Applied anatomy of round window and adjacent structures of tympanum related to cochlear implantation

IntroductionVarious aspects of the round window anatomy and anatomy of posterior tympanum have relevant implications for designing cochlear implant electrodes and visualizing the round window through facial recess. Preoperative information about possible anatomical variations of the round window and its relationships to the adjacent neurovascular structures can help reduce complications in cochlear implant surgery.ObjectiveThe present study was undertaken to assess the common variations in round window anatomy and the relationships to structures of the tympanum that may be relevant for cochlear implant surgery.MethodsThirty-five normal wet human cadaveric temporal bones were studied by dissection for anatomy of round window and its relation to facial nerve, carotid canal, jugular fossa and other structures of posterior tympanum. The dissected bones were photographed by a digital camera of 18 megapixels, which were then imported to a computer to determine various parameters using ScopyDoc 8.0.0.22 version software, after proper calibration and at 1× magnification.ResultsWhen the round window niche is placed posteriorly and inferiorly, the distance between round window and vertical facial nerve decreases, whereas that with horizontal facial nerve increases. In such cases, the distance between oval window and round window also increases. Maximum height of the round window in our study ranged from 0.51–1.27 mm (mean of 0.69 ± 0.25 mm). Maximum width of round window ranged from 0.51 to 2.04 mm (mean of 1.16 ± 0.47 mm). Average minimum distance between round window and carotid canal was 3.71 ± 0.88 mm (range of 2.79–5.34 mm) and that between round window and jugular fossa was 2.47 ± 0.9 mm (range of 1.24–4.3 mm).ConclusionThe distances from the round window to the oval window and facial nerve are important parameters in identifying a difficult round window niche. Modification of the electrode may be a better option than drilling off the round window margins for insertion of cochlear implant electrodes.     

Influencia de la existencia de una dehiscencia en un canal semicircular en el espesor óseo de los canales contralaterales

ObjectivesOur objective was to determine if the existence of dehiscence in the superior or posterior semicircular canal was associated with the thinning of the bone roof in the rest of the vertical canals (superior or posterior).MethodsThe thickness of the superior and posterior semicircular canals contralateral to a dehiscence was studied using computerized tomography and compared statistically.ResultsWhen a superior semicircular canal had a dehiscence, the contralateral canal showed a significant mean decrease in its thickness of 0.5 mm (SD: 0.3 mm). This was not the case if the dehiscence was in the posterior semicircular canal, where the thickness of 2.1 mm remained unchanged (SD: 1.2 mm; P=.49).When a posterior semicircular canal showed dehiscence, no significant thinning was shown in the superior semicircular (1 mm; SD: 0.4) or in the posterior contralateral (1.3 mm; SD: 0.3) canals.ConclusionThe existence of a dehiscence in the superior semicircular canal is associated with bone thinning in the canal on the opposite side, but not with the posterior semicircular canal. In contrast, if the dehiscence is in the posterior semicircular canal, contralateral and superior canal thickness is not modified.     

Association between facial nerve second genu angle and facial canal dehiscence in patients with cholesteatoma: evaluation with temporal multidetector computed tomography and surgical findings

IntroductionOtitis media, mastoiditis or the pressure effect of tumorous lesions such as cholesteatoma can be the cause of facial canal dehiscence and facial nerve paralysis. The most common segment involved in dehiscence is the tympanic segment and the second most common is the lateral aspect of the facial canal in the oval window area.ObjectiveTo determine the prevalence of the facial canal dehiscence and the relationship between the angle at the second genu of the facial nerve and facial canal dehiscence.MethodsWe evaluated the surgical findings in 113 patients who underwent surgery for cholesteatoma. Facial canal dehiscence was detected in 62 of the 113 patients. Patients were divided into two groups: Group 1, with dehiscence of the facial canal and Group 2, without dehiscence of the facial canal.ResultsThe mean angles at the second genu of the facial nerve in Groups 1 and 2 were 117.8° ± 9.63° and 114° ± 9.9°, respectively. There was a statistically significant difference between the mean angles at the second genu for the two groups (p = 0.04).ConclusionIn patients with dehiscence of the facial canal, the angle at the second genu was found to be wider than those without dehiscence.     

