Electrophysiological reactions to intraoperative irritation of the optic nerve. Case report and review of possible mechanisms

BACKGROUND

Intraoperative control of optic nerve function conservation during neurosurgical operations currently relies mainly on visual evoked potential monitoring. Unfortunately, this detects peril only when the visual pathways are already compromised, sometimes irreversibly. In contrast, electrophysiological stimulation mapping of the nerves can be a fully preventive measure. However, direct sensory nerve mapping requires the patient to be awake during surgery, which is unfeasible for surgeries targeting the optic nerve area. Another possible approach to sensory nerve mapping involves unconditioned electrophysiological responses evoked by sensory nerve stimulation. The key point for this approach is the possibility of obtaining such responses for a particular sensory nerve under surgical anesthesia.

CASE REPORT

A 52-year-old woman presented with meningioma in the area of right optic nerve and chiasm. She underwent microsurgical removal of the tumor through the transciliary supraorbital approach. During surgery, electrodes at the inferior margin of the right orbit repeatedly recorded electrophysiological reactions following contacts and displacements of the right optic nerve by the surgical instruments.

CONCLUSIONS

The observed reactions suggest that either the unconditioned blink reflex or antidromic electroretinographic response to optic nerve irritation was conserved under total intravenous anesthesia. This observation might be of value for development of intraoperative optic nerve mapping. This in turn could increase patient safety by identifying the exact optic nerve location before any negative impact on it.

Intrinsic Connectivity Networks in the Self- and Other-Referential Processing

Neuroimaging studies have revealed a multitude of brain regions associated with self- and other-referential processing, but the question how the distinction between self, close other, and distant other is processed in the brain still remains unanswered. The default mode network (DMN) is the primary network associated with the processing of self, whereas task-positive networks (TPN) are indispensable for the processing of external objects. We hypothesize that self- and close-other-processing would engage DMN more than TPN, whereas distant-other-processing would engage TPN to a greater extent. To test this hypothesis, we used functional magnetic resonance imaging (fMRI) functional connectivity data obtained in the course of a trait adjective judgment task while subjects evaluated themselves, the best friend, a neutral stranger, and an unpleasant person. A positive association between the degree of self-relatedness and the degree of DMN dominance was revealed in cortical midline structures (CMS) and the left lateral prefrontal cortex. Relative to TPN, DMN showed greater connectivity in me than in friend, in friend than in stranger, and in stranger than in unpleasant conditions. These results show that the less the evaluated person is perceived as self-related, the more the balance of activity in the brain shifts from the DMN to the TPN.

A crisis for the future of forensic science: Lessons from the UK of the importance of epistemology for funding research and development

This study presents analysis of forensic science research funded by UK Research and Innovation (UKRI) research councils (2009–2018), representing 150 projects with a cumulative value of £56.1 m (0.01% of the total UKRI budget over this time period). The findings indicate that dedicated forensic science funding represents only 46.0% of the projects included in the dataset. Research focussed on developing technological outputs represented 69.5% of the total funding (£37.2 m) in comparison to foundational research which represented 19.2% (£10.7 m). Traditional forensic science evidence types such as fingerprints and DNA received 1.3% and 5.1% of the total funding respectively, in comparison to digital and cyber projects which received 25.7%. These data offer insight into the scale of the funding crisis in forensic science in the UK, and the need to increase the resources available, to develop ways of articulating value and to ensure that both technological and foundational research are enabled.

[An experience of neurophysiological monitoring in neurosurgery]

AIM

To evaluate the efficacy of neuromonitoring methods in prevention of postoperative neurological complications and estimation of predictive power of intraoperative changes in monitored characteristics.

MATERIAL AND METHODS

Retrospective study examined 240 patients, operated in the years 2014-2015 using intraoperative neurophysiological monitoring. One hundred and seventy-three patients suffered from hemispheric lesions and 67 had lesions located in or near the brainstem. Somatosensory evoked potentials (SSEP) were monitored in 152 cases, visual in 32, brainstem acoustic in 22, transcranial motor in 36; stimulation mapping of motor cortex was performed in 69 surgeries, and cranial nerves identification in 27. EEG was recorded in 7 patients, and 3 of them were woke up during the surgery for speech mapping.

RESULTS

The sensitivity of the SSEP in motor dysfunction detection was low (33%), while the specificity was relatively high (82%). These characteristics for visual and motor evoked potentials were close to 100% provided that the parameters of anesthesia met the corresponding requirements. The most effective methods in respect of prevention of postoperative dysfunctions were the stimulation mapping of functionally significant areas (motor and speech) and motor pathways mapping.

