Long-term surgical oncological and functional outcome of large petroclival and cerebellopontine angle epidermoid cysts: a multicenter study.

Cranial nerve (CN) disorders are the foremost symptoms in cerebellopontine angle (CPA) and petroclival area (PCA) epidermoid cysts (EC).The aim of this work was to  assess the long-term surgical results on CN function and tumor control in these patients. We performed a retrospective cohort study about 56 consecutive patients operated on for a CPA or PCA EC between January 2001 and July 2019 in six participating French cranial base referral centers. Sixteen patients (29%) presented a PCA EC and 40 a CPA EC (71%). The median clinical and radiological follow-up was 46 months (range 0-409). Preoperative CN disorders were present in 84% of patients (n = 47), 72% of them experienced CN deficits improvement at the last follow-up consultation (n = 34): 60% of cochlear and vestibular deficits (n = 9/15 in both groups), 67% of trigeminal neuralgia (n = 10/15), 53% of trigeminal hypoesthesia (n = 8/15), 44% of lower cranial nerve disorders (n = 4/9), 38% of facial nerve deficits (n = 5/8) and 43% of oculomotor deficits (n = 3/7) improved or were cured after surgery. New postoperative CN deficits occurred in 48% of patients (n = 27). Most of them resolved at the last follow-up, except for cochlear deficits which improved in only 14% of cases (n = 1/7). Twenty-six patients (46%) showed evidence of tumor progression after a median duration of 63 months (range 7-210). The extent of resection, tumor location, and tumor size was not associated with the occurrence of new postoperative CN deficit or tumor progression. A functional nerve-sparing resection of posterior fossa EC is an effective strategy to optimize the results on preexisting CN deficits and reduce the risk of permanent de novo deficits.

Data-Driven Prediction of the Therapeutic Window during Subthalamic Deep Brain Stimulation Surgery.

BACKGROUND: Moving from awake surgery under local anesthesia to asleep surgery under general anesthesia will require to precisely predict the outcome of deep brain stimulation. OBJECTIVE: To propose a data-driven prediction of both the therapeutic effect and side effects of the surgery. METHODS: The retrospective intraoperative data from 30 patients operated on in the subthalamic nucleus were used to train an artificial neural network to predict the deep brain stimulation outcome. A leave-one-out validation was undertaken to give a predictive performance that would reflect the performance of the predictive model in clinical practice. Three-dimensional coordinates and the amount of current of the electrodes were used to train the model. RESULTS: 130 electrode positions were reviewed. The areas under the curve were 0.902 and 0.89 for therapeutic and side effects, respectively. The mean sensitivity and specificity were 93.07% (SD 0.95) and 69.24% (SD 5.27) for the therapeutic effect, 73.47% (SD 10.55) and 91.82% (SD 0.12) for the side effect. CONCLUSION: Data-driven prediction could be an additional modality to predict deep brain stimulation outcome. Further validation is needed to precisely use this method for performing surgery under general anesthesia.

Becoming a neurosurgeon in France: A qualitative study from the trainees' perspective.

Introduction: The training of neurosurgeons is evolving in a world of socio-professional changes, including the technological revolution, administrative pressure on stakeholders, reduced working hours, geographical heterogeneity, generational changes, to name but a few. Research question: This qualitative study aimed to explore experiences and feedback of French neurosurgical trainees concerning their training. Material and methods: The grounded theory approach was used with 23 neurosurgical trainees' interviews. Inclusion was continued until data saturation. Six researchers (an anthropologist, a psychiatrist, and four neurosurgeons) thematically and independently analyzed data collected through anonymized interviews. Results: Data analysis identified three superordinate themes: (1) The Trainee-Senior Dyad, where the respondents describe a similar bipolarity between trainees and faculty (trainees oscillating between those who fit into the system and those who are more reluctant to accept hierarchy, faculty using an ideal pedagogy while others refuse to help or invest in training); (2) The difficulty to learn (describing pressure exercised on trainees that can alter their motivation and degrade their training, including the impact of administrative tasks); (3) A pedagogy of empowerment (trainee' feelings about the pertinent pedagogy in the OR, ideal sequence to progress, progressive empowerment especially during the shifts, and stress of envisioning themselves as a senior neurosurgeon). Discussion and conclusion: Respondents emphasize the heterogeneity of their training both intra- and inter-university-hospital. Their critical analysis, as well as the formalization of their stress to become autonomous seniors, can be an important link with the reforms and optimizations currently being carried out to improve and standardize the training of young French neurosurgeons.

Personal and psychosocial factors of burnout: A survey within the French neurosurgical community.

