Discussion
Phantosmia is an olfactory sensation that occurs when there is no odor
source. These phantom odors can be strong or weak, familiar or
unfamiliar, and cannot be detected by anyone in the immediate vicinity.
Phantosmia was defined as a qualitative disruption of smell function and
it was not observed in Bangladesh during the COVID-19 pandemic.
Persistent rhinosinusitis, craniofacial injury, cerebrovascular disease,
seizure disorders, psychological symptoms, brain radiotherapy,
neurologic disorders, iatrogenic causes, and neurologic and
neurodegenerative disorders are some of the causes of phantosmia. The
conductive or sensorineural underlying mechanism of this specific
symptom is still unknown (8). In patients with olfactory disorders,
phantosmia has been observed to occur up to 25% of the population, and
the incidence is higher in the elderly than in the younger population
(9). However, in our situation, the patient was a young one. COVID-19
patients, on the other hand, frequently report a lack of taste or smell
without nasal congestion or discharge (10, 11).It was clear that
late-onset symptoms like qualitative alterations (phantosmia) can
develop. In some situations, phantosmia developed after months of no
other symptoms (11). In a population-based survey, Sjolund et al. (12)
found that phantom odors were encountered fewer than once a month (54
%) and that the most commonly reported phantom smell was smokey or
burnt (46%). The odor of onion and garlic was present in our case,
which was unusual.
SARS-CoV-2 involves the spike protein, which is found in the
angiotensin-converting enzyme (ACE)-2 protein, to attach to a membrane
receptor complex and the proteolytic activities of host proteases such
as TMPRSS2 to invade cells (13, 14). ACE-2 is not generated by olfactory
nerve cells or olfactory epithelium mitral cells, according to recent
single-cell RNA-sequencing and immunostaining investigations, but it is
represented at a substantial level by other supporting cells in the
olfactory mucosa, such as sustentacular and microvillar cells (13, 15).
The Olfactory disorder has also been linked to viral illness of vascular
pericytes (which express ACE-2) and/or immunologically vascular
destruction in the olfactory epithelium and olfactory bulb; indeed,
magnetic resonance microscopy research discovered microvascular injury
in the olfactory bulbs of COVID-19 patients (16).
In SARS-CoV-2 positive patients in Europe and America, the prevalence of
smell and taste impairment ranges from 18.6% to 90% (17, 18). In one
sub-group study, they discovered that Chinese and Bangladeshi
participants were more likely than other South East Asian ethnicities to
have Olfactory and Taste Dysfunction (OTD) (19). Unfortunately, treating
these disorders is difficult. The use of systemic and local
glucocorticoids (20), as well as olfactory therapy (21) and
carbamazepine (5), has been shown to be beneficial. However, no data on
the efficacy of these strategies in post-COVID-19 STD is currently
available. However, due to safety concerns, existing evidence does not
support the usual prescription of systemic corticosteroids in this
circumstance.
On December 1, 2021, the Omicron variant of COVID 19 was discovered for
the first time in Dhaka, Bangladesh. Persons who had completed the whole
main immunization series and booster doses using mRNA vaccines for
COVID-19 can become infected with Omicron variant illnesses. In this
period, the Omicron variant may contribute as new symptoms and kinds of
compliance, thus we are also conscious of these unexpected COVID-19
symptoms as the variant change’s day by day.
Limitation, there was no endoscopy or rhinoscopy to examine the nasal
cavity and evaluate for disorders that could explain phantosmia. Imaging
techniques, such as Computed tomography, Magnetic resonance imaging
(MRI) and electroencephalogram (EEG) scans, were used to search for
problems in the nasal cavity, brain, or nervous system, which were also
not performed.
Although phantosmia or olfactory hallucinations have not previously been
linked to COVID-19 disease commonly, the onset of phantosmia due to
olfactory impairment is a known occurrence. Albeit the pathogenic cause
is unknown, phantosmia occurred following infection with COVID-19 and
subsided after the disease was resolved. Despite the small duration of
follow-up, this case report revealed the presence of a novel, unique.