Vestibular Nerve Research Articles

Dizziness

Dizziness is the quintessential symptom presentation in all of clinical medicine. It is a common reason that patients present to a physician. This chapter provides background information about the vestibular system, then reviews key aspects of history-taking and examination of the patient, then discusses specific disorders and common presentation types. Throughout the chapter the focus is on neurologic and vestibular disorders. Normal vestibular anatomy and physiology are discussed, followed by recommendations for history-taking and the physical examination. Specific disorders that cause dizziness are explored, along with common causes of non-specific dizziness. Common presentations are discussed, including acute severe dizziness, recurrent attacks, and recurrent positional vertigo. Finally, the chapter looks at laboratory investigations in diagnosis and management. Figures include population prevalence of dizziness symptoms, the anatomy of inner structures, primary afferent vestibular nerve activity, the head thrust test, the Dix-Hallpike maneuver, the supine positional test, the canalith repositioning procedure, and the barbecue roll maneuver. Tables list physiologic properties and clinical features of the components of the peripheral vestibular system, information to be acquired from history of the present illness, common symptoms patients report as dizziness, examination components, distinguishing among common peripheral and central vertigo syndromes, common causes of nonspecific dizziness, types of dizziness presentations, relevant imaging abnormalities on neuroimaging studies, vestibular testing components, and medical therapy for symptomatic dizziness. This review contains 8 highly rendered figures, 11 tables, and 69 references.

Dizziness

Dizziness is the quintessential symptom presentation in all of clinical medicine. It is a common reason that patients present to a physician. This chapter provides background information about the vestibular system, then reviews key aspects of history-taking and examination of the patient, then discusses specific disorders and common presentation types. Throughout the chapter the focus is on neurologic and vestibular disorders. Normal vestibular anatomy and physiology are discussed, followed by recommendations for history-taking and the physical examination. Specific disorders that cause dizziness are explored, along with common causes of non-specific dizziness. Common presentations are discussed, including acute severe dizziness, recurrent attacks, and recurrent positional vertigo. Finally, the chapter looks at laboratory investigations in diagnosis and management. Figures include population prevalence of dizziness symptoms, the anatomy of inner structures, primary afferent vestibular nerve activity, the head thrust test, the Dix-Hallpike maneuver, the supine positional test, the canalith repositioning procedure, and the barbecue roll maneuver. Tables list physiologic properties and clinical features of the components of the peripheral vestibular system, information to be acquired from history of the present illness, common symptoms patients report as dizziness, examination components, distinguishing among common peripheral and central vertigo syndromes, common causes of nonspecific dizziness, types of dizziness presentations, relevant imaging abnormalities on neuroimaging studies, vestibular testing components, and medical therapy for symptomatic dizziness. This review contains 8 highly rendered figures, 10 tables, and 68 references.

Dizziness

Dizziness is the quintessential symptom presentation in all of clinical medicine. It is a common reason that patients present to a physician. This chapter provides background information about the vestibular system, then reviews key aspects of history-taking and examination of the patient, then discusses specific disorders and common presentation types. Throughout the chapter the focus is on neurologic and vestibular disorders. Normal vestibular anatomy and physiology are discussed, followed by recommendations for history-taking and the physical examination. Specific disorders that cause dizziness are explored, along with common causes of non-specific dizziness. Common presentations are discussed, including acute severe dizziness, recurrent attacks, and recurrent positional vertigo. Finally, the chapter looks at laboratory investigations in diagnosis and management. Figures include population prevalence of dizziness symptoms, the anatomy of inner structures, primary afferent vestibular nerve activity, the head thrust test, the Dix-Hallpike maneuver, the supine positional test, the canalith repositioning procedure, and the barbecue roll maneuver. Tables list physiologic properties and clinical features of the components of the peripheral vestibular system, information to be acquired from history of the present illness, common symptoms patients report as dizziness, examination components, distinguishing among common peripheral and central vertigo syndromes, common causes of nonspecific dizziness, types of dizziness presentations, relevant imaging abnormalities on neuroimaging studies, vestibular testing components, and medical therapy for symptomatic dizziness. This review contains 8 highly rendered figures, 11 tables, and 69 references.

