TWIK-Related Spinal Cord K+ Channel Expression Is Increased in the Spinal Dorsal Horn after Spinal Nerve Ligation

PURPOSE: The TWIK-related spinal cord K+ channel (TRESK) has recently been discovered and plays an important role in nociceptor excitability in the pain pathway. Because there have been no reports on the TRESK expression or its function in the dorsal horn of the spinal cord in neuropathic pain, we analyzed TRESK expression in the spinal dorsal horn in a spinal nerve ligation (SNL) model. MATERIALS AND METHODS: We established a SNL mouse model by using the L5-6 spinal nerves ligation. We used real-time polymerase chain reaction and immunohistochemistry to investigate TRESK expression in the dorsal horn and L5 dorsal rot ganglion (DRG). RESULTS: The SNL group showed significantly higher expression of TRESK in the ipsilateral dorsal horn under pain, but low expression in L5 DRG. Double immunofluorescence staining revealed that immunoreactivity of TRESK was mostly restricted in neuronal cells, and that synapse markers GAD67 and VGlut2 appeared to be associated with TRESK expression. We were unable to find a significant association between TRESK and calcineurin by double immunofluorescence. CONCLUSION: TRESK in spinal cord neurons may contribute to the development of neuropathic pain following injury.

Comparison of therapeutic effects of anterior decompression and posterior decompression on thoracolumbar spine fracture complicated with spinal nerve injury

To compare the clinical therapeutic effects of anterior decompression and posterior decompression on thoracolumbar spine fracture [TSF] complicated with spinal nerve injury [SNI]. A total of 120 patients with TSF and SNI were selected and divided into a treatment group and a control group that were then treated by anterior decompression and posterior decompression respectively. The preoperative and postoperative motor scores, tactile scores, heights of injured vertebral body and Cobb's angles, as well as surgical times and intraoperative blood losses were recorded and compared. Before surgeries, the motor score, tactile score, height of injured vertebral body and Cobb's angle of the treatment group were similar to those of the control group [P>0.05]. After surgeries, the values of the treatment group were significantly different from those of the control group [P<0.05]. The two groups also had significantly different intraoperative blood losses and surgical times [P<0.05]. Compared with posterior decompression, anterior decompression improved spinal cord function better and relived spinal cord compression more effectively with a more reasonable mechanics of internal fixation. Although this protocol caused more blood loss, the overall therapeutic effects were more satisfactory

Estudio comparativo entre dos intensidades de ultrasonido continuo en la reparación del nervio espinal lesionado por compresión / Comparative study between two intensities of continuous ultrasound in the repair of the spinal nerve injured by compression

El ultrasonido continuo fundamenta su efectividad en la energía térmica que genera, favoreciendo la reparación nerviosa. Es por esto que surge la interrogante de que si al aplicar diferentes intensidades de ultrasonido continuo sobre el nervio espinal lesionado, la respuesta reparativa será igual o distinta. Para ello se utilizaron 12 ratas de sexo masculino a las que se les aisló quirúrgicamente el nervio isquiático, el cual fue pinzado durante 45 segundos con una fuerza constante de 40N. La compresión se realizó a 10mm sobre la bifurcación, luego se desinfectó y suturó. Inmediatamente después de la operación las ratas fueron agrupadas de a 3: A) control sano, B) control lesionado, C) aplicación de ultrasonido terapéutico de 0,5w/cm2 y D) aplicación de ultrasonido terapéutico de 1w/cm2. El grupo A se utilizó como control sano y no recibió irradiación. Las ratas del grupo B fueron lesionadas y no recibieron irradiación y las del grupo C y D fueron lesionadas e irradiadas transcutáneamente en la región correspondiente al recorrido del nervio isquiático utilizando intensidades de 0,5w/cm2 y 1w/cm2, 3 MHZ de frecuencia, un cabezal de 0,5cm2, durante 1 minuto y 10 días consecutivos. 28 días post operatorio se extrajeron los nervios isquiáticos y fueron sometidos a técnicas de tinción de H-E y Van Gieson. Se realizó el diagnóstico histopatológico y la morfometría: se midió el Grosor del Perineuro, Perímetro del núcleo del Schwannocito, Perímetro del Axón Mielínicoy Perímetro de la Mielina. Los resultados revelan que el ultrasonido continuo es efectivo en la reparación del nervio espinal, siéndolo más con 1w/cm2 que con 0,5w/cm2.

