The role of cochlear implant positioning on MR imaging quality: a preclinical in vivo study with a novel implant magnet system.

PURPOSES: To investigate the effects for Ultra 3D cochlear implant (CI) positioning on MR imaging quality, looking at a comprehensive description of intracranial structures in cases of unilateral and bilateral CI placement. METHODS: Four CI angular positions (90°, 120°, 135° and 160°) at 9 cm distance from the outer-ear canal were explored. The 1.5 T MRI assessment included our institutional protocol for the investigation of brain pathologies without gadolinium application. Three investigators (two experienced neuroradiologists and one experienced otoneurosurgeon) independently evaluated the MR findings. A 4-point scale was adopted to describe 14 intracranial structures and to determine which CI positioning allowed the best image quality score and how bilateral CI placement modified MRI scan visibility. RESULTS: A high positive correlation was found between the three blinded observers. Structures situated contralateral from the CI showed high-quality values in all four placements. Structures situated ipsilaterally provided results suitable for diagnostic purposes for at least one position. At 90°, artifacts mainly involved brain structures located cranially and anteriorly (e.g., temporal lobe); on the contrary, at 160°, artifacts mostly influenced the posterior fossa structures (e.g., occipital lobe). For the bilateral CI condition, MR imaging examination revealed additional artifacts involving all structures located close to either CI, where there was a signal void/distortion area. CONCLUSIONS: Suitable unilateral CI positioning can allow the visualization of intracranial structures with sufficient visibility for diagnostic purposes. Bilateral CI positioning significantly deteriorates the anatomical visibility. CI positioning might play a crucial role for patients who need post-operative MRI surveillance.

MRI-induced artifact by a cochlear implant with a novel magnet system: an experimental cadaver study.

PURPOSES: To primarily evaluate MRI-induced effects for Ultra 3D cochlear implantation in human cadavers in terms of artifact generation and MR image quality. METHODS: Three human cadaveric heads were submitted to imaging after unilateral and bilateral cochlear implantation. The 1.5 T MR examination protocol was chosen in accordance with our institutional protocol for the assessment of brain pathology. The maximal signal void size was measured according to each sequence and plane. Two experienced neuro-radiologists and one experienced otoneurosurgeon independently evaluated the MR image quality findings. A 4-point scale was used to describe the diagnostic usefulness of 14 brain structures. RESULTS: Shape and size of the artifacts were found to be highly related to MRI sequences and acquisition planes. MRI sequences and processing algorithms affected the ability to assess anatomical visibility. Image quality appeared either high or assessable for diagnostic purposes in 9 out of 14 of the ipsilateral structures, in at least one plane. Anatomical structures contralateral to the cochlear implant were highly visible in all conditions. Artifact intrusion clearly improved after application of metal artifact-reduction techniques. In the case of bilateral cochlear implant, a mutual interaction between the two implant magnets produced an additional artifact. CONCLUSIONS: We performed the first cadaver study aimed at systematically evaluating the MRI-induced artifacts produced by a cochlear implant with a novel four bar magnet system. Specific brain structures can be assessable for diagnostic purposes under 1.5 T MRI, with the cochlear implant magnet in place.

Feasibility of 3D printed salivary duct models for sialendoscopic skills training: preliminary report.

PURPOSES: To explore the feasibility of 3D printed salivary duct models for the sialendoscopic skills training. METHODS: Healthy volunteers and patients affected by obstructive salivary gland disorders were submitted to 3 Tesla MR sialography. The MR data underwent an image segmentation process to produce the 3D printed salivary duct prototypes. Sialendoscopies were carried out by three groups of investigators with different levels of endoscopic experience. Realism, usefulness of the training process and potential advantages of the 3D printed models in the preoperative surgical planning were evaluated by means of a specific survey. RESULTS: Four cases were included in our study: one healthy parotid, one submandibular gland, one case of lithiasis and one of stenosis involving the parotid gland. In all cases, the three groups of investigators successfully explored the salivary ducts up to the tertiary branches, detected the cause of obstruction and correctly treated it. Seven untoward events occurred during the operative sialendoscopies. Overall, the questionnaire score was about 79.3%, reflecting a positive impression regarding the models on behalf of all the investigators. CONCLUSIONS: 3D printed salivary duct models resulted feasible for the sialendoscopic skills training. The opportunity to reproduce the patient-specific anatomy may add further information useful in the preoperative decision making. These positive results should be verified by further researches and experiences.