Newborn hearing screening test with multiple auditory steady-state responses

IntroductionThe techniques most frequently used within a screening context (otoacoustic emissions and click auditory brainstem response) have well-known limitations in hearing loss detection.ObjectiveThis study examines the feasibility of a semi-automated multiple auditory steady-state responses (MSSR) system designed for neonatal hearing screening.MethodsA sample of 50 newborns without risk factors (well-babies) was tested within two weeks of birth. All had detectable auditory brainstem responses to clicks down to 40 dB nHL in both ears. Two amplitude modulated carrier tones of 500 and 2,000 Hz were mixed together and presented simultaneously. Each infant (and ear) was screened with the MSSR system; to simulate a hearing loss, a recording without stimulation was also obtained.ResultsMean auditory thresholds were 42.5 ± 7 dB HL at 500 Hz and 35.5 ± 6 dB HL at 2,000 Hz. The average duration of the MSSR recording was 2.6 ± 1.6 minutes for each tested ear and the overall duration of the screening procedure (including electrode fitting and infant preparation) was 17.8 ± 3.7 minutes. The diagnostic sensibility and the positive predictive values of the MSSR semi-automatic screening system was 100% and 96% respectively, with specificity of 96% and negative predictive values of 100%.ConclusionsAlthough the diagnostic efficiency of the semi-automated MSSR system was found adequate, further technological improvements are still necessary to facilitate its use in the context of universal newborn hearing screening program.     

Dentofacial development abnormalities in paediatric sleep-related breathing disorders

IntroductionThe recent interest in sleep-related breathing disorders has re-opened the old debate as to whether there is a causal relationship between upper respiratory obstruction and abnormalities in dentofacial development.ObjectiveTo establish the impact of dentofacial development on sleep-related breathing disorders in children.MethodThis is a prospective study in which the dentofacial studies of 30 children, diagnosed with a sleep-related breathing disorder using polysomnography, were compared with a control group of 30 healthy children. The ages of both groups were between 3 and 13 years.ResultsThe statistical analysis showed significant differences between the groups in the proportion of children with a narrow palate (83% of the problem group and 57% in the control; P = 0.024) and cross bite (40% and 13%; P = 0.020). On comparing the angles measured, the only statistically-significant difference was the skull base-mandibular plane angle: The problem children group had a mean of 37.59 ± 5.56 and the control group, a mean of 34.41 ± 4.62 (P = 0.023).ConclusionChildren with sleep-related breathing disorders have abnormalities in facial and dental development caused by upper respiratory obstruction. These anomalies, vertical growth of the face, narrow palate and dental occlusion changes should be taken into account when assessing the indication for a adenotonsillectomy.     

Variations in the labyrinthine segment of facial nerve canal revealed by high-resolution computed tomography

Objective

To study variations in the labyrinthine segment of fallopian canal and the associated middle and inner ear malformations.

Is there a correlation between nasal septum deviation and maxillary transversal deficiency? A retrospective study on prepubertal subjects

IntroductionDeviated nasal septum may cause a reduction of the nasal airflow, thus, during the craniofacial development, a reduced nasal airflow could originate a chronic mouth-breathing pattern, related with moderate to severe maxillary constriction. The aim of this retrospective study is to analyze the correlation between maxillary transverse deficiency and nasal septum deviation.MethodsFrontal cephalograms were performed on 66 posterior–anterior radiographs of subjects (34M, 32F; mean age 9.95 ± 2.50 years) with maxillary transverse deficiency and on a control group of 31 posterior–anterior radiographs of subjects (13M, 18F; 9.29 ± 2.08 years). Angular parameters of the nasal cavities were recorded and compared between the two groups using a Student's t-test.ResultsGenerally all the parameters are very similar between the two groups except for the ASY angle that differs for about the 27%; anyway the Student's t-test showed no statistically significant differences between the two groups (mostly p > 0.20).ConclusionsThis study failed to show an association between transverse maxillary deficiencies and nasal septum deviations. Moreover, no significant differences were found between the mean nasal cavities dimensions in subjects with transverse maxillary deficiency and the control group.     

