A Biochemical Analysis of the Stapes

Effect of stapes demineralisation on the development of cochlear otosclerosis

Objective

The involvement of the inner ear in otosclerosis may lead to the development of cochlear otosclerosis. The aim of this study was to analyse changes in the chemical composition and microstructure of the stapes in the course of otosclerosis compared to healthy stapes.

Materials and methods

This analysis included 31 patients with otosclerosis and 9 patients without otosclerosis. Microanalytical and diffraction techniques were used to assess the elemental distribution and orientation topography of the stapes.

Results

The concentration of Ca2+ in the study group was significantly lower in the area of the anterior crus of the stapes than in the posterior crus. A reduction in the Ca2+/P3+ ratio in the anterior crus was associated with deteriorated bone conduction and tinnitus. Degradation of the stapes microstructure in the area of otosclerotic lesions was observed with scanning electron microscopy.

Conclusions

Bone remodelling is most significant at the closest location to typical otosclerotic lesions with hydroxyapatite porosity and scale-like bone formation according to scanning electron microscopy. There is a relationship between the disturbance of calcium metabolism and the development of clinical symptoms of cochlear otosclerosis.

Retrospective Study of 157 Patients with Otosclerosis to Evaluate Association Between Carhart Notch on the Preoperative Bone-Conduction Audiogram and Postoperative Hearing and Balance Evaluated by the Vestibular Disorders Activities of Daily Living Scale

BACKGROUND A Carhart notch in the pure tone audiogram can be an indicator of stapes fixation in otosclerosis. This retrospective study of 157 patients with otosclerosis aimed to evaluate the association between the presence of a Carhart notch on the preoperative bone-conduction audiogram and postoperative hearing and balance evaluated by the Vestibular Disorders Activities of Daily Living scale. MATERIAL AND METHODS Patients with suspected otosclerosis based on medical history and audiometric tests were considered. The analysis included 157 consecutive patients who underwent surgery in the years 2016 to 2019, in whom the diagnosis of otosclerosis was confirmed during surgery. Carhart notch was defined as an impairment in the bone conduction threshold of ≥7.5 dB for 2000 Hz frequencies above the mean thresholds at higher and lower adjacent frequencies. The Vestibular Disorders Activities of Daily Living subjective scale was used in the preoperative period and 4 and 12 months after surgery. RESULTS The preoperative presence of Carhart notch and progressive sensorineural hearing loss were statistically significantly correlated with more common onset of tinnitus and then dizziness (P=0.006). Preoperative vertigo was observed in patients who had Carhart notch observed in the preoperative audiometric test. This vertigo more commonly coexisted with profound sensorineural hearing loss and minor or no improvement in average values of bone conduction after surgery (P=0.002). CONCLUSIONS Preoperative Carhart notch on audiogram and the severity of sensorineural hearing loss were associated with tinnitus and vertigo. However, preoperative Carhart notch was not associated with persistent postoperative tinnitus in patients with cochlear otosclerosis.

The risks of RELN polymorphisms and its expression in the development of otosclerosis

Otosclerosis (OTSC) is the primary form of conductive hearing loss characterized by abnormal bone remodelling within the otic capsule of the human middle ear. A genetic association of the RELN SNP rs3914132 with OTSC has been identified in European population. Previously, we showed a trend towards association of this polymorphism with OTSC and identified a rare variant rs74503667 in a familial case. Here, we genotyped these variants in an Indian cohort composed of 254 OTSC cases and 262 controls. We detected a significant association of rs3914132 with OTSC (OR = 0.569, 95%CI = 0.386–0.838, p = 0.0041). To confirm this finding, we completed a meta-analysis which revealed a significant association of the rs3914132 polymorphism with OTSC (Z = 6.707, p<0.0001) across different ethnic populations. Linkage analysis found the evidence of linkage at RELN locus (LOD score 2.1059) in the OTSC family which has shown the transmission of rare variant rs74503667 in the affected individuals. To understand the role of RELN and its receptors in the development of OTSC, we went further to perform a functional analysis of RELN/reelin. Here we detected a reduced RELN (p = 0.0068) and VLDLR (p = 0.0348) mRNA levels in the otosclerotic stapes tissues. Furthermore, a reduced reelin protein expression by immunohistochemistry was confirmed in the otosclerotic tissues. Electrophoretic mobility shift assays for rs3914132 and rs74503667 variants revealed an altered binding of transcription factors in the mutated sequences which indicates the regulatory role of these variations in the RELN gene regulation. Subsequently, we showed by scanning electron microscopy a change in stapes bone morphology of otosclerotic patients. In conclusion, this study evidenced that the rare variation rs74503667 and the common polymorphism rs3914132 in the RELN gene and its reduced expressions that were associated with OTSC.

