5-aminolevulinic-acid guided resection

5-aminolevulinic-acid guided resection

In addition to stereotactic localization as well as intraoperative brain mapping, techniques to enhance visual identification of tumor intraoperatively may be used and include 5-aminolevulinic-acid (5-ALA). 5-ALA is metabolized into fluorescent porphyrins, which accumulate in malignant glioma cells. These property permits use of ultraviolet illumination during surgery as an adjunct to map out the tumor. This has been proven with RCT where the use of 5-ALA leads to more complete resection (65% vs. 36%, p < 0.0001), which translates into a higher 6-month progression-free survival (41% vs. 21.1%, p = 0.0003) but no effect on OS 1).


Fluorescein can be used as a viable alternative to 5-ALA for intraoperative fluorescent guidance in brain tumor surgery. Comparative, prospective, and randomized studies are much needed 2)

Indications

Doses

The highest visible and measurable fluorescence was yielded by 20 mg/kg. No fluorescence was elicited at 0.2 mg/kg. Increasing 5-ALA doses did not result in proportional increases in tissue fluorescence or PPIX accumulation in plasma, indicating that doses higher than 20 mg/kg will not elicit useful increases in fluorescence 3).


Application of 5mg/kg ALA was evaluated as equally reliable as the higher dose regarding the diagnostic performance when guidance was performed using a spectroscopic system. Moreover, no PpIX was detected in the skin of the patients 4).

Over time, several other tumour entities have been identified to metabolize 5-ALA and show a similar fluorescence pattern during surgical resection.

Further research is warranted to determine the role of 5-ALA accumulation in post-ischaemic and inflammatory brain tissue 5).

The positive predictive values (PPVs), of utilizing the most robust ALA fluorescence intensity (lava-like orange) as a predictor of tumor presence is high. However, the negative predictive values (NPVs), of utilizing the absence of fluorescence as an indicator of no tumor is poor. ALA intensity is a strong predictor for degree of tumor cellularity for the most fluorescent areas but less so for lower ALA intensities. Even in the absence of tumor cells, reactive changes may lead to ALA fluorescence 6).

Reviews

Senders et al., systematically review all clinically tested fluorescent agents for application in fluorescence guided surgery (FGS) for glioma and all preclinically tested agents with the potential for FGS for glioma.

They searched the PubMed and Embase databases for all potentially relevant studies through March 2016.

They assessed fluorescent agents by the following outcomes: rate of gross total resection (GTR), overall and progression free survival, sensitivity and specificity in discriminating tumor and healthy brain tissue, tumor-to-normal ratio of fluorescent signal, and incidence of adverse events.

The search strategy resulted in 2155 articles that were screened by titles and abstracts. After full-text screening, 105 articles fulfilled the inclusion criteria evaluating the following fluorescent agents: 5 aminolevulinic acid (5-ALA) (44 studies, including three randomized control trials), fluorescein (11), indocyanine green (five), hypericin (two), 5-aminofluorescein-human serum albumin (one), endogenous fluorophores (nine) and fluorescent agents in a pre-clinical testing phase (30). Three meta-analyses were also identified.

5-ALA is the only fluorescent agent that has been tested in a randomized controlled trial and results in an improvement of GTR and progression-free survival in high-grade gliomas. Observational cohort studies and case series suggest similar outcomes for FGS using fluorescein. Molecular targeting agents (e.g., fluorophore/nanoparticle labeled with anti-EGFR antibodies) are still in the pre-clinical phase, but offer promising results and may be valuable future alternatives. 7).

Complications

Despite its benefits, 5-ALA has not reached widespread popularity in the United States, primarily because of lack of Food and Drug Administration (FDA) approval. Even if it were approved, 5-ALA does have specific limitations including low depth of penetration, autofluorescence of background parenchyma


Findings suggest that the administration of 5-ALA or the combined effect of 5-ALA, anaesthesia and tumour resection can cause a mild and reversible elevation in liver enzymes. It therefore appears safe to change the regime of monitoring. Routine blood samples are thus abolished, though caution remains necessary in patients with known liver impairment 8).

For near infrared imaging, additional investigators have explored fluorescein as well as novel near-infrared (NIR) agents 9) 10) 11)

Stummer et al. showed that 5–ALA guided resections carry a higher risk of post-operative neurological deterioration than conventional resections (26% vs 15%, respectively), even though the difference vanished within weeks 12).

