It is presented a series of two papers in this magazine "Medicina Legal de Costa Rica" about origin of neuropathological sudden death. In the first part it is analyzed the concept of sudden death and it is proposed a complete definition and its principal causes. It is also mentioned the concept of non traumatic forensic neuropathology, these pathologies of central nervous system that cause dead with no violent death involved. It is reviewed the main characteristics and the epidemiological profile based on actualized medical bibliography.

Sudden death; non traumatic forensic neuropathology; secular aneurisms; epilepsy; venousarterial malformations; central nervous system neoplasias; non traumatic subarachnoid bleeding; bacterial meningitis; intraparenquimal haematoma