Key nob appearance is seen in

PHONASTHENIA It is weakness of voice due to fatigue of phonatory muscles. Thyroarytenoid and interarytenoids or both may be affected. It is seen in abuse or misuse of voice or following laryngitis. Patient complains of easy fatiguability of voice. Clinical examination:- Indirect laryngoscopy shows three characteristic findings: 1. Elliptical space between the cords in weakness of thyroarytenoid. 2. Triangular gap near the posterior commissure in weakness of interarytenoid. 3. Key-hole appearance of glottis when both thyroarytenoid and interarytenoids are involved. Treatment:- Treatment is voice rest and vocal hygiene, emphasizing on periods of voice rest after excessive use of voice. Ref:- Dhingra; pg num:-314