Pathophysiology of Postoperative Hearing Disorders after Vestibular Schwannoma Resection: Insights from Auditory Brainstem Response and Otoacoustic Emissions.

Background: In order to better understand the pathophysiology of surgically induced hearing loss after vestibular schwannoma (VS) surgery, we postoperatively analyzed the hearing status in a series of patients where hearing was at least partially preserved. Methods: Hearing was assessed through tonal audiometry, speech discrimination score, maximum word recognition score (dissyllabic word lists-MaxIS), otoacoustic emissions (OAEs), and auditory brainstem response (ABR). The magnetic resonance imaging (MRI) tumor characterization was also noted. Results: In a series of 24 patients operated on for VS over 5 years, depending on the results of this triple hearing exploration, we could identify, after surgery, patients with either a myelin alteration or partial damage to the acoustic fibers, others with a likely partial cochlear ischemia, and some with partial cochlear nerve ischemia. One case with persisting OAEs and no preoperative ABR recovered hearing and ABR after surgery. Long follow-up (73 ± 57 months) revealed a mean hearing loss of 30 ± 20 dB with a drastic drop of MaxIS. MRI revealed only 25% of fundus invasion. Conclusion: a precise analysis of hearing function, not only with classic audiometry but also with ABR and OEAs, allows for a better understanding of hearing damage in VS surgery.

Endoscopic endonasal odontoidectomy for basilar invagination in children: Literature review and case report.

BACKGROUND: Basilar invagination (BI) is an uncommon clinical condition of the craniocervical junction (CCJ). Surgical management depends on 2 factors: mobility and reducibility; in cases of irreducible dislocation or persistent compression, odontoidectomy should be considered. CASE DISCUSSION: We present the case of a 13-year-old boy with severe BI, causing cervical myelopathy with progressive gait disorder. The patient underwent cervical traction followed by posterior decompression and occipitocervical fusion. Postoperatively, symptoms initially improved, until new neurological deterioraton set in 4 months later. Follow-up neuroimaging showed compression of the bulbo-medullary junction, with severe brainstem kinking and appearance of a cervical syrinx. Secondary surgery via an endoscopic endonasal approach (EEA) was deemed necessary to relieve the compression. Postoperative course was unremarkable, with steady clinical improvement and a return to independent activities of daily living within 6 months. LITERATURE REVIEW: A systematic literature review indicated that EEA conserves the palate and oropharynx mucosae, thus causing less airway and swallowing complications than the transoral approach. CONCLUSION: In selected cases with persistent anterior compression, odontoidectomy on EEA is a safe, effective and valid alternative for managing CCJ pathology.

Pituitary Abscess: A Challenging Preoperative Diagnosis-A Multicenter Study.

Background and Objectives: Pituitary abscess (PA) is a rare occurrence, representing less than 1% of pituitary lesions, and is defined by the presence of an infected purulent collection within the sella turcica. Pas can be classified as either primary, when the underlying pituitary is normal prior to infection, or secondary, when there is associated a pre-existing sellar pathology (i.e., pituitary adenoma, Rathke's cleft cysts, or craniopharyngioma), with or without a recent history of surgery. Preoperative diagnosis, owing to both non-specific symptoms and imaging features, remains challenging. Treatment options include endonasal trans-sphenoidal pus evacuation, as well as culture and tailored antibiotic therapy. Methods: A retrospective multicenter study, conducted on a prospectively built database over a 20-year period, identified a large series of 84 patients harboring primary sellar abscess. The study aimed to identify crucial clinical and imaging features in order to accelerate appropriate management. Results: The most common clinical presentation was a symptom triad consisting of various degrees of asthenia (75%), visual impairment (71%), and headache (50%). Diagnosis was achieved in 95% of cases peri- or postoperatively. Functional recovery was good for visual disturbances and headache. Pituitary function recovery remained very poor (23%), whereas the preoperative diagnosis represented a protective factor. Conclusions: In light of the high prevalence of pituitary dysfunction following the management of PAs, early diagnosis and treatment might represent a crucial issue. Currently, there are no standard investigations to establish a conclusive preoperative diagnosis; however, new, emerging imaging methods, in particular nuclear imaging modalities, represent a very promising tool, whose potential warrants further investigations.

A Laboratory Investigation on a Tailored Skin and Muscle Flap Variant for the Retrosigmoid Approach.

