METHOD OF TREATING DEEP BRAIN TUMORS LOCATED NEAR CORTICOSPINAL AND CORTICOBULBAR TRACTS, USING STEREOTACTIC PHOTODYNAMIC THERAPY UNDER SPECTRAL FLUORESCENCE AND NEUROPHYSIOLOGICAL MONITORING Russian patent published in 2024 - IPC A61N5/67 

FIELD: medicine.

SUBSTANCE: invention relates to medicine, namely to neurosurgery, neurology and clinical neurophysiology, and can be used for stereotactic photodynamic therapy under spectral-fluorescent monitoring of deep brain tumours located mainly near corticospinal and corticobulbar tracts, with continuous assessment of functional integrity of corticospinal and corticobulbar tracts. Disclosed is a method for conducting stereotactic photodynamic therapy under spectral-fluorescent and continuous neurophysiological monitoring, during which, as part of preoperative preparation, a photosensitizer is administered to the patient: orally 5-aminolevulinic acid – Alasense, at concentration of 20 mg/kg 5 hours before the operation and/or intravenously drop-by-drop chlorine photosensitizer: photoditazine, photoran, photolon, in concentration of 1 mg/kg for 3 hours before operation. Stimulating subdermal electrodes for transcranial electrical stimulation are installed in projections of points C1-C2 of international system 10-10, in point Fz there is an anode of a monopolar stimulator for subcortical mapping; recording electrodes for assessing the corticospinal tract in target muscles: biceps brachii, triceps brachii, abductor pollicis brevis and abductor digiti minimi in the upper extremity on the left, in the contralateral direction; vastus lateralis, tibialis anterior, abductor hallucis in lower extremity on the left, contralateral to the centre; abductor pollicis brevis and abductor digiti minimi in the upper extremity on the right and abductor hallucis in the lower extremity on the right, ipsilateral to the centre. When the stereotactic needle is introduced along the selected trajectory to the tumour, direct pulses of electric current in cathode polarity are rhythmically supplied to the output of the monopolar stimulator connected to the needle in order to verify the proximity and functional integrity of corticospinal and corticobulbar tracts. In case of motor evoked potentials at current strength 10 mA, which indicates location of corticospinal and corticobulbar tracts in 10 mm from end of stereotactic needle in 10 mm, immersion of the needle is stopped to maintain a safe distance to the corticospinal and corticobulbar tracts in case of developing acute cerebral oedema in the radiation area. In parallel, spectral fluorescence diagnostics is carried out, during which the content of photosensitizers in the analysed tissues is continuously assessed by calculating fluorescence indices, which are determined by the ratio of areas under the fluorescence spectrum of the photosensitizer and spectrum of backscattered laser radiation according to formulas where η_Ce6 - fluorescence index of the chlorine series photosensitizer, rel. units, I_675–685 is the area under the fluorescence spectrum of the photosensitizer between wavelengths of 675–685 nm, I_625-640 is the area under the spectrum of backscattered laser radiation between wavelengths of 625–640 nm, where η_PpIX is the fluorescence index of photosensitizer of 5-ALA-induced PnIX relative units, I_695–710 is the area under the fluorescence spectrum of the photosensitizer between wavelengths 695–710 nm, I_625–640 is the area under the spectrum of backscattered laser radiation between wavelengths of 625–640 nm. Stereotactic photodynamic therapy is carried out with laser radiation sources with wavelengths of 635 nm and/or 660 nm for selective exposure to PnIX and Ce6. During the photodynamic therapy, the motor evoked potentials obtained by transcranial electrical stimulation are continuously assessed to control the functional integrity of the corticospinal tracts. If the amplitude of motor evoked potentials on the contralateral muscles decreases in relation to tumour by 50% and the increase in the latency from the obtained before the photodynamic therapy procedure, the radiation is stopped, considering this as a manifestation of acute cerebral oedema, on which there is an effect causing damage to the corticospinal and/or corticobulbar tracts.

EFFECT: method enables to conduct stereotactic photodynamic therapy of deep brain tumours under spectral fluorescence and neurophysiological monitoring with continuous control of functional integrity of corticospinal and corticobulbar tracts and allows to prevent formation or increase of neurological deficit.

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