[Application of robotized radiosurgical system CyberKnife for the treatment of neurosurgical patients].

Robotized system for radiosurgery CyberKnife (Accuray Inc., USA) is the first device dedicated and optimized for advanced irradiation during 1-7 fractions (i.e. radiosurgery and hypofractionation). CyberKnife is characterized by elaborate guidance system, high precision of dose delivery, possibility of conformal dose distributions with high gradient of target borderline dose which is most important in proximity of critical structures. The first CyberKnife system in Russia was installed in Burdenko Neurosurgery Institute. The paper presents 2-year experience of treating patients using CyberKnife. From April 2009 till October 2011 896 patients were treated using CyberKnife. Mean age was 48 years. Overall number of sessions was 2626. Radiosurgical procedures were performed in 21.8% of patients. 91% of cases were treated for intracranial lesions. Limited follow-up period in all kinds of pathology demonstrated results consistent with standard fractionation or radiosurgery. The rates of observed complications were also comparable with accepted techniques. CyberKnife system plays significant role in everyday activity of department of radiation therapy. In careful and thorough selection of patients it allows efficient and high-quality treatment of patients with neurosurgical diseases.

[First experience of stereotactic radiation therapy for vestibular schwannoma using CyberKnife].

Currently stereotactic radiosurgery has become the treatment of choice in small vestibular schwannomas. This paper discusses our first experience of application of CyberKnife system for stereotactic irradiation of these tumors. From April 2009 till June 2011 we treated 62 patients (35 female and 27 male) with vestibular schwannomas. Stereotactic radiosurgery using CyberKnife system was performed in 33 patients. Mean tumor volume was 2 +/- 1.4 cm3. Hypofractionated treatment was used in 30 cases (31 tumor). Mean tumor volume reached was 7 +/- 6.2 cm3 (range - 0.5-31.3 cm3). In a case of a patient with NF2 simultaneous irradiation of bilateral tumors was performed. Most frequently we applied 3 fractions 6 Gy each (17 observations of 31, or 55%) and 5 fractions with mean dose 5 Cy (10 cases, or 32%). Follow-up period varied from 1 to 26 months (mean 9 +/- 4.5 months). By the end of this study (June 30, 2011) surgical resection was required in the only case of 47-years old male patient with cystic schwannoma of left vestibular nerve 5 months after radiation treatment, due to progressive growth of the cyst and increased brainstem compression. Tumor growth control was established in 97.5% of cases. Stabilization of auditory function was achieved in 77.5% of series. Effective hearing was preserved in 75% of patients. Facial nerve palsy after stereotactic radiation treatment was observed in 2 cases (3%). Incidence of trigeminal nerve dysfunction was significantly higher: sensation disturbances occurred in 6 (10%) patients: 3% after radiosurgery and 16.7% after hypofractionation. We did not obtain significant correlations between risk of cranial nerve complications and dosimetric or demographic factors. However we observed stable tendency: larger initial volume of the tumor and presence of trigeminal nerve dysfunction before treatment were poor prognostic factors for trigeminal neuropathy. Stereotactic irradiation using CyberKnife system is effective and sufficiently safe technique for management of vestibular schwannoma. The paper demonstrates high rates of tumor stabilization, hearing preservation and minimal incidence of complications associated with trigeminal or facial nerve.

[Application of SPECT/CT in neurosurgical practice].

The paper presents the experience of application of single-photon emission computed tomography (SPECT) and CT in neurosurgery. Combination of these two techniques in the single system provides higher precision of both methods. The novel technique allows assessment of tumor spread in the brain, differential diagnosis of tumor regrowth and radiation-induced necrosis, evaluation of cerebral perfusion in epilepsy, traumatic brain injury (TBI), and diagnostics of secondary CNS lesions. Examples of primary diagnosis, dynamic follow-up and differential diagnosis of cerebral neoplasms, localization of epileptogenic foci in planning of surgery, prediction of outcome after TBI and evaluation of spread of metastatic skeletal involvement and further application of acquire data are presented.

[Linear accelerator-based stereotactic radiation treatment of patients with medial middle fossa meningiomas].

