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Krishnan K.G.,Goethe University Frankfurt | Schackert G.,Carl Gustav Carus University Hospital | Seifert V.,Goethe University Frankfurt
Neurosurgery | Year: 2010

Background: The functions of the human face are not only of esthetic significance but also extend into metaphoric nuances of psychology. The loss of function of one or both facial nerves has a remarkable impact on patients' lives. Objective: To retrospectively analyze the functional outcomes of microneurovascular facial reanimation using masseteric innervation. Methods: Seventeen patients with irreparable facial paralysis resulting from benign lesions involving the facial nuclei (n = 14) or Möbius syndrome (n = 3) were treated with free muscle flaps for oral commissural reanimation using ipsilateral masseteric innervation and using temporalis muscle transfer for eyelid reanimation. Results were analyzed by the absolute commissural excursion and commissural excursion index and by a patient self-evaluation score. Presence of synkinesis was documented. Follow-up ranged from 8 to 48 months (mean, 26.4 months). Results: Normalization of the commissural excursion index was observed in 8 of 17 patients (47%), an improvement was seen in 7 of 17 (41%), and failure was observed in 2 of 17 (12%). The individual dynamics of absolute commissural excursion and commissural excursion index changes are presented. A natural smiling response was observed in 10 of 17 patients (59%) but not in the remaining 7 (41%). This response reflected the patient's ability to relay the natural emotion of smiling through the masseteric nerve. Patients' self-evaluation scores were a level higher than objective indices. CONCLUSIONS: Innervation of free muscle flaps with the masseteric nerve for oral commissure reanimation might play an important role in patients with lesions of the facial nuclei (as in Möbius syndrome). Synkinesis persists for long periods after surgery. However, most of the patients learned to express their emotions by overcoming this phenomenon. Despite hypercorrection or inadequate correction, patients evaluated themselves favorably. © 2010 by the Congress of Neurological Surgeons. Source


Lunze K.,RWTH Aachen | Singh T.,State University of New York at Buffalo | Walter M.,RWTH Aachen | Brendel M.D.,Mellitus | And 2 more authors.
Biomedical Signal Processing and Control | Year: 2013

A method for optimal continuous insulin therapy for diabetes patients has been sought since the early 1970s. Although technical and medical advances have been made, a fully automated artificial pancreas to replace the functions of the natural organ is still a research aim. This review compares recent control algorithms for type 1 diabetic patients which automatically connect continuous glucose monitoring and insulin injection, without patient intervention. Black-box model and gray-box model based control strategies are described and their performances are evaluated, with a focus on their feasibility of implementation in a real-life situation. In conclusion, a satisfactory control strategy has not yet been proposed, mainly because most control algorithms rely on continuous blood glucose measurement which is not yet available. Modeling the effect of glucose ingestion as an external disturbance on the time evolution of blood glucose concentration, is now the norm for the control community. In contrast, the effects of physical activity on the metabolic system is not yet fully understood and remain an open issue. Moreover, clinical studies on evaluation of control performance are scarce. Therefore, research on blood glucose control needs to concentrate on advanced patient modeling, control optimization and control performance evaluation under realistic patient-oriented conditions. © 2012 Elsevier Ltd. All rights reserved. Source


Raiskup F.,Carl Gustav Carus University Hospital | Pinelli R.,ILMO | Spoerl E.,Carl Gustav Carus University Hospital
Current Eye Research | Year: 2012