Dizziness

Dizziness is the quintessential symptom presentation in all of clinical medicine. It is a common reason that patients present to a physician. This chapter provides background information about the vestibular system, then reviews key aspects of history-taking and examination of the patient, then discusses specific disorders and common presentation types. Throughout the chapter the focus is on neurologic and vestibular disorders. Normal vestibular anatomy and physiology are discussed, followed by recommendations for history-taking and the physical examination. Specific disorders that cause dizziness are explored, along with common causes of non-specific dizziness. Common presentations are discussed, including acute severe dizziness, recurrent attacks, and recurrent positional vertigo. Finally, the chapter looks at laboratory investigations in diagnosis and management. Figures include population prevalence of dizziness symptoms, the anatomy of inner structures, primary afferent vestibular nerve activity, the head thrust test, the Dix-Hallpike maneuver, the supine positional test, the canalith repositioning procedure, and the barbecue roll maneuver. Tables list physiologic properties and clinical features of the components of the peripheral vestibular system, information to be acquired from history of the present illness, common symptoms patients report as dizziness, examination components, distinguishing among common peripheral and central vertigo syndromes, common causes of nonspecific dizziness, types of dizziness presentations, relevant imaging abnormalities on neuroimaging studies, vestibular testing components, and medical therapy for symptomatic dizziness. This review contains 8 highly rendered figures, 11 tables, and 69 references.

The mammalian efferent vestibular system utilizes cholinergic mechanisms to excite primary vestibular afferents

Electrical stimulation of the mammalian efferent vestibular system (EVS) predominantly excites primary vestibular afferents along two distinct time scales. Although roles for acetylcholine (ACh) have been demonstrated in other vertebrates, synaptic mechanisms underlying mammalian EVS actions are not well-characterized. To determine if activation of ACh receptors account for efferent-mediated afferent excitation in mammals, we recorded afferent activity from the superior vestibular nerve of anesthetized C57BL/6 mice while stimulating EVS neurons in the brainstem, before and after administration of cholinergic antagonists. Using a normalized coefficient of variation (CV*), we broadly classified vestibular afferents as regularly- (CV* < 0.1) or irregularly-discharging (CV* > 0.1) and characterized their responses to midline or ipsilateral EVS stimulation. Afferent responses to efferent stimulation were predominantly excitatory, grew in amplitude with increasing CV*, and consisted of fast and slow components that could be identified by differences in rise time and post-stimulus duration. Both efferent-mediated excitatory components were larger in irregular afferents with ipsilateral EVS stimulation. Our pharmacological data show, for the first time in mammals, that muscarinic AChR antagonists block efferent-mediated slow excitation whereas the nicotinic AChR antagonist DHβE selectively blocks efferent-mediated fast excitation, while leaving the efferent-mediated slow component intact. These data confirm that mammalian EVS actions are predominantly cholinergic.

Effects of vestibular neurectomy and neural compensation on head movements in patients undergoing vestibular schwannoma resection

The vestibular system is vital for maintaining balance and stabilizing gaze and vestibular damage causes impaired postural and gaze control. Here we examined the effects of vestibular loss and subsequent compensation on head motion kinematics during voluntary behavior. Head movements were measured in vestibular schwannoma patients before, and then 6 weeks and 6 months after surgical tumor removal, requiring sectioning of the involved vestibular nerve (vestibular neurectomy). Head movements were recorded in six dimensions using a small head-mounted sensor while patients performed the Functional Gait Assessment (FGA). Kinematic measures differed between patients (at all three time points) and normal subjects on several challenging FGA tasks, indicating that vestibular damage (caused by the tumor or neurectomy) alters head movements in a manner that is not normalized by central compensation. Kinematics measured at different time points relative to vestibular neurectomy differed substantially between pre-operative and 6-week post-operative states but changed little between 6-week and > 6-month post-operative states, demonstrating that compensation affecting head kinematics is relatively rapid. Our results indicate that quantifying head kinematics during self-generated gait tasks provides valuable information about vestibular damage and compensation, suggesting that early changes in patient head motion strategy may be maladaptive for long-term vestibular compensation.

Impact of vestibular nerve preservation on facial and hearing outcomes in small vestibular schwannoma surgery: a technical feasibility study.

