Particulate Silicone Research Articles

Antegrade and Retrograde Endoscopic Dextranomer/Hyaluronic Acid Bladder Neck Bulking for Pediatric Incontinence

Endoscopic bladder neck bulking techniques offer the potential for a relatively noninvasive cure for a difficult clinical problem. We review our experience using antegrade and retrograde approaches. A total of 34 children (18 boys and 16 girls, mean age 11.7 years) have been treated since March 2003. Of the patients 28 (82%) had neurogenic bladder and 6 had nonneurogenic sphincteric incontinence. Urodynamics confirmed low detrusor leak point pressures and adequate bladder capacity. Patients were treated with either a retrograde or an antegrade approach. In 82% of patients an antegrade approach was used and a posttreatment suprapubic tube was placed. Mean followup was 11.7 months (range 3 to 31). Patients averaged 1.47 injections (range 1 to 5). Detailed followup of 19 patients revealed significant improvement in continence in 78% (mean 1.6 injections), with an average followup of approximately 1 year. Our 31 months of experience with antegrade/retrograde bladder neck bulking demonstrates that it is a viable therapy for this group of children. While some patients have experienced prolonged success, re-treatment can be beneficial. The antegrade approach offers several advantages, including intraoperative leak point pressures, improved visualization and placement of a suprapubic tube to limit post-procedural remodeling.

Long-Term Effects of Dextranomer Endoscopic Injections for Treatment of Urinary Incontinence: An Update of a Prospective Study of 31 Patients

A prospective study was initiated 7 years previously to assess the efficacy of endoscopic dextranomer based implants for pediatric structural incontinence. Preliminary results revealed that at 3 years 50% of the patients were either dry or significantly improved. We report long-term results in the same cohort of patients. A total of 33 children and adolescents 5 to 18 years old with severe incontinence due to sphincteric incompetence (exstrophy-epispadias complex in 13, neuropathic bladder in 16, bilateral ectopic ureter in 4) were enrolled. Of the patients 13 underwent 2 and 4 underwent 3 treatment sessions to achieve a definitive result. Mean injected volume was 3.9 ml (range 1.6 to 12) per session. At each evaluation patients were considered cured (dryness interval 4 hours), significantly improved (minimal incontinence requiring no more than 1 pad daily and no further treatment required) or treatment failures (no significant improvement). Videourodynamics were used to study the evolution of the bladder capacity, activity and compliance. A total of 31 patients were followed 3 to 7 years after the last injection. At 3 years after treatment 15 of 30 patients (50%) were dry or improved. One patient who had leakage after 3 years of dryness due to bladder deterioration subsequently underwent ileocystoplasty. At 4 years 12 of 25 patients (48%) were dry or improved. At 5 years 9 of 21 patients (43%) were dry, as were 4 of 11 (36%) at 6 years and 2 of 5 (40%) at 7 years of followup. The success rate according to pathological evaluation was comparable in neuropathic bladders (7 of 14, or 50%), exstrophy (3 of 6, or 50%) and epispadias (3 of 7, or 43%). Of 12 patients who underwent bladder neck plasty before the injection of bulking agent 7 (58%) were either dry or improved. The success rate was higher in males (13 of 23, or 57%) than in females (3 of 8, or 38%). Also, at puberty 2 males who were improved became dry. Bladder capacity increased in 12 of 18 initially small bladders and remained normal and stable in 9, while 4 initially dry patients had development of recurrent leakage secondary to bladder deterioration and underwent augmentation. Otherwise, there were no long-term side effects observed related to the injection of the bulking agent. Endoscopic treatment of severe organic urinary incontinence with dextranomer is durable for up to 7 years of followup in 40% of the patients.