Anatomic variations of the round window niche: radiological study and related endoscopic anatomy.

PURPOSE: In the last decades, literature has shown an increasing interest in round windows (RW) anatomy due to its pivotal role in deafness surgery. The high variability of this anatomical region, with particular regard to the round windows niche (RWN), has been studied by several authors through different methods of investigation. The aim of the present research was to radiologically examine the morphological variability of the RWN and to link the imaging findings to the endoscopic view. METHODS: High-resolution CT scans of 300 temporal bones without neuro-otological pathologies were retrospectively reviewed by 2 neuroradiologist and 1 ENT surgeon who independently evaluated the RWN morphological variations. To link the radiological to the endoscopic data, 45 cadaveric human temporal bones were submitted to a radiological evaluation and to an otoendoscopy conducted through a posterior tympanotomy approach. RESULTS: Three variants of the RWN were detected on coronal CT scan reconstructions: 155 "cylindrical-type", 97 "j-type" and 48 "truncated cone-type". For each radiological type the endoscopic findings showed a specific endoscopic position of the RW chamber, which results in different degrees of RW membrane visibility when analysed through a posterior tympanotomy approach. CONCLUSIONS: To the best of our knowledge, this is the first description of the above-mentioned RWN radiological variations supported by endoscopic data. This study suggests an additional anatomical evaluation that could be useful to predict the RW membrane visibility through a posterior tympanotomy approach. Further studies are required to support the clinical implications of our observations.

"TuNa-saving" endoscopic medial maxillectomy: a surgical technique for maxillary inverted papilloma.

The maxillary sinus is the most common site of sinonasal inverted papilloma. Endoscopic sinus surgery, in particular endoscopic medial maxillectomy, is currently the gold standard for treatment of maxillary sinus papilloma. Although a common technique, complications such as stenosis of the lacrimal pathway and consequent development of epiphora are still possible. To avoid these problems, we propose a modification of this surgical technique that preserves the head of the inferior turbinate and the nasolacrimal duct. A retrospective analysis was performed on patients treated for maxillary inverted papilloma in three tertiary medical centres between 2006 and 2014. Pedicle-oriented endoscopic surgery principles were applied and, in select cases where the tumour pedicle was located on the anterior wall, a modified endoscopic medial maxillectomy was carried out as described in this paper. From 2006 to 2014 a total of 84 patients were treated. A standard endoscopic medial maxillectomy was performed in 55 patients (65.4%), while the remaining 29 (34.6%) had a modified technique performed. Three recurrences (3/84; 3.6%) were observed after a minimum follow-up of 24 months. A new surgical approach for select cases of maxillary sinus inverted papilloma is proposed in this paper. In this technique, the endoscopic medial maxillectomy was performed while preserving the head of the inferior turbinate and the nasolacrimal duct ("TuNa-saving"). This technique allowed for good visualization of the maxillary sinus, good oncological control and a reduction in the rate of complications.

A novel device for intraoperative cauterization of bleeding points in endoscopic sinus surgery.

Hemostasis is a critical point in endoscopic sinus and skull base surgery. A variety of techniques are presently available for reducing intraoperative bleeding; however, several limitations of the classical instruments should be stated. For example, reaching bleeding points in an anatomically angled site with straightforward bipolar devices could be quite difficult. With the aim of solving this problem, we developed a simple system using a standard curved suction tube, a rubber catheter and a monopolar system. This device provides an integrated suction function and is able to reach all paranasal and skull base areas, making it extremely useful in gaining precise access to the site of bleeding while providing excellent endoscopic vision. The described monopolar suction tube has proven to be a valid instrument for intraoperative hemostasis in endoscopic procedures; moreover, it does not add any further cost, making it applicable in particular healthcare settings, such as those in developing countries.

Customized Cochlear Implant Positioning in a Patient With a Low- Grade Glioma: Towards the Best MRI Artifact Management.

