The Effects of Subarachnoid Administration of Preservative-Free S(+)-Ketamine on Spinal Cord and Meninges in Dogs

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 equine 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. (Anesth Analg 2012;114:450-55)

Neurotoxicity of subarachnoid hyperbaric bupivacaine in dogs

Background and Objectives. The study investigated possible neurotoxic effects of increasing concentrations and doses of bupivacaine administered into the subarachnoid space in dogs. Methods. Fifty animals were allocated to five experimental groups: G1, control; G2, 5 mg 0.5 bupivacaine in 10% glucose solution; G3, 10 mg of 1% bupivacaine in 10% glucose solution; G4, 20 mg 2% bupivacaine in 10% glucose solution, and G5, 20 mg 2% bupivacaine in water. After 72 hours of observation, the animals were killed and the spinal cords removed for histologic examination by light microscopy. Results. None of the animals showed any neurologic clinical disturbance following recovery from spinal anesthesia. One case of necrosis of nerve tissue was observed in G3 and four in G4. Conclusions. Increasing concentrations and doses of hyperbaric bupivacaine solutions increased the incidence of nerve tissue damage, which did not occur with hypobaric solutions. These results should contribute to the further understanding of neurologic complications following spinal anesthesia when large doses of local anesthetics in hyperbaric solutions are used.

Effects on mother and fetus of epidural and combined spinal-epidural techniques for labor analgesia

OBJETIVO: A peridural (AP) e a técnica de duplo bloqueio (DB) são utilizadas em analgesia para o trabalho de parto. Este estudo comparou os efeitos na mãe e no feto de ambas as técnicas em analgesia e anestesia para o parto. MÉTODOS: Quarenta parturientes ASA I e II receberam por via peridural 15 ml de ropivacaína a 0,125% (grupo AP) e 5 µg de sufentanil com 2,5 mg bupivacaína por via subaracnóidea (grupo DB). Foram avaliados: intensidade de dor, altura do bloqueio sensitivo, tempo de latência, bloqueio motor, duração da analgesia de parto, tempo para a resolução do parto, hipotensão materna e presença de prurido. Os recém-nascidos foram avaliados pelo índice de Apgar e escore da capacidade adaptativa e neurológica (ECAN), método de Amiel-Tison. RESULTADOS: Não houve diferenças significativas entre os grupos na intensidade da dor, no tempo de latência, no nível do bloqueio sensitivo e no índice de Apgar. O bloqueio motor, a duração da analgesia e o tempo para resolução do parto foram maiores no grupo DB, do qual sete parturientes apresentaram prurido leve. ECAN foi maior no grupo AP após meia hora, duas horas e 24 horas. Noventa e cinco por cento dos recém-nascidos do grupo AP e 60% do grupo DB foram considerados neurologicamente vigorosos ao exame de 24 horas. CONCLUSÃO: As duas técnicas mostraram-se eficazes para analgesia do trabalho de parto. As parturientes do grupo DB apresentaram prurido e trabalho de parto mais prolongado. Recém-nascidos de mães que receberam analgesia de parto via peridural apresentaram melhor ECAN.

Porencephaly and cortical dysplasia as cause of seizures in a dog

Background: Seizures are a common problem in small animal neurology and it may be related to underlying diseases. Porencephaly is an extremely rare disorder, and in Veterinary Medicine it affects more often ruminants, with only few reports in dogs.Case presentation: A one-year-old intact male Shih-Tzu dog was referred to Veterinary University Hospital with history of abnormal gait and generalized tonic-clonic seizures. Signs included hypermetria, abnormal nystagmus and increased myotatic reflexes. At necropsy, during the brain analysis, a cleft was observed in the left parietal and occipital lobes, creating a communication between the subarachnoid space and the left lateral ventricle, consistent with porencephaly; and also a focal atrophy of the caudal paravermal and vermal portions of the cerebellum. Furthermore, the histological examination showed cortical and cerebellar neuronal dysplasia.Conclusions: Reports of seizures due to porencephaly are rare in dogs. In this case, the dog presented a group of brain abnormalities which per se or in assemblage could result in seizure manifestation.