ENDOCOCHLEAR POTENTIAL AND POTASSIUM CONCENTRATION RECORDING IN MINIPIG COCHLEA

Objective To record the endocochlear potential (EP) and calculate potassium concentration [K+] in Minipig cochleae. Methods We used multi-barreled electrodes to measure the EP and the potential, [K+].EP and potassium electrode recording were made in 9 cochleae from 5 minipigs to get normal EP values.Results The average EP value in the cochlea from the minipigs was 77.3 ± 14 mV. The average [K+] for the minipigs was 147.1 ± 13 mM. Conclusions The EP and potential, [K+] in minipigs are lower than in the human and rodents. This may be the reason why porcine ABR thresholds are slightly higher than humans and rodents.     

The anatomic analysis of the vidian canal and the surrounding structures concerning vidian neurectomy using computed tomography scans

Introduction

The type of endoscopic approach chosen for vidian neurectomy can be specified by evaluating the vidian canal and the surrounding sphenoid sinus structures.

Anatomo-radiological study supporting the use of ipsilateral nasoseptal flap for the transpterygoid management of temporo-sphenoidal meningoceles. A review of 21 cases

ObjectivesSurgical treatment of temporo-sphenoidal meningoceles involves the reduction of the meningocele, watertight closure and defect coverage with a nasoseptal flap (NSF). It can be performed contralaterally or ipsilaterally: in the latter situation, the pedicle of the flap must be dissected into the pterygopalatine fossa. The objective of this study was to evaluate the benefit of using an ipsilateral NSF in transpterygoid approaches for the management of temporo-sphenoidal meningoceles, compared to a contralateral NSF, based on a radiological study.Material and methodsRetrospective monocentric study of 21 cases, between 2002 and 2018. Measurement of the NSF lengths, and lengths needed to cover the defect were evaluated on the preoperative scanner. Early and later failure and complication rates were evaluated.ResultsSeventeen cases of temporo-sphenoidal meningoceles with available CT scan were identified. The mean duration of follow up was 27.9 months [1–147]. Theoretical lengths of the ipsi and contralateral NSF were comparable: 71.4 ± 7.8 mm vs. 78.8 ± 8 mm, P = 0.729. In 8 cases/18 (42%), the theoretical length of the contralateral NSF was not long enough to cover the defect beyond the V2 (mean lack of 8.87 ± 6.6 mm). In all cases, the theoretical length of the ipsilateral NSF was sufficient to cover the defect. In the case series, failure and complication rates were similar.ConclusionThe use of an ipsilateral NSF for the transpterygoid management of temporo-sphenoidal meningoceles, although more complex, allows a better coverage of the defect, compared to the contralateral NSF, which is not long enough in 42% of cases.     