Introduction An anatomical study was conducted to test a modified C-shaped flap designed for patients undergoing a keyhole approach and/or minicraniotomy for retrosigmoid approach (KRSA). Materials and Methods Ten heads specimens were used. The surgical technique investigated was based on a 4-cm C-shaped skin incision with medial convexity (placed 8 cm laterally to the external occipital protuberance, with the lower edge terminating 1.5 to 2 cm above the mastoid tip), which followed by careful subperiosteal dissection and completed by reflecting and securing the skin flap layer anteriorly and the muscle flaps superiorly and inferiorly by stitches. Anatomical findings, including depth of surgical corridor till to the cerebellopontine cistern (CPC) as well as the sparing of neurovascular structures, were evaluated in every specimen. Results Twenty surgical approaches to CPC were conducted, resulting in a short working distance to the target (32 mm) without any need for a self-retaining retractor. In every specimen, the integrity of occipital muscles and cutaneous nerves was maintained, and a solid multilayer closure was always achieved. These data suggest that landmarks-based design of this C-shaped incision could be helpful in avoiding damages to the soft tissues encountered during KRSA. Conclusion This modified approach provides a wide surgical corridor to access the CPC while ensuring the minimal invasiveness of the standard S-shaped incision. Compared with the latter, it preserves better the integrity of the surrounding soft tissues and appears less likely to cause any iatrogenic injury to occipital muscles and cutaneous nerves.

Present and future of the labyrinth imaging: Focus on the use of T2-weighted and contrast-enhanced delayed FLAIR (1 h) sequences.

OBJECTIVE: Part of the recent progress in the labyrinth imaging has been made possible by the rise of contrast-free T2-weighted and delayed (1h) FLAIR sequences. The aim of this article is to review evidence for the use of these two sequences to image the inner ear, especially the posterior membranous labyrinth. MATERIAL AND METHODS: We analyzed MRI-based papers (2007-2020)using high-resolution T2-weighted or contrast-enhanced FLAIR (1h) sequences to image the inner ear. RESULTS: T2-weighted sequences (3T MRI)enabled the visualization of the posterior membranous labyrinth with good correlation when compared to corresponding histological slices.Significant progress has been made, especially in terms of scanning time, aiming at reducing it, in order to decrease motions artifacts. The saccule is visible on a 3T MRI without significant motion artifacts. Its shape is ovoid, with a maximum height and width of 1.6 and 1.4 mm, respectively. An enlarged saccule was observed in 84%of patients with unilateral Meniere's disease, in 28%of patients with vestibular schwannomas (VS) and 47%of patients with intralabyrinthine schwannomas. VS obstructing the internal auditory canal caused a decrease of the perilymphatic signal (more moderate decrease in meningiomas) on T2 gradient-echo images. Contrast-enhanced FLAIR sequences are useful to image vestibular/facial neuritis and inflammatory inner ear diseases. CONCLUSION: Precise analysis of the posterior membranous labyrinth, in terms of size, shape and signal intensity, is possible on a 3T MRI using high-resolution gradient-echo T2-weighted sequences. Such sequences are an interesting add-on to delayed (4h30) FLAIR-based protocols for labyrinth imaging.

An image-guided (CT) assessment of a new asymmetric balloon for the treatment of epistaxis.

PURPOSE: The main objective was to perform an image-guided (CT) assessment of the efficacy of the CAVI-T™ balloon to compress the sphenopalatine artery (SPA) on cadaver heads, for the management of epistaxis. The secondary objectives were to analyse the deployment and stability of this balloon according to the volume injected into the nasal cavity, to optimise its use. METHODS: A descriptive anatomical study was performed. The catheterization of the SPA was performed on four fresh-frozen heads with a SPA approach through the maxillary sinus, leaving the nasal cavity unscathed. Computed Tomography images were acquired without and with the balloon, inflated by injections of progressive volumes of diluted iodine, for optimal contrast with the surrounding tissues. We evaluated the positioning of the balloon according to two predetermined markers on the device. RESULTS: Out of 68 image-guided acquisitions, the CAVI-T™ balloon compressed the SPA in 88% of cases. The other nasal cavity structures were compressed in 86% to 100% of the cases, depending on the positioning of the CAVI-T™ balloon, therefore allowing a complete obstruction of the nasal cavity. The device remained stable upon inflation and did not obstruct the nasopharynx. CONCLUSION: The CAVI-T™ balloon provided effective compression of the SPA and the different structures of the nasal cavity.

Endoscopic Transorbital Approaches to Anterior and Middle Cranial Fossa: Exploring the Potentialities of a Modified Lateral Retrocanthal Approach.