The Anatomy of the Thoracic Spinal Canal Investigated with Magnetic Resonance Imaging

BACKGROUND: We investigated, with magnetic resonance imaging, the distance of the dura mater to the spinal cord in patients without spinal or medullar disease at the 2nd, 5th, and 10th thoracic segments.METHODS: Fifty patients in the supine position underwent magnetic resonance imaging. Medial sagittal slices of the 2nd, 5th, and 10th thoracic segments were measured for the relative distances using the 1.5-T superconducting system (Gyroscan Intera, Philips Medical Systems, Best, the Netherlands). In 10 patients, the angles relative to the tangent at the insertion point on the skin were measured.RESULTS: The posterior dural-spinal cord distance is significantly greater at the midthoracic region (5th thoracic = 5.8 +/- 0.8 mm) than at the upper (2nd thoracic = 3.9 +/- 0.8 mm) and lower thoracic levels (10th thoracic = 4.1 +/- 1.0 mm) (P < 0.015). There were no differences between interspaces T2 and 110. There was no correlation between age and the measured distance between the dura mater and the spinal cord. The entry angle of the needle at T2 was 9.0 degrees +/- 2.5 degrees; at T5, 45.0 degrees +/- 7.4 degrees; and at T10, 9.50 degrees +/- 4.2 degrees.CONCLUSIONS: This study demonstrated that there is greater depth of the posterior subarachnoid space at the T2, T5, and T10 levels. The greater distance was found at T5. (Anesth Analg 2010;110:1494-5)

Contribuição das projeções oblíquas em mielografias de pequenos animais para a localização de lesões medulares causadas por processo degenerativo do disco intervertebral

Mielografia é uma técnica radiográfica na qual se administra meio de contraste no espaço subaracnóideo para avaliar a medula espinhal. Múltiplas projeções radiográficas fornecem uma exploração circunferencial da medula, auxiliando na localização mais precisa de compressões nesta região. Objetivou-se demonstrar a contribuição das projeções oblíquas, pouco exploradas em exames de mielografia, para a localização de lesões medulares extradurais em cães e gatos causadas por processo degenerativo do disco intervertebral. Foram avaliadas 116 mielografias e observou-se que em 36,2% dos casos as projeções oblíquas foram imprescindíveis para a localização exata das lesões. A associação entre as projeções ventrodorsal e oblíquas se mostraram mais úteis para a localização da lesão do que quando avaliadas isoladamente e as projeções oblíquas esquerda e direita foram igualmente importantes.

Endocrine changes in cerebrospinal fluid, pituitary effluent, and peripheral plasma of anesthetized ponies

Objective - To investigate the effects of inhalation and total IV anesthesia on pituitary-adrenal activity in ponies. Animals - 9 healthy ponies: 5 geldings and 4 mares. Procedure - Catheters were placed in the cavernous sinus below the pituitary gland and in the subarachnoid space via the lumbosacral space. After 72 hours, administration of acepromazine was followed by induction of anesthesia with thiopentone and maintenance with halothane (halothane protocol), or for the IV protocol, anesthesia induction with detomidine and ketamine was followed by maintenance with IV infusion of a detomidine-ketamine-guaifenesin combination. Arterial blood pressure and gas tensions were measured throughout anesthesia. Peptide and catecholamine concentrations were measured in pituitary effluent, peripheral plasma, and CSF. Peripheral plasma cortisol, glucose, and lactate concentrations also were measured. Results - Intravenous anesthesia caused less cardiorespiratory depression than did halothane. ACTH, metenkephalin, arginine vasopressin, and norepinephrine pituitary effluent and peripheral plasma concentrations were higher during halothane anesthesia, with little change during intravenous anesthesia. Pituitary effluent plasma β-endorphin and peripheral plasma cortisol concentrations increased during halothane anesthesia only. Dynorphin concentrations did not change in either group. Hyperglycemia developed during intravenous anesthesia only Minimal changes occurred in CSF hormonal concentrations during anesthesia. Conclusion - The pituitary gland has a major role in maintaining circulating peptides during anesthesia. Compared with halothane, IV anesthesia appeared to suppress pituitary secretion.

Pneumoencéfalo intraventricular após perfuração acidental de dura-máter. Relato de caso

BACKGROUND AND OBJECTIVES: The loss of resistance to air to identify the epidural space is widely used. However, the accidental perforation of the dura mater is one of the possible complications of this procedure, with an estimated incidence between 1% and 2%. The objective of this report was to describe the case of a patient with intraventricular pneumocephalus after the accidental perforation of the dura mater using the loss of resistance with air technique. CASE REPORT: Female patient, 26 years old, 75 kg, 1.67 m, physical status ASA I, with a 38-week pregnancy, was referred to the obstetric service for a cesarean section. Venipuncture was performed after placement of the monitoring. The patient was placed in a sitting position for administration of the epidural anesthesia. During the identification of the epidural space with the loss of resistance with air technique, an accidental perforation of the dura mater was diagnosed by observing free flow of CSF through the needle. The technique was modified to epidural anesthesia and anesthetics were administered by the needle placed in the subarachnoid space. In the first 24 hours, the patient developed headache and she was treated with caffeine, dypirone, hydration, hydrocortisone, and bed rest; despite those measures, the patient's symptoms worsened and evolved to headache in decubitus. A CT scan of the head showed the presence of pneumocephalus. After evaluation by a specialist, the patient remained under observation, with progressive improvement of the symptoms and was discharged from the hospital in the fifth day, without complications. CONCLUSIONS: Pneumocephalus after accidental perforation of the dura mater presented headache with the characteristics of headache secondary to loss of CSF, but with spontaneous resolution after the air was absorbed. Invasive measures, such as epidural blood patch, were not necessary. © Sociedade Brasileira de Anestesiologia, 2006.

