Systematic Review of Intraoperative Indocyanine Green for Assessment of Flap Perfusion

Utility of intraoperative indocyanine angiography for assessing flap perfusion in nasal and skull base reconstruction.

Background: Indocyanine green is a novel technology that has demonstrated objective ability to detect flap perfusion and improve intraoperative and postoperative decision making regarding flap viability and modification.

Objectives: To evaluate the efficacy of intraoperative ICG angiography in predicting postoperative flap viability, postoperative magnetic resonance imaging (MRI) enhancement, and clinical outcomes including the development of cerebrospinal fluid (CSF) leak, meningitis, and flap necrosis in the context of skull base defect reconstruction.

Search Methods: A systematic review of the published literature was performed using MEDLINE, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science from the date of inception to August 2020. Additionally, we searched Google Scholar to identify gray literature. Type of reconstruction, extent of intraoperative enhancement (pedicle vs. body), postoperative flap enhancement on imaging, total complications, complication rates, and postoperative flap necrosis were examined.

Selection Criteria: Case reports, case series, and prospective and retrospective trials were included if patients underwent reconstruction of a skull base defect and intraoperative ICG angiography was performed to assess flap perfusion by subjective or objective means.

Main Results: Search results yielded 189 studies. A total of 155 articles were excluded for following reasons: not treating with intravenous ICG, not utilizing ICG for assessing flap perfusion, not utilizing ICG for the purpose of skull base reconstruction, animal studies, and cadaveric studies. One relevant study was excluded because it included a duplicative dataset in the form of a published abstract. Eight studies, including 107 patients, were used in the final analysis. Skull base reconstruction techniques included local rotational flaps, regional rotational flaps, and microvascular free flap reconstruction. There were a total of 44 nasoseptal flap, two lateral nasal wall flap, 14 pericranial flap, and 47 free flap reconstructions included. Four studies specifically reported on postoperative MRI enhancement. Seven studies reported on complications, three of which had patients experiencing adverse events. Six studies specifically reported postoperative CSF leak. Two studies specifically reported meningitis as a complication. Only one study specifically reported on the development of flap necrosis. Intraoperative ICG perfusion was significantly associated with postoperative MRI enhancement (p = 0.0082) and flap viability (p = 0.0126). With respect to complications, lack of flap perfusion was associated with flap necrosis and complications (p = 0.0009). However, there was no association between flap perfusion and the development of CSF leak (p = 0.302) or meningitis (p = 1.000).

Conclusion: Intraoperative ICG flap perfusion is significantly associated with postoperative MRI enhancement, flap viability, and fewer total complications. This study is significantly limited by a small number of patients evaluated with ICG angiography, among which few had limited to no perfusion. Furthermore, there were too few events to evaluate the relationship of ICG and specific complication like CSF leak and meningitis. Larger, multi-institutional studies might shed light on the ability of ICG angiography to predict complications and guide intraoperative decision making about the adequacy of CSF leak repair.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
12 February 2021