In Vivo Localization of the Human Velocity Storage Mechanism and Its Core Cerebellar Networks by Means of Galvanic-Vestibular Afternystagmus and fMRI

Humans are able to estimate head movements accurately despite the short half-life of information coming from our inner ear motion sensors. The observation that the central angular velocity estimate outlives the decaying signal of the semicircular canal afferents led to the concept of a velocity storage mechanism (VSM). The VSM can be activated via visual and vestibular modalities and becomes manifest in ocular motor responses after sustained stimulation like whole-body rotations, optokinetic or galvanic vestibular stimulation (GVS). The VSM has been the focus of many computational modelling approaches; little attention though has been paid to discover its actual structural correlates. Animal studies localized the VSM in the medial and superior vestibular nuclei. A significant modulation by cerebellar circuitries including the uvula and nodulus has been proposed. Nevertheless, the corresponding neuroanatomical structures in humans have not been identified so far. The aim of the present study was to delineate the neural substrates of the VSM using high-resolution infratentorial fMRI with a fast T2* sequence optimized for infratentorial neuroimaging and via video-oculography (VOG). The neuroimaging experiment (n=20) gave first in vivo evidence for an involvement of the vestibular nuclei in the VSM and substantiate a crucial role for cerebellar circuitries. Our results emphasize the importance of cerebellar feedback loops in VSM most likely represented by signal increases in vestibulo-cerebellar hubs like the uvula and nodulus and lobule VIIIA. The delineated activation maps give new insights regarding the function and embedment of Crus I, Crus II, and lobule VII and VIII in the human vestibular system.

The human egomotion network

All volitional movement in a three-dimensional space requires multisensory integration, in particular of visual and vestibular signals. Where and how the human brain processes and integrates self-motion signals remains enigmatic. Here, we applied visual and vestibular self-motion stimulation using fast and precise whole-brain neuroimaging to delineate and characterize the entire cortical and subcortical egomotion network in a substantial cohort (n=131). Our results identify a core egomotion network consisting of areas in the cingulate sulcus (CSv, PcM/pCi), the cerebellum (uvula), and the temporo-parietal cortex including area VPS and an unnamed region in the supramarginal gyrus. Based on its cerebral connectivity pattern and anatomical localization, we propose that this region represents the human homologue of macaque area 7a. Whole-brain connectivity and gradient analyses imply an essential role of the connections between the cingulate sulcus and the cerebellar uvula in egomotion perception. This could be via feedback loops involved updating visuo-spatial and vestibular information. The unique functional connectivity patterns of PcM/pCi hint at central role in multisensory integration essential for the perception of self-referential spatial awareness. All cortical egomotion hubs showed modular functional connectivity with other visual, vestibular, somatosensory and higher order motor areas, underlining their mutual function in general sensorimotor integration.

Positional changes in the uvula tip after adenotonsillectomy in children: preliminary result

Background

Adenotonsillectomy has become the primary treatment for children with sleep-disordered breathing or obstructive sleep apnea. However, few studies have investigated positional changes in the soft palate or uvula after adenotonsillectomy in children. The present study aimed to evaluate positional changes in the uvula tip using cephalometric analyses after adenotonsillectomy in children.

Methods

We analyzed 160 pediatric patients from December 2015 to July 2016, with 94 pediatric patients who underwent adenotonsillectomy as the experimental group and 66 children who were treated and followed up with frequent tonsillitis as the control group. Positional changes in the uvula tip after surgery in the adenotonsillectomy group were investigated using lateral cephalograms obtained within 1 month before surgery and 3–4 months after surgery. Two lateral cephalogram intervals for a few months in the control group who did not undergo adenotonsillectomy were analyzed.

Results

The palatal length (23.92 ± 3.47 vs. 24.46 ± 3.26; p = 0.032), palatal angle (43.13 ± 7.76 vs. 46.12 ± 5.91; p < 0.001), and retrouvula length (15.60 ± 3.51 vs. 16.60 ± 2.97; p = 0.009) were significantly increased on postoperative images relative to those on preoperative images. In the control group, there was a significant change in the palatal angle (2.99 ± 5.85 vs. 0.27 ± 4.14; p < 0.001) and retrouvula length (0.99 ± 3.64 vs. 0.05 ± 1.44; p = 0.025), but not in the palatal length (0.58 ± 2.38 vs. 0.043 ± 1.26; p = 0.065).

