[Stereotaxis for human neurosurgery].

The article is devoted to main principles of acad. N.P. Bechtereva the scientific school such as the complex method to study the human brain, the method of intracerebral long-term electrodes, the stereotactic method (computerized stereotaxy) and their development combined with the modern method of intrascopy (tomography). The connection between multitude electrodes methods and investigations of pathophysiological mechanisms of Parkinson disease, temporal epilepsy, various forms of obsessive-compulsive syndromes is studied.

[Pathology of the anterior cingulate cortex in obsessive compulsive disorder].

In the present article the features of the functional activity of the anterior cingulate cortex (ACC), a key element of neuroanatomical brain system of an error detection, in drug-resistant forms of obsessive-compulsive disorder (OCD) are discussed on a basis of both original and literature data. Available data indicate the presence of functional deficit in the ACC during OCD. This allows to suggest that functions of the ACC in OCD patient are partially redistributed between other brain areas. Thus in contrast to the previously accepted notion, the ACC as the target ofstereotactic surgery for OCD is pathologically altered brain region. Probably this is the reason why stereotactic destruction of ACC does not lead to significant changes in the patient's psyche. The essence of the pathological reorganisation of the functional activity of the brain in OCD remains unclear and requires further investigation.

[The brain mechanism of error detection: the P.E.T. study].

In present research, the brain maintenance of the error detection mechanism was studied in resting condition and while subjects consciously implemented incorrect actions (i.e. deception). Assessment of the regional cerebral blood flow revealed involvement of anterior cingulated cortex in deception. The obtained data indicate that it is impossible to consciously control the activity of the error detection mechanism. PET study of patients with obsessive compulsive disorder in resting condition revealed a decrease of brain glucose metabolism in the anterior cingulated cortex in comparison with healthy subjects. These data pointed to malfunctioning of the error detection mechanism. The findings support the formerly proposed hypothesis about the impact of the error detection mechanism in formation and support of obsessive compulsive disorder.

[Cryosurgical method in functional stereotactic neurosurgery].

Method of cryodestruction of deep subcortical structures is used in functional stereotactic operations in patients with chronic progressing diseases of the central nervous system. The PAH device produces cooling the tissues in the target point of the brain to -70 degrees C, which allows to obtain the destruction focus with volume 0.2 or 1 cm3. The source of cooling in the apparatus is solid cryodestruction carbonic acid. The method was used in 352 patients. The results of operations showed high degree of repeatability of geometric parameters of the obtained foci in the target structures, as well as the absence of the general and pronounced local tissue reaction to the cryodestruction foci. There was low percentage of hemorrhagic and infectious complications.

[Diagnosis and therapy of resistant temporal epilepsy]. / Diagnostika i lechenie rezistentnykh visochnykh épilepsii.

A complex research of epileptogenic focus (electroencephalography, invasive electroencephalography, MRI, PET) has allowed to localize a primary epileptogenic zone in medial temporal epilepsy in amygdale in 52% of the patients, in the anterior hippocampus--in 30% cases, a simultaneous and equivalent involvement of both amygdale and anterior hippocampus was diagnosed in 18% of the patients examined. Stereotaxic selective amygdalehippocampotomy was found to be effective in patients with resistant medial and lateral temporal epilepsy. The attacks stopped in 36% of the cases. In other patients frequency and duration of epileptic paroxysms considerably reduced, the structure of the paroxysms changed.

Human auditory-cortex mechanisms of preattentive sound discrimination.

Intracranial event-related potentials (ERPs) were recorded in neurological patients to infrequent higher-pitch 'deviant' tones and to frequent 'standard' tones when they occurred, in random order in a mixed sequence of standard and deviant tones and when they occurred in separate sequences, that is, infrequent tones alone with intervals similar to inter-deviant intervals of the mixed sequence and frequent tones alone with intervals similar to those between the standard tones of the mixed sequence. When the tones were ignored, ERPs showed three types of responses revealing three different processes involved in stimulus discrimination in the superior temporal cortex: (1) a pitch-dependent response in the primary auditory cortex; (2) an interstimulus-interval dependent response in the secondary auditory cortex; and (3) a change-detection ('mismatch') response in the auditory association cortex. When the tones were attended, ERPs to deviant and standard tones showed differences also in the basal ganglia-thalamic circuits and in the hippocampus, indicating their involvement in attentive processing of auditory stimulus changes.

[Functional stereotaxy with magnetic resonance tomographic guidance]. / Funktsional'naia stereotaksiia s magnitno-rezonansno-tomograficheskim navedeniem.

The paper summarizes experience with stereotactic operations by magnetic resonance imaging data by using a Russian OREOL stereotactic manipulator. It describes methods of preoperative preparation of patients by employing diagnostic magnetic resonance tomographs. A number of points of the procedure for identification and localization of deep target structures from magnetic resonance images in parkinsonism, temporal epilepsy and some mental disorders.

Differential approach to psychosurgery of obsessive disorders.

One of the most frequent indications of psychosurgical treatment is incurable obsessions. Up to now, capsulotomy or cingulotomy has been preferred. In our opinion, the variety of obsessive conditions require a more thorough approach to the selection of interbrain targets. Forty-seven patients with pure obsessive-compulsive disorders as well as disorders connected with depressions, epileptic syndrome, schizophreniform state and Gilles de la Tourette's syndrome with extremely severe resistance to medical therapy were examined. Eighteen patients were operated on. Surgical treatment is permissible only in cases fulfilling the three following criteria: (1) clinicopsychopathological permissibility (duration of disease, resistance to medication, psychopathological status); (2) physiological permissibility (the presence of a brain target, defining the psychopathological status), and (3) technical permissibility (the availability of proper stereotactic, imaging, electrophysiological and other apparatus necessary to carry out the surgical treatment). One supposes that the outcome of surgical treatment is determined by all three criteria. For the purpose of improving the efficiency of stereotactic treatment, a number of methods of surgical treatment depending on the psychopathological status are suggested. For example, in case of comorbidity of obsession with the epileptiform syndrome, we suggest cingulotomy (capsulotomy) and amygdalotomy; in case of comorbidity with depression we suggest cingulotomy and innominatotomy. The long-term observation of the outcome of stereotactic treatment covers a period from 2 up to 9 years.