Risk Factor for Additional Intravenous Medication during Transforaminal Full-endoscopic Lumbar Discectomy under Local Anesthesia.

Transforaminal full-endoscopic lumbar discectomy (TELD) can be performed under local anesthesia. However, there have been no reports on risk factors for a change in vital signs or the need for additional medications to maintain adequate analgesia during this procedure. The purpose of this study was to identify risk factors for additional intravenous medication during TELD under local anesthesia. The following factors were retrospectively evaluated in 113 consecutive patients who underwent TELD under local anesthesia at our institution: demographic characteristics, radiological features at the intervertebral disc level, distance between the superior articular process and the exiting nerve root, height of the intervertebral disc, height of the bulging disc, height of the intervertebral foramen, and distance from the insertion site to the spinous process on magnetic resonance imaging (MRI) and computed tomography (CT) scans of the lumbar spine. Logistic regression analysis was performed to determine factors associated with the need for additional drugs. In all, 23 cases (20.4%) required additional intraoperative medications because of hypertension, hypotension, bradycardia, or pain. Logistic regression analysis revealed that age (partial regression coefficient 0.05, p = 0.02) and bulging disc height (partial regression coefficient -0.7, p = 0.003) influenced the need for additional drugs. There were significant associations of need for additional intravenous medication with older age (>62 years) and a smaller bulging disc height (<8.2 mm). Patients with these factors require close monitoring for changes in vital signs or increasing pain when performing TELD under local anesthesia and may need additional intravenous medication.

Rapamycin suppresses microglial activation and reduces the development of neuropathic pain after spinal cord injury.

Rapamycin is an inhibitor of the mammalian target of rapamycin (mTOR) signaling pathway, plays an important role in multiple cellular functions. Our previous study showed rapamycin treatment in acute phase reduced the neural tissue damage and locomotor impairment after spinal cord injury (SCI). However, there has been no study to investigate the therapeutic effect of rapamycin on neuropathic pain after SCI. In this study, we examined whether rapamycin reduces neuropathic pain following SCI in mice. We used a mouse model of thoracic spinal cord contusion injury, and divided the mice into the rapamycin-treated and the vehicle-treated groups. The rapamycin-treated mice were intraperitoneally injected with rapamycin (1 mg/kg) 4 h after SCI. The rapamycin treatment suppressed phosphorylated-p70S6K in the injured spinal cord that indicated inhibition of mTOR. The rapamycin treatment significantly improved not only locomotor function, but also mechanical and thermal hypersensitivity in the hindpaws after SCI. In an immunohistochemical analysis, Iba-1-stained microglia in the lumbar spinal cord was significantly decreased in the rapamycin-treated mice. In addition, the activity of p38 MAPK in the lumbar spinal cord was significantly attenuated by rapamycin treatment. Furthermore, phosphorylated-p38 MAPK-positive microglia was relatively decreased in the rapamycin-treated mice. These results indicated rapamycin administration in acute phase to reduce secondary neural tissue damage can contribute to the suppression of the microglial activation in the lumbar spinal cord and attenuate the development of neuropathic pain after SCI. The present study first demonstrated that rapamycin has significant therapeutic potential to reduce the development of neuropathic pain following SCI. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:93-103, 2017.