The continuous ultrasound bases its efficiency on the heat energy it generates, favoring the nervous repair. Therefore, the question arises whether the reparative response will be equal or different under varying intensities of continuous ultrasound application on the disabled spinal nerve. For the study we used 12 male rats; the ischiatic nerve was surgically isolated and compressed during 45 seconds with a constant force of 40N. The compression was realized at 10 mm on the bifurcation, and was subsequently disinfected and sutured. Immediately following the operation the rats were separated in groups of 3: A) Healthy control, B) Injured control, C) Application of therapeutic ultrasound of 0.5 w/cm2 and D) Application of therapeutic ultrasound of 1 w/cm2. Group A was used as healthy control and did not receive irradiation. The rats in group B were injured and did not receive irradiation and those of groups C and D were injured and were transcutaneously irradiated in the area corresponding to the ischiatic nerve using intensities of 0.5 w/cm2 and 1 w/cm2, 3 MHZ of frequency. We used a compress of 0.5 cm2, during 1 minute and for 10 consecutive days. 28 days post operative ischiatic nerves were removed and submitted to technologies of H.E and VG stain. Histopathological and morphometrical diagnosis was realized: Thickness of the Perineurium, schwannocyte perimeter, Myelin Axon and Myelin perimeters were measured. The results revealed that the continuous ultrasound is effective in the repair of the spinal nerve, more so with 1 w/cm2 than with 0.5 w/cm 2.

Intrathecal Lamotrigine Attenuates Mechanical Allodynia and Suppresses Microglial and Astrocytic Activation in a Rat Model of Spinal Nerve Ligation

PURPOSE: Lamotrigine, a novel anticonvulsant, is a sodium channel blocker that is efficacious in certain forms of neuropathic pain. Recently, microglial and astrocytic activation has been implicated in the development of nerve injury-induced neuropathic pain. We have assessed the effects of continuous intrathecal administration of lamotrigine on the development of neuropathic pain and glial activation induced by L5/6 spinal-nerve ligation in rats. MATERIALS AND METHODS: Following left L5/6 spinal nerve ligation (SNL), Sprague-Dawley male rats were intrathecally administered lamotrigine (24, 72, or 240 microg/day) or saline continuously for 7 days. Mechanical allodynia of the left hind paw to von Frey filament stimuli was determined before surgery (baseline) and once daily for 7 days postoperatively. On day 7, spinal activation of microglia and astrocytes was evaluated immunohistochemically, using antibodies to the microglial marker OX-42 and the astrocyte marker glial fibrillary acidic protein (GFAP). RESULTS: Spinal-nerve ligation induced mechanical allodynia in saline-treated rats, with OX-42 and GFAP immunoreactivity being significantly increased on the ipsilateral side of the spinal cord. Continuously administered intrathecal lamotrigine (240 microg/day) prevented the development of mechanical allodynia, and lower dose of lamotrigine (72 microg/day) ameliorated allodynia. Intrathecal lamotrigine (72 and 240 microg/day) inhibited nerve ligation-induced microglial and astrocytic activation, as evidenced by reduced numbers of cells positive for OX-42 and GFAP. CONCLUSION: Continuously administered intrathecal lamotrigine blocked the development of mechanical allodynia induced by SNL with suppression of microglial and astrocytic activation. Continuous intrathecal administration of lamotrigine may be a promising therapeutic intervention to prevent neuropathy.

Tratamiento con ultrasonido continuo de alta intensidad en nervios isquiáticos de rata (Sprague Dawley) lesionados por compresión / Treatment with continuous high-intensity ultrasound on rat sciatic nerve (Sprague Dawley) and compression injuries

Actualmente las patologías compresivas de nervios espinales son de alta incidencia. Como una forma de contribuir con fundamentos morfológicos a la aplicación de ultrasonido terapéutico se realizó la presente experiencia, que se refiere a la reparación de los nervios espinales luego de una injuria compresiva. Para esto se utilizaron 9 ratas Sprague Dawley las cuales fueron separadas en tres grupos con 3 ratas cada uno: A) control sano, B) control lesionado y C) aplicación de ultrasonido terapéutico de 1w/cm2. Las ratas de los grupos B y C fueron anestesiadas y se les aisló quirúrgicamente el nervio isquiático, el cual fue pinzado durante 45 segundos con una fuerza constante de 40N. La compresión se realizó a 10mm sobre su bifurcación distal, luego se desinfectó y suturó. 24 horas después de la compresión las ratas del grupo C fueron irradiadas con un equipo de ultrasonido terapéutico, utilizando 1w/cm2 de intensidad con frecuencia de 3 MHZ y un cabezal de 0,5cm2, durante 1 minuto y en 10 días seguidos. 28 días después de la irradiación se extrajeron los nervios isquiáticos y fueron sometidos a técnicas histológicas de rutina con tinción de HE y VG. Se realizó el diagnóstico histopatológico y la morfometría donde se midió: grosor del perineuro, perímetro de los núcleos de neurilemocitos, perímetro del axón mielínico, perímetro de la mielina, ancho del núcleo del fibroblastocito y largo del núcleo del fibroblastocito. Los resultados permiten concluir que el ultrasonido de modalidad continua estimula la regeneración del nervio espinal lesionado por compresión.

