Olfactory cleft dilatation

Olfactory cleft stenosis and obstruction on paranasal sinus CT scan in pre-septo-rhinoplasty patients: normal variants or pathologic findings?

OBJECTIVE(S)

To determine the frequency of olfactory cleft (OC) stenosis and obstruction on paranasal sinus CT scans in pre-septorhinoplasty of patients who had septal deviation, septopyramidal deformation or nasal obstruction without other sinonasal conditions.

METHODS

This retrospective study included patients referred to our institution between December 2013 and December 2021 for septorhinoplasty due to nasal obstruction without other sinonasal or neurological conditions. All patients underwent preoperative paranasal sinus CT scan and olfactory testing. OC stenosis was quoted as none, partial, or total (less than 1/3 contact between nasal septum and ethmoid turbinates, 1/3-2/3, more than 2/3, respectively), as well as OC obstruction as none, partial, or complete (obstruction of less than 1/3 of OC, 1/3-2/3, more than 2/3, respectively). Radiologic evaluation was validated by near perfect interobserver agreement.

RESULTS

A total of 75 patients (32 women, 43 men) with a mean age of 44.2 ± 15.64 (23-74) years were included, of which 36 were normosmic and 39 hyposmic. OC stenosis was partial in 58.7% (n = 44) of the patients, absent in 28% (n = 21), and total in 13.3% (n = 10), without difference between normosmic and hyposmic patients (p = .66). OC obstruction was absent in 52% (n = 39) and partial in 46.7% (n = 35), without difference between normosmic and hyposmic patients (p = .51). Only one normosmic patient had complete OC obstruction.

CONCLUSION

OC partial stenosis and partial obstruction were frequent findings in pre-septorhinoplasty patients without respiratory mucosa disease and did not influence their olfactory status. Total stenosis and complete obstruction were rarer and require further investigation.

CLINICAL RELEVANCE STATEMENT

Isolated partial olfactory cleft stenosis and obstruction should be considered normal variants, whereas the impact of complete olfactory cleft stenosis and obstruction on patient's olfactory status remains to be determined.

KEY POINTS

• The incidence of olfactory cleft stenosis and obstruction in asymptomatic patients remains unknown, even though it is encountered in clinical practice. • Partial and total olfactory cleft stenosis occurred in 58.7% and 13.3% of the patients; partial obstruction occurred in half of the cases, but complete obstruction was extremely rare. • There are frequent findings of partial olfactory cleft obstruction and stenosis, but complete obstruction and total stenosis should be further investigated.

A new surgical technique to increase airflow in the olfactory cleft: superior turbinate lateralization procedure

BACKGROUND

The olfactory cleft (OC) is the most important anatomical site for the maintenance of olfactory function. Obstruction of airflow in the OC by various conditions, such as inflammation, leads to poor olfactory function. Therefore, it is important to increase OC airflow while performing endoscopic sinus surgery (ESS). However, no technique to increase airflow has yet been established.

METHODS

We designed a superior turbinate lateralization (STL) procedure that displaces the entire ST bone laterally by eliminating the connection between the posterior ST and the anterior wall of the sphenoid sinus. The effect of the STL procedure was investigated in terms of anatomy and olfactory function.

RESULTS

ESS with the STL procedure was performed on seven patients with chronic rhinosinusitis and nasal polyps. The cross-sectional area of the OC at 3 months postoperatively was significantly larger than that before ESS. In addition, the Open Essence test and questionnaires revealed significantly improvements in sense of smell. Airflow in the OC was significantly higher in STL procedure group than in the non-STL procedure group.

CONCLUSION

The STL procedure enlarges the bony framework of the OC, and by increasing OC airflow, facilitates the transport of odorants to the olfactory epithelium, thereby improving olfactory perception.

Parameter characteristics in intranasal drug delivery: A key to targeting medications to the olfactory airspace

BACKGROUND

The nose is a viable pathway for topical drug delivery to the olfactory cleft for treatment of obstructive smell loss and nose-to-brain drug delivery. This study investigates how variations in nasal vestibule morphology influence intranasal spray drug transport to the olfactory cleft and olfactory roof/bulb regions.

METHODS

The unilateral nasal vestibule morphology in three healthy subjects with healthy normal nasal anatomy was classified as Elongated (Subject DN001), Notched (Subject DN002), and Standard (Subject DN003). Computational fluid and particle dynamics modelling were used to simulate nasal airflow and drug particle transport to the olfactory cleft and olfactory roof/bulb regions in each subject-specific nasal cavity. To evaluate highest drug depositions in these regions, the particle transport simulations involved extensive parameter combination analyses: 6 inspiratory flow rates mimicking resting to sniffing (10-50 L/min); 5 spray release locations (Top, Bottom, Central, Lateral, and Medial); 5 head positions (Upright, Tilted Forward, Tilted Back, Supine, and Mygind); 3 particle velocities (1, 5, and 10 m/s); 350,000 μm-particles (1-100 μm) and 346,500 nanoparticles (10-990 nm).

