The role of 5-aminolevulinic acid in spinal tumor surgery: a review

Abstract

Purpose: Primary intradural spinal neoplasms account for a small proportion of central nervous system tumors. The primary treatment for these tumors consists of maximal safe resection and preservation of neurologic function. Gross total resection, which is associated with the lowest rate of tumor recurrence and longer progression-free survival for most histologies, can be difficult to achieve. Currently, the use of 5-aminolevulinc acid (5-ALA) which takes advantage of Protoporphyrin IX (PpIX) fluorescence, is a well-established technique for improving resection of malignant cerebral gliomas. This technique is being increasingly applied to other cerebral neoplasms, and multiple studies have attempted to evaluate the utility of 5-ALA-aided resection of spinal neoplasms.

Methods: The authors reviewed the existing literature on the use of 5-ALA and PpIX fluorescence as an aid to resection of primary and secondary spinal neoplasms by searching the PUBMED and EMBASE database for records up to March 2018. Data was abstracted from all studies describing spinal neurosurgical uses in the English language.

Results: In the reviewed studies, the most useful fluorescence was observed in meningiomas, ependymomas, drop metastases from cerebral gliomas, and hemangiopericytomas of the spine, which is consistent with applications in cerebral neoplasms.

Conclusions: The available literature is significantly limited by a lack of standardized methods for measurement and quantification of 5-ALA fluorescence. The results of the reviewed studies should guide future development of rational trial protocols for the use of 5-ALA guided resection in spinal neoplasms.

Keywords: 5-Aminolevulinc acid; Fluorescence guided resection; Protoporphyrin IX; Spinal neoplasm.

Figures

Fig. 1

Flowchart showing literature search method

Fig. 2

Magnetic resonance imaging (MRI) of the case described by Inoue et al. Preoperative T1-weighted (a) and T2 weighted (b) sagittal MRI revealed a homogeneously enhanced intramedullary T3-5 tumor with cyst formation extending to T8. Postoperative T1-weighted sagittal MRI (c) confirmed complete tumor resection with no signs of recurrence 2 years after surgery. Reprinted from Inoue et al. [13] 5-aminolevulinic acid fluorescence-guided resection of intramedullary ependymoma: Report of 9 cases. Neurosurgery 72:159–168. Reprinted with permission Oxford University Press

Fig. 3

Intraoperative images of ependymoma resection described by Inoue et al. Note that the images obtained using white light (left column) are coupled with images using 5-aminolevulinic acid (5-ALA) fluorescence (right). (a and b) After dissection of the posterior medial sulcus, the tumor, which had a vivid reddish fluorescence (asterisk), was encountered. c Dissection of the lateral wall of the tumor from the spinal cord. The tumor was encapsulated and easily distinguished from the surrounding spinal cord parenchyma under the microscope. d A slight fluorescence was noted on the surface of the tumor (asterisk). e and f At the ventrocaudal edge of the tumor, gray tissue was left untouched on the basis of negative 5-ALA fluorescence (asterisk). g Characteristic perivascular pseudorosettes (arrows) and ependymal rosettes (arrowheads) were observed in the tissue with 5-ALA-positive fluorescence. Hematoxylin and eosin stain. Scale bars = 200 µm. Reprinted from Inoue et al. [13] 5-aminolevulinic acid fluorescence-guided resection of intramedullary ependymoma: Report of 9 cases. Neurosurgery 72:159–168. Reprinted with permission from Oxford University Press