Conclusion

The findings of the present study suggest that the uvula tip is displaced in the anteroinferior direction 3 or 4 months after adenotonsillectomy in children. Thus, clinicians should be aware that the retropalatal space may expand after adenotonsillectomy in the pediatric population.

Estimation of the hyperelastic parameters of fresh human oropharyngeal soft tissues using indentation testing

Patient-specific finite element (FE) modeling of the upper airway is an effective tool for accurate assessment of obstructive sleep apnea (OSA) syndrome. It is also useful for planning minimally invasive surgical procedures under severe OSA conditions. A major requirement of FE modeling is having reliable data characterizing the biomechanical properties of the upper airway tissues, particularly oropharyngeal soft tissue. While some data characterizing this tissue's linear elastic regime is available, reliable data characterizing its hyperelasticity is scarce. The aim of the current study is to estimate the hyperelastic mechanical properties of the oropharyngeal soft tissues, including the palatine tonsil, soft palate, uvula, and tongue base. Fresh tissue specimens of human oropharyngeal tissue were acquired from 13 OSA patients who underwent standard surgical procedures. Indentation testing was performed on the specimens to obtain their force-displacement data. To determine the specimens' hyperelastic parameters using these data, an inverse FE framework was utilized. In this work, the hyperelastic parameters corresponding to the commonly used Yeoh and 2nd order Ogden models were obtained. Both models captured the experimental force-displacement data of the tissue specimens reasonably accurately with mean errors of 11.65% or smaller. This study has provided estimates of the hyperelastic parameters of all upper airway soft tissues using fresh human tissue specimens for the first time.

The association of OSAS and uvula: the role of MRI in this egg-chicken problem in OSAS

PURPOSE

Obstructive sleep apnea syndrome (OSAS) is a condition resulting from repetitive partial or complete upper airway obstruction, and its etiology remains uncertain. Polysomnography is the gold standard diagnostic test for OSAS. However, there are long wait times for this evaluation, so questionnaires or ancillary diagnostic methods are used to select appropriate patients. One of these is magnetic resonance imaging (MRI). The present study aimed to investigate the association between clinical features of OSAS and uvular changes on MRI.

MATERIALS AND METHODS

A total of 102 participants, 80 with OSAS and 22 controls, were included in the study. All participants underwent full-night polysomnography, MRI, and anthropometric measurements.

RESULTS

In comparisons of MRI measurements of the uvula, statistically significant differences in uvular length, thickness, and angle were observed between the OSAS and control groups. MRI measurement significantly associated with apnea-hypopnea index was uvular thickness. Evaluation of anthropometric and MRI measurements revealed statistically significant associations between waist circumference and uvular thickness, uvular width, and oropharyngeal space among the OSAS patients.

CONCLUSION

Thickened uvula on MRI is associated with the presence of OSAS, and its thickness is well correlated with the severity of the diseases. Thus, it may be a reliable indicator of OSAS and could be used as a supportive finding to identify patients suitable for referral for diagnostic polysomnography.

Central positional nystagmus: Characteristics and model-based explanations

The central vestibular system operates to precisely estimate the rotational velocity and gravity orientation using the inherently ambiguous information from peripheral vestibular system. Therefore, any lesions disrupting this function can generate positional nystagmus. Central positional nystagmus (CPN) can be classified into the paroxysmal (transient) and persistent forms. The paroxysmal CPN has the features suggesting a semicircular canal origin regarding the latency, duration, and direction of nystagmus. Patients with paroxysmal CPN commonly show several different types of nystagmus classified according to the provoking positioning. The persistent form of CPN mostly appears as downbeat nystagmus while prone or supine, or apogeotropic or geotropic horizontal nystagmus when the head is turned to either side while supine. CPN may be ascribed to erroneous neural processing within the velocity-storage circuit that functions in estimating angular head velocity, gravity direction, and inertia. Paroxysmal CPN appears to be post-rotatory rebound nystagmus due to lesions involving the cerebellar nodulus and uvula. In contrast, persistent CPN may arise from erroneous gravity estimation. The overlap of lesion location responsible for both paroxysmal and persistent CPN may account for the frequent coexistence of both forms of nystagmus in a single patient.

The First Report of Small Cell Cancer of the Uvula Presenting With Ectopic Adrenocorticotropic Hormone Syndrome

Small cell carcinoma (SmCC) of the head and neck is a rare occurrence. We herein present a case of a 62-year-old female who was diagnosed with small cell cancer of the uvula. The patient developed increased body swelling, elevated blood pressure, persistent hypokalemia and new onset diabetes mellitus. Further workup confirmed a diagnosis of Cushing's syndrome secondary to ectopic adrenocorticotropic hormone (ACTH) production. To our knowledge, this is only the second case of SmCC of the uvula described in literature, and the first associated with any paraneoplastic syndrome. By reporting this case, we aim to characterize the tumor clinical course and highlight the aggressive nature of its growth.

