Identifying normosmics: a comparison of two populations

Effect of endoscopic endonasal skull base approaches on olfactory function and facial development in children

INTRODUCTION

Endoscopic approaches for skull base pathologies are increasingly being performed, and the subsequent complications, especially in the long term, have also been partially clarified. However, there is no information on the effects of endoscopic endonasal skull base surgeries (EESBS) in children on odor and facial development in parallel with long-term development. We conducted this study to investigate postoperative olfactory function and facial development in pediatric patients who underwent skull base surgery using the endoscopic endonasal method.

METHODS

We evaluated the smell test, sinonasal symptoms, and facial development of pediatric patients who underwent endoscopic endonasal skull base surgery after long-term follow-up. Odor was evaluated using the "Sniffin' Sticks" test kit, which assessed the T (odor threshold), D (odor discrimination), and I (odor identification) parameters. Sinonasal symptoms were evaluated using the SNOT-22 (sinus-nose outcome test) questionnaire. SNA (sella-nasion-A point), SNB (sella-nasion-B point), and ANB (A point-nasion-B point) angles were calculated from maxillofacial tomography and magnetic resonance imaging) to evaluate facial development. Data were compared with those of the healthy control group.

RESULTS

We included 30 patients comprising 19 (63.3%) boys and 11 (36.7%) girls, with no age difference between case and control groups. The mean follow-up period was 7 years. Odor test data, cephalometric measurements, and SNOT-22 analysis results showed no statistically significant differences between the two groups.

CONCLUSION

To our knowledge, this is a comprehensive study with the longest follow-up period in terms of evaluation of facial development after EESBS in children to analyze odor using the Sniffin' Sticks test kit and the quality of life using SNOT-22. Olfactory function, facial development, and quality of life remained unaffected after long-term follow-up after EESBS  in children. Although this surgical approach is minimally invasive, we recommend considering the possibility of complications, and the procedure should be performed by an experienced surgical team with adequate equipment.

The brain functional connectivity alterations in traumatic patients with olfactory disorder after low-level laser therapy demonstrated by fMRI

BACKGROUND

Low-level laser therapy (LLLT) has been clinically accepted to accelerate the nerve regeneration process after a nerve injury or transection. We aimed to investigate the neuronal basis and the influence of LLLT on brain functional networks in traumatic patients with olfactory dysfunction.

METHODS

Twenty-four Patients with traumatic anosmia/hyposmia were exposed to pleasant olfactory stimuli during a block-designed fMRI session. After a 10-week period, patients as control group and patients who had completed the sessions of LLLT were invited for follow-up testing using the same fMRI protocol. Two-sample t-tests were conducted to explore group differences in activation responding to odorants (p-FDR-corrected <0.05). Differences of functional connectivity were compared between the two groups and the topological features of the olfactory network were calculated. Correlation analysis was performed between graph parameters and TDI score.

RESULTS

Compared to controls, laser-treated patients showed increased activation in the cingulate, rectus gyrus, and some parts of the frontal gyrus. Shorter pathlength (p = 0.047) and increased local efficiency (p = 0.043) within the olfactory network, as well as decreased inter-network connectivity within the whole brain were observed in patients after laser surgery. Moreover, higher clustering and local efficiency were related to higher TDI score, as manifested in increased sensitivity to identify odors.

CONCLUSIONS

The results support that low-level laser induces neural reorganization process and make new connections in the olfactory structures. Furthermore, the connectivity parameters may serve as potential biomarkers for traumatic anosmia or hyposmia by revealing the underlying neural mechanisms of LLLT.

Sensitivity and Specificity of Self-Reported Olfactory Function in a Home-Based Study of Independent-Living, Healthy Older Women

INTRODUCTION

The 2011-14 US National Health and Nutrition Examination Survey chemosensory protocol asks adults to self-rate their orthonasal (via nostrils) and retronasal (via mouth) smell abilities for subsequent odor identification testing. From data collected with a similar protocol, we aimed to identify a self-reported olfactory index that showed the best sensitivity (correctly identifying dysfunction) and specificity (correctly indentifying normosmia) with measured olfaction.

METHODS

In home-based testing, 121 independent-living older women (age 73±7 years) reported their olfactory function by interviewer-administered survey. Olfactory function was measured orthonasally via composite (odor threshold, identification task) or identification task alone.

RESULTS

Only 16 % of women self-rated "below average" smell function. More women perceived loss of smell (38 %) or flavor (30 %) with aging. The rate of measured dysfunction was 30 % by composite (threshold and identification) and 21.5 % by identification task, the latter misclassifying some mild dysfunction as normosmia. An index of self-rated smell function and perceived loss yielded the most favorable sensitivity (65 %) and specificity (77 %) to measured function. Self-rated olfaction showed better agreement with severe measured dysfunction; mild dysfunction was less noticed.

CONCLUSIONS

Self-reported indices that query about current and perceived changes in smell and flavor with aging showed better sensitivity estimates than those previously reported. Specificity was somewhat lower-some older adults may correctly perceive loss unidentified in a single assessment, or have a retronasal impairment that was undetected by an orthonasal measure.

IMPLICATIONS

Our findings should inform self-rated measures that screen for severe olfactory dysfunction in clinical/community settings where testing is not routine.