Injection laryngoplasty for management of unilateral vocal fold paralysis

The purpose of this review is to provide an up-to-date review of injection laryngoplasty technique and currently available injectable materials in the management of unilateral vocal fold paralysis (UVP). Many new materials are currently available as substances for injection laryngoplasty. These materials have been developed along distinct of lines reasoning that address the inherent shortcomings of the previously available injectable substances, namely, poor tissue biocompatibility and poor persistence within the larynx. Accordingly, the past decade has seen heightened efforts toward developing implants with improved biocompatibility and longevity. The past year has witnessed publications reporting animal studies and, on occasion, human clinical trials involving the intralaryngeal injection of calcium hydroxyl-appetite, autologous fascia, particulate silicone and hyaluronic acid derivatives, and others, for managing glottic insufficiency. In recent years, the application of injection laryngoplasty to unilateral vocal fold paralysis (UVP) has regained popularity. The technique of injection laryngoplasty has several appealing qualities including relative technical ease, low cost, and wide availability in many clinical settings. A growing number of injectable substances have been developed and tested in the clinical setting of glottic insufficiency. When used to manage unilateral vocal fold paralysis, however, injection laryngoplasty has one irrefutable shortcoming: an inability to address posterior glottic insufficiency. Therefore, while injection laryngoplasty technique becomes increasingly popular for vocal fold augmentation in cases vocal fold paresis, atrophy, and scarring, its role in the treatment of UVP should be limited to cases with an appropriate glottal defect. These techniques should be considered as part of a complimentary armamentarium with framework surgery.

Particulate silicone for vocal fold medialization: Histologic evaluation in a rabbit model

Problem: To study the tissue reaction of the paralyzed vocal chord in response to the injection of particulate plastics in a rabbit model. Methods: The study used 45 New Zealand rabbits with surgical vocal fold paralysis. Histologic reaction was analyzed 6 weeks and 6 months after a vocal chord injection of Teflon or of silicone elastomer. Results: The histological study showed a greater proportion of chronic granulomatous inflammation in animals injected with silicone than in those injected with Teflon. The immunohistochemical study showed a higher degree of phagocytosis of silicone particles than the Teflon particles. The silicone group presented a more severe fibrous reaction than the Teflon group, but the difference was not significant. Conclusion: Silicone has a greater viscosity than Teflon, owing to the size of the particles. Silicone induces more fibrosis and a larger proportion of foreign giant cells in the host. Because of this histological reaction, silicone particles present greater anchorage and stability. Significance: This study demonstrates that the injected silicone is an appropriate material for the medialization of paralyzed vocal cords in some special cases. Support: Support: Supported in part by a grant from the National Health Ministry of Spain.

PARTICLE MIGRATION AFTER TRANSURETHRAL INJECTION OF CARBON COATED BEADS FOR STRESS URINARY INCONTINENCE

Despite 20 years of experience with injectable bulking agents for stress urinary incontinence results are rather disappointing. The satisfying initial results of collagen injection are rapidly decreasing with time, whereas synthetic bulking agents have shown problems with migration and biocompatibility. The ideal bulking agent would be permanent with a good clinical long-term success rate. We report our experience with Durasphere (Carbon Medical Technologies, Inc., St. Paul, Minnesota), a new injectable bulking agent containing carbon coated beads. Seven men and 13 women with a mean age of 62.5 years underwent transurethral submucosal injection. The 13 female patients had been diagnosed with type III stress urinary incontinence and each had undergone at least 1 unsuccessful previous operation for urinary incontinence. There were iatrogenic and traumatic sphincter lesions in 6 and 1 of the male patients, respectively. Mean volume injected per treatment was 6.0 cc. Mean followup was 10 months. After 6 months 76.9% of the female patients were improved but after 12 months the success rate decreased to 33%. In the male patients after 6 months the success rate was 66%, which decreased to 33% after 12 months. At the 6-month followup we observed significant migration of the carbon coated beads into the local and distant lymph nodes as well as into the urethral mucosa. Due to limited success and proved particle migration, carbon coated beads do not show any improvement over existing bulking materials. The clinical effect of bead migration must be determined before extended use of this substance.