The relationship of the uvula with snoring and obstructive sleep apnea: a systematic review

Currently, the relationship between uvula size and sleep-disordered breathing (snoring and obstructive sleep apnea) lacks data for objective interpretation. This study conducted a systematic review of the international literature for research describing the measurable characteristics of the uvula (i.e., size, length, width) and any association with snoring and obstructive sleep apnea (OSA). PubMED, Scopus, Google Scholar, Embase, and the Cochrane Library were each systematically searched from inception through November 15, 2016. We screened 1037 titles and abstracts. We conducted a full review of 54 downloaded articles. Sixteen articles met inclusion and exclusion criteria. The 16 studies included a total of 2604 patients. The selected articles included data and information for (1) normative data for uvular size in the control groups, (2) snoring and uvula size, (3) OSA and uvula size, and (4) overall uvula function. Our review noted variability in findings; however, in general, a uvular length > 15 mm was considered elongated and a uvular width > 10 mm was considered to be wide. The studies included in this systematic review reveal a relationship between uvula size, snoring, and OSA. Further, larger uvulas appear associated with more severe snoring and OSA. The direct correlation between uvula size and its relationship specifically to snoring and OSA remain as topics for future prospective research.

[Modern modifications of uvulopalatopharyngoplasty]

Uvulopalatopharyngoplasty (UPPP) was first described in 1964 with regard to surgical treatment of snoring and in 1981 with regard to treatment of obstructive sleep apnea (OSA). The initial surgical techniques for OSA were very invasive, frequently leading to significant morbidity and complications. Wolfgang Pirsig et al. were the first in Germany to recognize that a radical surgical technique increased only the complications, not the efficacy of UPPP. The less invasive surgical technique developed based on these findings is still established in Germany. A meta-analysis from 1996 described a success rate of UPPP of about 50%. High-quality randomized trials demonstrate significant superiority of UPPP plus tonsillectomy compared to untreated controls. However, the objective outcome measures of classic UPPP could not be improved even with additional patient selection criteria, and the effects of UPPP often deteriorate over time. To overcome these limitations, various modifications of UPPP have been developed. Due to limited data, evaluation of these new techniques and their comparison with conventional UPPP is difficult at present. In studies comparing a modification of UPPP with the standard approach, the tested modification was demonstrated to be superior. A relevant limitation of the available data results from the small number of institutions (usually not more than two) that investigated the respective modification and the follow-up periods of usually only 6 months. Data are also too sparse to reliably assess complication rates. For conventional UPPP there are considerably more data, wider experience with long-term outcome, and more robust studies examining treatment effects beyond basic respiratory parameters. At present, modifications of UPPP should be principally employed in clinical trials.

Delineating function and connectivity of optokinetic hubs in the cerebellum and the brainstem

Optokinetic eye movements are crucial for keeping a stable image on the retina during movements of the head. These eye movements can be differentiated into a cortically generated response (optokinetic look nystagmus) and the highly reflexive optokinetic stare nystagmus, which is controlled by circuits in the brainstem and cerebellum. The contributions of these infratentorial networks and their functional connectivity with the cortical eye fields are still poorly understood in humans. To map ocular motor centres in the cerebellum and brainstem, we studied stare nystagmus using small-field optokinetic stimuli in the horizontal and vertical directions in 22 healthy subjects. We were able to differentiate ocular motor areas of the pontine brainstem and midbrain in vivo for the first time. Direction and velocity-dependent activations were found in the pontine brainstem (nucleus reticularis, tegmenti pontis, and paramedian pontine reticular formation), the uvula, flocculus, and cerebellar tonsils. The ocular motor vermis, on the other hand, responded to constant and accelerating velocity stimulation. Moreover, deactivation patterns depict a governing role for the cerebellar tonsils in ocular motor control. Functional connectivity results of these hubs reveal the close integration of cortico-cerebellar ocular motor and vestibular networks in humans. Adding to the cortical concept of a right-hemispheric predominance for visual-spatial processing, we found a complementary left-sided cerebellar dominance for our ocular motor task. A deeper understanding of the role of the cerebellum and especially the cerebellar tonsils for eye movement control in a clinical context seems vitally important and is now feasible with functional neuroimaging.

