Disorders of olfaction in pathologies of the peripheral part of the olfactory system
As already mentioned, the smallest particles of odorous substances in the air must penetrate into the olfactory gap to cause irritation of the terminal branches of the olfactory nerve. With violation of nasal breathing, the sharpness of the olfactory sensation decreases.
The disorders of the olfactory function of can occur if there are obstacles to the passage of smelling substances to the olfactory area - this is the so-called respiratory hyposmia. The reason for reducing the sense of smell in such cases are: curvature of the nasal septum, atresia of the nasal passages of atresia of the choana, polyps and tumors of the nose.
Elimination of these obstacles for ingress of odorous substances into the olfactory area can completely restore the olfactory function.
In addition to mechanical obstructions to ingest odorous substances on the olfactory area, the reduction of olfactory function or complete loss of it may result from the damage to the olfactory nerve or the terminal branching of the olfactory nerve in the nasal mucosa. In this case, there will come an essential anosmia or hyposmia. The latter are observed in pathological processes that cause profound lesions of the mucosa of the olfactory region of the nose( for example, in the lake).
The destruction of the endings of the olfactory nerve can also occur when a variety of cauterizing substances enter the olfactory area.
Pathological processes in the main sinus and lattice( inflammatory, with tuberculosis, syphilis), extending to the olfactory area, can also cause a decrease in smell.
In inflammatory diseases of the paranasal sinuses, accompanied by accumulation of pus in the olfactory area, the sense of smell can suffer greatly depending on the nature and duration of the process.
In cases where the polyp exists for a long time and presses on the olfactory area, anosmia can also occur as a result of atrophy of the olfactory cells. To this kind of violation of the sense of smell must be attributed anosmia, observed in old age. Disturbance of smell can occur due to the inflammatory process or the toxic effect of certain substances directly acting on the nasal mucosa or through general intoxication.
Various kinds of intoxication with chemicals( nicotine, morphine, atropine) or in connection with infectious diseases( diphtheria, influenza) can cause inflammation in the olfactory nerve itself and as a result, a decrease in smell.
In connection with injuries that have caused damage to the olfactory area( for example, with fractures of the skull in the lamina cribrosa), damage to the olfactory nerve trunk and a reduction in smell may occur.
In addition to anosmia and hyposmia, there is still parosmia, that is, a state where smells are perceived but incorrectly determined. In these cases, instead of a smell, the subject calls another. Then there is hyperosmia, that is, an increased perception of odors, causing headache, vomiting and dizziness.
It is necessary to mention the phenomena of violation of smell - kakosmiyah, manifested in perceptions of bad smells. A kakosmia is the sensation of a bad smell that arises without the perception of this odor from outside, but is caused by the existence of some internal source of smell reaching the olfactory receptor( with diseases of the paranasal sinuses, caseous tonsillitis, etc.).
Very valuable differential diagnostic data in the process of olfactory function analysis gives a division into a purely olfactory component and a taste: for all peripheral lesions, like a chronic runny nose, hypertrophies of mucous membranes, polyps, sinus diseases, oes, postoperative nasal mucosa disorders,more or less often the olfactory part;tactile and taste components are not affected( respiratory impairment of smell, hyposmia, anosmia).Only with large changes caused by the radical operation of the nose carcinoma and very intensive radium treatment, when the trigeminal nerve is killed along with the olfactory nerve, along with the olfactory component, both tactile and flavoring drop out. If, however, we find a dropout of all three components without a particularly pronounced change on the part of the nose, this indicates a defeat of the central origin. In addition to the above-mentioned organic impairment of smell, there is also a functional damage to the sense of smell in neuroses and psychoses.
The loss of the tactile and taste components, together with the olfactory component in the normal mucous membrane of the nose, excludes the simulation or functional suffering. Individual fluctuations in olfactory perception, a decrease in smell in old age, abnormal fatigue and involuntary errors should be taken into account.