Just as tumour tissue is often indiscernible from normal brain tissue, functionally critical tissues are indistinguishable from tissues with less clinically relevant functions.

Thus, knowing when to stop a resection due to proximity to areas of crucial neurological functions is of obvious and utmost importance. Detailed knowledge of the normal brain anatomy and distribution of function is not sufficient during glioma resection. Interindividual variability and functional relocation (i.e., plasticity) induced by the presence of an infiltrating tumour 13) requires an exact functional brain map at the site of surgery in order to spare areas involved in crucial (so-called eloquent) functions. Preoperative localisation of function, either with functional MRI (fMRI) or navigated transcranial magnetic stimulation (nTMS), provides an approximate map 14) 15).

Furthermore, intra-operative direct cortical and subcortical electrical stimulation (DCS) for functional analysis of the tissue in the tumour’s infiltration zone is required for accurate identification of areas that need to be spared in order to retain the patient’s functional integrity 16) 17). Motor evoked potentials (MEP) provide real-time information on the integrity of the primary motor cortex and the corticospinal tract 18). Direct cortical mapping and phase reversal identify the primary motor and sensory cortices. Subcortical mapping can estimate the distance to the pyramidal tract, acting as guidance close to functionally critical areas 19). When integrated into the existing surgical tools, continuous and dynamic mapping enables more extensive resection while simultaneously protecting motor function 20). Using these techniques and a detailed electrophysiological “Bern-concept”, a group achieved complete motor function protection in 96% of patients with high-risk motor eloquent tumours 21). Furthermore, localisation of cortical and subcortical regions relevant to language function is essential for speech preservation during resection of gliomas in proximity to presumed speech areas 22) and requires the patient to be awake during the brain mapping part of surgery. Similarly, intra-operative mapping of visual functions may contribute to increased resections while avoiding tissue essential for vision within the temporal and occipital lobes 23).

References

1)

Stummer W, Pichlmeier U, Meinel T, Wiestler OD, Zanella F, Reulen HJ; ALA-Glioma Study Group. Fluorescence-guided surgery with 5-aminolevulinic acid for resection of malignant glioma: a randomised controlled multicentre phase III trial. Lancet Oncol. 2006 May;7(5):392-401. PubMed PMID: 16648043.
2)

Hansen RW, Pedersen CB, Halle B, Korshoej AR, Schulz MK, Kristensen BW, Poulsen FR. Comparison of 5-aminolevulinic acid and sodium fluorescein for intraoperative tumor visualization in patients with high-grade gliomas: a single-center retrospective study. J Neurosurg. 2019 Oct 4:1-8. doi: 10.3171/2019.6.JNS191531. [Epub ahead of print] PubMed PMID: 31585425.
3)

Stummer W, Stepp H, Wiestler OD, Pichlmeier U. Randomized, Prospective Double-Blinded Study Comparing 3 Different Doses of 5-Aminolevulinic Acid for Fluorescence-Guided Resections of Malignant Gliomas. Neurosurgery. 2017 Apr 1. doi: 10.1093/neuros/nyx074. [Epub ahead of print] PubMed PMID: 28379547.
4)

Haj-Hosseini N, Richter J, Hallbeck M, Wårdell K. Low dose 5-aminolevulinic acid: Implications in spectroscopic measurements during brain tumor surgery. Photodiagnosis Photodyn Ther. 2015 Mar 25. pii: S1572-1000(15)00031-9. doi: 10.1016/j.pdpdt.2015.03.004. [Epub ahead of print] PubMed PMID: 25818546.
5)

Behling F, Hennersdorf F, Bornemann A, Tatagiba M, Skardelly M. 5-Aminolevulinic acid accumulation in a cerebral infarction mimicking high-grade glioma, a case report. World Neurosurg. 2016 May 10. pii: S1878-8750(16)30271-6. doi: 10.1016/j.wneu.2016.05.009. [Epub ahead of print] PubMed PMID: 27178236.
6)

Lau D, Hervey-Jumper SL, Chang S, Molinaro AM, McDermott MW, Phillips JJ, Berger MS. A prospective Phase II clinical trial of 5-aminolevulinic acid to assess the correlation of intraoperative fluorescence intensity and degree of histologic cellularity during resection of high-grade gliomas. J Neurosurg. 2015 Nov 6:1-10. [Epub ahead of print] PubMed PMID: 26544781.
7)