Otosclerosis – analysis of factors influencing the improvement of hearing after surgical treatment

<b>Introduction:</b> Otosclerosis is a disease that occurs only in humans, in the course of which there are foci of pathological ossification in the temporal bone. The etiology of the dise ase is not fully understood. Treatment of the conductive component of hearing loss is surgical. The results of the treatment are influenced by factors related to the surgery, the local condition of the middle ear and the function of the inner ear. </br></br> <b>Aim:</b> The aim of the study is to identify factors influencing the improvement of hearing in patients treated surgically due to otosclerosis. </br></br> <b>Material and methods:</b> The study included patients who underwent otosclerosis for the first middle ear surgery and under-went stapedotomy. Considering the factors that may affect the outcome of surgical treatment, the patients qualified for the analysis were divided into subgroups. All patients underwent a medical history and physical examination of otorhinolaryn-gology and a complete set of audiological examinations. </br></br> <b> Results:</b> A statistically significant reduction in cochlear reserve was observed in all patients after stapedotomy. The be-neficial effect of the performed treatment on the improvement of threshold values of bone conduction in patients with mild sensorineural hearing loss was also confirmed. Intraoperative removal of adhesions present in the tympanic cavity significantly improved hearing in terms of bone conduction values, especially at 500 Hz. </br></br> <b> Conclusions:</b> (1) The conducted study confirmed the influence of factors related to the local condition of the middle ear lining on the final result of otosclerosis surgery; (2) Audiometric markers of cochlear otosclerosis, observed before surgical treat-ment, are an unfavorable factor in the improvement of hearing after the performed treatment.

The suitability of scanning electron microscopy in the evaluation of bone structure surfaces and selection of alloplastic materials for facial skeletal reconstruction

INTRODUCTION

Functional and aesthetic problems can arise even from small losses created in the facial skeleton. Injuries and oncological surgeries are the most frequent causes of these losses within the facial skeleton. Advances in surgical interventions have allowed for ever-increasing degrees of resections, increasing oncological radicality as well as treatment effectiveness, providing the patient with the chance for a longer life. However, this subsequently requires the use of even more advanced reconstruction techniques in order to restore quality of life and comfort to the patient, as well as enable their return to professional and social activities. The necessity of reconstructive surgery applies not only to patients with cancer, but also to patients with impaired or failing sensory and organ function as a result of inflammatory conditions, injuries, or non-oncological surgeries. There are many available reconstruction procedures, which depend on the location of the loss, the type of tissue lost, the degree of loss and patient-dependent factors. Materials used in reconstruction surgeries may include the patients' tissues when available, and artificial reconstruction materials otherwise.

MATERIAL AND METHODS

The analysis involved fragments of bone tissue removed during surgery. Due to the nature of the medical procedure and the inability to replant the tissue, it was regarded as medical waste. The preparations used were observed under an optical microscope and an electron scanning microscope, and a chemical analysis was performed. The chemical composition of samples was analysed using a low vacuum detector (LVD) at an accelerating voltage of 15 kV and 10 kV and at a spot size of 4 and 3.5. The observations were performed in a secondary electron (SE) detection system.

RESULTS

Observation of parameters under an optical microscope and of images obtained using an electron scanning microscope showed the presence of typical, compact bone tissue with varied surface shapes in each case (various degrees of unevenness and porosity). Chemical composition analysis confirmed the presence of compounds from the CaO-P2O5-H20 system. The Ca/P (calcium/phosphorus) ratio obtained from the chemical analysis varied from 1.33 to 2.1, and indicated a varied morphology of calcium phosphates forming the bone structures of the facial skeleton.

CONCLUSIONS

1. Calcium phosphates are characterised by excellent biocompatibility because of their chemical affinity to bone, and are ideal for the reconstruction of bone losses within the facial skeleton. 2. Biodegradable polymers have the highest functional potential among several groups of biomaterials used in tissue engineering because of their ability to be tailored individually, in addition to their high biocompatibility.