Concentração sérica da proteína C reativa como indicador preditivo do prognóstico clínico em indivíduos com hemorragia subaracnóidea aneurísmática

Pós-graduação em Bases Gerais da Cirurgia - FMB

Effects caused by the spinal administration of ketamine S (+) 5% with no preservatives, using a single puncture, and located on the spinal cord and meninges in rabbits

PURPOSE: To evaluate the effect of ketamine S (+) 5% with no preservatives and administered as a subarachnoid single puncture on the spinal cord and meninges of rabbits.METHODS: Twenty young adult female rabbits, each weighing 3500-5000 g and having a spine length between 34 and 38 cm, were divided by lot into two groups (G): 0.9% saline in G1 and ketamine S (+) 5% in G2, by volume of 5 μg per cm column (0.18 mL). After intravenous anaesthesia with ketamine and xylazine, the subarachnoid space was punctured at S1-S2 under ultrasound guidance, and a random solution was injected. The animals remained in captivity for 21 days under medical observation and were sacrificed by decapitation. The lumbosacral spinal cord portion was removed for immunohistochemistry to assess the glial fibrillary acidic protein (GFAP), and histology was assessed using hematoxylin and eosin (HE) stain.RESULTS:No histological lesions were found in the nervous tissue (roots and cord) or meninges in either group.CONCLUSION: The ketamine S (+) 5% unpreserved triggered no neurological or histological lesions in the spinal cord or meninges of rabbits.

Efeitos cardiorrespiratórios da administração subaracnóide de cetamina ou da associação com ifenprodil em equinos anestesiados com sevofluorano

Pós-graduação em Cirurgia Veterinária - FCAV

Falha no bloqueio após anestesia subaracnoidea: frequência e fatores contribuintes

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação da pressão liquórica em pacientes obstétricas submetidas à anestesia subaracnoidea que apresentaram cefaleia pós-punção dural

Pós-graduação em Anestesiologia - FMB

Efeitos da administração subaracnoidea em punção única, de cetamina S(+) a 5%, sem conservantes, sobre a medula espinal e as meninges de coelhos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Does spinal block through tattooed skin cause histological changes in nervous tissue and meninges?: an experimental model in rabbits

Although there is no documented evidence that tattoo pigments can cause neurological complications, the implications of performing neuraxial anesthesia through tattooed skin are unknown. In this study, we aimed to assess whether spinal puncture performed through tattooed skin of rabbits determines changes over the spinal cord and meninges. In addition, we sought to evaluate the presence of ink fragments entrapped in spinal needles. Thirty-six young male adult rabbits, each weighing between 3400 and 3900 g and having a spine length between 38.5 and 39 cm, were divided by lot into 3 groups as follows: GI, spinal puncture through tattooed skin; GII, spinal puncture through tattooed skin and saline injection; and GIII, spinal puncture through skin free of tattoo and saline injection. After intravenous anesthesia with ketamine and xylazine, the subarachnoid space was punctured at S1-S2 under ultrasound guidance with a 22-gauge 2½ Quincke needle. Animals in GII and GIII received 5 μL/cm of spinal length (0.2 mL) of saline intrathecally. In GI, the needle tip was placed into the yellow ligament, and no solution was injected into the intrathecal space; after tattooed skin puncture, 1 mL of saline was injected through the needle over a histological slide to prepare a smear that was dyed by the Giemsa method to enable tissue identification if present. All animals remained in captivity for 21 days under medical observation and were killed by decapitation. The lumbosacral spinal cord portion was removed for histological analysis using hematoxylin-eosin stain. None of the animals had impaired motor function or decreased nociception during the period of clinical observation. None of the animals from the control group (GIII) showed signs of injuries to meninges. In GII, however, 4 animals presented with signs of meningeal injury. The main histological changes observed were focal areas of perivascular lymphoplasmacyte infiltration in the pia mater and arachnoid. There was no signal of injury in neural tissue in any animal of both groups. Tissue coring containing ink pigments was noted in all GI smears from the spinal needles used to puncture the tattooed skin. On the basis of the present results, intrathecal injection of saline through a needle inserted through tattooed skin is capable of producing histological changes over the meninges of rabbits. Ink fragments were entrapped inside the spinal needles, despite the presence of a stylet.