Dysosmia is a variety of disorders of the perception of odors, which are manifested by an increase or decrease in olfactory function, an inability to recognize familiar aromas. Dysosmia occurs in inflammatory processes in the nasal cavity, traumatic brain injuries, and other neurological or psychiatric diseases. To find out the root cause of dysosmia, olfactometry, ENT examination, radiography and tomography of the skull bones are performed. Medications are not prescribed until an accurate diagnosis is made.
The manifestations depend on the characteristics of the olfactory disorder. Patients may notice a decrease in sensitivity to odors or a complete loss of sense of smell. Dysosmia is more often formed gradually: first, sensitivity to weak aromas disappears, and then even sharp odorous substances (for example, ammonia) cease to differ. Often, the taste sensations decrease at the same time. If dysosmia is formed against the background of inflammatory diseases, violations of the sense of smell are combined with mucous secretions, nasal congestion, itching and burning sensation.
In other cases, there is an increase in sensitivity to aromas, when even familiar odors cause discomfort to a person, cause headaches and other unpleasant sensations. With a perversion of the sense of smell, patients may notice a sudden sensation of stench, which is described as the smell of feces, gasoline, chemicals (cacosmia). Violations of olfactory function do not pose a threat to human life, but sometimes they become the first symptoms of severe neurological diseases, therefore, when they appear, you should seek qualified medical help.
The olfactory zone of the nasal mucosa, containing specific nerve receptors, is located in the upper nasal conch. In order for a person to feel odors, air together with odorous substances must pass through this part of the respiratory tract. In the presence of mechanical obstacles to the passage of air to anatomical structures, there are violations of the sense of smell by the type of decreased sensitivity to some or all odors. This condition is often caused by curvature of the nasal septum, hypertrophic rhinitis, sinusitis and adenoids.
Pathological insensitivity to odorous substances can be provoked by violations on the part of different departments of the olfactory analyzer. Normally, information from the receptors of the nasal mucosa through special fibers enters the subcortical structures and the center of smell in the cerebral cortex. Dysosmia is noted in traumatic injury and rupture of the olfactory nerve due to traumatic brain injuries, errors during neurosurgical operations. With unilateral damage to nerve structures, the loss of sense of smell is determined only on the side of the pathological process.
Inhibition of sensitivity to various aromas develops during pathological processes in the mucous membrane of the nasal cavity (for example, atrophic rhinitis), when peripheral nerve receptors are destroyed. Odor perception disorders also occur in degenerative brain diseases (Parkinson’s disease, Alzheimer’s disease) and brain tumors. In this case, dysosmia is caused by gradual atrophy and death of nerve cells of the olfactory zone.
A special mechanism of olfactory impairment is characteristic of epilepsy. In this disease, patients note the appearance of unpleasant odors, which is associated with the formation of excitation zones in the brain, impulses from which spread to various parts of the cortex. Dysosmia can also occur in the absence of organic pathology — the symptom is observed in acute psychoses, hysterical states. The development of olfactory dysfunction is associated with a functional disruption of the connections between the peripheral and central nervous systems.
Classification of dysosmia
Olfactory disorders are divided into acquired and congenital (with Kallman syndrome). All pathological conditions are classified into two groups: symptoms of irritation (increased sensitivity to different odors) and symptoms of loss (decreased sense of smell). To choose the right method of treatment, classification by type of disorders is also important, according to which the following types of olfactory disorders are distinguished:
- Hyperosmia. Sensitivity to odors of normal intensity increases with autoimmune diseases, Lyme disease, brain pathologies (Parkinson’s disease, multiple sclerosis). The symptom also occurs during pregnancy.
- Hyposmia. A decrease in the function of the sense of smell is possible both with damage to the cortical centers and with a violation of the receptors of the nasal mucosa due to acute or chronic inflammatory processes. The sign is typical for smokers.
- Anosmia. Complete loss of sense of smell occurs after brain injuries, with nasal polyps, destructive processes in the mucous layer. The symptom is pathognomonic for intoxication of the body with salts of heavy metals, acrylates.
- Parosmia. Distorted perception of odors most often occurs in the period of convalescence after inflammatory diseases (rhinitis, sinusitis). A type of parosmia is cacosmia, which is observed in sinusitis, dental pathology.
- Olfactory hallucinations (phantosmia). The sensation of a nonexistent smell becomes a harbinger of the onset of an epileptic seizure. Also, the disorder develops with cerebral injuries, neoplasms.
- Olfactory agnosia. Familiar smells cease to be recognized when the area of the cerebral cortex responsible for olfactory function is affected. The symptom is determined by strokes, brain tumors, abscesses.
Depending on the location of the lesion, rhinogenic olfactory disorders are isolated, which are associated with chronic rhinitis, curvature of the nasal septum, nasal polyps, and sensorineural. The latter, in turn, are divided into peripheral (pathology of the olfactory nerve endings in the nasal cavity) and central (damage to the brain centers of smell). Combined dysosmia is singled out separately, when nasal breathing disorders are combined with changes in the mucous membrane of the olfactory region.