Reflexo extensor radial do carpo e tibial cranial pré e pós bloqueio anestésico em gatos (Felis cattus)

Abstract

The extensor carpi radialis and cranial tibial reflexes are considered myotatics reflexes, however this has recently been called into question during by a study performed in dogs. The present study aimed to confirm and assess the response to testing the extensor carpi radialis and cranial tibial reflexes in cats, before and after anesthetic block of the brachial and lumbosacral plexus, respectively, demonstrating whether or not they depend on the myotatic reflex arc. Fifty-five cats with normal neurological examinations were selected, disregarding breed and gender, with ages ranging from 8 months to 4 years, that would be undergoing elective castration. They were divided into two groups. Group A consisted of 26 animals, where the cranial tibial reflex was tested and compared in both hindlimbs after anesthetic induction and 15 minutes after epidural anesthetic block with 2% lidocaine (0.22ml/kg). In group B, consisting of 29 animals, the extensor carpi radialis reflex was tested and compared in one of the forelimbs after anesthetic induction and 15 minutes after brachial plexus block with 2% lidocaine at a dose of 3.5mg/kg diluted in an equal volume of 0.9% saline solution. Regarding quality of the reflexes, in group A, 14.81% of the cats had a decreased cranial tibial reflex before the anesthetic block, while 85.19% were considered normal. After the block, 25.93% were considered decreased and 74.07%, normal. In group B, 55.17% were considered as having a decreased extensor carpi radialis reflex and 44.83%, normal before the brachial plexus block. After the block, 68.96% showed a decreased reflex, and 27.59%, normal. None of the cats showed increased or absent reflexes before the blocks. Regarding the presence of reflexes before and after the anesthetic blocks, the statistical outcome in both groups was not significant (P = 0.013, with a significance level of 1%). Considering the results of this research, it is concluded that the responses obtained when testing the extensor carpi radialis and cranial tibial reflexes may not be strictly myotatic, not depending on the functional integrity of the components of the reflex arc to occur. It is possible that these reflexes in cats are idiomuscular responses, as is cited in human literature. Therefore, they are not trustworthy reflexes for the neurological examination in Felis cattus.