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Oxygen and glucose were measured in arterial and venous blood of 10 patients operated on for arterial aneurysms of the cerebral vessels. The blood was collected through catheters inserted on the right and left from the internal jugular vein bulb. Blood samples were collected at the beginning and end of surgery simultaneously from 3 sites: artery and right and left veins. The values for the right and left jugular veins initially differed much in 5 out of 11 cases. The causes of these differences are discussed, but this fact makes us doubt the efficacy of catheterization of one internal jugular vein for assessing the cerebral metabolism in various clinical situations.

Internal carotid aneurysms in the ophthalmic area presents a challenge in cerebrovascular neurosurgery. The study was undertaken to provide evidence for the application of intravascular aspiration during direct surgical interventions and to outline their variants used at the N. N. Burdenko Institute of Neurosurgery. The study included 4 (3 females and 1 male) patients with large and giant internal carotid aneurysms of parasphenoidal site who were treated at the Institute. Clipping of the aneurysmal neck was made by employing intravascular blood aspiration from the aneurysm. The technique proved to be effective in proximal monitoring the carotid artery at surgery. It substantially reduced aneurysmal blood flow and wall tension, thus favouring aneurysmal dissection to make clipping.

The purpose of this work was to evaluate the method of identification of motor structures of the bottom of the IV ventricle in order to find the zone through which it is possible to safely approach the bulky formation and to assess the efficacy of subsequent monitoring of these structures for the prevention of their intraoperative injury. Fourteen patients with bulky tumors of the caudal portions of the brain stem aged 4 to 57 were examined. Motor structures of the brain stem (nerves VII or IX, X, and XII, depending on the site of injury) were identified by direct electrostimulation of the surface of the rhomboid fossa and recording of the motor functions by mechanography of EMG. The results indicate that intraoperative identification of motor structures followed by monitoring thereof is a useful instrument which helps reduce the surgical risk of injuring these structures during surgery on the brain stem.

The injurious effects of self-retained retractors on brain tissue during surgery were studied in patients with various neurosurgical diseases of the brain. The first part of the study was devoted to retraction pressure in neurosurgical patients. The highest values were observed in patients with abnormalities of the chiasmal-sellar area, median cranial fossa, and aneurysms of the anterior portions of Willis' circle. The second part was devoted to a retrospective analysis which revealed a high incidence of complications caused by the use of retractors in patients with tumors of the chiasmal-sellar area and median cranial fossa. In the third part we assessed the preventive effect of some methods aimed at reduction of the brain volume during surgery. Preliminary intravenous infusion of mannitol solution, puncture of the tumor cyst, ventricular and, possibly, lumbar draining were found to be prophylactically useful. Acute hyperventilation and intravenous preinjection of a saluretic were ineffective.

Intraoperative electrooculograms (EOG) of 44 patients with bulky formations in the posterior cranial fossa demonstrated a good correlation of the sum of EOG waves caused by mechanical stimulation (aspiration, retraction, etc.) and the sum of complexes of EOG waves, on one hand, and the outcome, on other, in patients with brain stem involvement and less so in those with involvement of the cerebellum. The method is not informative for predicting the status of stem structures in surgery on the pontocerebellar angle. Stimulation of cerebral tissue caused by electrocoagulation cannot be recognized by EOG because it is associated with electric artefacts.

Pressor reaction to laryngoscopy and intubation of the trachea was studied in 32 patients with neurosurgical diseases of the brain (supratentorial tumors and arterial aneurysms) under conditions of induction anesthesia with propofol (diprivan) in the mean dose of 2.85 mg/kg. Diprivan alone did not block the development of pronounced pressor reaction to intubation. Combination of diprivan in the same dose with dipidolor (0.4 mg/kg) ensured complete blocking of the pressor reaction in neurosurgical patients. Combination of diprivan and fentanyl (2.85 mg/kg) blocked the development of a pressor reaction not so effectively and not in all the examinees.

Using a new device, INVOS-3100 cerebral oximeter, the rSO2 parameter (oxygen saturation of blood hemoglobin in cerebral vessels) was monitored during neurosurgical interventions in 84 patients with cerebrovascular diseases (arterial aneurysms, arteriovenous malformations, and carotid-cavernous anastomoses). Six patients developed grave ischemic complications. In five of them the cerebral oximeter showed a more than 5% reduction of the parameter in question (by 11%, on an average). The findings permit a conclusion that cerebral oximetry is an adequate method of early diagnosis of ischemia in neurosurgical patients with cerebrovascular diseases.

A new device is described: cerebral oximeter intended for monitoring cerebral oxygenation and early diagnosis of cerebral ischemia and hypoxia. The advantages and shortcomings of the proposed method are analyzed in comparison with other current methods for the early diagnosis of cerebral ischemia.

A case with a difficult intubation of the trachea in a patient with anterior dislocation of C(VI) vertebra and unstable cervical portion of the spine is described. A special Bullard fiberoptic laryngoscope was effectively used in this patient for orotracheal intubation. Use of this laryngoscope is a good alternative to other methods of tracheal intubation in patients with injuries and unstable cervical portion of the spine.

