Which of the following is a notable complication of infectious mononucleosis?

A notable complication of infectious mononucleosis, which is primarily caused by the Epstein-Barr virus, is spleen rupture. This occurs due to the significant enlargement of the spleen—often referred to as splenomegaly—accompanying the disease. The spleen plays a critical role in the immune system and can become very engorged during an infectious process. The risk of spleen rupture is particularly high after physical activities or trauma, which can lead to serious internal bleeding and necessitate emergency medical intervention.

The other options, while they may present in various medical scenarios, are not recognized as complications specifically associated with infectious mononucleosis. Cardiac arrest is not directly linked to this viral infection, and cases of neurological decline are rare and generally not attributable to mono. Chronic pain syndrome may occur in various contexts but isn't a well-documented complication of infectious mononucleosis. Understanding the complications specific to infectious mononucleosis is essential for effective patient management and prevention of severe outcomes.