Spectroscopic measurement of 5-ALA-induced intracellular protoporphyrin IX in pediatric brain tumors

5-Aminolevulinic acid (5-ALA) in paediatric brain tumour surgery-a systematic review and exploration of fluorophore alternatives

PURPOSE

Paediatric brain tumours represent the most common solid malignancies in children, with extent of resection being a critical prognostic factor. Fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA) is well-established for adult high-grade gliomas, but its efficacy and safety in paediatric populations remain unclear. This systematic review evaluates the utility of 5-ALA fluorescence-guided surgery in paediatric brain tumours and explores alternative fluorophores.

METHODS

A systematic review was conducted according to PRISMA guidelines, analysing studies from MEDLINE and EMBASE published up to October 2024. Data on patient demographics, tumour fluorescence patterns, surgical outcomes, and adverse effects were extracted. Statistical analyses assessed fluorescence differences across tumour types and administration parameters.

RESULTS

Twenty-three studies, including 281 paediatric patients (mean age, 10 years), were analysed. The most common tumours included pilocytic astrocytomas (n = 45), medulloblastomas (n = 45), glioblastomas (n = 35), and ependymomas (n = 27). Strong fluorescence was observed more frequently in high-grade gliomas compared to low-grade gliomas (p < 0.00001), non-glioma tumours (p < 0.00001), and high-grade non-glioma tumours (p = 0.000485). Adverse effects were mostly transient; rare complications included transaminitis and dermatologic reactions.

CONCLUSION

5-ALA fluorescence-guided surgery shows promise in the resection of high-grade gliomas in paediatric patients, improving intraoperative visualisation. However, limited fluorescence in low-grade and non-glioma tumours underscores the need for tumour-specific approaches. Emerging alternatives, such as fluorescein sodium and tozuleristide, offer potential advantages. Future research should focus on optimising 5-ALA dosing, refining timing protocols, and conducting robust prospective trials to establish efficacy and safety in paediatric populations.

Utility and Safety of 5-ALA Guided Surgery in Pediatric Brain Tumors: A Systematic Review

Background: 5-Aminolevulinic acid-guided surgery for adult gliomas has been approved by the European Medicines Agency and the US Food and Drug Administration, becoming a reliable tool for improving gross total resection rates and patient outcomes. This has led several medical centers to explore the off-label use of 5-ALA in the resection of pediatric brain tumors, assessing its efficacy and safety across various tumor types. However, given the differences between children and adults, the appropriateness of 5-ALA use in pediatric populations has not yet been fully established. Methods: We collected eligible publications from Embase, Scopus, PubMed, and Proquest, ultimately selecting 27 studies. Data extraction and retrospective analysis of 249 surgical cases were conducted to determine the current efficacy and safety of 5-ALA in pediatric brain tumors. The fluorescence rate and utility stratified by several clinical features, including WHO grade, tumor classification, and tumor location, were analyzed. Results: Most studies suggest that 5-ALA can enhance tumor identification in high-grade tumors, including glioblastomas and anaplastic astrocytomas. Changes in survival or recurrence rates associated with 5-ALA-guided resection have not been reported. None of the cases reported significant postoperative complications related to the use of 5-ALA. Conclusions: 5-ALA can aid in the resection of high-grade gliomas in pediatric patients. The efficacy of 5-ALA in low-grade gliomas and other tumors may require enhancement with additional tools or modified administration protocols. The safety of 5-ALA has reached a preliminary consensus, although further randomized controlled trials and data on survival and molecular characteristics are needed.

Does 5-ALA Fluorescence Microscopy Improve Complete Resectability in Cerebral/Cerebellar Metastatic Surgery? A Retrospective Data Analysis from a Cranial Center

(1) Background: In this study, the intraoperative fluorescence behavior of brain metastases after the administration of 5-aminolevulinic acid (5-ALA) was analyzed. The aim was to investigate whether the resection of brain metastases using 5-ALA fluorescence also leads to a more complete resections and thus to a prolongation of survival; (2) Methods: The following variables have been considered: age, sex, number of metastases, localization, involvement of eloquent area, correlation between fluorescence and primary tumor/subtype, resection, and survival time. The influence on the degree of resection was determined with a control MRI within the first three postoperative days; (3) Results: Brain metastases fluoresced in 57.5% of cases. The highest fluorescence rates of 73.3% were found in breast carcinoma metastases and the histologic subtype adenocarcinoma (68.1%). No correlation between fluorescence behavior and localization, primary tumor, or histological subtype was found. Complete resection was detected in 82.5%, of which 56.1% were fluorescence positive. There was a trend towards improved resectability (increase of 12.1%) and a significantly longer survival time (p = 0.009) in the fluorescence-positive group; (4) Conclusions: 5-ALA-assisted extirpation leads to a more complete resection and longer survival and can therefore represent a low-risk addition to modern surgery for brain metastases.

