Increase in high frequency EEG activity explains the poor performance of EEG spectral entropy monitor during S-ketamine anesthesia.

OBJECTIVE: To study the effects of S-ketamine on the EEG and to investigate whether spectral entropy of the EEG can be used to assess the depth of hypnosis during S-ketamine anesthesia. METHODS: The effects of sub-anesthetic (159 (21); mean (SD) ng/ml) and anesthetic (1,959 (442) ng/ml) serum concentrations of S-ketamine on state entropy (SE), response entropy (RE) and classical EEG spectral power variables (recorded using the Entropy Module, GE Healthcare, Helsinki, Finland) were studied in 8 healthy males. These EEG data were compared with EEG recordings from 6 matching subjects anesthetized with propofol. RESULTS: The entropy values decreased from the baseline SE 85 (3) and RE 96 (3) to SE 55 (18) and RE 72 (17) during S-ketamine anesthesia but both inter- and intra-individual variation of entropy indices was wide and their specificity to indicate unconsciousness was poor. Propofol induced more pronounced increase in delta power (P<0.02) than S-ketamine, whereas anesthetic S-ketamine induced more high frequency EEG activity in the gamma band (P<0.001). Relative power of 20-70 Hz EEG activity was associated with high SE (P=0.02) and RE (P=0.03) values during S-ketamine anesthesia. CONCLUSIONS: These differences in low and high frequency EEG power bands probably explain why entropy monitor, while adequate for propofol, is not suitable for assessing the depth of S-ketamine anesthesia. SIGNIFICANCE: The entropy monitor is not adequate for monitoring S-ketamine-induced hypnosis.

Focal and global cortical hypometabolism in patients with newly diagnosed infantile spasms.

OBJECTIVE: To evaluate the occurrence and prognostic importance of focal defects in cerebral cortical glucose metabolism in infants with newly diagnosed symptomatic and cryptogenic infantile spasms. PATIENTS AND METHODS: Ten children with symptomatic and seven with cryptogenic infantile spasms underwent MRI, video-EEG, and PET using fluorodeoxyglucose as a tracer within 2 weeks of diagnosis. PET was repeated at 1 year of age in 12 patients. RESULTS: Cortical hypometabolic foci were found in 13 children (77%) with newly diagnosed spasms (six cryptogenic and seven symptomatic). The hypometabolic foci disappeared in seven of nine reexamined at age 1. The occipital foci disappeared in all (n = 6). Focal findings on PET correlated well with focal findings on video-EEG. There was no difference in quantitative cortical or subcortical glucose metabolic rate at the onset of infantile spasms between children with cryptogenic and symptomatic etiology of spasms. The glucose metabolic rate at the onset of spasms or focal lesions in glucose metabolism did not have prognostic value for seizure outcome. CONCLUSIONS: Infantile spasms are often associated with transient cortical, especially occipital, hypometabolic foci that are not necessarily associated with structural lesions and do not indicate a poor prognosis.

[Role of external biliary drainage in common bile duct lithiasis. Apropos of 172 case reports]. / Place du drainage biliaire externe dans la lithiase cholédocienne. A propos de 172 observations.

A series of 172 lithiasis of the common bile duct has been analysed. Priority has always been given to the external drainage by a T tube. It seems to be the simplest method, with the lowest morbidity. 6 patients, as 3.48% are deceased precociously after the intervention in keeping with the gravity of the lesions and the general state.