Olfaction, one of the body's five senses, plays a crucial role in recognizing odors through olfactory nerve cells located in the nasal cavity's mucous membrane. Each olfactory nerve cell possesses an odor receptor. When microscopic odor molecules from the environment enter the nose, they stimulate these receptors, transmitting signals to the brain, enabling us to identify and differentiate scents. Loss of smell is a condition where an individual experiences a reduced or complete inability to perceive odors.

Sinuses are air-filled cavities within the facial skull bones. Lined with a mucous membrane, sinuses secrete mucus to trap dust and bacteria upon inhalation, while also warming and humidifying the air before it reaches the lungs. The circulation of air within the nasal sinuses facilitates odor molecules in reaching the olfactory region, aiding the brain in odor recognition.

Sinusitis leads to inflammation and swelling of the sinus lining, accompanied by increased mucus secretion. This obstructs the sinus drainage process, causing mucus to accumulate and reducing airflow within the nasal cavity. Consequently, odor molecules struggle to reach the olfactory region, resulting in a diminished or complete loss of the sense of smell. In some cases, nasal polyps or obstruction of the olfactory cleft can exacerbate these symptoms.

Doctor Tra Linh performs a nasal endoscopy for a patient. Illustration: Tam Anh General Hospital

Furthermore, the prolonged inflammatory response associated with chronic sinusitis can directly affect olfactory nerve cells, leading to a gradual decline in their function over time.

Most instances of reduced or lost sense of smell due to rhinosinusitis can improve once the inflammation is effectively managed. Depending on the underlying cause and severity of the condition, a doctor may prescribe nasal rinses with saline solution, topical corticosteroid sprays, anti-inflammatory medications, or treatment for co-occurring allergies. Olfactory training, involving smelling essential oils like lemon, eucalyptus, rose, or clove, can also stimulate the olfactory nerves and enhance the ability to perceive odors.

For prolonged sinusitis cases where medical treatment is ineffective, or when accompanied by nasal polyps or a deviated septum, a doctor may recommend endoscopic sinus surgery for thorough treatment and to mitigate complications.

Doctor Chau Tra Linh, Specialist Level I

Ear, Nose, and Throat Center

Tam Anh General Hospital, TP HCM