Quantitative analysis of lidocaine hydrochloride delivery by diffusion across tissue expander membranes.

Permeability of Silastic tissue expander shells to lidocaine was studied to investigate the feasibility of intraluminal lidocaine injection for pain relief during soft-tissue expansion. Both intact expanders and an apparatus using isolated Silastic membrane segments were used to partition solutions of various lidocaine concentrations, and the rate of diffusion was quantitatively measured using a fluorescence polarization immunoassay. Lidocaine flux was found to follow Fick's law of passive diffusion with respect to time, surface area, and concentration gradient for the first 9 hours, with a permeability coefficient of 10.3 +/- 2.6 micrograms (h.cm2.percent)-1 (mean +/- SD) and diffusion coefficient of 7.5 x 10(-7) cm2/min for an average membrane thickness of 473 +/- 23 microns. After 9 hours, the lidocaine flux decreased exponentially, although the concentration gradient across the membrane remained essentially the same order of magnitude. Plasma proteins in the outer bathing solution and methylparaben used as a preservative in the standard lidocaine formulation had no influence on the change in transport flux with time. At the end of the linear portion of the diffusion curve, less than 2 percent of the total intraluminal lidocaine had crossed the membrane. Potential toxicity in the event of implant rupture limits the maximum total lidocaine dose to approximately 500 mg within an expander at any one time. Within these limits, the capacity for lidocaine delivery of 500 mg lidocaine by a 640-cc tissue expander would be only 6 mg during the first 9 hours after administration.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of time on human breast capsule histology: smooth and textured silicone-surfaced implants.

Although the histology of capsular tissue is well described in the literature, most studies in humans do not correlate histologic findings with implant age (number of years an implant was in place before sampling). As such, questions regarding the long-term histology in humans remain. The microanatomy of 93 human periprosthetic capsular tissues surrounding 22 textured and 71 smooth silicone-surfaced prostheses was studied. The implants were divided into two groups according to the time between implantation and capsulectomy: between 0 and 5 years or more than 5 years. Hematoxylin and eosin and Masson trichrome-stained sections were analyzed by light microscopy, with and without polarization. Eighteen of the textured implants contained silicone gel and four contained saline. Sixty of the smooth implants contained silicone gel, eight contained saline, and in three, the filler type was not known. For the majority of patients, surgery was performed for augmentation mammaplasty, and the implants were removed because of capsular contracture. The following histologic features were assessed: synovial-like metaplasia, villous hyperplasia, density of the collagenous capsule, alignment of collagen fibers within the capsule, and the presence of foreign material and of a foreign body reaction. The following trends were observed. In smooth implants, increasing implant duration was associated with a decrease in the presence of synovial-like metaplasia (p = 0.003) and villous hyperplasia; there was no significant difference in the presence of a dense collagenous capsule, the orientation of collagen fibers, or the presence of a foreign body reaction. An increase was observed in the presence of foreign material (p = 0.01). In textured implants, increasing implant duration was associated with a decrease in the presence of synovial-like metaplasia, villous hyperplasia (p = 0.003), dense collagenous architecture, and parallel orientation of collagen fibers (p = 0.017). An increase in the presence of a foreign body type reaction and foreign material (p = 0.024) was observed. In comparing textured and smooth-surfaced implants, synovial-like metaplasia was observed more often in the textured group, both at 0 to 5 years (p = 0.01) and at greater than 5 years (p < 0.01). Textured implants more often had villous hyperplasia at 0 to 5 years (p = 0.03) but not beyond 5 years. Smooth implants more often had a dense collagenous capsule than textured implants after 5 years. No significant difference was seen in the orientation of collagen fibers in capsules around smooth and textured implants at 0 to 5 years. After 5 years, the incidence of capsules with collagen fibers arranged parallel to the implant surface was significantly greater in the smooth group than in the textured group (p = 0.01). The presence of a foreign body type reaction was seen more often in the textured group between 0 and 5 years (p = 0.01) and at greater than 5 years (p < 0.01), and the presence of foreign material was more often seen in the textured group between 0 and 5 years (p = 0.06) and at greater than 5 years (p < 0.01). In summary, the cytologic changes around implants seem to be dynamic in nature, and implantation duration and shell type play a significant role. Synovial-like metaplasia, villous hyperplasia, and foreign material were more often observed in the textured group within the 0 to 5 year interval. Beyond 5 years, synovial-like metaplasia, a foreign body type reaction, and foreign material were more often observed in the textured group. Differences in the density of collagenous capsules were not significant at any time point, and collagen fibers oriented parallel to the implant surface were more often observed in the smooth group after 5 years. The significance of these findings awaits further investigation.

Chest-wall deformity after tissue expansion for breast reconstruction.

