This chapter provides a concise yet comprehensive review of neurological conditions arising from systemic metabolic disturbances, nutritional deficiencies, and exposure to toxins, drugs, and physical agents. These disorders often present with diverse and overlapping neurological symptoms, requiring clinicians to maintain a high index of suspicion and integrate clinical, laboratory, and imaging data for accurate diagnosis. Understanding the pathophysiological mechanisms underlying these conditions is essential for timely intervention and improved outcomes, as the neurologic sequelae of many of the pathologies discussed are preventable or reversible when identified early.