Particulate Silicone for Use in Periurethral Injections: Local Tissue Effects and Search for Migration

We examined the histologic behavior and migratory tendencies of a silicone-based injectable paste (Macroplastique) with potential application in treating urinary incontinence. Thirteen female dogs were studied. Six received 2 periurethral injections of large-particle paste, with a median diameter of 110 micrometer, and 7 received similar injections with small-particle paste (median diameter, 73 micrometer). The paste was radiolabeled with cobalt-57. Histologic analysis was performed at 4 or 9 months. The pathologic appearance revealed intact large-particle injection sites. The small-particle sites had dissipated significantly. This was confirmed by nuclear imaging. Large particles produced an encapsulated fibrous sheath without local migration. There was a histiocytic reaction within the injection site but no granuloma formation. Distant migration was observed in 1 dog (short term, large particle), without an inflammatory response. Migration of silicone occurred locally and distantly in animals that received small particles. X-ray microanalysis confirmed the presence of silicone particles.

Twenty years of experience with particulate silicone in plastic surgery

The use of particulate silicone in plastic surgery involves the introduction of solid silicone into the body. The silicone is in small pieces in order for it to adapt to the shape of the defect. This way large quantities can be introduced through small incisions. It is also possible to distribute the silicone particles from outside the skin to make the corrections more regular. This method has been very useful for correcting post-traumatic depressions in the face and all areas where the depression has a rigid back support. We consider it the treatment of choice for correcting the funnel chest deformity.

Twenty years of experience with particulate silicone in plastic surgery

Twenty years of experience with particulate silicone in plastic surgery

Silicone rubber temporomandibular joint (TMJ) meniscal replacements: postimplant histopathologic and material evaluation.

Medical grade silicone rubber has long been considered a suitable meniscal replacement, but there has been increasing concern about migration of this material into adjacent tissues. The objectives of this study were to determine the definitive composition of tissue-incorporated material which is presumed by light microscopy to be silicone and to identify long term histopathologic sequelae of meniscal replacements. Adult female patients underwent meniscectomy and replacement with silicone rubber (Silastic) implants. After 12 to 18 months, recurrence of symptoms in 8% of these cases led to implant removal with excision of peri-implant fibrous pseudocapsules. Excised tissues, including one preauricular lymph node and implants were submitted for light microscopy, SEM, and energy dispersive x-ray microanalysis (EDX) for the identification of elemental composition, critical surface tension measurement, and internal reflection infrared spectroscopy. EDX revealed prominent peaks for silicon in both pseudocapsular and nodal tissues. Morphologic findings surrounding the long-term implants included foreign body reaction, synovitis, dystrophic calcification, fibrocartilaginous metaplasia, hyalinization, and scarring. Particulate silicone debris induced a pathologic response in the tissues and migrated to nodes. These findings suggest that periodic evaluation be performed over the life of such implants to rule out breakdown under function. These findings should intensify the search for improvements or replacements for silicone rubber as an interpositional material in the temporomandibular joint.

Silicone and rheumatic diseases

Silicone generally has been regarded as a biologically inert material. However, recent reports suggest that inflammatory responses to silicone occur. There is some experimental and clinical evidence of a direct inflammatory response to the presence of liquid or particulate silicone. These include granulomatous skin reaction to injected silicone, synovitis around silicone prosthetic joints, and lymphadenopathy proximal to silicone prostheses. There are case reports of systemic rheumatic disease following silicone prostheses, but no definitive proof of a direct relationship between silicone prostheses and systemic disease. The clinical features of the reported cases following breast augmentation include breast tenderness, axillary adenopathy, sclerodermatous skin changes, arthritis, Raynaud's phenomenon, rheumatoid factors, and ANAs. Prior epidemiologic evidence and the number and consistency of our own and others' clinical findings suggest that silicone may indeed be associated with inflammatory processes and rheumatic diseases.

Reactive synovitis from particulate silastic.

A reactive synovitis secondary to intra-articular particles of silicone elastomer developed in three patients who had undergone Silastic hemiarthroplasty. In an attempt to duplicate this phenomenon, we used an animal model in which finely ground particulate silicone elastomer was introduced into the knee joints of adult New Zealand White rabbits. In three of thirteen rabbits (p = 0.066) histological evidence of inflammatory changes developed in the synovial tissue, similar to those seen in our patients. Intraarticular particulate silicone elastomer created by abrasion of a Silastic hemiarthroplasty may be responsible for the development of an iatrogenic reactive synovitis.