Currently, the pathologies of spinal nerves are of high incidence. As a way to contribute to morphological grounds the application of therapeutic ultrasound was used in the repair of spinal nerves after a compressive injury. 9 tests were carried out using Sprague Dawley rats which were separated into three groups with 3 rats each: A) healthy control, B) injured control and C) the application of therapeutic ultrasound 1w/cm2. The rats in groups B and C were anesthetized and sciatic nerve was surgically isolated, which was clamped for 45 seconds with constant force of 40N. Compression was performed on the distal bifurcation 10mm, then disinfected and sutured. 24 hrs after compression, rats in group C were irradiated with a therapeutic ultrasound equipment, using 1w/cm2 of intensity with frequency of 3 MHz and a head of 0.5 cm2 for 1 minute, for 10 days. 28 days after irradiation sciatic nerve was removed and subjected to routine histological staining with HE and VG. Histopathological diagnosis was made and morphometry which measured: perineum thickness, perimeter of the nuclei of neurolemocyte cell, perimeter of myelinated axons, perimeter of myelin, the fibroblastocyte core width and length of the fibroblastocyte nucleus. The results show that the continuous mode ultrasound stimulates the regeneration of injured spinal nerve compression.

Origem e distribuição dos nervos isquiáticos em caprinos da raça Saanen / Origin and distribution of the ischiatic nerves in goats of the Saanen breed

Estudaram-se a origem e distribuição dos nervos isquiáticos, de ambos os antímeros, em 30 caprinos (Capra hircus) da raça Saanen, sendo 16 machos e 14 fêmeas. Estes animais foram coletados após morte natural e submetidos à fixação em solução aquosa, a 10 por cento, de formaldeído. Os nervos isquiáticos originaram-se 28 vezes (93,3 por cento) do ramo ventral do sexto nervo espinhal lombar e dos ramos ventrais do primeiro e segundo nervos espinhais sacrais; além disso, esses nervos tabém receberam duas vezes (6,7 por cento), contribuição do ramo ventral do terceiro nervo espinhal sacral. Os nervos isquiáticos cederam, em todos os animais, ramos para os músculos glúteos médios, glúteos profundos, gluteobíceps, gêmeos, semitendíneos e semimembranáceos. Sobretudo, notaram-se arranjos peculiares desses ramos musculares para cada espécime. Através da aplicação da prova de Wilcoxon, com nível de significância de 0,05, não se observaram diferenças significativas entre as freqüências de ramos musculares dos nervos isquiáticos, que foram cedidos para os antímeros direito e esquerdo, e ainda em relação ao sexo dos caprinos da presente investigação.

The origin and distribution of the ischiatic nerves at both sides were studied in 30 goats (Capra hircus) of the Saanen breed, being 16 males and 14 females. These specimens were collected after natural death of the animals and submitted to fixation in a 10 percent formaldehyde solution. The ischiatic nerves arose from the ventral branch of the sixth lumbar and the first and second sacral spinal nerves in 28 cases (93.3 percent). In addition, these nerves also received contributions from the ventral branch of the third sacral spinal nerve in two cases (6.7 percent) at both sides. In all animals, the right and left ischiatic nerves gave off branches to the muscles gluteus medius, gluteus profundus, gluteobiceps, gemelli, semitendinosus, and semimembranosus muscles. In particular, peculiar arrangements of these muscular branches were noticed for each specimen. By using the Wilcoxon test with significance level at 0.05, there were no significant differences among the frequencies of muscular branches of the ischiatic nerves emitted to the right and left sides, and also in relation to the sex of the goats in the present investigation.

The Interaction of Gabapentin and N(6)-(2-phenylisopropyl)-adenosine R-(-)isomer (R-PIA) on Mechanical Allodynia in Rats with a Spinal Nerve Ligation