Management of small vestibular schwannomas (VSs) remains controversial. When surgery is chosen, the preservation of facial and cochlear nerve function is a priority. In this report, we introduce and evaluate a technique to anatomically preserve the vestibular nerves to minimize manipulation and preserve the function of the facial and cochlear nerves. The vestibular nerve preservation technique was prospectively applied to resect small VS tumors in patients with serviceable preoperative hearing (American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A or B). Clinical and radiological data were recorded and analyzed. Ten patients met the inclusion criteria. The mean (SD) age was 40.4 (12.5) years. Follow-up ranged from 6weeks to 2years. The maximum tumor diameter parallel to the internal auditory canal ranged from 10 to 20mm (mean, 14.9 (3.1) mm). There were three Koos grade 3 and seven Koos grade 2 tumors. Gross total resection was achieved in all cases. Both the facial and cochlear nerves were anatomically preserved in all cases. Postoperatively, 7 patients (70%) remained in the AAO-HNS class A or B hearing category. None of the patients had new vestibular symptoms, and all had House-Brackmann grade 1 facial function. Nervus intermedius dysfunction was observed in 1 patient preoperatively, which worsened postoperatively. Two patients had new nervus intermedius symptoms postoperatively. Improvement of facial nerve and hearing outcomes is feasible through the intentional preservation of the vestibular nerves in the resection of small VSs. Longer follow-up is required to rule out tumor recurrence.

The spectrum of acute vestibular neuropathy through modern vestibular testing: A descriptive analysis

ObjectiveAcute vestibular neuropathy (AVN), often referred to as vestibular neuritis, is a cranial neuropathy responsible for a significant proportion of cases of acute vertigo. This study describes the spectrum of lesion patterns in AVN as identified by video head impulse testing (vHIT) which assesses the high frequency vestibulo-ocular reflex function of the semicircular canals, and cervical and ocular vestibular evoked myogenic potentials (VEMPs) which assess otolith function. MethodsWe used vHIT and VEMPs to assess 35 patients with vestibular neuropathy in the acute stage. ResultsUnilateral superior division vestibular nerve involvement was the most common variant (57.1%), followed by unilateral superior and inferior division (28.5%), bilateral superior division (8.5%) and unilateral inferior division (5.7%). We observed a partial inverse correlation between the proportion of afferent fibers from an organelle, and the likelihood that the test of that organelle’s function will be abnormal. ConclusionvHIT and VEMPs provide more detailed characterization of lesion pattern in AVN than caloric testing. SignificanceComparison of lesion patterns from neuro-physiological testing with what is known about the proportional distribution of afferent fibers from the vestibular end-organelles suggests a new, neuro-anatomically based insight regarding susceptibility of these pathways to AVN.

Outcome of a Ceratohyiodectomy in a Criollo Mare with Temporohyoid Osteoarthropathy

Background: Temporohyoid osteoarthropathy (THO) is a progressive disease that causes acute onset of peripheral vestibular signs with or without facial paralysis. Ankylosis of temporhyoid joint occurs which predispose to fractures of the involved bones and consequently causes the commonly neurological signs observed. Clinical signs vary depending on the stage of the disease and the nerves affected. Surgical treatment is advised to improve survival rates in which the ceratohyoidectomy is currently known as the most advantageous. The aim of the present study is to report a case and outcome of a ceratohyoidectomy procedure in a Criollo mare presenting THO of the right temporohyoid joint.Case: A 17-year-old Criollo mare was referred to the Equine clinical hospital of the Federal University of Pelotas with a 5-day history of facial paralysis on the right side, head tilt and difficulty to chew and swallow. Auricular, palpebral and labial ptosis along with deviation of the lip and nostril to the left were observed. A corneal ulcer was also identified in the right eye. Complementary imaging exams (endoscopy of the guttural pouches and radiography of the head) were performed and showed thickening of the right stylohyoid bone confirming a diagnosis of THO. Anti-inflammatory and antibiotic therapy were administered and the corneal ulcer was treated with topical antibiotics and autologous serum. Due to rapid deterioration of clinical signs, the mare was referred to surgery. A ceratohyoidectomty procedure was performed under general anesthesia. In this procedure, the ceratohyoid bone was disarticulated from the ceratohyoid-basihyoid joint and removed. During the procedure, a branch of the linguofacial vein was accidentally incised causing hemorrhage, the branch was identified and successfully ligated. Recovery was uneventful. Supportive treatment with anti-inflammatory and antibiotics was continued after surgery and two sessions of electro-acupuncture was also performed to improve the nerve paralysis. The electro-acupuncture was discontinued due to mare’s negative behavior on needle insertion in the face. The treatment of the ulcer was changed since no improvement was observed in the first days. Twenty-eight days after hospitalization, the mare was discharged with the ulcer healed and significant improvement of neurological signs. A complete recovery occurred within three months.Discussion: The Criollo mare was referred to the hospital presenting mild neurological signs consistent with vestibular alteration and facial nerve paralysis. The THO diagnosis was confirmed using complementary imaging exams in which the endoscopy of the guttural pouch is considered the most common when computed tomography, a more sensitive one, is not available. Unilateral ceratohyoidectomy was performed as a surgical choice of treatment since it has a higher survival rate and lower recurrence rate in comparison to medical treatment and to stylohyoidectomy. As the main intraoperative complication, a vessel was accidentally incised, however this is described to occur in some cases. Despite that, the procedure was successfully performed and the mare had a complete recovery of the neurological signs and corneal ulcer. In conclusion, this report showed that it is important to have a complete diagnosis of these diseases and a consistent treatment plan to improve patient’s survival and quality of life.Keywords: neurologic disease, peripheral vestibular signs, facial paralysis, ceratohyoid bone, ceratohyoidectomy.