FINDINGS

Particle size groups with highest depositions in olfactory cleft: DN001 left = 28.4% at 11-20 μm, right = 75.3% at 6-10 μm; DN002 left = 16.8% at 1-5 μm, right = 45.3% at 30-40 nm; DN003 left = 29.1% at 21-30 μm, right = 15.9% at 6-10 μm. Highest depositions in olfactory roof/bulb: DN001 left = 6.5% at 11-20 μm, right = 26.4% at 11-20 μm; DN002 left = 3.6% at 1-5 μm, right = 2.6% at 1-5 μm; DN003 left = 2.8% at 21-30 μm, right = 1.7% at 31-40 μm.

INTERPRETATION

DN001 (Elongated nasal vestibule) had the most deposition in the olfactory regions. Micron-particles size groups generally had better deposition in the olfactory regions.

Critical review of diagnosis in rhinology and its therapeutical implications

Diagnosis in rhinology is currently based on the concept of inflammation (chronic rhinosinusitis [CRS]) or the clinical concept of chronic nasal dysfunction (CND). The complementarity between these two approaches can be discussed by a critical review of the literature structured by the analysis of the fundamental and diagnostic bases and the therapeutic implications linked to each. The concept of CRS is based on the anatomical continuity of the nasal and sinus respiratory mucosa and molecular biology data, seeking to analyze the mechanisms of chronic inflammation and to identify proteins and biomarkers involved in the different supposed endotypes of chronic inflammation of this mucosa. The concept of CND seeks to analyze medical, instrumental or surgical diagnostic and therapeutic strategies, taking account of both inflammatory and non-inflammatory causes impacting the anatomy or physiology of each of the three noses (olfactory, respiratory and sinus) that make up the mid-face sinonasal organ of evolution-development (Evo-Devo) theory. Thus, the concept of CRS offers an endotypic approach, based on biological characterization of mucosal inflammation, while the concept of CND offers a compartmentalized phenotypic and pathophysiological approach to sinonasal diseases. The joint contribution of these two concepts in characterizing nasal functional pathology could in future improve the medical service provided to patients.

Review of olfactory cleft roof anatomy

Progress in skull-base endoscopic surgery has improved our knowledge of olfactory cleft (OC) anatomy. This article presents a review of current knowledge concerning the OC roof: descriptive anatomy, radiological exploration, and endoscopic observation. The OC is a narrow area in the most superior part of the nasal cavity. Its roof is the thinnest structure separating the nasal cavities from the brain; it comprises three superimposed tissues: nasal mucosa, ethmoid cribriform plate (ECP), and dura mater. The ECP comprises the anterior ECP containing the ethmoidal slit (ES) medially and the cribroethmoidal foramen (CEF) laterally; and the posterior ECP, comprising the olfactory foramina. The OC roof is bordered anteriorly by the nasal bone roof, laterally by the lateral ethmoid masses, and posteriorly by the jugum and anterior wall of the sphenoid sinuses. Imaging is crucial for analyzing this wall, providing precise detailed information on conformation and anatomic relations with adjacent structures such as the anterior ethmoidal artery. Understanding OC roof anatomy and correct interpretation of imaging are essential for safety in present-day functional endoscopic sinus surgery and anterior skull-base oncologic surgery.

Does endoscopic balloon dilatation improve intranasal drug delivery to the olfactory cleft? A pre-clinical cadaver feasibility study

Background

Although systemic steroids have been shown to improve olfactory function, topical steroids have not demonstrated the same efficacy. This could a result of limited drug delivery to the narrow, superiorly placed olfactory cleft. This study aimed to examine the penetration of intranasal drugs to the olfactory cleft following endonasal balloon dilatation.

Methods

Balloon dilatation was performed in 12 thawed, fresh-frozen cadaver specimens. In the Mygind position, nasal drops mixed with blue food dye were administered into the nostril before and after the dilatation procedure. Endoscopic videos were recorded to assess dye staining of the olfactory cleft and osteo-meatal complex using a 4-point Likert scale.

Results

Prior to balloon dilatation, the mean penetration of nasal drops into the olfactory cleft was 1.34, which improved significantly (p < 0.05) to 2.66 following the procedure. There was no change in dye penetration into the osteo-meatal complex after balloon dilatation.

Conclusion

The results of this exploratory study suggest that balloon dilatation may improve the delivery of nasal drops to the olfactory cleft area. The clinical applicability and impact on olfactory function will require further assessment.

Ambiguous "olfactory" terms for anatomic spaces adjacent to the cribriform plate: A publication database analysis and quest for uniformity

