silicon and Foreign-Body-Migration

The injection of fluid silicone was formerly an acceptable therapy for recontouring post-traumatic or age-related changes of the face and neck. About 20 years after the use of silicone injections, the number of patients presenting with late complications is increasing. Such complications include migration of the silicone, granuloma formation, chronic cellulitis, skin ulcers and and scarring, all of which are difficult to treat medically or surgically. Recent data in the literature support the notion that fluid silicon is a potential carcinogen. These patients require a careful approach combining the limited surgical possibilities with the support needed to live with such a problem. Using a case report as an example, we discuss the diagnostic and therapeutic problems associated with this phenomenon which is relatively uncommon in Europe.

Topics: Cellulitis; Cicatrix; Female; Foreign-Body Migration; Humans; Injections; Middle Aged; Plastic Surgery Procedures; Risk Assessment; Silicon; Skin Ulcer

Topics: Adult; Breast Implants; Catheters, Indwelling; Equipment Failure; Female; Foreign-Body Migration; Humans; Silicon; Ventriculoperitoneal Shunt

Micromotion of implanted silicon multielectrode arrays (Si MEAs) is thought to influence the inflammatory response they elicit. The degree of strain that micromotion imparts on surrounding tissue is related to the extent of mechanical integration of the implanted electrodes with the brain. In this study, we quantified the force of extraction of implanted four shank Michigan electrodes in adult rat brains and investigated potential cellular and extracellular matrix contributors to tissue-electrode adhesion using immunohistochemical markers for microglia, astrocytes and extracellular matrix deposition in the immediate vicinity of the electrodes. Our results suggest that the peak extraction force of the implanted electrodes increases significantly from the day of implantation (day 0) to the day of extraction (day 7 and day 28 postimplantation) (1.68 +/- 0.54 g, 3.99 +/- 1.31 g, and 4.86 +/- 1.49 g, respectively; mean +/- SD; n = 4). For an additional group of four shank electrode implants with a closer intershank spacing we observed a significant increase in peak extraction force on day 28 postimplantation compared to day 0 and day 7 postimplantation (5.56 +/- 0.76 g, 0.37 +/- 0.12 g and 1.87 +/- 0.88 g, respectively; n = 4). Significantly, only glial fibrillary acidic protein (GFAP) expression was correlated with peak extraction force in both electrode designs of all the markers of astroglial scar studied. For studies that try to model micromotion-induced strain, our data implies that adhesion between tissue and electrode increases after implantation and sheds light on the nature of implanted electrode-elicited brain tissue reaction.

Topics: Animals; Cell Adhesion; Cerebral Cortex; Device Removal; Electrodes, Implanted; Foreign-Body Migration; Microelectrodes; Motion; Prostheses and Implants; Prosthesis Failure; Rats; Rats, Sprague-Dawley; Silicon

Topics: Artifacts; Breast; Breast Implants; Female; Foreign-Body Migration; Humans; Magnetic Resonance Spectroscopy; Prosthesis Failure; Reproducibility of Results; Research Design; Silicon; Silicone Gels

Topics: Animals; Artifacts; Breast; Breast Implants; Female; Foreign-Body Migration; Humans; Liver; Magnetic Resonance Spectroscopy; Prosthesis Failure; Rats; Reproducibility of Results; Research Design; Sensitivity and Specificity; Silicon; Silicone Gels

Over a period of 6 years, 58 patients aged between 55 +/- 16 years have been treated for post-intubation tracheal stenosis (STPI). These patients were characterised by their frequency of an underlying respiratory or cardiac failure, a duration of intubation which was sometimes short and a delay between the extubation and the detection of stenosis which was les than one month in about one half of the cases. Thirty of the 58 patients presented with respiratory distress on admission. All the stenoses were treated initially by mechanical dilatation using a rigid bronchoscope. Radial incisions using an Nd-Yag laser were performed when necessary to facilitate the dilatation. The great majority of stenoses which were not fitted up with a tracheal endoprosthesis (EPT) at the first attempt recurred, leading to repeated therapeutic bronchoscopies (221 sessions in all). Fitting an EPT (Dumon prosthesis) was necessary in 35 cases on 12 occasions at the first attempt with the first bronchoscopy, and 23 times following a recurrence. Amongst the recurring stenoses a stabilisation was obtained at the price of repeated dilatations (4.3 sessions on average in only nine patients). Seven patients finally had a surgical resection and anastamosis of the trachea, of whom four had a transitory instillation of an EPT for the stenosis. The removal of the EPT was later attempted in 11 patients. Four did not present with any symptomatic recurrence. The secondary migration of the EPT is in practice one of the main inconveniences of the silicon prosthesis (8 cases now experienced). Our approach, which used to favour the mechanical dilatation has lead to a relatively high number of failures and thus to repeated bronchoscopies. This has lead us to re-define our therapeutic approach. The current schema which we propose is in the course of being validated in which we use EPT and surgical repair of the trachea more often. Only short stenoses (less than 1 cm) with a diaphragm are treated by dilatation and laser. The others are fitted initially with an EPT. The final management is guided by the progress in the stenosis, the tolerance of the endoprosthesis and the operability of the patients.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Anastomosis, Surgical; Bronchoscopy; Dilatation; Endoscopy; Female; Foreign-Body Migration; Humans; Intubation, Intratracheal; Laser Therapy; Male; Middle Aged; Prostheses and Implants; Recurrence; Respiratory Insufficiency; Silicon; Tracheal Stenosis