5-ALA induced PpIX fluorescence spectroscopy in neurosurgery: a review

The review begins with an overview of the fundamental principles/physics underlying light, fluorescence, and other light-matter interactions in biological tissues. It then focuses on 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) fluorescence spectroscopy methods used in neurosurgery (e.g., intensity, time-resolved) and in so doing, describe their specific features (e.g., hardware requirements, main processing methods) as well as their strengths and limitations. Finally, we review current clinical applications and future directions of 5-ALA-induced protoporphyrin IX (PpIX) fluorescence spectroscopy in neurosurgery.

Challenges in, and recommendations for, hyperspectral imaging in ex vivo malignant glioma biopsy measurements

The visualization of protoporphyrin IX (PPIX) fluorescence with the help of surgical microscopes during 5-aminolevulinic acid-mediated fluorescence-guided resection (FGR) of gliomas is still limited at the tumor margins. Hyperspectral imaging (HI) detects PPIX more sensitively but is not yet ready for intraoperative use. We illustrate the current status with three experiments and summarize our own experience using HI: (1) assessment of HI analysis algorithm using pig brain tissue, (2) a partially retrospective evaluation of our experience from HI projects, and (3) device comparison of surgical microscopy and HI. In (1), we address the problem that current algorithms for evaluating HI data are based on calibration with liquid phantoms, which have limitations. Their pH is low compared to glioma tissue; they provide only one PPIX photo state and only PPIX as fluorophore. Testing the HI algorithm with brain homogenates, we found proper correction for optical properties but not pH. Considerably more PPIX was measured at pH 9 than at pH 5. In (2), we indicate pitfalls and guide HI application. In (3), we found HI superior to the microscope for biopsy diagnosis (AUC = 0.845 ± 0.024 (cut-off 0.75 µg PPIX/ml) vs. 0.710 ± 0.035). HI thus offers potential for improved FGR.

Spontaneous intracerebral haemorrhage secondary to 5-ALA-induced thrombocytopaenia in a paediatric patient: case report and literature review

INTRODUCTION

The primary objective of neurosurgical management of malignant gliomas is maximal safe resection of the tumour. One of the main obstacles in achieving this is the ability to accurately discriminate between tumour edges and the surrounding healthy brain tissue. The use of fluorescence-guided surgery utilising 5-aminolevulinic acid (5-ALA), first introduced more than 20 years ago, has become an invaluable adjunct in high-grade glioma surgery in adults. However, as 5-ALA is not licensed for use in paediatric patients, the safety profile for such use remains undetermined.

CASE REPORT

We describe the case of a 4-year-old boy who underwent 5-ALA-guided resection of a fourth ventricle anaplastic ependymoma. Although complete resection was achieved and the patient awoke from surgery well with no neurological deficits, the patient developed acute transaminitis, anaemia, thrombocytopaenia and coagulopathy postoperatively. The patient had a sudden neurological deterioration on postoperative day 2; imaging revealed that he had suffered a spontaneous right frontal intracerebral haemorrhage. The patient returned to theatre for surgical decompression and evacuation of the haematoma, and ultimately went on to make a full recovery.

CONCLUSION

The use of 5-ALA in paediatric patients can be helpful in maximising surgical resection, but the associated safety profile remains undefined. Further research is urgently warranted in order to characterise the efficacy and risk of the use of 5-ALA in the paediatric population.

5-ALA fluorescence in randomly selected pediatric brain tumors assessed by spectroscopy and surgical microscope

PURPOSE

Fluorescence-guided surgery applying 5-aminolevulinic acid (5-ALA) in high-grade gliomas is an established method in adults. In children, results have so far been ambiguous. The aim of this study was to investigate 5-ALA-induced fluorescence in pediatric brain tumors by using the surgical microscope and a spectroscopic hand-held probe.

METHODS

Fourteen randomly selected children (age 4-17) with newly MRI-verified brain tumors were included. No selection was based on the suspected diagnosis prior to surgery. All patients received 5-ALA (20 mg /kg) either orally or via a gastric tube prior to surgery. Intratumoral fluorescence was detected with the microscope and the probe. Moreover, fluorescence in the skin of the forearm was measured. Histopathology samples revealed seven low-grade gliomas, four medulloblastomas, one diffuse intrinsic pontine glioma, one glioblastoma and one atypical meningioma. Blood samples were analyzed, and potential clinical side effects were monitored.