OBJECTIVE: To report the personalized decision-making pro- cess adopted for a cochlear implant (CI) candidate requiring magnetic resonance imaging (MRI) brain surveillance. STUDY DESIGN: Clinical capsule report. SETTING: Tertiary academic referral center. PATIENT: A 23-year-old man affected by posttraumatic bilat- eral profound hearing loss, already in radiological follow-up for a suspected small left cuneal low-grade glioma. INTERVENTIONS: A multidisciplinary approach involving preoperative MRI simulations and 3D printed (3DP) models aiming to adapt the CI position to facilitate MRI brain lesion visibility. MAIN OUTCOME MEASURES: MRI visibility and surgical approach. RESULTS: Preoperative MRI scans with the placement of an Ultra 3D CI were performed simulating different implant location to assess the brain lesion visibility in MRI. CI was positioned 9 cm away from the external auditory canal with an angle of 90 degrees. To assess the technical feasibility of the surgical procedure, a patient-specific 3DP head model was produced preoperatively. The postoperative course was uneventful, the patient showed a significant benefit from CI, and the brain lesion was highly visible at the MRI follow-up. CONCLUSIONS: The employment of strategies aimed at improving the MRI quality in CI recipients still represents a topic requiring attention. Thanks to multidisciplinary team collaboration, in our case, the CI position was successfully determined to allow unhindered MRI visibility of a specific intracranial structure.

Bulging of the Oval Window in Common Cavity Deformity: A Possible Predictor of Meningitis.

OBJECTIVE: To investigate the prevalence-rate of oval window bulging in the common cavity and its association with bacterial meningitis. PATIENTS: CT and clinical files of 29 children with preliminary diagnosis of common cavity deformity were collected from 13 Italian centers. INTERVENTION: A retrospective case review study was conducted with a centralized evaluation of the temporal bone CT imaging was performed at Azienda Ospedale - Università Padova, Padova, Italy. MAIN OUTCOME MEASURE: Diagnosis of common cavity was reviewed; in addition, a fluid protrusion into the middle-ear cavity through the oval window at CT imaging was considered as oval window bulging. Its association with the history of bacterial meningitis was investigated. RESULTS: Common cavity deformity was confirmed in 14/29 children (mean-age 11.4 ±â€Š3.8; age-range 5-20; nine females) referred with this diagnosis. In 7/14 patients, the common cavity deformity was bilateral (i.e., 21 common cavities). Oval window bulging was found in 3/19 common cavities (concomitant middle-ear effusive otitis hampered the evaluation in two cases), while the internal acoustic meatus fundus was defective in 10/21 cases. History of bacterial meningitis was found in three children (21%) and two of them had oval window bulging at CT. In the case unrelated to oval window bulging, meningitis occurred late at the age of 12 during acute otitis contralateral to common cavity deformity (ipsilaterally to incomplete partition type 1). CONCLUSION: Patients harboring common cavity deformity have a high risk of meningitis in their first years of life. Oval window bulging seems to be associated with a higher risk of meningitis. This information might be important for appropriate surgical planning.

Genetics of Inner Ear Malformations: A Review.

Inner ear malformations are present in 20% of patients with sensorineural hearing loss. Although the first descriptions date to the 18th century, in recent years the knowledge about these conditions has experienced terrific improvement. Currently, most of these conditions have a rehabilitative option. Much less is known about the etiology of these anomalies. In particular, the evolution of genetics has provided new data about the possible relationship between inner ear malformations and genetic anomalies. In addition, in syndromic condition, the well-known presence of sensorineural hearing loss can now be attributed to the presence of an inner ear anomaly. In some cases, the presence of these abnormalities should be considered as a characteristic feature of the syndrome. The present paper aims to summarize the available knowledge about the possible relationships between inner ear malformations and genetic mutations.

Retrosigmoidal placement of an active transcutaneous bone conduction implant: surgical and audiological perspectives in a multicentre study.