BACKGROUND: Among the new perspectives to revolutionize skull base surgery, there are the transorbital neuroendoscopic (TONES) approaches to reach the anterior and middle cranial fossa (ACF and MCF). We conceived to explore the potentialities of a modified superiorly and medially extended lateral retrocanthal (LRC) approach. METHODS: Six head specimens were dissected. Applying the established conic model and the key surgical landmark of sphenofrontal suture, we tested the feasibility of a modified LRC to reach ACF and MCF; computed tomography (CT) scans were performed before and after dissection to obtain a morphometric analysis of the surgical corridors using a polygonal surfaces model. RESULTS: Through our anatomical study, we were able to identify and explore 3 different surgical corridors to reach the ACF and MCF: the superomedial, the superolateral, and the inferolateral. The superomedial corridor appeared most suitable to reach the medial part of the ACF and the optic-carotid region, whereas through the superolateral and inferolateral corridors it was possible to reach and explore the lateral part of ACF and MCF. The mean volumes of the 3 surgical corridors calculated on post-dissection CT scans were: 12.72 ± 1.99, 5.69 ± 0.34, and 6.24 ± 0.47 cm3, respectively. CONCLUSIONS: The development of TONES approaches has not replaced the traditional open or endoscopic approach; nonetheless, identification of surgical corridors and the possibility to combine them represent a major breakthrough. Clinical studies are necessary to demonstrate their validity and test the effectiveness, safety, and reproducibility of TONES approaches in managing lesions harboring in the ACF and MCF.

Meniere's attack - a volume or pressure phenomenon?

Meniere's disease (MD) still raises since its discovery in 1860 pathophysiological and etiopathogenical issues. The main pathophysiological feature that has emerged for decades is an anatomic one, the endolymphatic hydrops (EH), defined by the inflation of the endolymphatic part of the membranous labyrinth. However, the causal relationship between EH and MD has not been proven.Several attempts have been achieved in animals to induce EH. The best known is the blockage of the vestibular duct, which causes a chronic volume inflation of the endolymphatic part. This model is characterized by the discrepancy between electrophysiological findings and scala media inflation. Pressure measurements vary among studies.The endolymphatic infusion model, which attempts to model the acute clinical picture of MD consistently shows pressure equilibration between the endolymphatic and perilymphatic compartments, and rapid recovery of the electrophysiological finding once the injection is stopped.

Endoscopic Transorbital Approaches to Anterior and Middle Cranial Fossa: A Laboratory Investigation on Surgical Anatomy and Potential Routes.

Background Transorbital neuroendoscopic (TONES) approaches promise to open up new horizons for skull base surgery, offering alternative routes to reach the anterior and middle cranial fossa (ACF and MCF, respectively). Objective The aim of this anatomical study is to acquire new surgical anatomy knowledge and exploit it for the refinement of TONES approaches, as an alternative to open surgery, to reduce the distance to the target, and the risk of neurovascular lesions in pathological conditions extending beyond the orbital cavity. Materials and Methods Six head specimens (12 orbits) were studied/dissected. The orbit was approached and divided in a four clockwise quadrants manner to simulate three transconjunctival routes: the precaruncular (PC), preseptal (PS), and lateral retrocanthal (LRC), and one transpalpebral route-the superior eyelid crease (SLC). The boundaries and the most important anatomical landmarks were identified and are herein duly detailed with particular attention to the neurovascular structures encountered in each of those routes. Results The dissections showed that the PC approach facilitates the treatment of optic nerve and frontal sinus pathologies, whereas LRC appears safer to reach ACF and MCF allowing for a free multiplanar working channel (up to 180 degrees) to the floor, roof, and lateral-to-medial walls. Conclusion The plane of tendon lateral canthal's insertion and the sphenofrontal suture (SFS) were identified as the key anatomical landmarks for TONES approaches. Further studies are warranted to establish a practical clinical algorithm based on the anatomical four clockwise quadrants herein implemented/proposed, and the key surgical landmarks identified.

Auditory biophysics of endolymphatic hydrops.

Audiological tests in patients with Menière's disease reveal abnormal patterns relevant for diagnostic purposes with some success. Electrocochleography, otoacoustic emissions and immittance measurements share a moderate sensitivity but a good specificity. Their potential for monitoring the patients suggests means to understand the characteristic time course of Menière's disease and the pathophysiology behind its attacks. Besides, magnetic resonance imaging now allows direct evaluation of endolymphatic hydrops. One issue is now to understand the links between volume inflation of endolymphatic spaces, which sometimes remains asymptomatic, and the functional signs, in the hope that a better understanding of what triggers the attacks may guide future treatments. This article provides a short review of the possible biophysical significance of audiological tests of Menière's disease, and of the attempts to make sense of functional and imaging data and of the patterns they form when combined.

Importance of signal intensity on T1-weighted spin-echo sequence for the diagnosis of chronic cholesteatomatous otitis.