A prospective longitudinal study of chest-wall deformity after tissue expansion for breast reconstruction was performed in 19 women. CT imaging was a sensitive method for detecting occult deformity. Using a semiquantitative scale for measuring deformity, all patients and 94 percent of expanders had some thoracic abnormality after tissue expansion. Rib and chest-wall contour changes were observed under 81 and 68 percent of the expanders, respectively. Routine chest roentgenograms were not a sensitive method for evaluating these deformities. The magnitude of deformity after unilateral expansion was not significantly different from that after bilateral expansion. Linear regression analysis indicated that early periprosthetic capsular contracture was negatively correlated with chest wall deformity. Only one patient experienced a clinically noticeable complication from chest compression--transient postexpansion exertional dyspnea. After removing the expanders and placing permanent implants along with capsulotomy, the mean deformity index decreased by 57 percent after 10.5 months median follow-up, which was highly significant (p less than 0.001). Our findings suggest that chest-wall deformity is a common occurrence after tissue expansion in patients undergoing breast reconstruction and is usually of minor clinical significance.

Postmastectomy brachial plexus injury exacerbated by tissue expansion.

A neurapraxic injury to the brachial plexus was seen after modified radical mastectomy and immediate tissue expander placement. Neurological recovery proceeded until a sudden deterioration 42 hours after the fourth expansion. Deflation of the expander from an initial pressure of 18 mm Hg to 8 mm Hg led to relief from all acute symptoms, which were primarily in the distribution of the nerve most severely involved at the time of the initial injury, the median nerve. The history of previous neurapraxia and anatomical relationships between the tissue expander, pectoralis minor tendon, and neurovascular structures suggest that impairment of nerve function occurred through a compressive mechanism resembling a double-crush phenomenon.

Intraluminal lidocaine for analgesia after tissue expansion: a double-blind prospective trial in breast reconstruction.

A double-blind prospective placebo controlled trial of intraluminal lidocaine for pain relief after tissue expansion was performed in 18 women undergoing breast reconstruction. In contrast to others' claims of effective analgesia, no difference in the incidence of immediate or late pain after expansion could be demonstrated between 100 mg of lidocaine and placebo. The overall incidence of early pain was 8%. This was significantly less frequent than late pain, which occurred after 36% of all expansions. Postexpansion pain (early or late) was reported after nearly one-half of all expansions, most of which was ascribed to late pain. The incidence of pain did not significantly depend on the temporal progression of breast expansion, nor was there a difference in the incidence and prevalence of pain for patients undergoing unilateral versus simultaneous bilateral expansion.

Prospective comparison of axial computed tomography and standard and panoramic radiographs in the diagnosis of mandibular fractures.

Objective data comparing sensitivity and accuracy between traditional and computed imaging techniques used for diagnosing mandibular fractures is sparse. To address the paucity of information the authors studied prospectively 33 mandibular fractures in 21 consecutive patients with standard mandibular series, panoramic tomography, axial computed tomography (CT), and coronal CT. Differences in diagnostic accuracy and sensitivity as compiled by four blinded reviewers were calculated. Although overall sensitivities of mandibular fracture detection were not statistically significant between the imaging studies, a distinction between the four methods did exist. Coronal CT was the most accurate imaging method, followed by mandibular series, panoramic topography, and axial CT. Excluding technically inadequate studies, panoramic tomography was 100% accurate and sensitive. Diagnostic accuracy and sensitivity did not correlate measurably with reviewers' impressions of the quality of a particular exam. Axial CT detected significantly fewer angle fractures than standard radiographs (60% vs. 98%, p = 0.006) and coronal CT (60% vs. 100%, p = 0.008). False-positives were unusual except for plain mandibular radiographs. The clear definition of both coronal and axial CT scans made their analysis simpler than the plain radiographs. Lack of fracture displacement was the single most important factor in missed fractures with all modalities. Despite reviewer concerns about the quality of the plain mandibular series, the high accuracy and sensitivity of this imaging technique and applicability in all patients, coupled with its low cost, make it an excellent screening exam for all patients with suspected mandibular fractures. In clinically stable and cooperative patients with mandibular trauma, panoramic radiography and coronal CT are recommended to confirm clinical suspicions when the mandibular series is equivocal. To supplement the mandibular series in the uncooperative or multisystem trauma patient, axial CT scans have not been beneficial. These diagnostic modalities do not obviate the need for a careful physical exam.

Intracranial and extracranial reduction osteoplasty for craniodiaphyseal dysplasia.

Craniodiaphyseal dysplasia is a rare, sporadic form of craniotubular bone dysplasia, characterized by massive generalized hyperostosis and sclerosis, particularly of the skull and facial bones, leading to severe deformity. The clinical course is typically characterized by progressive encroachment of the craniofacial foramina and brain by the relentless deposition of bone. Compression of cranial nerves, the foramen magnum, and intracranial contents commonly leads to blindness, loss of hearing, and death. This report describes a unique case of craniodiaphyseal dysplasia manifesting with asymmetric craniofacial and axial hyperostosis. The tubular bones demonstrated the characteristic diaphyseal endostosis, undertubulation, and relative overgrowth on the involved side. Significant brain compression with signs and symptoms of increased intracranial pressure was managed successfully with decompressing craniectomy at age 12 years, enlarging the anterior and middle fossae. Calvarial thickness measured nearly 4 cm. Further calvarial, midfacial, and mandibular recontouring were performed 6 and 22 months later. Follow-up in our case indicates that close observation is mandatory to manage further progression of the disease.