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Deep Learning Technology: Sebastian Arnold, Betty van Aken, Paul Grundmann, Felix A. Gers and Alexander Löser. Learning Contextualized Document Representations for Healthcare Answer Retrieval. The Web Conference 2020 (WWW'20)
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Even though dysosmia often goes away on its own over time, there are both medical and surgical treatments for dysosmia for patients that want immediate relief. Medical treatments include the use of topical nasal drops and oxymetazoline HCL, which give an upper nasal block so that the air flow can't reach the olfactory cleft. Other medications suggested include sedatives, anti-depressants, and anti-epileptic drugs. The medications may or may not work and for some patients, the side effects may not be tolerable. Most patients benefit from medical treatment but for some surgical treatment is required. Options include a bifrontal craniotomy and an excision of the olfactory epithelium, which cuts all of the fila olfactoria. According to some studies, transnasal endoscopic excision of the olfactory epithelium has been described as a safe and effective phantosmia treatment. The bifrontal craniotomy results in permanent anosmia and both surgeries are accompanied with the risks associated with general surgery.
The frequency of phantosmia is rare in comparison with the frequency of parosmia. Parosmia has been estimated to be in 10-60% of patients with olfactory dysfunction and from studies, it has been shown that it can last anywhere from 3 months to 22 years. Smell and taste problems result in over 200,000 visits to physicians annually in the US. Lately, it has been thought that phantosmia might co-occur with Parkinson's disease. However, its potential to be a premotor biomarker for Parkinson's is still up for debate as not all patients with Parkinson's disease have olfactory disorders
Due to the rareness of the disorder there is no well-defined treatment. Sometimes the patients are just told to live with the disorder or the patients end up performing "stereotypical methods" that might help in reducing the severity of the odor. This might include forced crying, bending over holding knees while holding breath, rinsing the nose with saline water and gagging. All these behaviours at the end fail to resolve the hallucination. Various treatments like prophylactic have been suggested but more research is needed for its confirmation. Also, due to being a poorly understood disorder, and having analogies to some psychiatric conditions, some patients are told that they have a mental illness. It is also usual for these patients to have suicidal thoughts as they are not provided with much support or hope from many physicians.
One of the surgical treatments proposed has included olfactory bulb ablation through a bifrontal craniotomy approach. But a counter-argument by Leopold, Loehrl and Schwob (2002) has stated that this ablation process results in a bilateral permanent anosmia and includes risks associated with a craniotomy. According to them, the use of transnasal endoscopic exhibition of olfactory epithelium is a safe and effective treatment for patients with unremitting Phantosmia with the olfactory function being potentially spared.
It is also cautioned that the surgery is challenging one and is associated with major risks, and that it should be restricted to expertise centres.
On the other hand, many cases have also reported that the strength of their symptoms have decreased with time. (Duncan and Seidan, 1995)
A case involving long term phantosmia has been treated with the use of an anti depressive medication by the common name Venlafaxine. The brand name of the drug is Effexor. The relation between mood disorders and phantosmia is unknown, and is a widely researched area. In many cases, the symptoms of phantosmia have been reduced by the use of anti seizure and anti depressants that act on the central and peripheral neurons.
The most commonly used treatment method is the removal of the olfactory epithelium or the bulb by means of surgery to alleviate the patient from the symptoms.
Other traditional methods include the use of topical anesthetics (Zilstorff-Pederson, 1995) and use of sedatives.
This antidepressant medication is a serotonin norepinephrine reuptake inhibitor (SNRI). In the case study of a 52-year-old female suffering from phantosmia for 27 years, a dose of 75 mg a day relieved and eliminated her symptoms. The drug was prescribed initially in order to treat her depression.
