracilis muscle with its overlying skin paddle separated into two components, was transferred for simultaneous correction of both problems. The blood supply to the gracilis and to the skin paddle originated from the same source vessel and therefore required the anastomosis of only one set of vessels. The versatility of this compound flap allows for a wide arc of rotation of the skin paddle around the muscle. All flaps were transferred successfully without complications. Satisfactory results of facial reanimation were recorded in five patients after all stages were completed. The remaining three patients are undergoing physical therapy and waiting for revision of the skin paddle.

Adolescent↗

PubMed2002

Technique evolution for facial paralysis reconstruction using functioning free muscle transplantation--experience of Chang Gung Memorial Hospital.

The author performed facial reanimation by using functioning free muscle transplantation in 116 cases from 1986 to 2000. Three consecutive five-year periods are presented in relation to each stage of the author's technical improvement. The first five years bulkiness and asymmetrical smiling with weak gum exposure were encountered and required correction. The second five years was a period of technical improvement, but with residual deformities. The third five-year period was one of technique refinement. The author extended the utility of the gracilis for different and more challenged problems, such as the use of a muscle plus skin two-unit composite flap connected by the septoperforator nutrients, not only for facial reanimation but also for intra-oral contracture release or extra-oral facial soft tissue and skin deficits replacement.

Facial Paralysis↗

PubMed2002

The reconstructive strategy for improving elbow function in late obstetric brachial plexus palsy.

Children with previously untreated obstetric brachial plexus palsy frequently have abnormal elbow function because of motor recovery with aberrant reinnervation, or because of paresis or paralysis. From 1988 to 1997 (9-year period), 62 children with obstetric brachial plexus palsy with resulting elbow deformity underwent various methods of palliative reconstruction to improve elbow function. For motor recovery with aberrant reinnervation, release of aberrantly reinnervated antagonistic muscles and augmentation of paretic muscles form the basis of surgical intervention. The surgical procedures included triceps-to-biceps transfer, biceps-to-triceps transfer, brachialis-to-triceps transfer, or combined biceps- and brachialis-to-triceps transfer. Choice of procedures was individualized and randomly determined on the basis of the degree and pattern of aberrant reinnervation between elbow flexors and extensors. In patients' motor recovery with paresis or paralysis, persistently weak elbow flexion was salvaged with a functioning free muscle transplantation or Steindler's flexorplasty, or regional shoulder muscle transfer. In addition, patients with aberrant reinnervation between shoulder abductors and elbow flexors underwent anterior deltoid-to-biceps transfer with a fascia lata graft. All patients had a minimum follow-up of 2 years. Results are assessed and discussed and a reconstructive algorithm is recommended. In general, reconstruction of elbow extension should precede that of elbow flexion. Biceps-to-triceps transfer with preservation of an intact brachialis muscle, or brachialis-to-triceps transfer with preservation of an intact biceps, allows 50 percent of these patients to achieve acceptable elbow flexion and extension in a single-stage procedure.

Adolescent↗

PubMed2002

Surgical strategy for improving forearm and hand function in late obstetric brachial plexus palsy.

For the purpose of treatment, obstetric brachial plexus palsy can be subdivided into two distinct phases: initial obstetric brachial plexus palsy, and late obstetric brachial plexus palsy. In the latter, nerve surgery is no longer practical, and treatment often requires palliative surgery to improve function of the shoulder, elbow, forearm, and hand. Late obstetric brachial plexus palsy in the forearm and hand includes weakness or absence of wrist or metacarpophalangeal or interphalangeal joint extension; weakness or absence of finger flexion; forearm supination, or less commonly pronation contracture; ulnar deviation of the wrist; dislocation of the radial or ulnar head; thumb instability; or sensory disturbance of the hand. Palliative reconstruction for these forearm and hand manifestations is more difficult than for the shoulder or elbow because of the lack of powerful regional muscles for transfer. This report reviews the authors' experience performing more than 100 surgical procedures in 54 patients over a 9-year period (between 1988 and 1997) with a minimum of 2 years' follow-up. Surgical treatment is highly individualized, but the optimal age for forearm and hand reconstruction is usually later than for shoulder and elbow reconstruction because of the requirement for a preoperative exercise program. Multiple procedures for forearm and hand function were often performed on any given patient. Frequently, these were done simultaneously with reconstructive procedures for improving shoulder and/or elbow function. Traditional tendon transfer techniques do not provide satisfactory reconstruction for those deformities. Many of the authors' patients required more complex techniques such as nerve transfer and functioning free-muscle transplantation to augment traditional techniques of tendon and/or bone management. Sensory disturbance of the forearm and hand in late obstetric brachial plexus palsy seems a minor problem and further sensory reconstruction is unnecessary.

Adolescent↗

PubMed2002

Have we found an ideal soft-tissue flap? An experience with 672 anterolateral thigh flaps.

The free anterolateral thigh flap is becoming one of the most preferred options for soft-tissue reconstruction. Between June of 1996 and August of 2000, 672 anterolateral thigh flaps were used in 660 patients at Chang Gung Memorial Hospital. Four hundred eighty-four anterolateral thigh flaps were used for head and neck region recontruction in 475 patients, 58 flaps were used for upper extremity reconstruction in 58 patients, 121 flaps were used for lower extremity reconstruction in 119 patients, and nine flaps were used for trunk reconstruction in nine patients. Of the 672 flaps used in total, a majority (439) were musculocutaneous perforator flaps. Sixty-five were septocutaneous vessel flaps. Of these 504 flaps, 350 were fasciocutaneous and 154 were cutaneous flaps. Of the remaining 168 flaps, 95 were musculocutaneous flaps, 63 were chimeric flaps, and the remaining ten were composite musculocutaneous perforator flaps with the tensor fasciae latae. Total flap failure occurred in 12 patients (1.79 percent of the flaps) and partial failure occurred in 17 patients (2.53 percent of the flaps). Of the 12 flaps that failed completely, five were reconstructed with second anterolateral thigh flaps, four with pedicled flaps, one with a free radial forearm flap, one with skin grafting, and one with primary closure. Of the 17 flaps that failed partially, three were reconstructed with anterolateral thigh flaps, one with a free radial forearm flap, five with pedicled flaps, and eight with primary suture, skin grafting, and conservative methods. In this large series, a consistent anatomy of the main pedicle of the anterolateral thigh flap was observed. In cutaneous and fasciocutaneous flaps, the skin vessels (musculocutaneous perforators or septocutaneous vessels) were found and followed until they reached the main pedicle, regardless of the anatomic position. There were only six cases in this series in which no skin vessels were identified during the harvesting of cutaneous or fasciocutaneous anterolateral thigh flaps. In 87.1 percent of the cutaneous or fasciocutaneous flaps, the skin vessels were found to be musculocutaneous perforators; in 12.9 percent, they were found as septocutaneous vessels. The anterolateral thigh flap is a reliable flap that supplies a large area of skin. This flap can be harvested irrespective of whether the skin vessels are septocutaneous or musculocutaneous. It is a versatile soft-tissue flap in which thickness and volume can be adjusted for the extent of the defect, and it can replace most soft-tissue free flaps in most clinical situations.

Adolescent↗