OBJECT: The neurosurgical community is particularly exposed to burnout. The objectives of this study were to report the prevalence and associated factors of burnout within the French neurosurgical community using validated academic and psychologic scales. METHODS: A national survey was sent to 141 French residents and 432 neurosurgeons between April and July 2019. Burnout was surveyed using the Maslach burnout inventory. The survey included demographic data and several academic psychologic scales. A stepwise multiple regression was used to determine factors that are associated with burnout scores. RESULTS: The response rate was 100% and 23.6% for residents and neurosurgeons, respectively. Prevalence of burnout within the French neurosurgical community was 49%. There were no significant differences between residents and neurosurgeons. Two categories of factors were associated with the main dimensions of burnout during the stepwise multiple regression: personality and factors related with neurosurgical practice. Personality types such as neuroticism were negatively associated with burnout while agreeableness was protective. Work addictive profile with excessive work and absorption at work were negatively associated. Factors associated with neurosurgical practice such as conflict of work into family life, unbalanced effort to reward ratio, work duration were negatively associated. Pleasure at work was protective. CONCLUSION: Prevalence of burnout is high among French neurosurgeons. Predictive models can be used to identify and prevent burnout among profiles at risk.

Functional atlases for analysis of motor and neuropsychological outcomes after medial globus pallidus and subthalamic stimulation.

Anatomical atlases have been developed to improve the targeting of basal ganglia in deep brain stimulation. However, the sole anatomy cannot predict the functional outcome of this surgery. Deep brain stimulation is often a compromise between several functional outcomes: motor, fluency and neuropsychological outcomes in particular. In this study, we have developed anatomo-clinical atlases for the targeting of subthalamic and medial globus pallidus deep brain stimulation. The activated electrode coordinates of 42 patients implanted in the subthalamic nucleus and 29 patients in the medial globus pallidus were studied. The atlas was built using the representation of the volume of tissue theoretically activated by the stimulation. The UPDRS score was used to represent the motor outcome. The Stroop test was represented as well as semantic and phonemic fluencies. For the subthalamic nucleus, best motor outcomes were obtained when the supero-lateral part of the nucleus was stimulated whereas the semantic fluency was impaired in this same region. For the medial globus pallidus, best outcomes were obtained when the postero ventral part of the nucleus was stimulated whereas the phonemic fluency was impaired in this same region. There was no significant neuropsychological impairment. We have proposed new anatomo-clinical atlases to visualize the motor and neuropsychological consequences at 6 months of subthalamic nucleus and pallidal stimulation in patients with Parkinson's disease.

Improvement of Pyramidal Tract Side Effect Prediction Using a Data-Driven Method in Subthalamic Stimulation.

OBJECTIVE: subthalamic nucleus deep brain stimulation (STN DBS) is limited by the occurrence of a pyramidal tract side effect (PTSE) induced by electrical activation of the pyramidal tract. Predictive models are needed to assist the surgeon during the electrode trajectory preplanning. The objective of the study was to compare two methods of PTSE prediction based on clinical assessment of PTSE induced by STN DBS in patients with Parkinson's disease. METHODS: two clinicians assessed PTSE postoperatively in 20 patients implanted for at least three months in the STN. The resulting dataset of electroclinical tests was used to evaluate two methods of PTSE prediction. The first method was based on the volume of tissue activated (VTA) modeling and the second one was a data-driven-based method named Pyramidal tract side effect Model based on Artificial Neural network (PyMAN) developed in our laboratory. This method was based on the nonlinear correlation between the PTSE current threshold and the 3-D electrode coordinates. PTSE prediction from both methods was compared using Mann-Whitney U test. RESULTS: 1696 electroclinical tests were used to design and compare the two methods. Sensitivity, specificity, positive- and negative-predictive values were significantly higher with the PyMAN method than with the VTA-based method (P < 0.05). CONCLUSION: the PyMAN method was more effective than the VTA-based method to predict PTSE. SIGNIFICANCE: this data-driven tool could help the neurosurgeon in predicting adverse side effects induced by DBS during the electrode trajectory preplanning.

Image-guided preoperative prediction of pyramidal tract side effect in deep brain stimulation: proof of concept and application to the pyramidal tract side effect induced by pallidal stimulation.

Deep brain stimulation of the medial globus pallidus (GPm) is a surgical procedure for treating patients suffering from Parkinson's disease. Its therapeutic effect may be limited by the presence of pyramidal tract side effect (PTSE). PTSE is a contraction time-locked to the stimulation when the current spreading reaches the motor fibers of the pyramidal tract within the internal capsule. The objective of the study was to propose a preoperative predictive model of PTSE. A machine learning-based method called PyMAN (PTSE model based on artificial neural network) accounting for the current used in stimulation, the three-dimensional electrode coordinates and the angle of the trajectory, was designed to predict the occurrence of PTSE. Ten patients implanted in the GPm have been tested by a clinician to create a labeled dataset of the stimulation parameters that trigger PTSE. The kappa index value between the data predicted by PyMAN and the labeled data was 0.78. Further evaluation studies are desirable to confirm whether PyMAN could be a reliable tool for assisting the surgeon to prevent PTSE during the preoperative planning.