Effect of different head impulse procedures on vestibulo-ocular reflex gain

Objectiveto study the effects on vestibulo-ocular reflex (VOR) gain using both video head impulse test (vHIT) and Suppression Head impulse test (SHIMP) either using the outward or the inwards head impulse.MethodsTwenty healthy subjects were enrolled in the study. They were examined using otometric vHIT and SHIMP test lateral plane using the lateral outwards head impulse ten impulses for each side and the inwards head impulse ten impulses for each side. The VOR gain resulting from the outwards versus inwards head impulse during the vHIT and SHIMP were statistically compared.ResultsTwenty healthy subjects, 10 Males and 10 females with a mean age 35 ± 11.7. Paired t- test showed no statistical significance difference in the mean VOR gain of right lateral semicircular canal (1.1 ± .12) using outwards versus (1.03 ± .22) inwards head impulses, nor for the left lateral semicircular canal mean VOR gain (1.1 ± .22) using outwards head impulse (1.1 ± .3) for inwards head impulse in vHIT. Paired t- test showed no statistical significance difference in the mean VOR gain of right lateral semicircular canal (0.96 ± 0.2)using outwards versus (1.04 ± 0.2) inwards head impulses, nor for the left lateral semicircular canal mean VOR gain (0.98 ± 0.25) using outwards head impulse (1.1 ± 0.28) for inwards head impulse in SHIMP test. No statistical significant difference was found between the VOR gain resulting from the right versus the left semicircular canal.ConclusionThe starting head position does not affect the VOR gain using both vHIT and SHIMP tests.     

筛动脉眶内段及窦内段的应用解剖研究

目的：研究筛动脉的走行规律及局部位置关系,为筛窦手术和视神经管减压术提供参考。方法：采用显微解剖学技术对６０ 侧成人筛动脉眶内段和窦内段进行观察和测量。结果：筛前动脉眶内段长（５．１６±１．２４）ｍ ｍ ,管径为（０．５６±０．１７）ｍ ｍ ;筛后动脉眶内段长（９．０８±２．２９）ｍ ｍ ,管径为（０．３７±０．１４）ｍ ｍ 。筛动脉的周围有致密结缔组织构成的筋膜鞘,该鞘包绕与之并行的筛神经和筛静脉,筋膜鞘在筛动脉窦内段亦存在。筛动脉窦内行程有三种类型：走在骨管内;走在筛房顶壁和筛粘膜之间;部分走在骨管内。结论：在筛窦手术或视神经管减压术中,正确寻找和处理筛动脉有重要意义     

Computer-assisted versus traditional technique in fibular free-flap mandibular reconstruction: A CT symmetry study

ObjectivesIn the past few years, virtual planning has been increasingly used for mandibular reconstruction. The objective of our study was to evaluate and compare symmetry and the accuracy of morphologic reconstruction in patients undergoing mandibular reconstruction by fibular free flap between traditional freehand technique and computer-aided surgical cutting guides.Material and methodsA single-center retrospective study included all cases of mandibular reconstruction using fibular free flap. In the three-dimensional (3D) group, virtual surgery planning with cut guides was used (Materialise ®), while the Control group underwent traditional freehand reconstruction. Morphometric comparisons were made to evaluate reconstruction accuracy between pre- and post-operative CT scans (mean deviations of 3 angles and 3 lengths). Mandible symmetry was calculated by comparing each angle and length in the affected and non-affected sides of the mandible.ResultsThirty-three patients treated between January 2015 and June 2018 were included: 25 patients in the 3D group and 8 in the control group. The average number of mandibular segments was 2.16 ± 0.55 in the 3D group and 1.75 ± 1.16 in the control group (p = 0.005). Mean deviations between pre- and post-operative values of the coronal mandibular angle (angle formed by the line through the two condyles and the ramus), mandibular body height and mandibular ramus length on the affected side were significantly lower in the 3D group than in the control group. Sagittal mandibular angle symmetry was better in the 3D group than, in the control group (ratios of affected over non-affected sides: 1.07 ± 0.04 vs 1.12 ± 0.1; p = 0.034).ConclusionVirtual surgical planning for fibula free-flap reconstruction helps to improve reconstruction accuracy and maintains a significantly greater symmetry than the traditional freehand technique, and should improve functional and esthetic outcome in mandibular reconstruction.     

