Table 1.

Ibanez complication grading scheme.

Grade	Nature of the Complication	Example of Complication
1	Any medical or surgical non–life-threatening deviation from normal operative/postoperative course, requiring either non-invasive treatment or no treatment at all.	-Medical: acute urinary retention, non-infectious diarrhea -Surgical: CSF leak not requiring reoperation, seizures or CNS infections managed with appropriate treatments
2	Medical or surgical complication requiring invasive treatment, with or without general anesthesia.	-Medical: deep vein thrombosis requiring vena cava filter -Surgical: wound revision, CSF leak requiring surgical repair or drainage
3	Medical or surgical life-threatening complications requiring ICU care, with either single or multi-organ failure.	-Medical: acute myocardial infarction, lung distress, renal failure -Surgical: acute hydrocephalus requiring drainage, severe meningitis, iatrogenic ischemia
4	Any medical or surgical complication leading to operative or postoperative death.	Perioperative death as the ultimate endpoint

CSF: cerebrospinal fluid, CNS: central nervous system, ICU: intensive care unit.