Medial middle fossa meningiomas are challenging for neurosurgical treatment. Invasion of cranial nerves and vessels leads to high risk of complications after removal of such meningiomas. Currently methods of conformal stereotactic radiation treatment are applied wider and wider for the discussed lesions. During a 3.5-year period 80 patients with medial middle fossa meningiomas were treated in Burdenko Moscow Neurosurgical Institute using linear accelerator "Novalis". In 31 case radiation treatment was preceded by surgical resection. In majority of patients symptoms included cranial nerve dysfunction: oculomotor disturbances in 62.5%, trigeminal impairment--in 37.5%, visual deficit--in 43.8%, facial nerve palsy--in 1.25%. 74 patients underwent radiotherapy with classical fractioning, 2--in hypofractionated mode and 4 received radiosurgery. In cases of classical fractioning mean marginal dose reached 46.3 Gy during 28-33 fractions, in hypofractioning (7 fractions)--31.5 Gy, in radiosurgery--16.25 Gy. Mean follow-up period was 18.4 months (6-42 months). Control of tumor growth was achieved in 97.5% of cases (78 patients): in 42 (52.5%) lesion shrinked, in 36 (45%) stabilization was observed. Clinical examination revealed improvement of visual function in 15 patients (18%) and deterioration in 2 (2.5%). No new neuropathies were found. Stereotactic radiation treatment is the method of choice for medial anterior and middle fossa meningiomas due to effective control of tumor progression and minimal rate of complications.

[Linear accelerator-based stereotactic radiotherapy and radiosurgery in treatment of neurosurgical patients].

Radiation methods are essential in management of certain types of neurooncological, neurovascular and functional brain pathology. Application of stereotactic technique of irradiation allows sufficient damaging impact on target (tumor, AVM, functional structures) and maximal protection of surrounding brain tissues. Indications to radiation treatment of intracranial lesions are expanding with evolution of stereotactic methods. The paper deals with the first experience of linear accelerator-based treatment of patients with intracranial neurosurgical pathology in this country. Techniques of stereotactic radiotherapy (SRT) and radiosurgery (SRS), indications to SRS and SRT in different modes of fractioning are described in details. Additionally specific complications, radiation reactions and feasibility of neurovisualization in diagnosis of radiation-induced brain damage are discussed.

[Stereotactic radiotherapy and radiosurgery in treatment of patients with intracranial schwannomas].

Aim of this study is to assess the role of stereotactic radiosurgery (SRS) and radiotherapy (SRT) in management of cranial nerves schwannomas by analysis of tumor control, clinical response and variables affecting treatment outcomes. Between April 2005 and January 2009 patients with schwannomas of VIII (63), V (14) and caudal nerves (2) were treated in Burdenko Moscow Neurosurgical Institute using linear accelerator. Mean age was 49 years (13-82). In 42 cases radiation treatment was preceded by surgical resection. 13 patients had type I or II neurofibromatosis. Mean volume of the tumor was 3.9 cm3 (0.5-14.4 cm3) and 13.4 cm3 (2.8-41.3 cm3) for SRS and SRT, respectively. Mean SRS dose was 12 Gy (10.8-14.4 Gy) for vestibular schwannomas and 15 Gy (13.2-18 Gy) for schwannomas of other nerves. In hypofractionated SRT the dose of 35 Gy was delivered in 7 fractions or 30 Gy in 6 fractions. In cases of classical fractioning total dose of 50-60 Gy was divided into daily fractions of 1.8-2.0 Gy. Radiographic tumor control rate reached 97.5% at the last follow-up. 5 patients experienced trigeminal dysfunction, it was transient in 3 cases and persistent in 2. Permanent decline in House-Brackmann facial nerve scale developed in 2 of 79 patients. After treatment effective hearing (class I-II) was preserved in 7 of 9 patients (67%) who had same level of hearing before SRS. Linear accelerator-based stereotactic radiation treatment provides long-term tumor control associated with high rates of preservation of neurological functions. No further tumor surgery was necessary in 100% of cases with solitary tumors with a minimal follow-up of 5 years.

[Single-photon emission-computed tomography with the Testascan multidetector gamma tomograph in neurologic practice]. / Odnofotonnaia émissionnaia komp'iuternaia tomografiia s mnogodetektornym gamma-tomografom TESTASKAN v nevrologicheskoi praktike.

The paper is concerned with the results of single-photon emission tomography and gamma-topography in patients with cerebral tumors, cerebral circulatory disorders and pathology of the liquor system. Tomographic investigation was shown to enhance the accuracy and reliability of the detection of cerebral tumors. Single-photon emission computerized gamma-tomography (SPECT) permitted the detection of structural and morphological cerebral changes in disturbed cerebral circulation of various etiology. SPECT together with computerized tomography and radionuclide cisternography was shown to be an auxiliary method for visualization of the cerebral cisterns. Radionuclide tomographic images as compared to gamma-topographic findings of the brain possessed a high statistical significance and good resolution.

[Radioanatomy of cerebral perfusion in single-photon emission-computed tomography using 99mTc-labelled amines]. / Radioanatomiia mozgovoi perfuzii pri odnofotonnoi émissionnoi komp'iuternoi tomografii s mechennymi 99mTc aminami.