The systolic pulmonary artery pressure and the E/e’ ratio decrease after septoplasty in patients with grade 2 and 3 pure nasal septal deviation

IntroductionNasal septal deviation may contribute to a wide range of symptoms including nasal obstruction, headache, increased secretion, crusting, mucosal damage, and loss of taste and smell. Excessive increase in the respiratory resistance, as seen in nasal septal deviation, results in reduced lung ventilation, thereby potentially leading to hypoxia, hypercapnia, pulmonary vasoconstriction. The deformities in the nasal cavity can be associated with major respiratory and circulatory system diseases.ObjectiveTo investigate cardiovascular effects of septoplasty by comparing pre- and postoperative transthoracic echocardiography findings in nasal septal deviation patients undergoing septoplasty.MethodsThe prospective study included 35 patients with moderate and severe nasal septal deviation (mean age, 23.91 ± 7.01) who underwent septoplasty. The Turkish version of the nasal obstruction symptom evaluation, NOSE questionnaire, was administered to each participant both pre- and postoperatively in order to assess their views on the severity of nasal septal deviation, the effect of nasal obstruction, and the effectiveness of surgical outcomes. A comprehensive transthoracic echocardiography examination was performed both preoperatively and at three months postoperatively for each patient and the findings were compared among patients.ResultsMean preoperative NOSE score was 17.34 ± 1.62 and the mean postoperative score was 2.62 ± 1.68 (p = 0.00). Mean preoperative systolic pulmonary artery pressure value was 22.34 ± 4.31 mmHg and postoperative value was 18.90 ± 3.77 mmHg (p = 0.00). Mean E/e’ ratio was 5.33 ± 1.00 preoperatively and was 5.01 ± 0.90 postoperatively (p = 0.01). The NOSE scores, systolic pulmonary artery pressure values, and the E/e’ ratios decreased significantly after septoplasty (p < 0.05 for all), whereas no significant difference was found in other transthoracic echocardiography parameters (p > 0.05).ConclusionThe decrease in NOSE scores following septoplasty indicated that the satisfaction levels of the patients were increased. Upper airway obstruction secondary to nasal septal deviation may be a cardiovascular risk factor and may affect transthoracic echocardiography measurements. Moreover, the significant decrease in the systolic pulmonary artery pressure value and E/e’s ratio following septoplasty indicated that negative echocardiographic findings may be prevented by this surgery.     

Computed tomography based analysis of the lamina papyracea variations and morphology of the orbit concerning endoscopic surgical approaches

IntroductionRadiologic evaluation is mandatory to assess the type of endoscopic approach concerning sinonasal pathology and reconstruction of fractured defects before any treatment modalities are instituted related to medial wall of the orbit.ObjectiveThe goal was to provide improved understanding of the lamina papyracea variations and the relationship with the orbital morphometry.MethodsThis retrospective study was performed using computed tomography scans of 200 orbits and results were compared with respect to age, sex, laterality and LP variations.ResultsLamina papyracea variations were categorized as type A, 80.5% (161/200); type B, 16% (32/200); type C, 3.5% (7/200). For medial wall the anterior and posterior lamina papyracea heights and angles were found as 17.14 mm, 147.88° and 9.6 mm, 152.72°, respectively. Also, the length of the lamina papyracea, the mean area of the orbital floor, medial wall, lamina papyracea and orbital entrance were 33.3 mm, 7.2 cm², 6.89 cm², 4.51 cm² and 12.46 cm² respectively. The orbital height and width were measured as 35.9 mm and 39.2 mm respectively. The mean orbital cavity depth was 46.3 mm from optic foramen to the orbital entrance and the orbital volume was 19.29 cm³. We analyzed the morphometric measurements tending to increase with aging and greater in men and the relationship of them with lamina papyracea types.ConclusionPrecise knowledge of the lamina papyracea anatomy using computed tomography is essential for safer and more effective surgery and preforming the dimensions of an implant. In this way, the postoperative complications can be decreased and the best outcome can be provided.     

