Olfactory Nerve | Cranial Nerve I / CN I Assessment

The olfactory nerve is the first of the 12 cranial nerves and is responsible for the sense of smell. Disturbance of the sense of smell includes hyposmia, which is diminished smell, or anosmia, which is the absence of smell. These occur due to peripheral damage of the olfactory nerve, for example, because of rhinitis, trauma to the face, or side effects of medication, OR because of central damage to the olfactory bulb or tract.  

The olfactory nerve only has a sensory function, namely the detection of nonirritating odors.

While some authors recommend using common smells such as coffee or vanilla, Davidson et al. (1997) propose a simple and reliable method, which is the alcohol sniff test, for which a 70% isopropyl alcohol pad is used that is available in most clinics and wards and that has a familiar smell. No diagnostic properties are available on this test so the clinical value remains unknown.

The patient is in standing or sitting position and is asked to close the eyes and keep them shut. One nostril is held shut as each nostril is tested separately.
Hold the opened alcohol pad under the patient’s nose at a couple of centimeters distance and ask them to identify the smell. Repeat the same process with the other nostril.

21 OF THE MOST USEFUL ORTHOPAEDIC TESTS IN CLINICAL PRACTICE

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Learn more about the assessment of all cranial nerves below:

• Cranial Nerve II: Optic Nerve
• Cranial Nerve III:Oculomotor Nerve
• Cranial Nerve IV: Trochlear Nerve
• Cranial Nerve V: Trigeminal Nerve
• Cranial Nerve VI: Abducens Nerve
• Cranial Nerve VII: Facial Nerve
• Cranial Nerve VIII: Vestibulocochlear Nerve
• Cranial Nerve IX: Glossopharyngeal Nerve
• Cranial Nerve X: Vagus Nerve
• Cranial Nerve XI: Accessory Nerve
• Cranial Nerve XII: Hypoglossal Nerve

Davidson, T. M., & Murphy, C. (1997). Rapid clinical evaluation of anosmia: the alcohol sniff test. Archives of otolaryngology–head & neck surgery, 123(6), 591-594.

Cameron, M. H., & Klein, E. L. (2010). Screening for Medical Disease—Nervous System Disorders. Journal of Hand Therapy, 23(2), 158-172.