What occurs when Kernig's sign is positive?

When Kernig's sign is positive, it indicates that there is discomfort or pain when the leg, which is initially bent at both the hip and knee, is extended. This sign is primarily used as a clinical indicator of meningeal irritation, which can occur in conditions such as meningitis.

When the healthcare provider attempts to extend the leg while the patient lies supine, the reaction is often accompanied by the patient's reported pain, particularly due to stretching of the thecal sac and irritation of the nerve roots that can occur with inflammation. Therefore, the presence of pain upon this movement signifies a positive Kernig's sign, reflecting potential meningeal irritation.

The other options do not accurately describe the manifestation of a positive Kernig's sign. There may be some inability or reluctance to move the leg due to pain, but complete immobility or a lack of response to stimuli is not characteristic of this sign.