Proprioceptive innervation of the human lips.

The objective of this study was to analyze the proprioceptive innervation of human lips, especially of the orbicularis oris muscle, since it is classically accepted that facial muscles lack typical proprioceptors, that is, muscle spindles, but recently this has been doubted. Upper and lower human lips (n = 5) from non-embalmed frozen cadavers were immunostained for detection of S100 protein (to identify nerves and sensory nerve formations), myosin heavy chain (to label muscle fibers within muscle spindles), and the mechano-gated ion channel PIEZO2. No muscle spindles were found, but there was a high density of sensory nerve formations, which were morphologically heterogeneous, and in some cases resemble Ruffini-like and Pacinian sensory corpuscles. The axons of these sensory formations displayed immunoreactivity for PIEZO2. Human lip muscles lack typical proprioceptors but possess a dense sensory innervation which can serve the lip proprioception.

Exploring somatosensory innervation of the human lip: A focus on the vermilion.

BACKGROUND: The lips are a vital component of the face and are densely innervated to perform various functions. The lip edges are covered with mucocutaneous tissue called vermilion which is particularly receptive to touch and temperature. The aim of this study was to investigate the somatosensory innervation of human lips, focusing on sensory corpuscles and the presence of mechano-gated (ASIC2, PIEZO2, and TRPV4) and thermosensing (TRPV1, TRPM2, and RPM8) ion channels within them. METHODS: Twelve intact lips (6 upper and 6 lower) were obtained from non-embalmed frozen cadavers (five females and seven males) with an age range of 60-80 years. The specimens were divided into three zones (medial, lateral, and median). The morphotypes of sensory corpuscles and their immunohistochemical profile was analysed. The occurrence of ion channels involved in mechanosensation and temperature detection was examined using various antibodies. Sensory corpuscle density was quantified in vermilion sections, and statistical analyses were conducted to assess differences between the upper and lower lips, as well as between females and males (p < 0.05). RESULTS: Different morphotypes of sensory corpuscles were identified: Ruffini-like associated with hair follicles, Meissner and glomerular corpuscles in the vermilion, and less classifiable sensory corpuscles within the mucosa. The density of sensory corpuscles in the vermilion was higher in the upper lip than in the lower lip; glomerular corpuscles predominated in the medial and median segments, whereas Meissner corpuscles were more abundant in the lateral segment. No sex-related differences were observed in the density or distribution of the two main corpuscular morphotypes. In contrast, the axons of both the glomeruli and Meissner corpuscles regularly displayed ASIC2 and PIEZO2 immunoreactivity, whereas immunoreactivity for TRPV1, TRPV4, TRPM2, and TRPV8 was absent. CONCLUSIONS: These results demonstrate that the sensory corpuscles of the vermilion are a mixture of those typical of glabrous skin mucocutaneous tissues. The presence of PIEZO2 and ASIC2 in their axons suggests that these sensory corpuscles function as mechanosensors.

Risk factors associated with fixation-related complications in microsurgical free flap reconstruction of the mandible.

BACKGROUND: Hardware complications (loosening of screws, infection, or exposure of the plate) in mandibular reconstruction with vascularized osseous free flaps impose significant morbidity, and frequently require revision surgery. Purpose of this study was to identify possible contributing factors for hardware complications. METHODS: This is a retrospective cohort study involving case series of patients who underwent microvascular mandible reconstructions between 2000 and 2020. Patient demographics, pathological, clinical, and treatment-related factors were analyzed in univariate and multivariate analyses. RESULTS: Ninety-one patients were enrolled, encompassing 63 reconstructions with fibular free flaps, 26 reconstructions with scapular, and 2 reconstructions with iliac flaps. Rate of hardware complications and plate exposure was 14.3% and 7.7%, respectively, with a median follow-up time for extrusion of 29 months. In univariate analysis, preoperative radiotherapy (odds ratio [OR] = 6.57, p = .01), and secondary mandible reconstruction (OR = 4.3, p = .04) were significant predictors of hardware complications, and plate exposure was most frequently found in secondary reconstruction (37.5%, OR = 11.8, p = .04). Hypertension was the most commonly found comorbidity (24%), and it trended toward significance regarding plate exposure (p = .05). Only secondary mandible reconstruction was associated with osteosynthesis complications (OR = 12.53, p = .01) and plate exposure (OR = 23.86, p = .005) on multivariate analysis, while preoperative radiation therapy did not retain its relevance on plate exposure. CONCLUSION: Secondary mandible reconstructions with vascularized osseous free flaps have a higher risk of osteosynthesis complications than primary reconstructions.

Pacinian Corpuscles as a Diagnostic Clue of Ledderhose Disease-A Case Report and Mapping of Pacinian Corpuscles of the Sole.

