Axono-cortical evoked potentials: A proof-of-concept study.

Awake surgery is currently considered the best method to tailor intraparenchymatous resections according to functional boundaries. However, the exact mechanisms by which electrical stimulation disturbs behavior remain largely unknown. In this case report, we describe a new method to explore the propagation toward cortical sites of a brief pulse applied to an eloquent white matter pathway. We present a patient, operated on in awake condition for removal of a cavernoma of the left ventral premotor cortex. At the end of the resection, the application of 60Hz stimulation in the white matter of the operculum induced anomia. Stimulating the same site at a frequency of 1Hz during 70seconds allowed to record responses on electrodes put over Broca's area and around the inferior part of central sulcus. Axono-cortical evoked potentials were then obtained by averaging unitary responses, time-locked to the stimulus. We then discuss the origin of these evoked axono-cortical potentials and the likely pathway connecting the stimulation site to the recorded cortical sites.

Comparison of cardiac output measured by oesophageal Doppler ultrasonography or pulse pressure contour wave analysis.

BACKGROUND: Maintaining adequate organ perfusion during high-risk surgery requires continuous monitoring of cardiac output to optimise haemodynamics. Oesophageal Doppler Cardiac Output monitoring (DCO) is commonly used in this context, but has some limitations. Recently, the cardiac output estimated by pulse pressure analysis- (PPCO) was developed. This study evaluated the agreement of cardiac output variations estimated with 9 non-commercial algorithms of PPCO compared with those obtained with DCO. METHODS: High-risk patients undergoing neurosurgery were monitored with invasive blood pressure and DCO. For each patient, 9 PPCO algorithms and DCO were recorded before and at the peak effect for every haemodynamic challenge. RESULTS: Sixty-two subjects were enrolled; 284 events were recorded, including 134 volume expansions and 150 vasopressor boluses. Among the 9 algorithms tested, the Liljestrand-Zander model led to the smallest bias (0.03 litre min(-1) [-1.31, +1.38] (0.21 litre min(-1) [-1.13; 1.54] after volume expansion and -0.13 litre min(-1) [-1.41, 1.15] after vasopressor use). The corresponding percentage of the concordance was 91% (86% after volume expansion and 94% after vasopressor use). The other algorithms, especially those using the Winkessel concept and the area under the pressure wave, were profoundly affected by the vasopressor. CONCLUSIONS: Among the 9 PPCO algorithms examined, the Liljestrand-Zander model demonstrated the least bias and best limits of agreement, especially after vasopressor use. Using this particular algorithm in association with DCO calibration could represent a valuable option for continuous cardiac output monitoring of high risk patients. CLINICAL TRIAL REGISTRATION: Comité d'éthique de la Société de Réanimation de Langue Française No. 11-356.

Functionally tailored transcortical approach of deep-seated lesions: an alternative to the transulcal approach? a technical case report.

It is commonly believed that sulci offer a natural path to reach deep-seated lesions. However, it has also been argued that this approach carries a risk of damaging the vessels during the opening of the sulcus.We therefore were prompted to test the possibility of finding a transcortical path identified as non-functional by intraoperative brain mapping. A successful resection is presented of a left posterior is thmusclear cell ependymoma through a selected corridor based on functional mapping in an awake patient.MRI performed at 12 months showed no tumour recurrence. Pre- and postoperative extensive testing confirmed an improvement of the patient's cognitive functions. Therefore, we were able to demonstrate the feasibility of a functionally tailored transcortical approach as an alternative to the transulcal approach for deep-seated lesions. This concept should be validated in a larger patient series.

[Usefulness of Bispectral Index (BIS) monitoring for early detection of cerebral hypoperfusions]. / Intérêt du monitorage de l'index bispectral (BIS) pour la détection précoce des hypoperfusions cérébrales.

OBJECTIVES: The goal of the study was to assess whether clinically significant cerebral hypoperfusion in awake patients would be associated with some alterations in the values of the bispectral index (BIS) monitoring. STUDY DESIGN: Observational study. POPULATION AND METHODS: We monitored the BIS during endovascular carotid artery occlusion testing in awake patients. RESULTS: Twenty-eight patients were included. Twenty-one adequately tolerated the procedure. Their BIS value remained stable throughout the procedure. Four patients had poor angiographic tolerance, but no clinical symptoms. Their BIS value slightly decreased during the test (minimal BIS: 83 [79-87]). Three patients had poor clinical and angiographic tolerance of the occlusion. They all experienced an immediate and dramatic decrease in their BIS value (minimal BIS: ipsilateral to clamping: 50 [45-60]; contralateral to clamping: 48 [45-52]). In all patients, the clinical symptoms and the BIS normalized after deflating the occlusion balloon. CONCLUSION: In awake patients, the observed values of the BIS monitoring seem to be associated with clinically relevant cerebral hypoperfusion.

[Postoperative comfort in pediatric outpatient tonsillectomy]. / Evaluation du confort postopératoire après amygdalectomie en ambulatoire chez l'enfant.

OBJECTIVE: Evaluate the comfort in children after ambulatory tonsillectomy, disregarding the surgical technique and with a systematic prescription of paracetamol and codeine. The study lasted 4 days including the day of surgery. STUDY DESIGN: [corrected] Prospective study during 5 months. PATIENTS AND METHODS: We performed a prospective study over a five-month period to evaluate the comfort in children after ambulatory tonsillectomy. Opioids were used for analgesia during surgery, morphine and propacetamol in the recovery room, and a systematic prescription of paracetamol-codeine between Day 0 to Day 3 at home. The assessment of pain was made by nurses and the family, considering 6 endpoints: spontaneous pain and when swallowing by verbal scale (0 to 4), occurrence of PONV (0 or 1), quality of sleep (0 or 1), quality of feeding (0 or 1) and play (0 or 1), combined in a global score of 0 to 12, with a score < or = 4 very satisfactory. RESULTS: 78 children were included, 49 tonsillectomy by dissection, 29 by Sluder. The score were < or = 4 at Day 0 and Day 1 in 53 children, but statistical analysis (univariate analysis) showed difference between the two surgical procedures with a global comfort score better and PONV lower with dissection procedure. CONCLUSION: The use of paracetamol-codeine after tonsillectomy offers a reliable analgesia with very satisfactory scores of comfort. Such prescription is effective in ambulatory tonsillectomy if a rigorous selection of patients is made.