BACKGROUND: The N-methyl-d-aspartate receptor antagonist ketamine and its active enantiomer, S(+)-ketamine, have been injected in the epidural and subarachnoid spaces to treat acute postoperative pain and relieve neuropathic pain syndrome. In this study we evaluated the effects of a single dose of preservative-free S(+)-ketamine, in doses usually used in clinical practice, in the spinal cord and meninges of dogs. METHODS: Under anesthesia (IV etomidate (2 mg/kg) and fentanyl (0.005 mg/kg), 16 dogs (6 to 15 kg) were randomized to receive a lumbar intrathecal injection (L5/6) of saline solution of 0.9% (control group) or S(+)-ketamine 1 mg/kg(-1) (ketamine group). All doses were administered in a volume of 1 mL over a 10-second interval. Accordingly, injection solution ranged from 0.6% to 1.5%. After 21 days of clinical observation, the animals were killed; spinal cord, cauda equina root, and meninges were removed for histological examination with light microscopy. Tissues were examined for demyelination (Masson trichrome), neuronal death (hematoxylin and eosin) and astrocyte activation (glial fibrillary acidic protein). RESULTS: No clinical or histological alterations of spinal tissue or meninges were found in animals from either control or ketamine groups. CONCLUSION: A single intrathecal injection of preservative-free S(+)-ketamine, at 1 mg/kg(-1) dosage, over a concentration range of 6 to 15 mg/mL injected in the subarachnoid space in a single puncture, did not produce histological alterations in this experimental model.
BACKGROUND: The N-methyl-d-aspartate receptor antagonist ketamine and its active enantiomer, S(+)-ketamine, have been injected in the epidural and subarachnoid spaces to treat acute postoperative pain and relieve neuropathic pain syndrome. In this study we evaluated the effects of a single dose of preservative-free S(+)-ketamine, in doses usually used in clinical practice, in the spinal cord and meninges of dogs. METHODS: Under anesthesia (IV etomidate (2 mg/kg) and fentanyl (0.005 mg/kg), 16 dogs (6 to 15 kg) were randomized to receive a lumbar intrathecal injection (L5/6) of saline solution of 0.9% (control group) or S(+)-ketamine 1 mg/kg(-1) (ketamine group). All doses were administered in a volume of 1 mL over a 10-second interval. Accordingly, injection solution ranged from 0.6% to 1.5%. After 21 days of clinical observation, the animals were killed; spinal cord, cauda equina root, and meninges were removed for histological examination with light microscopy. Tissues were examined for demyelination (Masson trichrome), neuronal death (hematoxylin and eosin) and astrocyte activation (glial fibrillary acidic protein). RESULTS: No clinical or histological alterations of spinal tissue or meninges were found in animals from either control or ketamine groups. CONCLUSION: A single intrathecal injection of preservative-free S(+)-ketamine, at 1 mg/kg(-1) dosage, over a concentration range of 6 to 15 mg/mL injected in the subarachnoid space in a single puncture, did not produce histological alterations in this experimental model.
Authors: Steven P Cohen; Anuj Bhatia; Asokumar Buvanendran; Eric S Schwenk; Ajay D Wasan; Robert W Hurley; Eugene R Viscusi; Samer Narouze; Fred N Davis; Elspeth C Ritchie; Timothy R Lubenow; William M Hooten Journal: Reg Anesth Pain Med Date: 2018-07 Impact factor: 6.288
Authors: Joakim Johansson; Jonas Sjöberg; Marie Nordgren; Erik Sandström; Folke Sjöberg; Henrik Zetterström Journal: Scand J Trauma Resusc Emerg Med Date: 2013-05-14 Impact factor: 2.953