INTRODUCTION: The retrosigmoidal (RS) placement of the Bonebridge system (BB) has been advocated for cases of unfavourable anatomical or clinical conditions which contraindicate transmastoid-presigmoidal positioning. However, these disadvantageous conditions, combined with the considerable dimensions of the implant, may represent a challenge, especially for surgeons with no skull base experience. Moreover, the literature reports only limited experience concerning RS implantation of the BB system. METHODS: A multicentre, retrospective study was conducted to analyse the surgical and functional outcomes of a wide population of patients undergoing RS placement of the BB system by means of a surgical technique specifically developed to overcome the intraoperative issues related to this surgery. Twenty patients with conductive or mixed hearing loss and single sided deafness were submitted to RS implantation of the BB system. RESULTS: Audiological assessment concerning the measurement of the functional and effective gain by pure-tone audiometry (28 dB HL and -12.25 dB HL, respectively) and speech audiometry (24.7 dB HL and -21 dB HL, respectively) was conducted. A high overall subjective improvement of quality of life was recorded with the Glasgow Benefit Inventory questionnaire. No major complications, such as device extrusions or other conditions requiring revision surgery, were reported during the follow-up period (median: 42 months). CONCLUSIONS: In our study, which has one of the largest cohort of patients reported in the literature, RS placement of the BB system was safe and effective. Our functional results showed comparable hearing outcomes with presigmoidal placement. The effective gain, rarely investigated in this field, may be the object of further research to improve our understanding of bone conduction mechanisms exploited by bone conduction hearing implants.

Isolated Eustachian Tube Osteoma: Common Lesion in Uncommon Site.

Isolated Eustachian tube osteomata are a very rare entity indeed, with the last case being reported in 1979. We describe a case of the otoscopic finding of a blue-yellowish eardrum and successive identification by computed tomography scan of an osteoma localized in the Eustachian tube. Clinical presentation and diagnostic and therapeutic phases in comparison with the literature will be discussed.

A 3D printed custom-made mask model for frameless neuronavigation during retrosigmoid craniotomy. A preclinical cadaveric feasibility study.

BACKGROUND: A 3D printing custom-made mask model was tested in terms of feasibility and accuracy for frameless neuronavigation during retrosigmoid approach. METHODS: A virtual 3D model of a cadaveric injected head was obtained from a high-resolution Computed Tomography (CT) scan and 3D Printed (3DP). The course of the transverse and sigmoid sinus was marked. A transparent custommade 3DP mask model was created as a cast of 3D model. The area of the lateral sinuses was grooved to allow the surgeon to use the mask as a template to draw the course of the sinuses on the patient skull. A right retrosigmoid approach was performed on formalin-fixed injected cadaveric head. Inion and other conventional landmarks were used to mark the course of the sinuses. 3DP mask was used to re-mark the course of the sinuses. The mismatch between the landmarks-based and 3DP mask-based track was assumed as a measure of the accuracy of the 3DP mask model. RESULTS: 3DP mask model resulted precise, feasible, easy and fast to use. A perfect interlocking with the retrosigmoid area was noted. Mismatch between the landmarks-based and 3DP mask-based track was of 4 and 6 mm for transverse and sigmoid sinus, respectively. CONCLUSION: 3DP custom-made mask model is feasible, easily reproducible and reliable for the implementation of a frameless neuronavigation during retrosigmoid approach. Its accuracy is greater than that of the bone landmark neuronavigation. In selected cases, 3DP mask can be a valid option to image-guided optical or electromagnetic tracking systems. KEY WORDS: 3D Printing, Neuronavigation, Retrosigmoid Approach, Sigmoid Sinus, Transverse Sinus.

A 3D printed custom-made mask model for frameless neuronavigation during retrosigmoid craniotomy. A preclinical cadaveric feasibility study.

