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We treated two patients with recurrent glioblastoma multiforme using Nd:YAG laser irradiation in the framework of a salvage therapy. The underlying concept is to achieve cytoreduction by partial coagulation of the tumor. Magnetic resonance imaging (MRI) follow-up examinations revealed a volume reduction of the laser-irradiated areas, while the untreated parts of the tumor exhibited a progression. The survival time after the diagnosis of the recurrence was 16 and 20 months, respectively, which is substantially (about four times) longer than the natural history of the disease would suggest. In conclusion, cytoreduction by laser irradiation may be a promising option for patients suffering from recurrent glioblastoma multiforme. Future work should optimize the therapeutic regimen and evaluate this treatment approach in controlled clinical trials.

In patients with recurrent glioblastoma multiforme (GBM), local minimally invasive treatment modalities have gained increasing interest recently because they are associated with fewer side effects than open surgery. For example, local tumor coagulation by laser-induced interstitial thermotherapy (LITT) is such a minimally invasive technique. We monitored the metabolic effects of stereotaxy-guided LITT in a patient with a recurrent GBM using amino acid positron emission tomography (PET). Serial 11C-methyl-L-methionine positron emission tomography (MET-PET) and contrast-enhanced computed tomography (CT) were performed using a hybrid PET/CT system in a patient with recurrent GBM before and after LITT. To monitor the biologic activity of the effects of stereotaxy-guided LITT, a threshold-based volume of interest analysis of the metabolically active tumor volume (MET uptake index of ≥ 1.3) was performed. A continuous decline in metabolically active tumor volume after LITT could be observed. MET-PET seems to be useful for monitoring the short-term therapeutic effects of LITT, especially when patients have been pretreated with a multistep therapeutic regimen. MET-PET seems to be an appropriate tool to monitor and guide experimental LITT regimens and should be studied in a larger patient group to confirm its clinical value.

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In our intensive care unit, brain stem auditory evoked potentials (BAEP) are measured continuously in comatose patients. For this study we examined 15 patients who fulfilled the criteria of brain death (2). Loss of BAEP in these patients inevitably means loss of brain stem function and consecutive death. Our investigation shows that continuous BAEP monitoring can be helpful for the assessment of brain death and for the earlier decision of organ explantation.

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Background:The most common type of primary brain tumors are gliomas. For patients unsuitable for open microsurgery having been treated by radiochemotherapy, laser irradiation has proven to be an alternative palliative option. From summer 1997 until winter 2006 we performed about 60 laser-interstitial thermotherapy (LITT) treatments, starting with patients with large recurrent tumors who had no other therapeutic option. In the present article we report about the neurobiological background, the technique and our experience with LITT of cerebral gliomas.Materials and method:For laser irradiation we used a specially designed light guide (LITT standard applicator; Trumpf Medizintechnik, Umkirch, Germany). The tip of this light guide is a special optical diffuser which is characterized by a homogeneous spherical or ellipsoid emission profile. The light guide was introduced into an appropriate protective sheath (Somatex, Teltow, Germany). For the laser light source, we used a continuous wave 1064-nm Nd:YAG laser (mediLas fibertom 4060 N; Dornier MedTech, Weßling, Germany). Laser irradiation was performed under general anesthesia in a 0.5 T open configuration magnetic resonance (MR) system (Signa SP; General Electric, Milwaukee, WI, USA). Usually, the tip of the light guide was positioned in the center of the tumor using the built-in localization system (Flashpoint 3000; IGT, Boulder, CO, USA) in combination, where appropriate, with a specially designed navigation system (Localite™, Bonn, Germany). The position of the light guide was then controlled using multiplanar reconstructions of T1-weighted sequences. For near real-time control, temperature monitoring was performed using an experimental software package based on the temperature-dependent shift of the MR signal. Laser irradiation was ceased when the temperature monitoring revealed a steady state temperature profile within the heated tissue. Since 2008 we have used traditional stereotactic targeting and methionine positron emission tomography/computed tomography (MET-PET/CT) instead of the ‘open’ MR system for planning and follow-up in LITT of brain tumors.Results:We started the LITT treatment of gliomas in the early 1990s (benign gliomas in eloquent regions/not suitable for surgery). In 1997 we started to treat patients with recurrent gliobastomas/anaplastic gliomas. All of these patients had an increased survival in comparison to the natural course of recurrent glioblastomas. There were no procedure-related deaths or permanent neurological deficits. Two factors seem to be important for the overall success of the LITT procedure: 1) an early enrollment in the LITT therapy after diagnosis of a tumor recurrence, and 2) a corresponding smaller tumor mass at the beginning of the therapy.Conclusion:Cytoreduction by laser irradiation seems to be a promising option for patients suffering from gliomas.

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