Senders JT, Muskens IS, Schnoor R, Karhade AV, Cote DJ, Smith TR, Broekman ML. Agents for fluorescence-guided glioma surgery: a systematic review of preclinical and clinical results. Acta Neurochir (Wien). 2017 Jan;159(1):151-167. doi: 10.1007/s00701-016-3028-5. Review. PubMed PMID: 27878374; PubMed Central PMCID: PMC5177668.
8)

Offersen CM, Skjoeth-Rasmussen J. Evaluation of the risk of liver damage from the use of 5-aminolevulinic acid for intra-operative identification and resection in patients with malignant gliomas. Acta Neurochir (Wien). 2016 Nov 10. [Epub ahead of print] PubMed PMID: 27832337.
9)

Shinoda J, Yano H, Yoshimura SI, et al. Fluorescence-guided resection of glioblastoma multiforme by using high-dose fluorescein sodium. Technical note. J Neurosurg. 2003;99(3):597–603.
10)

Rey-Dios R, Cohen-Gadol AA. Technical principles and neurosurgical applications of fluorescein fluorescence using a microscope-integrated fluorescence module. Acta Neurochir (Wien). 2013;155(4):701–706.
11)

Swanson KI, Clark PA, Zhang RR, et al. Fluorescent cancer-selective alkylphosphocholine analogs for intraoperative glioma detection. Neurosurgery. 2015;76(2):115–123.
12)

Stummer W1, Tonn JC, Mehdorn HM, Nestler U, Franz K, Goetz C, et al. ALA-Glioma Study Group. Counterbalancing risks and gains from extended resections in malignant glioma surgery: a supplemental analysis from the randomized 5–aminolevulinic acid glioma resection study. J Neurosurg. 2011;114(3):613–23. doi: 10.3171/2010.3
13)

Ojemann G, Ojemann J, Lettich E, Berger M. Cortical language localization in left, dominant hemisphere. An electrical stimulation mapping investigation in 117 patients. J Neurosurg. 1989;71(3):316–26.
14)

Seghier ML, Lazeyras F, Pegna AJ, Annoni JM, Zimine I, Mayer E, et al. Variability of fMRI activation during a phonological and semantic language task in healthy subjects. Hum Brain Mapp. 2004;23(3):140–55.
15)

Krieg SM, Shiban E, Buchmann N, Gempt J, Foerschler A, Meyer B, et al. Utility of presurgical navigated transcranial magnetic brain stimulation for the resection of tumors in eloquent motor areas. J Neurosurg. 2012;116(5):994–1001. doi: 10.3171/2011.12.JNS111524
16) , 22)

Duffau H, Capelle L, Sichez N, Denvil D, Lopes M, Sichez JP, et al. Intraoperative mapping of the subcortical language pathways using direct stimulations. An anatomo-functional study. Brain. 2002;125(1):199–214.
17)

Duffau H, Capelle L, Denvil D, Sichez N, Gatignol P, Taillandier L, et al. Usefulness of intraoperative electrical subcortical mapping during surgery for low-grade gliomas located within eloquent brain regions: functional results in a consecutive series of 103 patients. J Neurosurg. 2003;98(4):764–78.
18)

Seidel K, Beck J, Stieglitz L, Schucht P, Raabe A. The warning-sign hierarchy between quantitative subcortical motor mapping and continuous motor evoked potential monitoring during resection of supratentorial brain tumors. J Neurosurg. 2013;118(2):287–96.
19)

Seidel K, Beck J, Stieglitz L, Schucht P, Raabe A. Low Threshold Monopolar Motor Mapping for Resection of Primary Motor Cortex Tumors. Neurosurgery. 2012;71(1):104–14.
20)

Raabe A, Beck J, Schucht P, Seidel K. Continuous dynamic mapping of the corticospinal tract during surgery of motor eloquent brain tumors: evaluation of a new method. J Neurosurg. 2014;120(5)1015–24. doi: 10.3171/2014.1.JNS13909.
21)

Schucht P, Seidel K. Beck J, Murek M, Jilch A, Wiest R, et al. Intraoperative monopolar mapping during 5-ALA-guided resections of glioblastomas adjacent to motor eloquent areas: evaluation of resection rates and neurological outcome. Neurosurg Focus. 2014;27(6):E16.
23)

Gras-Combe G, Moritz-Gasser S, Herbet G, Duffau H. Intraoperative subcortical electrical mapping of optic radiations in awake surgery for glioma involving visual pathways. J Neurosurg. 2012;117(3):466–73.

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