The studies were carried out in 33 patients with intrastem volumetric tumors. In 6 patients the monitoring was impossible because of technological problems. Somatosensory evoked potentials (SSEP) were recorded in 10 and acoustic stem evoked potentials (ASEP) in 18 out of 27 patients and the findings correlated to changes in the neurological status on day 1 postoperation. In 3 out of 9 patients operated on in a sitting posture SSEP monitoring during the main stage of the operation became impossible because the response disappeared due to an air layer above the parietal cortex. Transitory or constant changes in SSEP at the stage of tumor removal were detected in 5 patients. In 9 patients intraoperative changes in ASEP were recorded. False-positive results of ASEP monitoring were obtained in 4 cases. In 2 cases a discrepancy between intraoperative changes of SSEP and the postoperative neurologic deficit were detected. The authors discuss the technological and methodological problems of intraoperative monitoring of evoked potentials and approaches to solution of these problems.

The efficacies of three methods for the prevention of venous air embolism, positive pressure at the end of expiration, inflatable cervical tourniquet, and controlled moderate hypoventilation, were compared in 16 patients with neurosurgical abnormalities of the posterior cranial fossa. Attaining of positive values of intrasinus pressure was the criterion of efficacy of prophylactic measures. The results indicate that cervical tourniquet and hypoventilation methods are simple and highly effective for the prevention of air embolism. However, they should be used with care in patients with initially pronounced intracranial hypertension, in the presence of arterial hypotension, and their use should be limited in time--till the stage of opening the dura mater. The method of creation of positive pressure at the end of expiration is not only useless, but may even become hazardous because of the possible development of systemic hemodynamic disorders.

A clinical case of severe ischemic damage in the hand developed in a patient with cerebral ampullar aneurysm due to catheterization of the radial artery for intraoperative BP monitoring is described. The problems of the expediency of radial artery catheterization, complications associated with the procedure, factors causing those complications and their prognosis are being discussed.

The authors analyze the clinical efficacy of a combined method for the prevention of pressor reaction to laryngoscopy and tracheal intubation, based on the combination of common clinical doses of fentanyl (4 micrograms/kg b. m.) and intravenous infusion of nitroglycerin solution in 26 patients with brain vessel aneurysms. This method effectively prevented the dangerous rise of arterial pressure during laryngoscopy and tracheal intubation.

Spontaneous respiration (SR) was retained during surgery in 17 patients with vascular pathology in the posterior sections of the circle of Willis (arteriovenous malformations of posterior cranial fossa, arterial aneurysm) to control brain stem function and preserve its blood flow. SR disturbances developed during the basic stage of the operation in 4 patients and were caused by the occlusion of various vessels in posterior sections of the circle of Willis. The control of SR parameters as part of intraoperation monitoring in patients with vascular pathology in posterior sections of the circle of Willis makes it possible to assess the retention of brain stem blood flow and thus to optimize surgical tactics.

Spontaneous respiration (SR) was used for dynamic control of brain stem functions in 21 patients during excision of intramedullary tumours and brain stem hematomas. SR disturbances developed during tumour removal from caudal stem sections in 4 patients, in 2 of them the course of the postoperative period was severe. It seems expedient to include into the programme of intraoperation monitoring of patients operated on the brain stem the SR parameters for dynamic assessment of brain stem function.

Visual EEG monitoring and EEG monitoring using a special "Neuro-2" monitor controlling the changes in quantitative EEG parameters (power range and coherence) have been used during surgery in 42 patients with arterial aneurysms of brain vessels performed in conditions of profound controlled arterial hypotension. Computer processing facilitates EEG analysis and reveals the most early signs of the developing cerebral ischemia on the basis of specific changes in power ranges and coherence.

A case of repeated massive air embolism in a patient with posterior cranial fossa tumour operated on in a sitting position is described. Early diagnosis and timely intensive therapy made it possible to arrest the complication development.

In 43 patients serial SSER recordings were made during operations for the clipping of arterial aneurysms of cerebral vessels performed under controlled arterial hypotension. SSER recordings during the preliminary phase of the operation showed an average decrease in the response amplitude of 20% during trepanation and a reduction (by 23% of the initial value) during the phase of arterial hypotension. The response recovered to 84% of its initial level by the moment of the beginning of the operation. There was no statistically significant relationship between serial SSER parameter values during arterial pressure reduction and the duration or degree of hypotension. The results testify to the higher information content of such SSER parameters as the amplitude of the first positive complex, as compared with latency criteria and in particular the CCT. It has also been found that a significant increase in the information value of the SSER for the evaluation of ischemia effect on the brain function may be obtained by synchronous stimulation of both arms and registration of cortical responses from both hemispheres.

A rare clinical case--anesthesiological management in craniopagus--is described. Problems arising in the course of anesthesia during surgical separation of such children are reviewed.

The effect of ataralgesia (diazepam and fentanyl anesthesia) on cerebral blood flow and metabolism has been studied in 9 patients with arterial aneurysms of cerebral vessels. The decrease of cerebral blood flow under anesthesia was observed in 8 out of 9 patients. The brain metabolism reaction varied showing a decrease in 6 patients and an increase in 3 patients.

Test for stress-induced hyperglycemia showed that deep sodium nitroprusside-controlled arterial hypotension in ataralgesia is a powerful stress-producing factor. Additional neurovegetative inhibition by administration of small doses of ganglioblocking agent pentamine is suggested for the prevention hypotension-induced stress.