Smell and taste disorders

Olfaction and taste promote satisfaction and protection in daily life. The astute facial plastic surgeon recognizes the importance of a baseline smell test to document the patients' olfactory status before surgery. After surgery, the surgeon must be alert to the possible mechanisms of hyposmia and anosmia and the pertinent treatment strategies. The surgeon must also understand the importance of counseling the patient and family regarding the cause of the dysfunction and the proper treatments. This article updates the facial plastic surgeon on the importance of smell and taste and associated disorders with a current review of the literature.

Olfactory function following open rhinoplasty: A 6-month follow-up study

Background

Patients undergoing any type of nasal surgery may experience degrees of postoperative olfactory dysfunction. We sought to investigate "when" the olfactory function recovers to its preoperative levels.

Methods

In this cohort design, 40 of 65 esthetic open rhinoplasty candidates with equal gender distribution, who met the inclusion criteria, were assessed for their olfactory function using the Smell Identification Test (SIT) with 40 familiar odors in sniffing bottles. All the patients were evaluated for the SIT scores preoperatively and postoperatively (at week 1, week 6, and month 6).

Results

At postoperative week one, 87.5% of the patients had anosmia, and the rest exhibited at least moderate levels of hyposmia. The anosmia, which was the dominant pattern at postoperative week 1, resolved and converted to various levels of hyposmia, so that no one at postoperative week 6 showed any such complain. At postoperative week six, 85% of the subjects experienced degrees of hyposmia, almost all being mild to moderate. At postoperative six month, the olfactory function had already reverted to the preoperative levels: no anosmia or moderate to severe hyposmia. A repeated ANOVA was indicative of significant differences in the olfactory function at the different time points. According to our post hoc Benfronney, the preoperative scores had a significant difference with those at postoperative week 1, week 6, but not with the ones at month 6.

Conclusion

Esthetic open rhinoplasty may be accompanied by some degrees of postoperative olfactory dysfunction. Patients need a time interval of 6 weeks to 6 months to fully recover their baseline olfactory function.

Olfactory dysfunction and its measurement in the clinic and workplace

OBJECTIVES

To provide an overview of practical means for quantitatively assessing the sense of smell in both the clinic and workplace. To address basic measurement issues, including those of test sensitivity, specificity, and reliability. To describe and discuss factors that influence olfactory function, including airborne toxins commonly found in industrial settings.

METHODS

Selective review and discussion.

RESULTS

A number of well-validated practical threshold and suprathreshold tests are available for assessing smell function. The reliability, sensitivity, and specificity of such techniques vary, being influenced by such factors as test length and type. Numerous subject factors, including age, sex, health, medications, and exposure to environmental toxins, particularly heavy metals, influence the ability to smell.

CONCLUSIONS

Modern advances in technology, in conjunction with better occupational medicine practices, now make it possible to reliably monitor and limit occupational exposures to hazardous chemicals and their potential adverse influences on the sense of smell. Quantitative olfactory testing is critical to establish the presence or absence of such adverse influences, as well as to (a) detect malingering, (b) establish disability compensation, and (c) monitor function over time.

Effects of head injury on olfaction and taste

Traumatic events such as motor vehicle accidents, falls, or assaults can lead to dysfunction in olfaction or gustation. Mechanisms of posttraumatic olfactory dysfunction include direct injury to the sinonasal tract or olfactory epithelium, shearing effect on olfactory fibers at the cribriform plate, or brain contusion or intraparenchymal hemorrhage. Posttraumatic gustatory dysfunction is rare, but may occur as a result of direct injury to the tongue, injury to cranial nerves VII or IX, or brain contusion or hemorrhage. Evaluation of head-injured patients presenting with olfactory or gustatory complaints should include a thorough history, including assessment for pre-and posttraumatic chemosensory dysfunction and potential mechanisms of injury, complete head and neck examination including nasal endoscopy and cranial nerve testing, and focused radiographic imaging, usually CT of the sinuses and skull base. Formal olfactory and gustatory testing may be performed using various techniques, although in cases potentially involving litigation, methodologies able to detect malingering should be used. Treatable causes of chemosensory disturbance, most notably conductive olfactory losses caused by chronic rhinosinusitis or nasal obstruction, should be ruled out. In the event of neurosensory deficits, recovery may occur up to 12 to 18 months after the traumatic event. All patients should be counseled regarding the risks of their chemosensory deficits, and given suggestions for appropriate compensatory strategies.

Olfactory threshold and nasal mucosal changes in experimentally induced common cold

Common cold is a most common disease in man accompanied by an experience of a diminished sense of smell. Controlled studies of the sense of smell are lacking and the cause as well as degree of impairment of smell in common cold has not been satisfactorily evaluated. We have investigated whether impaired olfactory ability accompanies common cold and if the loss is related to nasal blockage and to the amount of nasal discharge. For this purpose we measured the threshold of olfaction in volunteers before and after nasal inoculation with coronavirus 229E. The absolute olfactory threshold was assessed by a modified discrimination step test with dilutions of butanol. Symptoms of common cold were registered using a four-grade scale. Nasal obstruction was measured by nasal peak expiratory flow and by acoustic rhinometry and nasal discharge by weight of pre-weighted handkerchiefs. Individuals with a cold had impaired olfaction and the change in smelling ability correlated to the nasal congestion but not to the nasal discharge in analysis of multiple linear regression.