Trigeminal neuropathy presenting secondary to SARS-CoV-2 infection.

Introduction: A 58-year-old woman presented to a multidisciplinary facial pain clinic in October 2021 complaining of a constant pain in the right side of her face since contracting coronavirus SARS-CoV-2 18 months earlier. The pain extending from the right temple down to her right cheek extraorally and including the maxillary teeth and right side of tongue intraorally. This was accompanied by anosmia, diplopia on lateral gaze, and dizziness. Methods: Clinical examination was supplemented with several neurophysiological tests to confirm the diagnosis including an MRI brain scan, quantitative sensory testing, electrophysiological blink reflex testing, corneal confocal microscopy, and pain and short-form anxiety and depression questionnaires. Results: Quantitative sensory testing showed unilateral loss of perception in thermal and mechanical sensibility and bilateral hyperalgesia indicating central sensitization. Bilateral corneal confocal microscopy showed an abnormally reduced corneal nerve fibre length on the right side. MRI, blink reflex, and masseter inhibitory testing findings were normal. Conclusion: This case study is the first case of trigeminal neuropathy related to SARS-CoV-2 infection reported in the literature. It also discusses the successful management of the patient's trigeminal neuropathic pain.

Crystallographic and X-ray scattering study of RdfS, a recombination directionality factor from an integrative and conjugative element.

The recombination directionality factors from Mesorhizobium spp. (RdfS) are involved in regulating the excision and transfer of integrative and conjugative elements. Here, solution small-angle X-ray scattering, and crystallization and preliminary structure solution of RdfS from Mesorhizobium japonicum R7A are presented. RdfS crystallizes in space group P212121, with evidence of eightfold rotational crystallographic/noncrystallographic symmetry. Initial structure determination by molecular replacement using ab initio models yielded a partial model (three molecules), which was completed after manual inspection revealed unmodelled electron density. The finalized crystal structure of RdfS reveals a head-to-tail polymer forming left-handed superhelices with large solvent channels. Additionally, RdfS has significant disorder in the C-terminal region of the protein, which is supported by the solution scattering data and the crystal structure. The steps taken to finalize structure determination, as well as the scattering and crystallographic characteristics of RdfS, are discussed.

Corneal Confocal Microscopy Detects Small-Fiber Neuropathy in Burning Mouth Syndrome: A Cross-Sectional Study.

AIMS: To assess the utility of corneal confocal microscopy in identifying small fiber damage in patients with burning mouth syndrome (BMS). METHODS: A prospective cross-sectional cohort study was conducted at two United Kingdom dental hospitals between 2014 and 2017. A total of 17 consecutive patients with idiopathic BMS aged between 18 and 85 years and 14 healthy age-matched control subjects were enrolled in this study. Corneal subbasal nerve plexus measures were quantified in images acquired using a laser-scanning in vivo corneal confocal microscope. The main outcome measures were corneal nerve fiber density, nerve branch density, nerve fiber length, and Langerhans cell density. RESULTS: Of the 17 patients with BMS, 15 (88%) were women, and the mean (standard deviation) age of the sample was 61.7 (6.5) years. Of the healthy controls, 7 (50%) were women, and the mean (standard deviation) age was 59.3 (8.68) years. Corneal nerve fiber density (no./mm2) (BMS: 29.27 ± 6.22 vs controls: 36.19 ± 5.9; median difference = 6.71; 95% CI: 1.56 to 11.56; P = .007) and corneal nerve fiber length (mm/mm2) (BMS: 21.06 ± 4.77 vs controls: 25.39 ± 3.91; median difference = 4.5; 95% CI: 1.22 to 6.81; P = .007) were significantly lower in BMS patients compared to controls, and Langerhans cell density (no./mm2) (BMS: 74.04 ± 83.37 vs controls: 29.17 ± 45.14; median difference = -21.27; 95% CI: -65.35 to -2.91; P = .02) was significantly higher. CONCLUSION: Using a rapid noninvasive ophthalmic imaging technique, this study provides further evidence for small fiber damage in BMS and has potential utility for monitoring disease progression and/or response. Furthermore, this technique shows a hitherto undocumented increased density of immune cells in this group of patients.

A model for studying epithelial attachment and morphology at the interface between skin and percutaneous devices.

Percutaneous devices are indispensable in modern medicine, yet complications from their use result in significant morbidity, mortality, and cost. Bacterial biofilm at the device exit site accounts for most infections in short-term devices. We hypothesize that advanced biomaterials can be developed that facilitate attachment of skin cells to percutaneous devices, forming a seal to preclude bacterial invasion. To study the skin/biomaterial interface systematically, we first identified biomaterials with physical properties compatible with histological processing of skin. Second, we developed an organ culture system to study skin response to implants. Organ cultures implanted with porous poly(2-hydroxyethyl methacrylate) [poly(HEMA)] or polytetrafluoroethylene (PTFE) could easily be evaluated histologically with preservation of the skin/biomaterial interface. Epithelial cells migrated down the cut edges of the biomaterial in a pattern seen in marsupialization of percutaneous devices in vivo. This in vitro model maintains skin viability and allows histologic evaluation of the skin/biomaterial interface, making this a useful, inexpensive test-bed for studies of epidermal attachment to modified biomaterials.

