Preemptive analgesia for postoperative pain relief in thoracolumbosacral spine operations: a double-blind, placebo-controlled randomized trial.

OBJECTIVEPreemptive administration of analgesic medication is more effective than medication given after the onset of the painful stimulus. The efficacy of preoperative or preemptive pain relief after thoracolumbosacral spine surgery has not been well studied. The present study was a double-blind, placebo-controlled randomized trial of preemptive analgesia with a single-shot epidural injection in adult patients undergoing spine surgery.METHODSNinety-nine adult patients undergoing thoracolumbosacral operations via a posterior approach were randomized to receive a single shot of either epidural placebo (group 1), hydromorphone alone (group 2), or bupivacaine with hydromorphone (group 3) before surgery at the preoperative holding area. The primary outcome was the presence of opioid sparing and rescue time-defined as the time interval from when a patient was extubated to the time pain medication was first demanded during the postoperative period. Secondary outcomes include length of stay at the postanesthesia care unit (PACU), pain score at the PACU, opioid dose, and hospital length of stay.RESULTSOf the 99 patients, 32 were randomized to the epidural placebo group, 33 to the hydromorphone-alone group, and 34 to the bupivacaine with hydromorphone group. No significant difference was seen across the demographics and surgical complexities for all 3 groups. Compared to the control group, opioid sparing was significantly higher in group 2 (57.6% vs 15.6%, p = 0.0007) and group 3 (52.9% vs 15.6%, p = 0.0045) in the first demand of intravenous hydromorphone as a supplemental analgesic medication. Compared to placebo, the rescue time was significantly higher in group 2 (187 minutes vs 51.5 minutes, p = 0.0014) and group 3 (204.5 minutes vs 51. minutes, p = 0.0045). There were no significant differences in secondary outcomes.CONCLUSIONSThe authors' study demonstrated that preemptive analgesia in thoracolumbosacral surgeries can significantly reduce analgesia requirements in the immediate postoperative period as evidenced by reduced request for opioid medication in both analgesia study groups who received a preoperative analgesic epidural. Nonetheless, the lack of differences in pain score and opioid dose at the PACU brings into question the role of preemptive epidural opioids in spine surgery patients. Further work is necessary to investigate the long-term effectiveness of preemptive epidural opioids and their role in pain reduction and patient satisfaction.Clinical trial registration no.: NCT02968862 (clinicaltrials.gov).

Brain mapping using transcranial magnetic stimulation.

Transcranial magnetic stimulation (TMS) is a novel brain stimulation technique that has advanced the understanding of brain physiology, and has diagnostic value as well as therapeutic potential for several neuropsychiatric disorders. The stimulation involves restricted cortical and subcortical regions, and, when used in combination with a visually guided technique, results in improved accuracy to target specific areas, which may also influence the outcome desired. This article reviews the principles underlying the mechanism of action of TMS, and discusses its use to obtain functional maps of the motor and visual cortex, including technical considerations for accuracy and reproducibility of mapping procedures.

An objective assessment of the advantages of retrograde parotidectomy.

OBJECTIVE: This study was undertaken to determine whether the retrograde parotidectomy approach is more efficient than standard anterograde parotidectomy without compromise of surgical effectiveness. METHODS: A retrospective analysis of patients undergoing parotidectomy was conducted. Cases were divided into those undergoing retrograde facial nerve dissection and those undergoing standard anterograde facial nerve dissection. From the review of medical records, standard demographic information, surgical time, histopathology, estimated blood loss, and use of facial nerve monitoring were determined. Pathology was reviewed to determine the size of the overall resection specimen as well as the size of the lesion excised and margin status. Postoperative complications were also recorded. Statistical comparisons were conducted between these 2 approaches for these clinical variables such as surgical time, blood loss, tumor margin status and relative volume of tissue removed during parotidectomy. RESULTS: 45 patients undergoing parotidectomy met inclusion criteria. The average patient age was 50.8 years with a female preponderance (73%). There were 19 standard parotidectomies and 26 retrograde approaches. Compared to standard parotidectomy, retrograde parotidectomy consumed less operative time (3.2 versus 1.8 hours, respectively), decreased intraoperative blood loss (67.9 cc versus 40.3 cc, respectively), and resulted in less removal of normal parotid tissue (volume of normal parotid tissue removed in excess of tumor: 23.0 cc versus 6.0 cc, respectively). No significant difference in surgical margin status was noted between anterograde and retrograde parotidectomy (P = 0.452). CONCLUSIONS: In appropriately selected cases, compared with standard anterograde parotidectomy, retrograde parotidectomy is more efficient and spares normal parotid tissue without compromising surgical margins. Facial nerve monitoring provides a useful adjunct for retrograde dissection.

Monitoring the electroencephalogram during bypass procedures.

Electroencephalographic monitoring has been performed since the early days of cardiopulmonary bypass. Despite this long experience, the technology has never been widely used for cardiac operations. This review examines the reasons for the limited use and describes technological advances that may alter this pattern.

Efficacious use of a cap shaped coil for transcranial magnetic stimulation of descending motor paths.

We report another technique of transcranial magnetic stimulation (TMS) for exciting the originating cells of the descending corticospinal tract. A cap shaped TMS coil has been described for simultaneously exciting muscles in all four extremities. This TMS coil is useful for monitoring the functional integrity of the descending motor paths during spinal cord surgery, because information regarding the integrity of both the left and right sides of the spinal cord motor paths can be obtained concurrently. Despite the improved design of the cap coil, careful placement is required for achieving bilateral spinal cord motor responses. Cortical mapping was used to identify the optimum scalp foci for the muscles studied. The cap coil must overlap these foci to simultaneously elicit compound muscle action potentials (CMAPs) in all four extremities. Increasing TMS stimulation intensity will increase the magnitude of the acquired CMAPs responses without significantly changing latency.

The use of transcranial magnetic stimulation for monitoring descending spinal cord motor function.

This report describes our initial clinical experience using transcranial magnetic stimulation for monitoring spinal cord motor function during surgical procedures. Motor evoked potentials were elicited using a cap shaped coil placed on the scalp of 27 patients while recording peripheral motor responses (compound muscle action potentials--CMAPs) from the upper (N = 1) or lower limbs (N = 26). Wherever possible, cortical somatosensory responses (SEPs) were also monitored by electrically stimulating the left and right posterior tibial nerve (N = 25) or the median nerve (N = 1). The judicious choice of anesthetic regimens resulted in successfully obtaining motor evoked responses (MEPs) in 21 of 27 patients and SEPs in 26 of 27 patients. Single pulse TMS resulted in peripheral muscle responses having large variability, whereas, the variability of SEPs was much less. Criteria based on response variability for assessing clinically significant changes in both MEPs and SEPs resulted in two false negative predictions for SEPs and none for MEPs when evaluating postoperative motor function. We recommend monitoring both sensory and motor pathways during procedures where placing the spinal cord at risk of damage.