5-Aminolevulonic Acid, a New Tumor Contrast Agent: Anesthesia Considerations in Patients Undergoing Craniotomy.

5-aminolevulinic acid (ALA) is used during resection of malignant gliomas due to its fluorescence properties and has been shown to render resection more effective than resection without ALA guidance. The aim of this narrative review is to categorize the adverse effects of ALA relevant to anesthesia providers. Intraoperative hypotension, porphyria-related side effects, alterations in blood chemistry and coagulation, photosensitivity, and increased levels of liver enzymes have all been reported. We also sought to examine the impact of dosage and timing of oral administration on efficacy of ALA and on these side effects. Twenty-seven studies met our inclusion criteria of patients undergoing craniotomy for glioma resection using ALA and occurrence of at least one adverse effect. The results of these studies showed that there was heterogeneity in levels of intraoperative hypotension, with some reporting an incidence as high as 32%, and that hypotension was associated with antihypertensive medication use. Clinical symptoms of porphyria, such as gastrointestinal disturbance, were less commonly reported. Photosensitivity of the skin after 5-ALA administration was well documented particularly in patients exposed to light; however, adverse effects on the eye were not adequately studied. Elevation in liver enzymes was a common finding postoperatively but was often clinically insignificant. The timing of oral administration presents practical issues for the preoperative management of patients undergoing resection with ALA. We provide guidance for perioperative management of patients who receive ALA for brain tumor resection. Controlled studies with adequate statistical power are required to further understand and prevent the adverse effects of ALA.