Purpose: To investigate the influence of osmolarity on the transepithelial permeability of riboflavin solutions in a cross-linking procedure. Methods: Several riboflavin 0.1% solutions that contained different NaCl and benzalkonium chloride (BAC) concentrations were applied to 36 rabbit eyes for 30min. To serve as a control, the epithelium was removed in group A (standard protocol). The groups then received the following solutions: (A) riboflavin 0.1% in NaCl 0.9% solution; (B) riboflavin 0.1% in NaCl 0.44% solution with BAC 0.02%; (C) riboflavin 0.1% in NaCl 0.44% solution with BAC 0.01%; (D) riboflavin 0.1% in NaCl 0.44% solution without BAC; (E) riboflavin 0.1% in NaCl 0.9% solution with BAC 0.02%; and (F) riboflavin 0.1% in NaCl 0.9% solution without BAC. Six eyes in each group were treated. The absorption coefficients of the corneas were measured to characterize the riboflavin penetration into the cornea. Results: There is a large difference in the transepithelial riboflavin penetration of riboflavin 0.1% + BAC 0.02% solutions that contain different NaCl concentrations (NaCl 0.9% versus NaCl 0.44%). The absorption coefficients differed by more than a factor of two (P=0.004). No statistically significant difference was found between riboflavin 0.1% in NaCl 0.44% solution containing BAC 0.02% and BAC 0.01%. Compared to the standard protocol, these solutions resulted in an absorption coefficient of 37% (BAC 0.02%) and 33% (BAC 0.01%) of the standard epithelium-off procedure. Conclusion: The transepithelial riboflavin solution should contain no dextran, but it should include 0.01% BAC and 0.44% NaCl to promote the permeability of riboflavin through the epithelium, resulting in a sufficient concentration of riboflavin in the corneal stroma. © 2012 Informa Healthcare USA, Inc. Source


Raiskup F.,Carl Gustav Carus University Hospital | Spoerl E.,Carl Gustav Carus University Hospital
Ocular Surface | Year: 2013

Changes in the biomechanical properties of the human cornea play an important role in the pathogenesis of corneal ectatic diseases. Biomechanical investigation shows significant differences between human ectatic corneas and normal corneas, including decreased stiffness and reduction of collagen crosslinks in the ectatic cornea. Induction of crosslinks is a well-established procedure in polymer chemistry to increase the elastic modulus of materials. Crosslinking (CXL) in connective tissue can occur during aging and as a side effect of diabetes mellitus. CXL has been used medically to increase stability and reduce the biodegradation of collagen-based biomaterials for bioprostheses. CXL of the cornea using riboflavin and UVA light with a wavelength of 370 nm and a dosage of 5.4 J/cm2 is a new approach that increases the mechanical and biochemical stability of stromal tissue. This technique combines the principles of CXL (chemical and nonenzymatic) and the biochemical mechanisms of photo-oxidative CXL with riboflavin as a photosensitizer. In this review, the enrichment of riboflavin in the stroma by standard (epi-off) and transepithelial (epi-on) CXL is discussed. The theoretical and experimental measurements of the absorption of UV light explain the stronger CXL effect in the anterior stroma and its importance for the prevention of damage to the endothelial cells. UV devices are described. Changes of the physical properties after CXL, as well as the cellular changes, are discussed. From these basic investigations, treatment parameters for effective and safe CXL are identified. © 2013 Elsevier Inc. Source


Raiskup F.,Carl Gustav Carus University Hospital | Spoerl E.,Carl Gustav Carus University Hospital
Ocular Surface | Year: 2013

Changes in the biomechanical properties of the human cornea play an important role in the pathogenesis of corneal ectatic diseases. A variety of conditions in primary acquired (keratoconus and pellucid marginal degeneration) or secondary induced (iatrogenic keratectasia after excimer refractive laser surgery) corneal ectatic disorders lead to reduced biomechanical resistance. Corneal collagen crosslinking (CXL) has emerged as a promising technique to slow or even to stop the progression of these corneal ectatic pathologies. In this procedure, riboflavin (vitamin B2) is administered in conjunction with ultraviolet A light (UVA, 365 nm). This interaction causes the formation of reactive oxygen species, leading to the formation of additional covalent bonds between collagen molecules, with consequent biomechanical stiffening of the cornea. Although this method is not yet accepted as an evidence-based medicine modality for the treatment of corneal primary or secondary ectasias, the results of prospective, randomized studies of CXL used in the treatment of these pathologic entities show significant changes in the properties of corneal tissue. This procedure is currently the only etiopathogenetic approach in ectatic eyes that can delay or stop the process of cornea destabilization, reducing the necessity for keratoplasty. Despite promising results, CXL is associated with issues that include long-term safety and duration of the stabilizing effect. Combination of CXL with vision-improving procedures, such as topography-guided custom ablation and implantation of intracorneal ring segments of phakic intraocular lenses, may expand the indications for this procedure. © 2013 Elsevier Inc. Source

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