Is it necessary to screen CN I routinely? The answer is no. Most neurologists rarely test this nerve; it is typically only tested if the patient complains of a problem. I usually ask patients whether they have difficulty with smell or taste. When checking smell,do each nostril separately by closing the other. Any scent can be used to test this nerve, but the stimulus should be nonirritating.
Some Clinical Hints
• Anosmia is the inability to recognize scent, and hyposmia is diminishment of smell.
• The sense of smell diminishes with increasing age.
• The most common causes of bilateral anosmia/hyposmia are the common cold and trauma to the nose and head.
• Neurological diseases that are associated with hyposmia include Parkinson’s disease, dementia, and vitamin B12 deficiency.
• Consider a subfrontal tumor in cases of unilateral anosmia.
• Hyposmia is commonly associated with a taste problem.
• The odor of ammonia is recognized through the trigeminal nerve (CN V); therefore,the patient who has no sense of smell,including to ammonia,should be considered to have a functional disorder (conversion)
Dr. D.Zeqiraj medical doctor at QKUK- Pristina, department of Infectious disease.