Cranial Nerve I
- A patient will not typically report loss of olfactory sense unless both olfactory bulbs are involved.
- Sense of smell may be altered by nasal or sinus problems.
- Sense of smell may be lost post-trauma secondary to tearing of the olfactory stria from the cribriform plate of the ethmoid bone.
- Loss of smell should alert the clinician to examine the patient for other signs of possible frontal lobe injury, such as changes in personality or unexplained visual loss.
- Unilateral loss is more significant, as it represents a more localized presentation of olfactory dysfunction.
- Sudden loss of smell (anosmia) is common with severe traumatic brain injuries secondary to damage of the olfactory nerve or with infections that damage olfactory receptors.
- Gradual loss of smell may indicate a tumor that is typically located at the base of the cranial fossa or may also be an early indicator of Alzheimer's.
- With non-organic anosmia the patient typically fails to react to ammonia.
- With true anosmia, ammonia should be sensed by the patient because ammonia acts by stimulating the pain endings of the trigeminal nerve.
Section: Cranial Nerve I
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