xRead - Olfactory Disorders (September 2023)

S.-C. Hong et al.

S30

indications for this endoscopic approach include severe, debilitating unilateral phantosmia that has been present for more than 2 years and can be eliminated with intranasal cocaine anesthesia of the ipsilateral olfactory mucosa. According to Leopold et al. [9], 10 patients underwent an excision of the olfactory epithelium as an endoscopic intranasal approach and 8 patients responded af fi rmatively to the long-term follow-up questionnaire. Two cerebro spinal fl uid (CSF) leaks were noted intraoperatively and these were patched successfully with mucoper iosteal grafts. Because of the related potential serious complications of CSF leak and meningitis, alternative forms of lesioning the epithelium through cauteriza tion techniques are being explored. One needs to spend a considerable amount of time evaluating and counseling patients with olfactory dis tortions. The rare patient who is plagued by these symptoms should be evaluated in a center where expert care can be given and where the most can be learned about this debilitating problem by collect ing information from many patients with the same condition. Since the symptoms usually dissipate over time, conservative management should be exhausted before considering surgical options. There are still many things to learn about olfactory distortion and further research is needed. Further knowledge of olfactory pathophysiology concerning the underlying mechanisms behind the most common forms of olfactory disorders is lacking. With advances in the science of olfaction we hope to discover new treatment strategies to recover smell loss and allow for proper regeneration of olfactory neurons after dam age. Until then, we as physicians need to do our best to counsel these patients and help them manage their occasionally debilitating symptoms. Conclusion

for speci fi c testing. One of our authors (D.A.L.) experienced a patient who had perceived an unpleas ant odor or taste for at least 20 years and was found to have a trimethylaminuria or fi sh-odor syndrome [23].

Treatment of olfactory distortion

Individuals with olfactory distortion need to be reas sured that they do not have a malignant disease or an infection. Most patients will note a gradual decrease in the symptom with time, and this can occur over several years [14,18]. Thus, ‘ watchful waiting ’ is an appropriate course to take. If seizures, migraines, psychiatric diseases or metabolic disturbances are suspected, appropriate referral is needed. If olfactory distortion can be blocked with nasal occlusion, one of the easiest things to try is topical nasal saline drops. These can be placed in limitless quantity every few hours in the head-down-and forward ( ‘ Mecca ’ ) position. Several medications, including sedatives, antide pressants, and anti-epileptic drugs, have been sug gested to treat olfactory distortions [17]. Currently, gabapentin (Neurontin ) is being used by several olfactory centers, although it lacks scienti fi c data supporting its ef fi cacy. Any medications that induce distortions of olfac tion should be identi fi ed and can often be disconti nued and replaced with other types of medications or modes of therapy [24]. Active pharmacologic disruption of the olfactory neurons has been proposed by Zilstorff [17]. The use of topical cocaine HCl will temporarily block most distortions by anesthetizing the neurons. The drug is applied as a drop into the nostril when the neck is fully extended while the patient is supine. Care must be exercised when using it, because undesired effects can occur, and extensive informed consent must be obtained from the patient before its use. In smell dysfunction following viral infection of the upper respiratory tract, alpha-lipoic acid was used orally at a dose of 600 mg/day for an average period of 4.5 months. At the end of treatment parosmias were less frequent (22%) than at the beginning of therapy (48%) [25]. Those who cannot be helped with the medical treatment may bene fi t from surgical therapies. Neurosurgical approaches using a bifrontal craniot omy to remove the olfactory bulbs or nerves have been reported [26,27]. These procedures necessarily result in bilateral permanent anosmia and include the risks and morbidity associated with a craniotomy. To treat a patient ’ s phantosmia and avoid a craniotomy, an excision of the olfactory epithelium as an endoscopic intranasal procedure has been performed [8]. The

Acknowledgment

This work was supported by the Konkuk University.

Declaration of interest: The authors report no con fl icts of interest. The authors alone are responsible for the content and writing of the paper.

References

[1] Miwa T, Furukawa M, Tsukatani T, Costanzo RM, Dinardo LJ, Reiter ER. Impact of olfactory impairment on quality of life and disability. Arch Otolaryngol Head Neck Surg 2001;127:497 – 503. [2] Bon fi ls P, Avan P, Faulcon P, Malinvaud D. Distorted odorant perception: analysis of a series of 56 patients with