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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.55 no.5 Campinas Sept./Oct. 2005
Postoperative cognitive dysfunction
Cognitive changes potentially related to surgical and/or anesthetic procedures are worrying many research groups worldwide.
Major difficulties to analyze observed results are posed by the multiple factors, which may contribute to or interfere with them.
Seemingly age, type of procedure, preoperative anxiety and type of anesthesia are some factors interfering with this postoperative complication 1.
In 2002, a group of German investigators has published a study on cognitive dysfunction after general anesthesia by studying serum concentration of S-100 protein and of specific neuronal enolase (SNE) as indicators of this change 2. The rational of this research was the use of S-100 protein in cardiac surgery, trauma and strokes as the marker for brain ischemia.
S-100 protein is found in astrocytes and Schwann cells, and specific neuronal enolase is found in neuronal cytoplasm and neuroendocrine cells. Its serum concentrations are changed after brain injuries or blood brain barrier dysfunction. Patients were submitted to tests to evaluate perception, attention, associative memory, visual and motor coordination. The conclusion was that specific neuronal enolase was not different in patients with or without postoperative cognitive dysfunction and that S-100 protein is of limited value due to poor specificity and possible extra-brain contamination since it is also produced by other tissues.
So, the perspective of an indicator has grown weak and investigators were solely left with the difficult windings of subjective parameters.
At every new study on the subject more questions are asked: which is the definition of significant cognitive dysfunction? Are neuropsychometric tests learned by patients during multiple evaluations? Which tests should be applied 3? Is regional anesthesia better than general anesthesia 4?
There are no simple answers or pre-established formulas, but research has to go on
In this edition, a Brazilian group adds a contribution to this subject by studying the prevalence and factors associated to postoperative cognitive dysfunction. I invite the readers to read the study and think about it. Brazilian population is aging and surgical management of elderly patients is a reality. Creating evidences contributing to clinical practice guidelines is a must.
However, it is important to consider that not only the elderly may present such changes; hospital admission and anesthesia or surgical procedure may also contribute for cognitive, emotional and socio-behavioral development changes in children 5.
Judymara Lauzi Gozzani, TSA, M.D.
Editor-in-Chief, Brazilian Journal of Anesthesiology
01. Canet J, Raeder J, Rasmussen LS et al - Cognitive dysfunction after minor surgery in the elderly. Acta Anaesthesiol Scand, 2003;47:1204-1210.
02. Linstedt U, Meyer O, Kropp P et al - Serum concentration of S-100 protein in assessment of cognitive dysfunction after general anesthesia in different types of surgery. Acta Anaesthesiol Scand, 2002;46:384-389.
03. Heyer EJ, Connolly ES - Serum concentration of S-100 protein in assessment of cognitive dysfunction after general anesthesia in different types of surgery. Acta Anaesthesiol Scand, 2003;47:911-912.
04. Wu CL, Hsu W, Richman JM et al - Postoperative cognitive function as an outcome of regional anesthesia and analgesia. Reg Anesth Pain Med, 2004;29:257-268.
05. Caldas JC, Pais-Ribeiro JL, Carneiro SR - General anesthesia, surgery and hospitalization in children and their effects upon cognitive, academic, emotional and sociobehavioral development - a review. Paediatr Anaesth, 2004;14:910-915.