Aural stimulation with capsaicin prevented pneumonia in dementia patients

ObjectiveIn the present study, we examined the effects of daily application of capsaicin ointment to the external auditory canal for 6 months on the development of pneumonia in elderly dementia patients at high risk of aspiration.MethodsTwenty-nine oldest-old bedridden dementia inpatients at high risk of aspiration were enrolled in the present study. Ointment containing 0.025% capsaicin was applied to each external auditory canal with a cotton swab alternatively once a day for 6 months.ResultsThe incidence of pneumonia during the 6 months before the intervention was 1.80 ± 0.37 in these patients. However, this incidence significantly decreased to 0.40 ± 0.29 (p < 0.01) during the 6 months of the alternative application of capsaicin ointment to each auditory canal. No adverse effect such as otalgia was observed.ConclusionThese findings suggest that daily long-term aural stimulation with capsaicin ointment enhanced the cough reflex via Arnold’s ear-cough reflex as a glottis protective measure, resulting in the reduction of incidence of pneumonia in elderly dementia patients at high risk of aspiration. The daily aural stimulation with capsaicin ointment may be a safe and promising intervention to prevent aspiration pneumonia in elderly people, especially those who cannot undergo swallowing exercise.     

Morphometric analysis of nasal shapes and angles in young adults

IntroductionThe size, angle, shape and type of nose are a signature indicating race, age and sex.ObjectiveDescribe and compare nasal angles, nose types, nostril models, and nasal profiles in young Turkish males and females.MethodsThe study group consisted of university students, 56 males and 59 females. Nasal measurements were obtained from all subjects, using anthropometric methods.ResultsThe nose types of females and males were 78% and 70% narrow nose, respectively. The means of females’ nasofrontal, nasal tip, nasolabial, and alar slope angles were 133.16° ± 8.88°; 77.91° ± 9.80°; 98.91° ± 10.01°, and 80.89° ± 8.33°, respectively. The means of males’ nasofrontal, nasal tip, nasolabial, and alar slope angles were 123.85° ± 13.23°; 82.16° ± 9.98°; 97.91° ± 8.78° and 85.98° ± 8.72°, respectively.ConclusionThe average values of the nose in this population may be used as a guide to plan corrective esthetic–cosmetic surgery and for burn scars of the nose.     

Is the C-reactive protein/albumin ratio a prognostic and predictive factor in sudden hearing loss?

IntroductionSudden hearing loss is a significant otologic emergency. Previous studies have revealed a coexistence of sudden hearing loss with chronic inflammation. The predictive importance of C-reactive protein/albumin values as a prognostic factor has been shown in various inflammatory and tumoral conditions.ObjectivesThe aim of this study was to determine whether the C-reactive protein/albumin ratio in sudden hearing loss can be used for prognostic purposes and whether there is a relationship between the neutrophil/lymphocyte ratio and the C-reactive protein/albumin ratio.MethodsA retrospective examination was made of 40 patients diagnosed with idiopathic sudden hearing loss and a control group of 45 healthy subjects. The pure tone averages of all the patients were determined on first presentation and repeated at 3 months after the treatment. The patients were separated into 2 groups according to the response to treatment. The neutrophil/lynphocyte ratio and the C-reactive protein/albumin ratios were calculated from the laboratory tests.ResultsThe patients included 16 females and 24 males with a mean age of 44.1 ± 14.2 years and the control group was composed of 23 females and 22 males with a mean age of 42.2 ± 13.8 years. The mean C-reactive protein/albumin ratio was 0.95 ± 0.47 in the patient group and 0.74 ± 0.13 in the control group. The difference was statistically significant (p = 0.009). The mean C-reactive protein/albumin ratio was 0.79 ± 0.12 in the response to treatment group and 1.27 ± 0.72 in the non-response group, with no significant difference determined between the groups (p = 0.418). The mean neutrophil/lymphocyte ratio was 3.52 ± 3.00 in the response to treatment group and 4.90 ± 4.60 in the non-response group, with no statistically significant difference determined between the groups (p = 0.261).ConclusionC-reactive/albumin ratio was significantly higher in patients with sudden hearing loss than in the control group. Although C-reactive protein/albumin ratio was found to be lower in sudden hearing loss patients who responded to treatment compared to those who did not, the difference between two groups was not statistically significant.     