Vestibular nerve dysfunction in patients with auditory neuropathy revealed by galvanic VEMPs

Vestibular nerve dysfunction in patients with auditory neuropathy revealed by galvanic VEMPs

Electrical vestibular nerve stimulation as an adjunctive therapy in the management of type 2 diabetes.

Vestibular nerve stimulation using the portable battery-operated vestibular nerve stimulator is a sophisticated method noninvasive, safe, and easy to operate. It was hypothesized that vestibular nerve stimulation is effective in the management of type 2 diabetes. Hence, the present study was undertaken to determine the effectiveness of vestibular nerve stimulation using portable battery-operated vestibular nerve stimulator in the management of diabetes. The present study was a double-blind randomized controlled trial with 1:1 split between the control and experimental groups. A total of 30 participants with type 2 diabetes were part of the study after obtaining the written informed consent. After recording the baseline values, the vestibular nerve stimulation was administered to the participants in the intervention group for 90days. Sham stimulation was administered to the control group for 90days. Outcome measures were recorded after 30days and after 90days of the intervention in both the groups. There was significant decrease in the total body weight, fasting, postprandial blood glucose, glycosylated hemoglobin levels, leptin, very low density lipoproteins levels followed by the intervention. There was significant improvement in both spatial and verbal memory scores. Depression and stress scores and systolic blood pressure decreased and remained in normal limits. The study results have proven multimodal action of vestibular stimulation. It not only acts on regulation of the glucose metabolism but also can regulate the autonomic activity and improve cognition and relieve stress. This is the interesting finding of our study, which needs detailed further research to support implementation of vestibular nerve stimulation as an adjunctive therapy in the management of diabetes.

MiR-205 Inhibits Sporadic Vestibular Schwannoma Cell Proliferation by Targeting Cyclin-Dependent Kinase 14

Sporadic vestibular schwannoma (VS) is a benign primary tumor that arises from the vestibular nerve. Growing VS can negatively compress the brain stem, which can lead to death. MicroRNAs (miRNAs) can negatively regulate target genes at the post-transcriptional level and are critical in tumorigenesis. Studies have demonstrated the tumor suppressive function of microRNA-205-5p (miR-205) across many cancers, but no studies have evaluated the role of miR-205 in sporadic VS. We conducted this study to examine the role of miR-205 in sporadic VS cell proliferation. We evaluated miR-205 expression in sporadic VS tissues and normal great auricular nerve by real-time quantitative polymerase chain reaction. Then, we transfected miR-205 mimics and control oligonucleotides into sporadic VS primary cells to examine the functional significance of miR-205 expression at a cellular level by CCK8 and colony formation and used dual-luciferase reporter assays to find the target gene of miR-205. We determined that miR-205 levels were downregulated in sporadic VS tissues in comparison to normal controls. In functional assays, miR-205 suppressed proliferation and colony formation ability of sporadic VS cells. CDK14 (cyclin-dependent kinase 14) was identified as a target gene of miR-205 by bioinformatics, and validated using dual-luciferase reporter assays. Moreover, miR-205 overexpression inhibited levels of phosphorylated PI3K and Akt. These findings suggested that miR-205 suppressed sporadic VS proliferation by targeting CDK14 and may be considered as a potential drug therapy for sporadic VS treatment in the future.