We examined the antiallodynic interaction between gabapentin and adenosine A1 receptor agonist, N(6)-(2-phenylisopropyl)-adenosine R-(-)isomer (R-PIA), in a rat model of nerve ligation injury. Rats were prepared with ligation of left L5-6 spinal nerves and intrathecal catheter implantation for drug administration. Mechanical allodynia was measured by applying von Frey filaments. Gabapentin and R-PIA were administered to obtain the dose-response curve and the 50% effective dose (ED50). Fractions of ED50s were administered concurrently to establish the ED50 of the drug combination. The drug interaction between gabapentin and R-PIA was analyzed using the isobolographic method. Adenosine A1 receptor antagonist was administered intrathecally to examine the reversal of the antiallodynic effect. Locomotor function changes were evaluated by rotarod testing. Intrathecal gabapentin and R-PIA and their combination produced a dose-dependent antagonism against mechanical allodynia without severe side effects. Intrathecal gabapentin synergistically enhanced the antiallodynic effect of R-PIA when coadministered. There were no significant changes in rotarod performance time, except gabapentin 300 microgram. In the combination group, the maximal antiallodynic effect was reversed by A1 adenosine receptor antagonist. These results suggest that activation of adenosine A1 receptors at the spinal level is required for the synergistic interaction on the mechanical allodynia.

The Thai Anesthesia Incidents Study (THAI Study) on nerve injury associated with anesthesia.

OBJECTIVES: The Thai Anesthesia Incidents Study (THAI Study) database was used to identify the incidence, outcome and contributing factors of nerve injuries associated with anesthesia in Thai people. MATERIAL AND METHOD: A prospective multicenter study was conducted in 20 hospital in Thailand from February 1, 2003 to January 31, 2004. All patients underwent anaesthesia were monitored for nerve injuries during the first 24 hours. The details of nerve injuries were recorded and analysed. RESULTS: The overall incidence of nerve injuries associated with anesthesia was 1.6 per 10,000 patients. Considering on spinal and regional anesthesia, the incidence was 5.2 per 10,000 patients. Lumbosacral roots comprised 65.4% of the injuries, the brachial plexus nerve 11.5%, and femoral nerve 7.7%. Contributing factors included type and duration of surgery and regional anesthesia. CONCLUSION: The incidence of nerve injuries associated with anesthesia in Thailand was 1.5 per 10,000 patients. The spinal anesthesia was predominantly associated with injury of lumbosacral root.

The Effect of Intrathecal Gabapentin on Mechanical and Thermal Hyperalgesia in Neuropathic Rats Induced by Spinal Nerve Ligation

Gabapentin decreases the level of glutamate and elevates that of garmma-amino-butyric acid in the central nervous system. Gabapentin was shown to have antinociceptive effects in several facilitated pain models. Intrathecal gabapentin was also known to be effective in reducing mechanical allodynia in animals with neuropathic pain. In this study, we investigated to see whether intrathecal gabapentin produces antihyperalgesic effects on thermal and mechanical hyperalgesia in neuropathic rats and whether its effects are associated with motor impairment. To induce neuropathic pain in Sprague-Dawley rats, left L5 and L6 spinal nerves were ligated. After a week, lumbar catheterization into subarachnoid space was performed. Then, paw withdrawal times to thermal stimuli and vocalization thresholds to paw pressure were determined before and up to 2 hr after intrathecal injection of gabapentin. Also, motor functions including performance times on rota-rod were determined. Intrathecal gabapentin attenuated significantly thermal and mechanical hyperalgesia in neuropathic rats, but did not block thermal and mechanical nociception in sham-operated rats. Intrathecal gabapentin of antihyperalgesic doses inhibited motor coordination performance without evident ambulatory dysfunction. This study demonstrates that intrathecal gabapentin is effective against thermal and mechanical hyperalgesia, in spite of moderate impairment of motor coordination.

Effects of MK-801 and Morphine on Spinal C-Fos Expression during the Development of Neuropathic Pain

The purpose of this study was to investigate the expression of c-fos in the spinal cord during the development of allodynia, induced by peripheral nerve injury. Following tight ligation of the left L5 and L6 spinal nerves of Sprague- Dawley rat, the lumbar spinal cord was postfixed following perfusion. Frontal frozen sections of 40nm were immunostained according to the peroxidase-antiperoxidase method. The allodynic threshold was checked with 8 calibrated von Frey filaments. MK-801 (0.3 mg/kg), morphine (3 mg/kg) and saline (as a placebo) were administered subcutaneously 30 min before, and 24 and 48 hrs after surgery. The tactile threshold decreased below 3 g since 2 days after surgery in the saline and morphine groups, but delayed a little in the MK-801 group. In the superficial layer the number of Fos-like immunoreactive neurones (Fos-LI) peaked at 2 hours and decreased thereafter, and reached normal levels 24 hrs following operation, for all groups. In the deep layer they were biphasic, - peaking at 2 and 24 hrs - in the saline group, but were suppressed in the morphine and MK-801 groups until 7 days following operation. The above discrepancy between the number of Fos-LI and the allodynic threshold showed that central sensitizations are not critically involved in the development of nerve injury induced tactile allodynia.