BACKGROUND: A 3D printing custom-made mask model was tested in terms of feasibility and accuracy for frameless neuronavigation during retrosigmoid approach. METHODS: A virtual 3D model of a cadaveric injected head was obtained from a high-resolution Computed Tomography (CT) scan and 3D Printed (3DP). The course of the transverse and sigmoid sinus was marked. A transparent custommade 3DP mask model was created as a cast of 3D model. The area of the lateral sinuses was grooved to allow the surgeon to use the mask as a template to draw the course of the sinuses on the patient skull. A right retrosigmoid approach was performed on formalin-fixed injected cadaveric head. Inion and other conventional landmarks were used to mark the course of the sinuses. 3DP mask was used to re-mark the course of the sinuses. The mismatch between the landmarks-based and 3DP mask-based track was assumed as a measure of the accuracy of the 3DP mask model. RESULTS: 3DP mask model resulted precise, feasible, easy and fast to use. A perfect interlocking with the retrosigmoid area was noted. Mismatch between the landmarks-based and 3DP mask-based track was of 4 and 6 mm for transverse and sigmoid sinus, respectively. CONCLUSION: 3DP custom-made mask model is feasible, easily reproducible and reliable for the implementation of a frameless neuronavigation during retrosigmoid approach. Its accuracy is greater than that of the bone landmark neuronavigation. In selected cases, 3DP mask can be a valid option to image-guided optical or electromagnetic tracking systems. KEY WORDS: 3D Printing, Neuronavigation, Retrosigmoid Approach, Sigmoid Sinus, Transverse Sinus.

Epidemiologic, Imaging, Audiologic, Clinical, Surgical, and Prognostic Issues in Common Cavity Deformity: A Narrative Review.

IMPORTANCE: Common cavity deformity is a rare congenital inner ear malformation associated with profound hearing loss and attributed to an early developmental arrest of the cochlear-vestibular structures. This narrative review highlights the need to identify reliable indicators of hearing rehabilitation outcome. OBSERVATIONS: Despite its relatively simple definition, common cavity deformity varies widely in morphologic features, presence of cochlear nerve fibers and remnants of Corti organ, and outcome after cochlear or brainstem implant. CONCLUSIONS AND RELEVANCE: Cochlear implant has been shown to be a valid option for common cavity deformity, but its outcome remains variable and poor. Identification of specific neuroradiologic, audiologic, and neurophysiologic prognostic features; tailoring of the surgical approach; and standardization of outcome measures are needed to optimize the management of common cavity deformity and hearing rehabilitation after implant.

"Emergency" Cochlear Implantation in Labyrinthitis Ossificans Secondary to Polyarteritis Nodosa: How to Face a Rare Entity.

Polyarteritis nodosa (PAN) is a systemic vasculitis affecting the small- and medium-sized arteries that may present with hearing impairment. In rare cases, PAN may be associated with progressive labyrinthitis ossificans (LO), an otologic emergency requiring early cochlear implantation (CI) to restore hearing before the complete, irreversible cochlear ossification. We report the first case in the literature of a patient affected by PAN with bilateral sudden sensorineural hearing loss and rapid LO who underwent "emergency" bilateral simultaneous CI. This case report emphasizes the importance of an early audiological evaluation in patients with PAN when LO is suspected. Multidisciplinary approach is mandatory when facing organ-specific manifestations in patients with PAN. Detailed discussion is provided with particular regard to clinical and radiological presentation as well as CI outcomes in such a rare and challenging case.

Invasive fungal rhinosinusitis in adult patients: Our experience in diagnosis and management.

BACKGROUND: This paper describes our experience in the management of acute and chronic invasive fungal rhinosinusitis (IFRS) in adults. METHODS: Medical files of all patients aged >18 years treated in our institutions for IFRS from 2002 to 2013 were retrospectively reviewed. RESULTS: A total of 18 cases (10 acute and 8 chronic) were recorded. In acute form, haematological malignancies represented the principal comorbidity (100%), while in chronic form this was diabetes mellitus (87.5%). All patients received systemic antifungal agents. Endoscopic sinus surgery was performed in 16/18 patients (88.9%). Among patients with an acute IFRS, 4/10 died of fungal infection (40%), on the other side 2/8 patients with chronic IFRS died of the evolution of the mycosis (25%). CONCLUSIONS: Acute and chronic IFRS are different entities: in acute form, prognosis is poor, so therapy should be promptly performed, although host immune status and evolution of the haematological disease are key factors for the outcome. In chronic form, a wide surgical excision of the disease is recommended in order to obtain a complete removal of fungal infection. In both forms, early clinical findings are non-specific and ambiguous, so diagnosis depends on a high index of suspicion, taking into account predisposing factors.