CONCLUSION

Intraoperative neuromonitoring reduces a number of neurological complications after neurosurgical operations. The SSEP method is not sensitive enough in surgeries that could affect motor centers and/or pathways, and multimodal monitoring combining SSEP and motor responses recording during transcranial and/or direct electrical brain stimulation. Successful monitoring requires highly coordinated actions between neurophysiologists, neurosurgeons and anesthesiologists.

Reciprocal relationships between the oscillatory systems of the brain

Resting EEG recordings were made from cohorts of 146 children aged 7-17 years and 132 adults aged 18-32 years and the levels of personality features and psychopathology were assessed using the Eysenck, Spilberger, Gray-Wilson, and Goodman questionnaires. Factor analysis was used to discriminate covariance of measures of the spectral power of EEG rhythms into positive and negative components. The latter were interpreted as a measure of inhibitory interactions between oscillatory systems. In children, positive covariance of rhythms was stronger than in adults, while reciprocal relationships between oscillatory systems were weaker. In adults, trait anxiety correlated positively with the strength of the reciprocal relationship between the alpha and delta oscillatory systems. In children, an analogous relationship was seen between anxiety and the strength of the reciprocal relationship between the theta and delta systems. The data are discussed in the light of the evolutionary interpretation of EEG rhythms.

[Reciprocal relationships between oscillatory systems of the brain]

Resting EEG data were collected from a sample of 146 children aged from 7 to 17 years and 132 adults aged from 18 to 32 years. Eysenck's, Spilberger's, Gray-Wilson's, and Goodman's questionnaires were used to assess personality and psychopathology. Using factor analysis, the covariance between spectral power measures was decomposed into factors reflecting common positive covariance and reciprocal relationships among different frequency bands. The latter were treated as measures of inhibitory interactions between different oscillatory systems. In children, the common positive covariance was higher, and inhibitory interactions were weaker than in adults. In adults, trait anxiety was positively related to the strength of reciprocal relationship between alpha and delta oscillatory systems. In children, similar relationship was found between anxiety and the strength of reciprocal relationship between theta and delta oscillatory systems. Findings are discussed in terms of evolutionary interpretation of brain oscillations.

A phase II study of the efficacy of recombinant interferon gamma in relapsing ovarian adenocarcinoma

Fourteen patients with relapsing ovarian cancer were treated with a regimen of intravenous interferon gamma (IFN gamma). During an initial induction phase, patients received 2 mg/m2 IFN gamma intravenously over 2 h daily for 5 days, repeated every 2 weeks for six courses. Patients who responded were continued on a maintenance phase, receiving 3 mg/m2 intravenously over 2 h, twice weekly every 2 weeks for 2 to 6 months. All patients had received prior cisplatin containing chemotherapy regimens. Of the 14 patients entered, 7 completed the six courses of the induction treatment. Four patients were clinical responders and continued on maintenance therapy. The most commonly reported toxicities included malaise, fever, and deteriorating performance status. There appears to be some clinically apparent antitumor activity demonstrated by this dosing schedule of interferon gamma in ovarian cancers.

Recombinant gamma interferon in advanced breast cancer: a phase II trial

Fifteen patients with advanced carcinoma of the breast who had failed prior chemotherapy, were treated with recombinant gamma interferon at a dose of 2mg/m2 (1mg = 2.4 X 10(7) international units) intravenously for five consecutive days every other week. The median patient age was 51 and all patients had a performance status of 0-2 (Karnofsky greater than or equal to 50). Thirteen patients had two or three sites of metastatic disease and seven were estrogen receptor positive. No complete or partial responses were noted. Although some patients had brief periods of stable disease, almost all patients progressed after one or two courses. Only one patient was able to receive six courses of induction therapy and a brief course of maintenance. Flu-like symptoms and nausea were seen in all patients; vomiting and anorexia were frequent. Hepatic toxicity manifested by enzyme elevation was common and was most severe in patients with liver metastases. In this study a highly purified biologically active gamma interferon was not associated with anti-tumor activity in previously treated women with metastatic breast cancer.

Mitomycin C intravesical therapy in noninvasive bladder cancer after failure on thiotepa

Mitomycin C 40 mg in 40 ml water was administered intravesically every week for 8 consecutive weeks to 60 patients with superficial bladder cancer. All patients had failed treatment with intravesical thiotepa and had evaluable disease. An objective response of 50% or greater reduction in measured tumor mucosal involvement was obtained in 68% of patients. Forty-two percent of the patients achieved a complete response, and this included 50% of patients with Grade III disease and 70% of patients with a T1 tumor. Median response duration in complete responders was 12.2 months with a range of 3.5 to 24.3 + months. Fifty-five percent of patients are still responding. Therapy was generally well tolerated, and in contrast to thiotepa, myelosuppression was not the dose-limiting effect. One third of all patients experienced symptoms of local irritation, and skin reactions were seen in 12% of patients.