The successful treatment of xerostomia is difficult to achieve and often unsatisfactory. This involves finding any correctable cause and removing it if possible, but in many cases it is not possible to correct the xerostomia itself, and treatment is symptomatic, and also focuses on preventing tooth decay through improving oral hygiene. Where the symptom is caused by hyposalivation secondary to underlying chronic disease, xerostomia can be considered permanent or even progressive. The management of salivary gland dysfunction may involve the use of saliva substitutes and/or saliva stimulants:
- Saliva substitutes – these include SalivaMAX, water, artificial salivas (mucin-based, carboxymethylcellulose-based), and other substances (milk, vegetable oil).
- Saliva stimulants – organic acids (ascorbic acid, malic acid), chewing gum, parasympathomimetic drugs (choline esters, e.g. pilocarpine hydrochloride, cholinesterase inhibitors), and other substances (sugar-free mints, nicotinamide).
Saliva substitutes can improve xerostomia, but tend not to improve the other problems associated with salivary gland dysfunction. Parasympathomimitic drugs (saliva stimulants) such as pilocarpine may improve xerostomia symptoms and other problems associated with salivary gland dysfunction, but the evidence for treatment of radiation-induced xerostomia is limited. Both stimulants and substitutes relieve symptoms to some extent. Salivary stimulants are probably only useful in people with some remaining detectable salivary function. A systematic review of the treatment of dry mouth found no strong evidence to suggest that a specific topical therapy is effective. The review reported limited evidence that oxygenated glycerol triester spray was more effective than electrolyte sprays. Sugar free chewing gum increases saliva production but there is no strong evidence that it improves symptoms. There is a suggestion that intraoral devices and integrated mouthcare systems may be effective in reducing symptoms, but there was a lack of strong evidence. A systematic review of the management of radiotherapy induced xerostomia with parasympathomimetic drugs found that there was limited evidence to support the use of pilocarpine in the treatment of radiation-induced salivary gland dysfunction. It was suggested that, barring any contraindications, a trial of the drug be offered in the above group (at a dose of five mg three times per day to minimize side effects). Improvements can take up to twelve weeks. However, pilocarpine is not always successful in improving xerostomia symptoms. The review also concluded that there was little evidence to support the use of other parasympathomimetics in this group.
A 2013 review looking at non-pharmacological interventions reported a lack of evidence to support the effects of electrostimulation devices, or acupuncture, on symptoms of dry mouth.
Xerostomia is a very common symptom. A conservative estimate of prevalence is about 20% in the general population, with increased prevalences in females (up to 30%) and the elderly (up to 50%).
The olfactory system is the system related to the sense of smell (olfaction). Many fish activities are dependent on olfaction, such as: mating, discriminating kin, avoiding predators, locating food, contaminant avoidance, imprinting and homing. These activities are referred to as “olfactory-mediated.” Impairment of the olfactory system threatens survival and has been used as an ecologically relevant sub-lethal toxicological endpoint for fish within studies. Olfactory information is received by sensory neurons, like the olfactory nerve, that are in a covered cavity separated from the aquatic environment by mucus. Since they are in almost direct contact with the surrounding environment, these neurons are vulnerable to environmental changes. Fish can detect natural chemical cues in aquatic environments at concentrations as low as parts per billion (ppb) or parts per trillion (ppt).
Studies have shown that exposures to metals, pesticides, or surfactants can disrupt fish olfaction, which can impact their survival and reproductive success. Many studies have indicated copper as a source of olfactory toxicity in fishes, among other common substances. Olfactory toxicity can occur by multiple, complex Modes of Toxic Action.
Early investigation by Hasler and Wisby (1951) examined how fish use olfactory imprinting to discriminate smells in order for fish to find their natal streams. This research provided the framework for testing synthetic chemicals used by hatcheries to examine homing and straying by hatchery fish. The investigation of the toxicity of mercury and copper to the olfactory systems in fish began in the early 1970s. Where they found that solutions of mercury chloride (HgCl) and copper sulfate (CuSO) depressed olfactory response during exposure to the two toxicants and found that toxicant concentration and olfactory response had an inverse relationship to each other.