OLFACTION IN ENDOSCOPIC SINUS SURGERY Mohammed Alsukayt R2 18/05/2016
Introduction Chronic Rhinosinusitis (CRS) accounts for 14-30% of olfactory dysfunction cases In patients with CRS, 28% to 84% complain of a decreased sense of smell. The most probable explanation is a combination of factors including a mechanical blockade to airflow, neuroepithelial edema, and the direct neurotoxic effects of viruses and bacterial toxins
Olfactory loss Hyposmia: Reduction in sense of smell Anosmia: Complete loss of smell Mechanisms: First, the obstruction of the olfactory cleft from polyps, nasal discharge, and mucosal edema decreases the ability of the odorant to reach the olfactory receptors. Second, underlying epithelial inflammatory damage from CRS can affect the health of the olfactory neurons or the neurons ability to transmit olfaction to the brain.
Anatomy The olfactory cleft is composed of pseudostratified columnar epithelium located below the cribriform plate and extending inferiorly along the septum for about 1 cm. Parasagittally, the olfactory epithelium is roughly 2 cm in length along the superoposterior septum and can extend posteriorly to the face of the sphenoid sinus and laterally to the upper portion of the superior and middle turbinates.
Physiology
Olfactory testing Subjective 0 to 100-mm visual analog scale (VAS) Objective Threshold tests Butanol threshold test (BTT) Identification tests University of Pennsylvania Smell Identification Test (UPSIT) Cross- cultural Smell Identification Test (CCSIT)
Olfactory Loss A scale of 0-4 via the ratio of the opacified area to the whole area of the olfactory cleft (0, no opacification; 1, 25%; 2, 25%-50%; 3, 50%-75%; 4, >75%). Kim and colleagues graded the olfactory cleft opacification on CT scan as Mild (0% 25%) Moderate (25% 75%) Severe (>75%) Kim DW, Kim JY, Jeon SY. The status of the olfactory cleft may predict postoperative olfactory function in chronic rhinosinusitis with nasal polyposis. Am J Rhinol Allergy 2011;25(2):e90 4.
Consideration for Olfactory Preservation Meticulous dissection should be used near turbinates and the superior septum to lessen the chance of mucosal stripping Unintentional turbinectomies Damage to the cribriform.
Lund-McKay and Lund-Kennedy Alt and colleagues found that higher scores on both the Lund-McKay Radiologic Score and the Lund-Kennedy Endoscopy Score correlated with smell loss in patients with CRSwNP. In patients with CRSsNP, the Lund- Kennedy score only weakly correlated with smell loss, and there was no correlation with severity of Lund-McKay score.
Olfaction Post FESS In 2009, Litvack et al. reported a prospective trial of 111 patients with olfactory impairment undergoing ESS for medically refractory CRS The results demonstrated that olfactory impairment improved following ESS for anosmic patients but not for patients with hyposmia. The improvements for anosmic patients were stable after 1 year follow-up. They hypothesized that anosmic patients typically had a mechanical obstruction to the olfactory cleft which was amenable to surgical removal.
According to the Lund-Kennedy score, 50 patients were divided into two groups: Favorable wound healing group, who was scored 0 Unfavorable wound healing group, who showed pathologic findings. Mild group who was scored 1-6 Severe group who was scored 7-12
Non-randomized clinical trial study 60 patients Surgical group (n=30) Fluticasone (8 weeks + FESS) Medical group (n=30) Futicasone for 8 weeks
SNOT-22 Item 12 Decreased Sense of Smell/Taste
Summary Understanding the olfactory anatomy and physiology and the mechanisms for smell loss in CRS is important. There are many olfactory tests that can be used to document a patient s complaint of smell loss. Preoperatively discussing the potential for smell loss after endoscopic sinus should be considered to address patient expectations. Further studies are needed in determining the exact cause and prognosis of olfactory loss in chronic rhinosinusitis patients
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