Complications of hydroxyapatite bone cement use in cochlear implantation?

OBJECTIVE AND IMPORTANCE: To highlight the complications of using hydroxyapatite (HA) bone cement when implanting a cochlear implant (CI) device. CLINICAL PRESENTATION: A case series of three patients who had undergone cochlear implantation are presented. A bony defect was seen in the external auditory meatal wall posteriorly in all three cases. This was intimately related to the site of HA bone cement, which had been used to anchor the electrode array at the time of the original implantation. Persistent otorrhoea was usually a feature at clinical presentation. INTERVENTION (AND TECHNIQUE): Removal of the HA bone cement and repair of the bony defect has resulted in resolution of the otorrhoea and a functioning CI is present in all cases without further complications. CONCLUSION: The use of HA bone cement in cochlear implantation may cause dehiscence of the external auditory meatal wall. Our experience has shown that the electrode array does not need to be secured with cement. It is therefore recommended by this centre that HA cement should not be used to secure the electrode array in cochlear implantation surgery.

Cutaneous and inflammatory response to long-term percutaneous implants of sphere-templated porous/solid poly(HEMA) and silicone in mice.

This study investigates mouse cutaneous responses to long-term percutaneously implanted rods surrounded by sphere-templated porous biomaterials engineered to mimic medical devices surrounded by a porous cuff. We hypothesized that keratinocytes would migrate through the pores and stop, permigrate, or marsupialize along the porous/solid interface. Porous/solid-core poly(2-hydroxyethyl methacrylate) [poly(HEMA)] and silicone rods were implanted in mice for 14 days, and for 1, 3, and 6 months. Implants with surrounding tissue were analyzed (immuno)histochemically by light microscopy. Poly(HEMA)/skin implants yielded better morphologic data than silicone implants. Keratinocytes at the poly(HEMA) interface migrated in two different directions. "Ventral" keratinocytes contiguous with the dermal-epidermal junction migrated into the outermost pores, forming an integrated collar surrounding the rods. "Dorsal" keratinocytes appearing to emanate from the differentiated epithelial layer, extended upward along and into the exterior portion of the rod, forming an integrated sheath. Leukocytes persisted in poly(HEMA) and silicone pores for the duration of the study. Vascular and collagen networks within the poly(HEMA) pores matured as a function of time up to 3-months implantation. Nerves were not observed within the pores. Poly(HEMA) underwent morphological changes by 6 months of implantation. Marsupialization, foreign body encapsulation, and infection were not observed in any implants.

Quantifying the effect of pore size and surface treatment on epidermal incorporation into percutaneously implanted sphere-templated porous biomaterials in mice.

The sinus between skin and a percutaneous medical device is often a portal for infection. Epidermal integration into an optimized porous biomaterial could seal this sinus. In this study, we measured epithelial ingrowth into rods of sphere-templated porous poly(2-hydroxyethyl methacrylate) implanted percutaneously in mice. The rods contained spherical 20-, 40-, or 60-µm pores with and without surface modification. Epithelial migration was measured 3, 7, and 14 days post-implantation utilizing immunohistochemistry for pankeratins and image analysis. Our global results showed average keratinocyte migration distances of 81 ± 16.85 µm (SD). Migration was shorter through 20-µm pores (69.32 ± 21.73) compared with 40 and 60 µm (87.04 ± 13.38 µm and 86.63 ± 8.31 µm, respectively). Migration was unaffected by 1,1' carbonyldiimidazole surface modification without considering factors of pore size and healing duration. Epithelial integration occurred quickly showing an average migration distance of 74.13 ± 12.54 µm after 3 days without significant progression over time. These data show that the epidermis closes the sinus within 3 days, migrates into the biomaterial (an average of 11% of total rod diameter), and stops. This process forms an integrated epithelial collar without evidence of marsupialization or permigration.

Characterization of an in vitro model for evaluating the interface between skin and percutaneous biomaterials.

Percutaneous devices play an essential role in medicine; however, they are often associated with a significant risk of infection. One approach to circumvent infection would be to heal the wound around the devices by promoting skin cell attachment. We used two in vitro assay models to evaluate cutaneous response to poly(2-hydoxyethyl methacrylate) (poly(HEMA)). One approach was to use a cell adhesion assay to test the effects of surface modification of poly(HEMA), and the second used an organ culture system of newborn foreskin biopsies implanted with porous poly(HEMA) rods (20 microm pores) to evaluate the skin/poly(HEMA) interface. Surface modification of poly(HEMA) using 1,1'-carbonyldiimidazole (CDI) enhanced keratinocyte, fibroblast, and endothelial cell adhesion. Keratinocytes in the organ culture model not only remained functionally and structurally viable as observed by immunohistochemistry and electron microscopy, but migrated into the pores of CDI-modified poly(HEMA) rods. No biointegration was seen in the non-CDI-modified poly(HEMA). Laminin 5 immunostaining was seen along the poly(HEMA)/skin interface in a pattern resembling the junctional epithelium of the tooth, the unique natural interface between the skin and tooth that serves as a barrier to bacteria. In vitro systematic evaluation of biomaterials for use in animal implant studies is both cost effective and time efficient.