Cholinergic Modulation of Membrane Properties of Calyx Terminals in the Vestibular Periphery

Vestibular nerve afferents are divided into regular and irregular groups based on the variability of interspike intervals in their resting discharge. Most afferents receive inputs from bouton terminals that contact type II hair cells as well as from calyx terminals that cover the basolateral walls of type I hair cells. Calyces have an abundance of different subtypes of KCNQ (Kv7) potassium channels and muscarinic acetylcholine receptors (mAChRs) and receive cholinergic efferent inputs from neurons in the brainstem. We investigated whether mAChRs affected membrane properties and firing patterns of calyx terminals through modulation of KCNQ channel activity. Patch clamp recordings were performed from calyx terminals in central regions of the cristae of the horizontal and anterior canals in 13–26 day old Sprague-Dawley rats. KCNQ mediated currents were observed as voltage sensitive currents with slow kinetics (activation and deactivation), resulting in spike frequency adaptation so that calyces at best fired a single action potential at the beginning of a depolarizing step. Activation of mAChRs by application of oxotremorine methiodide or inhibition of KCNQ channels by linopirdine dihydrochloride decreased voltage activated currents by ∼30%, decreased first spike latencies by ∼40%, resulted in action potential generation in response to smaller current injections and at lower (i.e., more hyperpolarized) membrane potentials, and increased the number of spikes fired during depolarizing steps. Interestingly, some of the calyces showed spontaneous discharge in the presence of these drugs. Together, these findings suggest that cholinergic efferents can modulate the response properties and encoding of head movements by afferents.

SURG-28. PRESENTATION OF A POSTERIOR FOSSA TUMOR AT A HOSPITAL IN WESTERN JAMAICA

Abstract The posterior cranial fossa is part of the cranial cavity, located between the foramen magnum and tentorium cerebelli that houses the cerebellum, pons and medulla oblongata. Commonly, tumors arising from this region in adults are cerebellar metastases or schwannomas of the vestibular nerve – the incidence of primary neoplasms is uncommon and more reserved for the pediatric population. A 28 year old female was in her usual state of health until last year when she started experiencing recurrent headaches with associated vomiting and intermittent loss of consciousness. A CT brain was done upon presentation to the hospital that revealed a 4th ventricle mass with obstructive hydrocephalus. A ventriculoperitoneal (VP) shunt was done thereafter to decompress the ventricular system, in anticipation for further surgical intervention for mass. Occipital craniotomy and resection of tumor was done and patient managed in a multidisciplinary manner in the intensive care unit. Post-operative course was marked by occipital pseudomeningocele with an associated CSF leak; a lumbar drain was placed in situ until complete resolution of leak. Histological analysis showed WHO Grade II Astrocytoma. Adult primary posterior fossa tumors are rare and can present with a constellation of symptoms. Although patient presented with findings in keeping with the diagnosis of an ependymoma, close clinical follow up will be required henceforth due to the refractory nature of such a low grade astrocytoma post-resection. Radiotherapy can also be considered in further management of case.

Improvement of Asymmetric Vestibulo-Ocular Reflex Responses Following Onset of Vestibular Neuritis Is Similar Across Canal Planes.