OBJECTIVE: The aim of our study was to evaluate the importance of a non-injected T1-weighted spin-echo sequence (T1WSE) combined with a non-echo-planar diffusion-weighted (non-EPDW) sequence for the pre-operative detection of cholesteatoma by the radiologist on MRI, compared to surgery. MATERIALS AND METHODS: In this retrospective case review, 113 patients with chronic otitis underwent surgery (gold standard) for a clinical suspicion of cholesteatoma. Our primary outcome was to compare non-EPDW images + a contrast-free T1WSE sequence for cholesteatoma detection. Our secondary outcome was to quantify the signal intensity value of the suspected lesions, relative to the signal intensity of the cerebellum (Sic) to calculate Signal Intensity Ratios (SIR = SI/Sic). The SIR values of cholesteatomatous and non-cholesteatomatous tissue were compared to surgical findings. Receiver-operating characteristic curve analysis determined an optimum SIR cut-off value for the prediction of cholesteatoma. RESULTS: The sensitivity (96.9%) of non-EPDW for the diagnosis of cholesteatoma was high, with good specificity (74.2%), and increased to 85.5% when combined to a T1WSE sequence. Additionally, the mean SIR values (on T1WSE) of cholesteatoma were significantly lower than non-cholesteatomatous tissue (p < 0.05). When nonEPDW and T1WSE were combined, a cut-off SIR value < 1.04, diagnosed cholesteatoma pre-operatively with very high specificity and sensibility (92.7% and 90.3% respectively). CONCLUSION: Our study showed that combining a nonEPDW sequence with the quantitative analysis of contrast-free T1W SE sequence in pre-operative patients enables the correct diagnosis of cholesteatoma with good sensitivity and specificity (> 90%) and reduces risks of false-positive cases for surgeons.

Sialendoscopy under conscious sedation versus general anesthesia. A comparative study.

OBJECTIVE: Sialendoscopy is a minimally invasive emerging approach, the general surgical technique has been published but many essential questions still need to be addressed with the aim of improving outcomes. For instance, should we systematically perform sialendoscopy under conscious sedation (CS) or general anesthesia (GA)? What are the limitations of CS? The objective of this study is to compare these two modalities. METHODOLOGY: A retrospective study of 70 patients who had undergone a sialendoscopy between 2014 and 2016 (34 under GA and 36 under CS). Comparisons were made between these two groups in term of operative time, stone size and location, tolerability, operative success and post-operative pain. RESULT: The patients' mean age was 45.33 years. The operative success rate among the GA group was 79.4% vs. 88.9% in the CS group (P = 0.276), while complications for both groups were comparable. All patients considered the intervention under CS to be tolerable. CONCLUSION: Sialendoscopy under CS or GA demonstrated the ability to access large and distal stones among the different salivary glands with an excellent tolerability. Anesthesia type should be based on surgeon and patient preference Nevertheless, patient reassurance and surgeon experience are important to producing a good result with CS.

Abnormal fast fluctuations of electrocochleography and otoacoustic emissions in Menière's disease.

The responses of cochlear hair cells to sound stimuli depend on the resting position of their stereocilia bundles, which is sensitive to the chemical and mechanical environment. Cochlear hydrops, a hallmark of Menière's disease (MD), which is likely to come with disruption of this environment, results in hearing symptoms and electrophysiological signs, such as excessive changes in the cochlear summating potential (SP) and in the postural shifts of distortion-product otoacoustic emissions (DPOAEs). Here, SP from the basal part of the cochlea and DPOAEs from the apical part of the cochlea were recorded concomitantly in 73 patients with a definite MD, near an attack (n = 40) or between attacks with no clinical symptoms (n = 33), to compare their sensitivities to posture and evaluate their stability. The phase of the 2f1-f2 DPOAEs was monitored during body tilt, with stimuli f1 = 1 kHz and f2 = 1.2 kHz at 72 dB SPL. Extratympanic electrocochleography was performed in response to 95-dBnHL clicks. The normal limits of the DPOAE phase shift with body tilt, [-18°, +38°], and of the SP to action-potential (AP) ratio, <0.40, were exceeded in 75% and 60% of patients, respectively, near an attack. In these patients, but not in the asymptomatic ones, both tests reveal fluctuating cochlear responses from one data sample to the next. They emphasize how hydrops hinders normal hair-cell operation and may generate fast fluctuations in inner-ear functioning. If these fluctuations also occur on shorter time scales, it might explain the imperfect diagnostic sensitivity of SP and DPOAE tests, as averaging procedures would tend to level out transient fluctuations characteristic of hydrops.