Final answer:
Nasal congestion and headaches are specific clinical signs of ethmoid sinusitis.
Step-by-step explanation:
Ethmoid sinusitis is characterized by specific clinical signs, such as nasal congestion and headaches. These symptoms are caused by inflammation of the ethmoid sinuses, which are located between the eyes and behind the bridge of the nose. Nasal congestion is a common sign of ethmoid sinusitis, as the inflammation can block the nasal passages. Headaches are also a characteristic symptom, as the ethmoid sinuses are located close to the frontal lobe of the brain, and the inflammation can cause pain and pressure in this area.