Cochlear abnormality in a case of Pallister-Hall syndrome

The multifaceted links between hearing loss and chronic kidney disease

Hearing loss affects nearly 1.6 billion people and is the third-leading cause of disability worldwide. Chronic kidney disease (CKD) is also a common condition that is associated with adverse clinical outcomes and high health-care costs. From a developmental perspective, the structures responsible for hearing have a common morphogenetic origin with the kidney, and genetic abnormalities that cause familial forms of hearing loss can also lead to kidney disease. On a cellular level, normal kidney and cochlea function both depend on cilial activities at the apical surface, and kidney tubular cells and sensory epithelial cells of the inner ear use similar transport mechanisms to modify luminal fluid. The two organs also share the same collagen IV basement membrane network. Thus, strong developmental and physiological links exist between hearing and kidney function. These theoretical considerations are supported by epidemiological data demonstrating that CKD is associated with a graded and independent excess risk of sensorineural hearing loss. In addition to developmental and physiological links between kidney and cochlear function, hearing loss in patients with CKD may be driven by specific medications or treatments, including haemodialysis. The associations between these two common conditions are not commonly appreciated, yet have important implications for research and clinical practice.

Syndromic Hearing Loss in Children

Pattern recognition of specific temporal bone radiological phenotypes, in association with abnormalities in other organ systems, is critical in the diagnosis and management of syndromic causes of hearing loss. Several recent publications have demonstrated the presence of specific radiological appearances, allowing precise genetic and/or syndromic diagnosis, in the right clinical context. This review article aims to provide an extensive but practical guide to the radiologist dealing with syndromic causes of hearing loss.

Bardet-Biedl Syndrome Presenting With Bifid Epiglottis: A Case Report and Review of Literature

Bifid epiglottis is a rare congenital laryngeal anomaly that is most commonly a syndromic rather than an isolated entity. It has been associated with specific syndromes, such as Pallister-Hall syndrome, Bardet-Biedl syndrome, and other related syndromes. Bardet-Biedl syndrome is a rare autosomal-recessive disorder characterized by hand and/or feet polydactyly, obesity, short stature, mental retardation, renal anomalies, and genital anomaly. Here we report a case involving a 25-year-old Saudi male patient who presented with hoarseness of voice since birth with no diurnal or diet association or other associated symptoms. On examination, he was noted to have craniofacial dysmorphism and polydactyly of the right hand and left foot. Fiberoptic nasopharyngolaryngoscopy (NPLS) revealed a laryngeal pedunculated rounded glottic mass and subglottic bulging with expiration and involuting with inspiration along with an abnormal-looking epiglottis having a separate cartilaginous framework with space in-between and bilateral mobile vocal cords. Computed tomography (CT) showed the vocal cord mass and a bifid epiglottis. Other investigations and labs were within normal range. The patient underwent vocal cord mass excision and soft tissue histopathology revealed a benign growth. On follow-up, the patient showed clinical improvement. In conclusion, this is a rare case of bifid epiglottis associated with Bardet-Biedl syndrome, which serves to highlight the significance of such anomalies in any syndromic patient presenting with airway symptoms. Our aim is to add more cases to the literature and to consider it as a differential diagnosis.

Development and Patterning of the Cochlea: From Convergent Extension to Planar Polarity

Within the mammalian cochlea, sensory hair cells and supporting cells are aligned in curvilinear rows that extend along the length of the tonotopic axis. In addition, all of the cells within the epithelium are uniformly polarized across the orthogonal neural-abneural axis. Finally, each hair cell is intrinsically polarized as revealed by the presence of an asymmetrically shaped and apically localized stereociliary bundle. It has been known for some time that many of the developmental processes that regulate these patterning events are mediated, to some extent, by the core planar cell polarity (PCP) pathway. This article will review more recent work demonstrating how components of the PCP pathway interact with cytoskeletal motor proteins to regulate cochlear outgrowth. Finally, a signaling pathway originally identified for its role in asymmetric cell divisions has recently been shown to mediate several aspects of intrinsic hair cell polarity, including kinocilia migration, bundle shape, and elongation.

Hypothalamic malformations in patients with X-linked deafness and incomplete partition type 3

Patients with X-linked deafness carry mutations in the POU3F4 gene and have pathognomonic inner ear malformations characterised by symmetrical incomplete partition type 3 (absent modiolus and lamina spiralis but preserved interscalar septum in a normal-sized cochlea) and large internal auditory meatus (IAM) with an increased risk of gusher during stapes surgery. We describe a range of fairly characteristic malformations in the hypothalamus of some patients with this rare condition, ranging from subtle asymmetric appearance and thickening of the tuber cinereum to more marked hypothalamic enlargement. We discuss the role of POU3F4 in the normal development of both the inner ear and hypothalamus and the proposed pathophysiology of incomplete partition type 3.