40 Pseudo Cranial Nerve I Dysfunction: Subjective Hyposmia and Subjective Hypogeusia but Normosmia and Normogeusia - 3 cases

Abstract

INTRODUCTION

Hyposmia refers to reduced ability to smell and hypogeusia is a partial loss of the ability to taste (Hummel, Basile, & Huttenbrink, 2016). Complaints of hyposmia and hypogeusia in the presence of normosmia and normogeusia has not heretofore been described. Three such cases are presented.

OBJECTIVE

To explore the complaints of reduced smell and taste with normal objective olfaction and gustation.

METHOD

All patients were given screening tests for smell and taste and obtained scores consistent with normosmia and normogeusia. The 12-item version of the Brief Smell Identification Test (B-SIT), using the odorants banana, chocolate, cinnamon, gasoline, lemon, onion, paint thinner, pineapple, rose, soap, smoke and turpentine was used. The Retronasal Olfactory Test was used to determine their perception of flavour and the Proplythiouracil Disc Taste Test used for gustation. Each patient also underwent a complete physical and neurological examination with any abnormalities mentioned.

RESULTS

Case 1: This 53 year old female, 8months prior to presentation, developed the flu followed by the inability to taste any foods and differentiate between smells, with everything smelling bitter.

Results: Chemosensory testing: Olfaction: Brief Smell Identification Test (B-SIT): 10 (normosmia). Retronasal Olfactory Test: Retronasal Smell Index: 9 (normal). Gustation: Propylthiouracil Disc Taste Test: 7 (normal).

Case 2: This 86 year old female, 6months prior to presentation, developed reduced taste, of gradual onset, to the point upon presentation was only 10% normal. She was able to taste lemons but very little else.

Results: B-SIT: 9 (normosmia). Retronasal Smell Index: 10 (normal). Propylthiouracil Disc Taste Test: 10 (normogeusia).

Case 3: This 63 year old female was nasute until 3months prior to presentation, when she developed an upper respiratory infection, followed by loss of smell and taste to 20% of normal.

Results: B-SIT: 10 (normosmia). Retronasal Smell Index: 7 (normal). Propylthiouracil Disc Taste Test: 10 (normogeusia).

CONCLUSION

Discordance between subjective and objective findings may be due to the wide distribution of normal in the general population in olfactory ability. The associated reduction in retronasal smell may then be interpreted by the patient as reduced ability to taste. Alternatively, complaints of hyposmia and hypogeusiamay be due to a non-organic need such as malingering or psychosomatic illness, or could represent a primary defect in the cortical integration of smell and taste, interpreted as reduction in perceived flavor, yet the primary sensory neurons and threshold as tested would appear to be normal. This disparity possibly indicates that the testing modalities are too insensitive to demonstrate more subtle sensory perception findings, and suggests the need for more refined testing methods for smell and taste.