gms | German Medical Science

Objective: The majority of gliomas affecting the corpus callosum are classified as not suitable for open microsurgery. Depending on the neuropathological findings of a stereotactic biopsy, there is no therapeutical option for the benign tumors. As a new option of minimally invasive therapy, we introduced the MR-guided laser-induced interstitial thermotherapy (LITT) for those cases. It offers a safe way of partial cytoreduction in the corpus callosum region.

Methods: A Nd/YAG laser (λ=1064nm, Dornier Medizintechnik, Germering, Germany) and a light guide ending in an optical diffuser (LITT Standard-Applikator, Trumpf, Umkirch, Germany) were used to transmit the laser energy into the tumor. Using MR-guidance (Signa SP/i, General Electric, Milwaukee, WI), up to three targets were chosen in the tumor. Per session, up to 10kJ were applied using a mean energy of 4.5±0.7kJ. Thermotherapy was controlled by MR thermometry based on the phase shift technique as a part of an experimental software package.

Patients: Two patients are demonstrated: A 42-year-old woman with a benign astrocytoma (II° WHO) of the anterior and middle parts of corpus callosum (Karnofsky index 100, minor paresis of the left hand). A 30-year-old male with newly diagnosed intrinsic brain tumor, astrocytoma (II° WHO) of the right parietal operculum.

Results: LITT was tolerated well without major complications. In the first case the MR-follow-up showed regression and volume reduction over more than five years. After 1 month we saw early MR-effects (zonation) in the T1 sequence with gadolinium. After 8 months we only saw the old residue of the laser coagulation zone and no progression. 1 year and 10 months later, one could again see the typical perimedian LITT effects in the T1 sequence with gadolinium. After 3 years we saw no changes. Clinical findings in the whole observation time: No neurological deficits and no complaints. Updated MR-examination just shows a paramedian scar with residual tumor without further growth. The Karnofsky-Index remained 100. In the second case clinical findings in the whole observation time remained without neurological deficits and complaints. Updated MR-examination shows similar effects as in the first case.

Conclusions: LITT can be used as a safe and repeatable minimally invasive therapy in “non surgical candidates” suffering from benign and malignant gliomas affecting the corpus callosum. A reduction of the tumor growth can be achieved preserving a good quality of life without prolonged hospitalization.