BACKGROUND: Plantar fibromatosis, known as Ledderhose disease, is a neoplastic disease characterized by a locally-aggressive bland fibroblastic proliferation. Although Pacinian corpuscles alterations are commonly described in palmar fibromatosis, there are still no references about Pacinian corpuscles alterations in the rarer plantar version. METHODS: We present a case report where a wide cutaneous resection, including the plantar fascia was performed, allowing a detailed study of Pacinian corpuscles. Pacinian corpuscles were analyzed using immunohistochemistry for neurofilament proteins, S100 protein, CD34, vimentin, glucose transporter 1, epithelial membrane antigen, neural-cell adhesion molecule, actin, desmin, type IV collagen, and high-affinity neurotrophin Trk-receptors. Moreover, the density and the size of the corpuscles were determined. RESULTS: A clear increase in the number (hyperplasia) of Pacinian corpuscles was evidenced in the Ledderhose disease plantar fascia in comparison with similarly aged normal subjects. Pacinian hypertrophy was not demonstrated, but a significant decrease in the number of corpuscular lamellae was noted, with a subsequent increase in the interlamellar spaces. Pacinian corpuscles from the pathological plantar fascia showed an abnormal structure and immunohistochemical profile, generally without identifiable axons, and also absence of an inner core or an intermediate layer. Moreover, other molecules related with trophic maintenance of corpuscles were also absent. Finally, a vascular proliferation was commonly noted in some corpuscles, which involved all corpuscular constituents. CONCLUSION: The observed Pacinian corpuscles hyperplasia could be considered a diagnostic clue of plantar fibromatosis.

Sensory innervation of the human palmar aponeurosis in healthy individuals and patients with palmar fibromatosis.

The human palmar aponeurosis is involved in hand proprioception, and it contains different sensory corpuscle morphotypes that serve this role. In palmar fibromatosis (classically referred to as Dupuytren's disease), the palmar aponeurosis undergoes fibrous structural changes that, presumably, also affect the nervous system, causing altered perception. We analysed the various sensory nerve formation morphotypes in the palmar aponeuroses of healthy subjects and patients with palmar fibromatosis. To do this, we used immunohistochemistry for corpuscular constituents and the putative mechanoproteins PIEZO2 and acid-sensing ion channel 2. Free nerve endings and Golgi-Mazzoni, Ruffini, paciniform and Pacinian corpuscles were identified in both the healthy and the pathological conditions. The densities of the free nerve endings and Golgi-Mazzoni corpuscles were slightly increased in the pathological tissues. Furthermore, the Pacinian corpuscles were enlarged and displayed an altered shape. Finally, there was also morphological and immunohistochemical evidence of occasional denervation of the Pacinian corpuscles, although no increase in their number was observed. Both PIEZO2 and acid-sensing ion channel 2 were absent from the altered corpuscles. These results indicate that the human palmar aponeurosis is richly innervated, and the free nerve endings and sensory corpuscles within the palmar aponeurosis undergo quantitative and qualitative changes in patients with palmar fibromatosis, which may explain the sensory alterations occasionally reported for this pathology.

Periostin and Human Teeth.

Periostin is a secreted matricellular protein that primarily interacts with type I collagen and fibronectin extracellular matrix proteins, and is widely distributed in tissues rich in collagen-rich connective tissues, including the periodontal ligament. Its expression in these tissues is especially regulated by mechanical load. While the expression and regulation of periostin in the teeth of murine models and cell lines is well known, its presence in human teeth is poorly documented. Here we update and summarize the available data on the distribution of periostin in the human periodontal ligament, gingiva and dental pulp.

Is there a higher prevalence of tinnitus in patients with temporomandibular disorders? A systematic review and meta-analysis.

The aim of this study was to determine whether there exists a higher prevalence of tinnitus in patients with temporomandibular disorders (TMDs) than in patients without TMDs. A systematic review was conducted in PubMed/MEDLINE for articles published between January 1992 and April 2018 in accordance with the PRISMA statement. Studies were included in this review only if they assessed TMDs using the research diagnostic criteria (RDC)/TMD or DC/TMD. A total of five studies were included in the systematic review, and a random-effects meta-analysis of three of the studies was conducted. In all of the selected studies, the prevalence of tinnitus was higher in patients with TMDs (35.8% to 60.7%) than in patients without TMDs (9.7% to 26.0%). The odds ratio of suffering from tinnitus among patients with TMDs was 4.45 (95% CI 1.64-12.11. P = 0.003). Thus, despite the limitations of the included studies, this review demonstrates that the prevalence of tinnitus in TMD patients is significantly higher than that in patients without TMD.

