The Lazarus Sign: When the Dead Seem to Move— Neurophysiology, Clinical Significance, and Ethical Implications of Spontaneous Motor Activity in Brain-Dead Patients

Background: The Lazarus sign—a spontaneous, bilateral upper-limb flexion movement observed in brain-dead patients—represents one of the most clinically and philosophically unsettling phenomena in critical care medicine. Despite its spinal origin, its resemblance to voluntary motion continues to challenge clinicians, distress families, and occasionally precipitate misdiagnoses of brain death. Objective: This paper provides a comprehensive and critical review of the neurophysiological mechanisms underlying the Lazarus sign, its prevalence among brain-dead patients, its differential diagnosis, and its ethical implications within the context of organ donation and end-of-life care. Methods: A narrative review was conducted by synthesizing peer-reviewed studies, case reports, and systematic reviews retrieved from PubMed, Scopus, and Google Scholar. Studies published between 1973 and 2025 addressing spinal reflexes in brain-dead patients were included. Results: The Lazarus sign is mediated exclusively by cervical and thoracic spinal cord circuitry, independent of brainstem or cortical input. It occurs in approximately 13–40% of brain-dead patients and may manifest spontaneously or in response to apnea testing, ventilator disconnection, nociceptive stimuli, or hypotension. Recent hypotheses implicate propriospinal interneurons and motor neuron proximity depolarization as key hodological mechanisms. Despite its spinal origin, the sign’s dramatic appearance remains a source of ethical tension and public misunderstanding. Conclusions: A thorough understanding of the Lazarus sign is imperative for neurologists, intensivists, and clinical teams involved in the determination of brain death. Education of clinical staff and proactive communication with families can prevent misinterpretation and uphold the integrity of neurological death criteria.