Pediatric emergency medicine trisk 0704 0704

CHAPTER 34 ■ HEARING LOSS ARIEL M HOCH Hearing loss during early childhood may compromise the ability to attain normal language Therefore, early recognition of hearing loss, with appropriate evaluation and treatment, is crucial to avoid cognitive impairment, which may negatively impact school performance, socialization, and emotional development When a child presents to the emergency department with hearing loss, a careful history and physical examination are often all that is needed to determine a cause Acute hearing loss is of two main types: conductive and sensorineural Conductive hearing loss is caused by abnormal transmission of sound waves to the inner ear, whereas sensorineural hearing loss is caused by defective processing of sound waves ( Table 34.1 ) Etiologies may be congenital or acquired Hearing loss can occur as an isolated symptom or in association with auditory or central nervous system (CNS) dysfunction The emergency physician must identify the etiology of hearing loss, especially those disorders that are associated with serious systemic disease PATHOPHYSIOLOGY Normal hearing is dependent on an intricate series of properly aligned anatomic and physiologic connections The auricle or outer ear is designed to receive sensory transmission, or sound waves, from the child’s environment When patent, the external ear canal transmits sound waves to the tympanic membrane and vibrations of the membrane produce movement of the middle ear ossicles, which result in the transmission of fluid waves to the inner ear fluid within the cochlea Here the specialized receptors, hair cells in the spiral organ of Corti, convert this mechanical energy to nerve impulses that are transmitted by the cochlear (acoustic) nerve, the auditory portion of the eighth cranial nerve, to the brain These nerve impulses are integrated by the brain and transformed into what is perceived as sound It is important to note that anatomically the acoustic apparatus is closely related to the vestibular system, which is concerned with the proprioceptive senses of posture and equilibrium Therefore, abnormalities in the inner ear may cause both auditory and vestibular symptoms DIFFERENTIAL DIAGNOSIS Conductive Hearing Loss