A precise nomenclature and terminology is the foundation of communication in Anatomy and related biomedical sciences. The olfactory bulbs and nerves lie above and below the cribriform plate (CP), respectively. Hence, many anatomical landmarks in this region have names adopting the term "olfactory" as qualifiers. Ambiguous use of these "olfactory" terms exists, with some potential repercussions on patient treatments. We performed a publication database analysis to determine the frequency of misuse of names for seven anatomical "olfactory" spaces close to the CP and nasal cavity. We searched PubMed® publications having the keyword "olfactory" in their title or abstract, plus one of seven other keywords: "groove", "fossa", "recess", "cleft", "vestibule", "sulcus", and "cistern". We reviewed all abstracts for accuracy of these terms relative to accepted norms or customary definitions. By February 2020, we found all these keywords in 1255 articles. For the terms olfactory "groove" and "fossa", the number of relevant articles (and percentage of those inaccurately using these terms) were 374 (1.1%), and 49 (8.2%), respectively. All 52 abstracts containing "olfactory" and "vestibule" were irrelevant, relating to the "nasal vestibule" and olfactory function, instead of "olfactory vestibule". Overall, terms used to describe "olfactory" spaces near the CP are seldom ambiguous or inaccurate, but the terms olfactory "groove" and "fossa" are occasionally misused, We propose several new "olfactory" terms for inclusion in the Terminologia Anatomica, and stress the need for uniform nomenclature leading to greater consistency and accuracy in clinical use of anatomical terms containing the word "olfactory" as a descriptor.

Endoscopic balloon dilatation of the olfactory cleft - a feasibility study of a novel technique in cadavers

Objective

Smell dysfunctions are common with almost 20% percent of the population affected. There are no interventional solutions for these patients. The aim of this study is to investigate the feasibility and security of the balloon dilatation technique.

Methods

This paper describes interventional steps and determines the feasibility and safety of endoscopic olfactory cleft dilatation via balloon device. We included 10 nasal cavities in the study and dilated olfactory cleft areas via balloon device.

Results

We could smoothly perform the procedure and did not observe any fractures on the skull base or olfactory cleft of the cadavers after dilatation.

Conclusions

A combination of this intervention with medical treatments can be promising for smell dysfunctions.

From ethmoidal air cells to ethmoturbinal passages

The concept of ethmoidal sinuses composed of ethmoidal air cells does not appear to fit with the embryological origin of the ethmoid. Post-natal formation of the paranasal sinuses, as visualized by MRI, appears to be fundamentally different from the embryological development of the ethmoid sinus. These two organs also appear to have very distinct functions: paranasal sinuses play a role in respiration and sanitization of the respiratory tract, while the ethmoid sinus plays a role in olfaction. However, human acquisition of bipedalism resulted in ethmoidal compartmentalization into olfactory clefts lined by olfactory mucosa and the ethmoidal labyrinth formed by a meshwork of ethmoturbinals that have lost their olfactory mucosa. Ethmoturbinals are septa that increase the surface area of olfactory mucosa in mammalian olfactory chambers. Embryological development of the human ethmoid sinus can be seen as the result of curved stacking of ethmoturbinal septa forming passages. Surgically, these passages can be accessed via the middle, superior and supreme meati. An ethmoidectomy technique following the ethmoturbinal passages can therefore be described. This structure of the ethmoidal labyrinth is both useful and necessary for the teaching of ethmoidal surgery.

Loss of smell in patients with COVID-19

Objective

To assess the physiopathology of olfactory function loss (OFL) in patients with coronavirus disease 2019 (COVID-19), we evaluated the olfactory clefts (OC) on MRI during the early stage of the disease and 1 month later.

Methods

This was a prospective, monocentric, case-controlled study. Twenty severe acute respiratory syndrome coronavirus 2 (SARS-CoV2)–infected patients with OFL were included and compared to 20 age-matched healthy controls. All infected patients underwent olfactory function assessment and 3T MRI, performed both at the early stage of the disease and at the 1-month follow-up.

Results

At the early stage, SARS-CoV2–infected patients had a mean olfactory score of 2.8 ± 2.7 (range 0–8), and MRI displayed a complete obstruction of the OC in 19 of 20 patients. Controls had normal olfactory scores and no obstruction of the OC on MRI. At the 1 month follow-up, the olfactory score had improved to 8.3 ± 1.9 (range 4–10) in patients, and only 7 of 20 patients still had an obstruction of the OC. There was a correlation between olfactory score and obstruction of the OC (p = 0.004).

Conclusion

OFL in SARS-CoV2–infected patients is associated with a reversible obstruction of the OC.

The Effect of Endoscopic Olfactory Cleft Opening on Obstructed Olfactory Cleft Disease

Purpose

This study was conducted to evaluate the effect of endoscopic olfactory cleft (OC) opening on olfaction in patients with obstructed OC disease. Materials and Methods. Patients with obstructed OC disease who underwent endoscopic OC opening for treatment were enrolled. The endoscopic olfactory cleft opening was performed under local anesthesia. Under an endoscopy, the middle and superior turbinates were gently lateralized to open the OC using an elevator. The phenyl ethyl alcohol threshold test was performed to evaluate the olfactory function both before and after surgery.

Results

An endoscopic OC opening was performed on 42 patients. Amongst them, the etiology of OC obstruction revealed anatomic anomalies in 14 patients, inflammatory process in 14, and anatomic anomalies as well as inflammatory process in 14. The phenyl ethyl alcohol threshold levels improved in 32 (76.2%) of the patients after surgery. The olfactory function was better improved in patients experiencing OC obstructed by inflammatory process than those by anatomic anomalies.

Conclusions

This study showed that endoscopic OC opening seemed to be effective in treating olfactory dysfunction in patients with obstructed OC disease caused by inflammatory process.