A study was made of the cerebral hemodynamics by assessing the distribution in single-photon emission computerized tomography with 99mTc-hexamethyl-propyleneminoxyne in health using a Testascan in 9 standard slices. The whole set of tomographic slices was conventionally divided into 3 levels. For better orientation in gamma-tomographic images, pictures were presented where in addition to scintigrams a morphological scheme of the cerebral parts with the marked parts perfused by cerebral arteries, was given.

[Gamma radionuclide topography of the brain in diagnosing inflammatory processes in children and adults]. / Radionuklidnaia gamma-topografiia golovnogo mozga v diagnostike vospalitel'nykh protsessov u detei i vzroslykh.

Gamma topography of the brain as a differential diagnostic method permits the recognition of an inflammatory process and specification of its localization. It can be widely used in an outpatient setting (both for children and adults). Altogether 61 patients were investigated: abscesses of the brain (36 patients, of them 16 children); focal arachnoencephalitis (14 patients, of them 5 children); arachnoiditis (11 patients). Gamma topography of the brain makes it possible to clarify early topical diagnosis of a process. Due to its simplicity, small radiation exposure and noninvasive character of the method can be recommended in outpatient clinics and hospitals both for children and adults.

[Computerized tomography, radionuclide gamma-topography and angiography in the diagnosis of brain abscesses of rhinosinusogenic origin]. / Komp'iuternaia tomografiia, radionuklidnaia gamma-topografiia, angiografiia v diagnostike abstsessov golovnogo mozga rinosinusogennogo proiskhozhdeniia.

X-ray and other methods were used to examine 21 patients with brain abscesses of rhinosinusogenic origin. The diagnostic methods including computer tomography, brain gamma-topography and cerebral angiography yielded objective information about the localization, size, distribution and multiplicity of brain abscesses. They were displayed as doughnuts or rings on computer tomograms and as pies on gamma-topograms. The noninvasive methods such as computer tomography or gamma-topography proved very helpful for assessing the efficacy of surgical intervention at an early postoperative stage.

[Radiological diagnosis of basal inflammatory processes in the brain (arachnoiditis, arachnoencephalitis) in paranasal sinusitis]. / Radiologicheskaia diagnostika bazal'nykh vospalitel'nykh protsessov golovnogo mozga (arakhnoidity, arakhnoéntsefality) pri paranazal'nykh sinuitakh.

The article presents radiological signs of basal processes (arachnoiditis, arachnoencephalitis) associated with paranasal sinusitis. gamma-Topography of the brain in inflammatory processes is distinguished by such typical radiological signs as a pathological accumulation of a radiopharmaceutical which is more often diffuse in nature. According to the findings of radionuclide cysternography the inflammatory process is characterized by a block of the subarachnoidal space of the frontobasal portions and an impairment of the CSF dynamics.

[Diagnosis of hypertensive syndromes of unclear origin (according to the results of radionuclide cisternography)]. / Diagnostika gipertenzionnogo sindroma neiasnogo geneza (po dannym radionuklidnoi tsisternografii).

Analysis of the findings of radionuclide cisternography in 34 patients with a hypertension syndrome of unclear genesis allowed 3 variants of an aggregate of radiological signs to be distinguished. The 1st and 2nd variants indicate diminution of the drainage function of the cerebral submeningeal space, which does not exclude the presence of a pathological process, one of tumorous genesis among others. The third variant which reveals open internal hydrocephalus (ventricular hydrocephalus) with diminished drainage activity of the submeningeal space of the brain excludes the existence of a three-dimensional pathological process, that of tumorous origin also. In hypertension syndrome of unclear genesis disturbed circulation of cerebrospinal fluid was always attended by its impaired resorption; not only a diminished reaction (function) but an accelerated reaction of drainage of the cerebrospinal fluid from its passages may occur when the maintaining drainage function of the submeningeal space of the spinal cord is manifested.

[Scintigraphy in the diagnosis of tumors of the 8th cranial nerve]. / Stsintigrafiia v diagnostike opukholei VIII nerva.

The indications for and the diagnostic value and the method of radioisotope gammaencephalography (GEG) in tumors of the 8th nerve and similar diseases (47 cases) were studied. The optimum time for conducting scintigraphy for the detection of tumors of the 8th nerve is 2 1/2-3 hours after injection of the isotope. Small tumors up to 2 cm in size are not revealed by GEG, stage II and stage III tumors are clearly demonstrated. GEG makes it possible to differentiate tumors of the 8th nerve from arachnoiditis of the cerebellopontine angle and stem encephalitis.