RESULTS

Microscopically, vague fluorescence was visible in two patients. Intratumoral fluorescence could be detected in five patients with the probe, including the two patients with vague microscopic fluorescence. Three of the oldest children had PpIX fluorescence in the skin. Nine children did not show any fluorescence in the tumor or in the skin. No clinical side effects or laboratory adverse events were observed.

CONCLUSION

Fluorescence could not be used to guide surgery in this study, neither with the surgical microscope nor with the hand-held probe. In nine children, no fluorescence was discerned and children with noticeable fluorescence were all older than nine years. 5-ALA was considered safe to apply in children.

5-ALA fluorescence-guided resection of pediatric low-grade glioma using the ORBEYE 3D digital exoscope: a technical report

OBJECTIVE

A case of low-grade glioma in which 5-aminolevulinic acid (5-ALA) fluorescence was visualized by a digital exoscope is presented.

CASE PRESENTATION

A 14-year-old girl with recurrent paroxysmal episodes of a strange smell and nausea underwent magnetic resonance imaging (MRI) for further investigation. The MRI showed a tumor with an enhanced nodule in the right temporal lobe. The patient received 5-ALA preoperatively, and intraoperative observation using a 4 K-3-dimension digital exoscope (Olympus ORBEYE) showed that the tumor was fluorescent, which was useful in determining the extent of tumor removal. Postoperative MRI showed that the tumor was completely removed. The histopathological diagnosis was pleomorphic xanthoastrocytoma. She was discharged without any complications.

CONCLUSIONS

5-ALA-fluorescence-guided resection of low-grade glioma using the ORBEYE was useful for determining the extent of removal.

Sublingual administration of 5-aminolevulinic acid for laser-induced photodiagnostics and photodynamic therapy of oral cavity and larynx cancers

BACKGROUND

The study aimed to develop a method for sublingual administration of 5-aminolevulinic acid to patients and evaluate its effectiveness in fluorescence diagnostics and photodynamic therapy of neoplasms of the oral cavity and larynx.

METHODS

The boundaries of the neoplasms were established by the video-fluorescence diagnostics and clarified using spectral-fluorescent diagnosis before and after photodynamic therapy.

RESULTS

The fluorescence diagnostics demonstrated a high accumulation of protoporphyrin IX, induced by sublingual administration of 5-aminolevulinic acid to patients before the photodynamic therapy and photobleaching of protoporphyrin IX in pathologically altered tissues after the photodynamic therapy. Glucose contained in the sublingual dose supports active transport of 5-ALA into the cells. It increases the PpIX accumulation in the cells, therefore improving the PD and PDT efficacy.

CONCLUSION

The study and the initially obtained results demonstrated the possibility and effectiveness of laser-induced photodiagnostics and photodynamic therapy with sublingual administration of 5-ALA to patients with premalignant lesions of the oral cavity and larynx. It can eliminate the threat of the transformation of these diseases into malignant tumors and prevent the need for surgical treatment.

A New Treatment Opportunity for DIPG and Diffuse Midline Gliomas: 5-ALA Augmented Irradiation, the 5aai Regimen

Prognosis for diffuse intrinsic pontine glioma (DIPG) and generally for diffuse midline gliomas (DMG) has only marginally improved over the last ~40 years despite dozens of chemotherapy and other therapeutic trials. The prognosis remains invariably fatal. We present here the rationale for a planned study of adding 5-aminolevulinic acid (5-ALA) to the current irradiation of DIPG or DMG: the 5aai regimen. In a series of recent papers, oral 5-ALA was shown to enhance standard therapeutic ionizing irradiation. 5-ALA is currently used in glioblastoma surgery to enable demarcation of overt tumor margins by virtue of selective uptake of 5-ALA by neoplastic cells and selective conversion to protoporphyrin IX (PpIX), which fluoresces after excitation by 410 nm (blue) light. 5-ALA is also useful in treating glioblastomas by virtue of PpIX's transfer of energy to O₂ molecules, producing a singlet oxygen that in turn oxidizes intracellular DNA, lipids, and proteins, resulting in selective malignant cell cytotoxicity. This is called photodynamic treatment (PDT). Shallow penetration of light required for PpIX excitation and resultant energy transfer to O₂ and cytotoxicity results in the inaccessibility of central structures like the pons or thalamus to sufficient light. The recent demonstration that keV and MeV photons can also excite PpIX and generate singlet O₂ allows for reconsideration of 5-ALA PDT for treating DMG and DIPG. 5-ALA has an eminently benign side effect profile in adults and children. A pilot study in DIPG/DMG of slow uptitration of 5-ALA prior to each standard irradiation session-the 5aai regimen-is warranted.