Minerva

Anaesthetists blame all kinds of anatomical barriers for patchy epidural analgesia, including air bubbles, fat, and fibrous bands in the epidural space. None was evident in an imaging study of 20 women receiving brachytherapy for cervical cancer (Anesthesiology1999;90:964-9). Computed tomography showed local anaesthetic solution spreading freely but not uniformly through the space, with a different distribution in almost every patient. The position of the catheter was also extremely variable: in eight women the catheter tip ended up in the posterior epidural space (where it should be), but in the rest the tip wandered into the intervertebral foramina or paravertebral tissues. Badly positioned epidural catheters contribute more to asymmetrical blocks than do anatomical barriers, the authors conclude.

Humans use two types of thinking to solve mathematical problems (Science1999;284:970-4): a visual and spatial sense of quantity is located in the left and right parietal lobes, while the processing of symbols is done in the left frontal lobe. Volunteers in a brain imaging study used their parietal lobes to solve approximate problems like: “Is 53 plus 68 closer to 120 or 159?” They used their left frontal lobe to work out more precise answers. Interestingly, exact arithmetic seems more language dependent than does processing of approximate numbers.

Humans—and some orthopaedic …