**Section 1**

X Preface

mission. I wish that this book will be part of series of books in all sub-specialities of otolaryngology and that it will enhance global collaboration not only between physicians but also for betterment of humankind. I wish the reader an enjoyable

I would like to thank my teachers and students from whom I gained knowledge throughout the years. Lastly, I dedicate this book to my wife Dr Pritam Kaur Mangat, my daughter Dr Manvin Kaur Gendeh and my son Dr Hardip Singh Gendeh for all

**Balwant Singh Gendeh, MBBS(Kashmir), MS (ORL-HNS) M'sia, AM(Mal),FAMM**  Senior Consultant ENT Surgeon/Rhinology(Endoscopic Sinus/ Skull Base Surgery and Functional & Cosmetic Nasal Surgery), Department of Otorhinolaryngology-Head

Neck Surgery(ORL-HNS)

Kuala Lumpur Malaysia

National University Malaysia Medical Center(UKMMC)

journey and hope you will find this book interesting.

their patience and understanding.

**Otology** 

**1** 

*USA* 

**Proteins Involved in Otoconia** 

*Boys Town National Research Hospital, Omaha, Nebraska* 

The vestibule of the inner ear senses head motion for spatial orientation and bodily balance. In vertebrates, the vestibular system consists of three fluid filled semicircular canals, which detect rotational acceleration, and two gravity receptor organs, the utricle and saccule, which respond to linear acceleration and gravity (**Figure 1**). The utricle and saccule are also referred to as the otolithic organs because they contain bio-crystals called otoconia (otolith in fish). These crystals are partially embedded in a honeycomb layer atop a fibrous meshwork, which are the otoconial complex altogether. This complex rests on the stereociliary bundles of hair cells in the utricular and saccular sensory epithelium (aka macula). When there is head motion, the otoconial complex is displaced against the macula, leading to deflection of the hair bundles. This mechanical stimulus is converted into electrical signals by the macular hair cells and transmitted into the central nervous system (CNS) through the afferent vestibular nerve. In the CNS, these electrical signals, combined with other proprioceptive inputs, are interpreted as position and motion data, which then initiate a series of corresponding neuronal responses to maintain the balance of the body. Electrophysiological and behavioral studies show that the size and density of these tiny biominerals determine the amount of stimulus input to the CNS (Anniko et al. 1988; Jones et al. 1999; Jones et al. 2004; Kozel et al. 1998; Simmler et al. 2000a;

Otoconia dislocation, malformation and degeneration can result from congenital and environmental factors, including genetic mutation, aging, head trauma and ototoxic drugs, and can lead to various types of vestibular dysfunction such as dizziness/vertigo and imbalance. In humans, BPPV (benign paroxysmal positional vertigo), the most common cause of dizziness/vertigo, is believed to be caused by dislocation of otoconia from the utricle to the ampulla and further in the semicircular canals (Salvinelli et al. 2004; Schuknecht 1962; Schuknecht 1969; Squires et al. 2004). In animals, otoconial deficiency has been found to produce head tilting, swimming difficulty, and reduction or failure of the airrighting reflexes (Everett et al. 2001; Hurle et al. 2003; Nakano et al. 2008; Paffenholz et al.

Despite the importance of these biominerals, otoconial research is lagging far behind that of other biomineralized structures, such as bone and teeth, partly due to anatomical and

**1. Introduction** 

Trune and Lim 1983; Zhao et al. 2008b).

2004; Simmler et al. 2000a; Zhao et al. 2008b).

 \*

Corresponding Author

**Formation and Maintenance** 

Yunxia Wang Lundberg\* and Yinfang Xu

*Vestibular Neurogenetics Laboratory,* 