Masseter muscle flap for reconstruction of intra-oral defects in patients with early cancer of posterior-inferior parts of the oral cavity

IntroductionEarly carcinomas of the oral cavity in the posterior-inferior regions poses a challenge for reconstruction due to the lack of muscle support underneath and the limited space available to use some of the frequently-used flaps.ObjectiveThis study was done to evaluate the efficacy of the superiorly based masseter muscle flap in reconstruction of intra-oral post- ablation defects in patients with early oral carcinoma of the posterior-inferior part of the oral cavity.MethodsA superiorly based masseter muscle flap were used to reconstruct the post-surgical intra- oral defect in 60 patients with early squamous cell carcinoma (T < 4 cm) of the posterior-inferior part of the oral cavity. The patients were followed up at 1-week and 1-month postoperatively to check for flap viability, complications, change in mouth opening and deviation of the mandible on mouth opening. To rule out any recurrence in the oral cavity masseter flaps, the patients were followed up for 1 year.ResultsThe flap was viable in all patients and underwent mucosalization. 7/60 patients had postoperative infections, while 2/60 patients developed an oro-cutaneous fistula which required a secondary corrective procedure. The mean ± standard deviation of change in mouth opening at 1 week postoperatively was +1.917 ± 3.36 mm, which increased to +2.633 ± 2.95 mm at 1 month after surgery. The Friedman test revealed that there was a statistically significant change in mouth opening from preoperative period to the1 week and 1 month postoperative periods (p = 0.000). Female patients showed better improvement in mouth opening postoperatively. The ipsilateral deviation of the mandible on mouth opening was between 0–5 mm in 39 patients, 5–10 mm in 17 patients and more than 10 mm in 4 patients. There were no recurrences noted in the masseter flaps used.ConclusionThe study infers that the superiorly based masseter muscle flap is a reliable method for reconstruction in early oral cancer patients yielding good functional results and acceptable cosmesis with nominal postoperative complications.     

Indirect laryngoscopy with rigid 70-degree laryngoscope as a predictor of difficult direct laryngoscopy

Introduction and objectivesThe commonly-used predictors for difficult airway management are not very accurate. We investigate the power of indirect laryngoscopy with the rigid 70-degree laryngoscope as a predictor of difficult visualisation of the larynx with direct laryngoscopy.MethodsWe performed preoperative indirect laryngoscopy with the rigid laryngoscope on 300 patients. The vision obtained was classified into four grades: 1 (vocal cords visible), 2 (posterior commissure visible), 3 (epiglottis visible) and 4 (no glottic structure visible). Grades 3 and 4 were considered predictors of difficult larynx visualisation. Next, direct laryngoscopy with the Macintosh laryngoscope was carried out on the patients under general anaesthesia. Positive value was defined as a Cormack and Lehane III and IV. Other common clinical predictors were also analysed. A logistic regression model using the relevant variables was elaborated. We also investigated predictors of difficult visualisation of the larynx with indirect laryngoscopy.ResultsThe model found and the coefficients for preparing it were: f(x)= -10.097 + 5.145 indirect laryngoscopy (3-4) + 3.489 retrognathia +2.548 mouth opening <3.5 cm +1.911 thyromental distance <6.5 cm +1.352 snorer + (0.151 * cm neck thickness). This model provided a correct result in 94.3% of cases. In the case of indirect laryngoscopy, the model found was: f (x) = -2.641 + 0.920 snorer + 0.875 cervical mobility.ConclusionsIndirect laryngoscopy was the independent variable with the greatest predictive power. Snoring is a common predictor in both laryngoscopy models.