Early treatment of Class III malocclusion with facemask therapy.

The facemask is a widely used device in the treatment of Class III malocclusion and is intended to anteriorly displace the superior maxilla or stimulate its growth in that direction. The main goal of this study was to evaluate the effects of treatment using orthopedic maxillary expansion with facemask therapy in patients with Class III malocclusion. Sixty-four patients, with a mean age of 8.14 ± 1.18 years at the start of treatment and a mean age of 9.78 ± 1.19 years at the end, were treated using orthopedic maxillary expansion and associated facemask therapy. The patients were evaluated using lateral head teleradiography before and after treatment, and the differences were analyzed. In addition, binary logistic regression was used as a model for predicting successful treatment. When comparing the changes achieved by treatment, statistically significant favorable changes were found at the skeletal level. Furthermore, an improvement in the airways at all levels was detected. Orthopedic maxillary expansion associated with facemask therapy has proven effective in treating early skeletal Class III malocclusion.

Searching for proprioceptors in human facial muscles.

The human craniofacial muscles innervated by the facial nerve typically lack muscle spindles. However these muscles have proprioception that participates in the coordination of facial movements. A functional substitution of facial proprioceptors by cutaneous mechanoreceptors has been proposed but at present this alternative has not been demonstrated. Here we have investigated whether other kinds of sensory structures are present in two human facial muscles (zygomatic major and buccal). Human checks were removed from Spanish cadavers, and processed for immunohistochemical detection of nerve fibers (neurofilament proteins and S100 protein) and two putative mechanoproteins (acid-sensing ion channel 2 and transient receptor potential vanilloid 4) associated with mechanosensing. Nerves of different calibers were found in the connective septa and within the muscle itself. In all the muscles analysed, capsular corpuscle-like structures resembling elongated or round Ruffini-like corpuscles were observed. Moreover the axon profiles within these structures displayed immunoreactivity for both putative mechanoproteins. The present results demonstrate the presence of sensory structures in facial muscles that can substitute for typical muscle spindles as the source of facial proprioception.

Pacinian Corpuscles in a Cervical Chondrocutaneous Remnant: A Case Report and Update of Pacinian Corpuscles.

Cervical chondrocutaneous remnants are congenital, benign, and rare neck masses. We present here for the first time the immunohistochemical profile of Pacinian corpuscles present in cervical chondrocutaneous remnants, removed, and localized in the territory of the second branchial arch from a 5-year-old girl. We have performed immunohistochemistry to analyze these sensory corpuscles using a battery of antibodies including markers for each corpuscle constituent. The central axon was immunoreactive for neurofilaments, neuron-specific enolase, and neural cell adhesion molecule; the Schwann-related cells forming the inner core displayed immunoreactivity for S100 protein, vimentin, and neural cell adhesion molecule; the outer core and the capsule were positive for vimentin, epithelial membrane antigen, and glucose transporter 1. These results are discussed in topographical differences. Moreover, a brief update about the structure, protein composition, and development of Pacinian corpuscles was performed.

Acid-sensing ion channels in healthy and degenerated human intervertebral disc.

Acid-sensing ion channels (ASICs) are a family of H(+)-gated voltage-insensitive ion channels that respond to extracellular acidification by regulating transmembrane Ca(2+) flux. Moreover, ASICs can also be gated by mechanical forces and may function as mechanosensors. The cells of the intervertebral disc (IVD) have an unusual acidic and hyperosmotic microenvironment. Changes in the pH and osmolarity determine the viability of IVD cells and the composition of the extracellular matrix, and both are the basis of IVD degeneration. In this study, the expression of ASICs (ASIC1, ASIC2, ASIC3 and ASIC4) mRNAs and proteins in human healthy and degenerated IVD was evaluated by quantitative reverse transcription-quantitative polymerase chain reaction and Western blot. The distribution of ASIC proteins was determined by immunohistochemistry. The mRNAs for all ASICs were detected in normal human IVD, and significantly increased levels were found in degenerated IVD. Western blots demonstrated the presence of proteins with estimated molecular weights of approximately 68-72 kDa. In both the annulus fibrosus (AF) and nucleus pulposus (NP) of normal IVD, ASIC2 is the most frequently expressed ASIC followed by ASIC3, ASIC1 and ASIC4. In the AF of degenerated IVD, there was a significant increase in the number of ASIC1 and ASIC4 positive cells, whereas in the NP, we found significant increase of expression of ASIC1, ASIC2 and ASIC3. These results describe the occurrence and localization of different ASICs in human healthy IVD, and their increased expression in degenerated IVD, thus suggesting that ASICs may be involved in IVD degeneration.