Background: We examined whether, after onset of acute unilateral vestibular neuritis (aUVN), initial disease effects, subsequent peripheral recovery and central compensation cause similar changes in vestibular ocular reflex (VOR) gains in all 3 semi-circular canal planes.Methods: 20 patients, mean age 56.5 years, with pathological lateral canal video head impulse test (vHIT) VOR gains due to aUVN, were subsequently examined with vHIT in all 3 canal planes on average 4.3 and 36.7 days (“5 weeks”) after aUVN onset.Results: Lateral and anterior deficit side (DS) average gains equaled 0.41 at aUVN onset. Non-deficit, normal, side (NS) gains were 0.88 and 0.81, respectively. Mean posterior DS gain was similar at onset, 0.43, provided only gains lower than 0.6 (lower limit of healthy controls) were considered. NS posterior mean gain at onset (0.68) was less (p ≤ 0.0006) than lateral and anterior NS gains. After 5 weeks, DS lateral, anterior and posterior canal gains increased (p ≤ 0.05), on average, to 0.65, 0.59, and 0.58, respectively. NS gains increased to 0.91, 0.87, and 0.76 (p = 0.007), respectively. At 5 weeks deficit-lateral/normal-lateral canal plane gain asymmetries were significantly (p < 0.0008) reduced from 36.9 to 19.4%, deficit-anterior/normal-posterior asymmetry decreased from 28.6 to 18.1%, while deficit-posterior/normal-anterior asymmetry changed from 29.7 to 21.4%, all to circa 20%. Roll plane asymmetries decreased slightly over 5 weeks (28.6–18.1%) but pitch plane asymmetries remained significantly less (p = 0.001), not different from 0% regardless of initial DS posterior canal vHIT gain. Yaw plane asymmetry changes are identical to those of the lateral canals (36.7–19.4%).Conclusions: These results indicate that, at onset, aUVN of the superior vestibular nerve has a similar effect on lateral and anterior deficit DS VOR gains, and on posterior DS canal VOR gains if the inferior nerve was also affected at onset. The significant improvements to equal 5 week levels of DS gains and slightly greater posterior NS gain improvements, compared to lateral and anterior NS gains, yielding a common canal plane gain asymmetry of 20% at 5 weeks, suggest similar neural compensation mechanisms were active along VOR pathways. Unexpectantly, canal plane improvement was not replicated in pitch plane asymmetries.

Modulation of sleep using electrical vestibular nerve stimulation prior to sleep onset: a pilot study.

Electrical stimulation of the vestibular system (VeNS) has been shown to improve Insomnia Severity Index (ISI) when delivered during sleep. We hypothesize that repeated electrical vestibular stimulation, when delivered prior to sleep onset, will improve ISI scores. The primary aim of this study was to assess the effect that VeNS had on ISI scores when delivered prior to sleep onset. A secondary aim was to provide initial data indicating "length of time to effect" that will allow more appropriate design of a larger randomized control trial (RCT). The present study was an experimental study (pre and post without control). The participants acted asself-controls. After recording the baseline values, electrical vestibular nerve stimulation was administered as intervention once in a day for 30min, 1h prior to sleep onset using ML1000 device (Neurovalens, UK) for 14days. There was significant decrease in the ISI scores followed by the electrical vestibular nerve stimulation. Further, participants reported a significant increase in well-rested sleep post the intervention period. This study supports our hypothesis that VeNS has a positive impact on ISI scores when delivered on a regular basis prior to sleep onset.

Molecular biology of sporadic vestibular schwannomas including genetic and epigenetic alterations

Introduction: Vestibular schwannomas (VSs) are benign tumors, developing from neoplastic Schwann cells, that produce myelin sheath covering vestibular nerve fibers. The majority of these tumors are sporadic VS and very rarely they can be associated with neurofibromatosis type 2 (NF2). VSs are usually characterized with slow growth rate, however some of them appear to have a cystic structure, grow more rapidly, can cause facial nerve palsy and brainstem compression. The molecular hallmark of both sporadic and NF-2 associated VS is the inactivation of supresor gene NF-2, also called merlin gene. Aim: In this review we summarize the current knowledge on the molecular biology of VS, including genetic and epigenetic aberrations, altered gene expression and specific microRNA expression profiles.

Artificial intelligence in detection and segmentation of internal auditory canal and its nerves using deep learning techniques.

Artificial intelligence (AI) in medical imaging is a burgeoning topic that involves the interpretation of complex image structures. The recent advancements in deep learning techniques increase the computational powers to extract vital features without human intervention. The automatic detection and segmentation of subtle tissue such as the internal auditory canal (IAC) and its nerves is a challenging task, and it can be improved using deep learning techniques. The main scope of this research is to present an automatic method to detect and segment the IAC and its nerves like the facial nerve, cochlear nerve, inferior vestibular nerve, and superior vestibular nerve. To address this issue, we propose a Mask R-CNN approach driven with U-net to detect and segment the IAC and its nerves. The Mask R-CNN with its backbone network of the RESNET50 model learns a background-based localization policy to produce an actual bounding box of the IAC. Furthermore, the U-net segments the structure related information of IAC and its nerves by learning its features. The proposed method was experimented on clinical datasets of 50 different patients including adults and children. The localization of IAC using Mask R-CNN was evaluated using Intersection of Union (IoU), and segmentation of IAC and its nerves was evaluated using Dice similarity coefficient. The localization result shows that mean IoU of RESNET50, RESNET101 are 0.79 and 0.74, respectively. The Dice similarity coefficient of IAC and its nerves using region growing, PSO and U-net method scored 92%, 94%, and 96%, respectively. The result shows that the proposed method outperform better in localization and segmentation of IAC and its nerves. Thus, AI aids the radiologists in making the right decisions as the localization and segmentation of IAC is accurate.