Extranodal NK/T Cell Lymphoma with Destruction of the Uvulae: A Case Report

INTRODUCTION

Extranodal Natural Killer (NK)/T-cell lymphoma (NKTCL) nasal type is a rare but well-known disease with poor prognosis. NKTCL is more prevalent in Asia and comprises about 7-10% of all non-Hodgkin lymphoma cases in this region. The characteristic clinical pattern of NKTCL is the destruction of the midline structures of the mid-face.

CASE REPORT

The present study examines a case of NKTCL in a 23-year-old man with a destructive ulcer of the palate and uvulae. Based on immunohistochemical results, after three months of delay, the definitive diagnosis was revealed to be Extranodal NK/T cell lymphoma. Following the third cycle of chemotherapy, the patient died due to sepsis and infection.

CONCLUSION

It is very common to misdiagnose NKTCL with other clinical conditions such as necrotizing stomatitis, deep fungal ulcers, Wegener's Granulomatosis disease, etc. Delay in diagnosis can worsen the course of the disease and its prognosis.

Lemierre's syndrome due to intratumoral abscess of the uvula

Lemierre’s syndrome (LS), described in detail in 1936, used to be a life-threatening entity until the advent of antibiotics. Tonsillitis or pharyngitis are the main primary infections and oropharyngeal anaerobic flora is the predominant etiology. However, other primary site infections, as well as other microbiological agents have been reported since the first description. Inflammatory symptoms in the neck and marked findings on physical examination predominate the majority of cases. Nonetheless, the authors report the case of a 54-year-old man with a history of dysphagia followed by cough, purulent expectoration, and fever. The bad condition of his dentition was noteworthy. During the diagnostic work-up, an ulcerated lesion in the uvula and a middle lobe pneumonia were disclosed. Streptococcus viridans was isolated from blood culture. On the fifth day of hospitalization, the patient died after a copious episode of hemoptysis. The autopsy findings depicted an abscess within a squamous cell carcinoma of the uvula, pharyngitis with carotid sheath spreading accompanied by pylephlebitis and thrombosis of the internal jugular vein up to the innominate vein, surrounded by an abscess in the mediastinum. Alveolar hemorrhage and pneumonia were also present. We conclude that the ulcerated carcinoma of the uvula housed an abscess, facilitated by the poor oral hygiene, which triggered LS and the descending mediastinitis. Pulmonary involvement was due to the septic embolism from the internal jugular vein. We would like to highlight the uvula abscess as the primary site of infection in this case of LS with S. viridans as the causative agent.

Double uvula in a fifty-six-year-old woman

Introduction:

Deformities of the uvula are considered as the dark area of otorhinolaryngology practice. This little and plain part of the human organism has various functions and its abnormalities might cause serious disabilities.

Case Presentation:

In our case report, we present a unique deformity of the uvula in a 56-year-old woman.

Discussion:

The aim of this report was to present a very rare condition, unique case “polyuvula”, and to review the literature regarding other uvula abnormalities.

Morphometric evaluation of soft palate in oral submucous fibrosis--a digital cephalometric study

The Present study was carried out to evaluate the morphology of soft palate in Oral Submucous Fibrosis (OSF) patients using digital lateral cephalogram. A total number of 70 patients were included in the study (Control group had 35 patients and Study group had 35 OSF patients) were evaluated for soft palate by digital lateral cephalogram. The anterio-posterior length and superior-inferior length of soft palate were measured. The morphology of soft palate was categorized as type 1, to type 6. Different types of soft palate were compared with stages of OSF. Among the Study group (35 patients) 62.9% had Stage 2 OSF. Leaf shaped (Type 1) soft palate was seen commonly in stage 2 OSF whereas butt shaped (Type 3) in stage 3 OSF. In the present study there was statistically significant difference in length (anterio-posterior) of Type 1 soft palate of OSF patients. In the present study as the OSF progressed to advanced stage there was gradual change from Type 1 and Type 2 variety of Soft palate to Type 3 and Type 6 variety of soft palate. The study observed that there was gradual reduction in the length of soft palate in anterior-posterior direction in OSF patients.

Deformities of the uvula in the oral cavity- a case series

BACKGROUND

Disorders of the palatal uvula is one of the least highlighted areas of medical literature, inspite the fact that uvula is a key organ in functions like speech, deglutition and mastication. The aim of this paper is to present a series of cases of wide range of uvular deformities ranging from bifid uvula to absence of uvula.