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Disorders of the Sense of Smell These are caused by conditions that interfere with the access of the odorant to the olfactory neuroepithelium (transport loss), injure the receptor region (sensory loss), or damage central olfactory pathways (neural loss). Currently no clinical tests exist to differentiate these different types of olfactory losses. Fortunately, the history of the disease provides important clues to the cause. The leading causes of olfactory disorders are summarized in Table 30-1; the most common etiologies are head trauma in children and young adults, and viral infections in older adults. Table 30-1 Causes of Olfactory Dysfunction Transport Losses Neural Losses Allergic. | Chapter 030. Disorders of Smell Taste and Hearing Part 2 Disorders of the Sense of Smell These are caused by conditions that interfere with the access of the odorant to the olfactory neuroepithelium transport loss injure the receptor region sensory loss or damage central olfactory pathways neural loss . Currently no clinical tests exist to differentiate these different types of olfactory losses. Fortunately the history of the disease provides important clues to the cause. The leading causes of olfactory disorders are summarized in Table 30-1 the most common etiologies are head trauma in children and young adults and viral infections in older adults. Table 30-1 Causes of Olfactory Dysfunction Transport Losses Neural Losses Allergic rhinitis AIDS Bacterial rhinitis and sinusitis Alcoholism Congenital abnormalities Alzheimer s disease Nasal neoplasms Cigarette smoke Nasal polyps Depression Nasal septal deviation Diabetes mellitus Nasal surgery Drugs toxins Viral infections Huntington s chorea Sensory Losses Hypothyroidism Drugs Kallmann syndrome Neoplasms Malnutrition Radiation therapy Neoplasms Toxin exposure Neurosurgery Viral infections Parkinson s disease Trauma Vitamin Bi2 deficiency Zinc deficiency Head trauma is followed by unilateral or bilateral impairment of smell in up to 15 of cases anosmia is more common than hyposmia. Olfactory dysfunction is more common when trauma is associated with loss of consciousness moderately severe head injury grades II-V and skull fracture. Frontal injuries and fractures disrupt the cribriform plate and olfactory axons that perforate it. Sometimes there is an associated cerebrospinal fluid CSF rhinorrhea resulting from a tearing of the dura overlying the cribriform plate and paranasal sinuses. Anosmia may also follow blows to the occiput. Once traumatic anosmia develops it is usually permanent only 10 of patients ever improve or recover. Perversion of the sense of smell may occur as a transient phase in the recovery process. .