Cervical and ocular vestibular evoked myogenic potentials in determining nerve division involvement in patients with a tumor located in the internal auditory canal

ObjectivesThe study aimed at the analysis of the parameters of acoustic cervical and ocular vestibular evoked myogenic potentials (AC-cVEMP and AC-oVEMP) response in patients with a confirmed tumor located in the internal auditory canal. It also aimed to assess to what degree a combination of these tests may be of benefit in the preoperative indication of the affected nerve division via preoperative determination whether the tumor originated from the superior or inferior division of the vestibular nerve, both divisions, or if it originated from a different nerve in the internal auditory canal. MethodsThe study group included 50 patients. Preoperative MRI scans were used to measure tumor diameter. AC-cVEMP and AC-oVEMP testing were performed before tumor resection. The surgeon was asked for a detailed description of the tumor origin. ResultsThe corrected amplitude of cVEMP was significantly lower on the tumor side than on the non-affected side and in the control group. The corrected Asymmetry Ratio (AR) of cVEMPs in patients with the tumor was significantly elevated above the reference values with the mean being 58.29% and the mean AR of oVEMPs in patients the tumor was 71.78% which made both results significantly higher than in the control group. Neither cVEMP nor oVEMP latency was significantly correlated with tumor size. Data obtained from cVEMP and oVEMP tests was an effective indicator of tumor origin in 74% of patients showing which division (or both divisions) of the VIIIth nerve was affected in comparison with information obtained from the surgeon. ConclusionsThe combined use of AC-cVEMP and AC-oVEMP tests may be useful in surgical planning in patients the tumor located in the internal auditory canal, providing a highly probable determination of the division of the affected nerve. Such information is valuable for the surgeon as it offers additional knowledge about the tumor before the procedure. cVEMP and oVEMP results may not be used as the basis for the calculation of tumor size in patients.

Galvanic vestibular evoked myogenic potentials: normative data and the effect of age

IntroductionGalvanic vestibular evoked myogenic potentials evaluate vestibular nerve responses using electric stimulation by records collected from the sternocleidomastoid muscle. A normal vestibular evoked myogenic potential response consists of the first positive, P1, and negative, N1, peaks. The response can be affected by factors such as age and gender and is also consequential in the diagnosis of pathologies. ObjectivesThe present study was performed to obtain normative data on healthy adults, to help in diagnosis by establishing clinical norms as well as to investigate changing test parameters with age in galvanic vestibular evoked myogenic potentials. MethodsA total of 100 healthy participants were included in the study. Galvanic vestibular evoked myogenic potential (current 3 mA, duration 1 ms) was performed randomly on both ears of each participant. The participants between the ages of 18–65 (mean age 39.7 ± 13.9) were divided into 5 groups according to their ages. Normative data of galvanic vestibular evoked myogenic potentials parameters were calculated in groups and in total, and age-related changes were examined. ResultsThe galvanic vestibular evoked myogenic potential waveform was elicited from all participants (200 ears). The latency of P1 and N1 was 7.82 ± 3.29 ms and 22.06 ± 3.95 ms, respectively. The P1−N1 amplitude value was 66.64 ± 24.5 µV. The percentage of vestibular asymmetry was 16.29 ± 11.99%. The latencies of P1 and N1 and P1−N1 amplitude values demonstrated significant differences among different age groups (p < 0.01). ConclusionsThe results of this study show that as age increased, latencies were prolonged, and amplitudes gradually decreased. The normative data aids in the diagnosis of retrolabyrinthine lesions and the increase in the clinical use of galvanic vestibular evoked myogenic potentials.