Monitoring of somatosensory and motor evoked potentials during open reduction and internal fixation of pelvis and acetabular fractures

Evoked potential as an adjuvant predictive tool for neurological deficit in acetabular and pelvic ring injuries: A meta-analysis

OBJECTIVES

To identify the value of the evoked potential as an adjuvant predictive tool in pelvic ring and acetabulum fractures focusing on the neurological deficit.

MATERIAL AND METHODS

Adhering to PRISMA guidelines, we performed a systematic review with a priori design to identify randomized controlled trials, retrospective and prospective cohort studies, and case-control studies of interventions in acetabular and pelvic ring injuries. The search strategy included the use of Title/Abstract related to: ("somatosensory" or "evoked potential" or "electrophysiology") and ("randomized controlled trials" or "clinical studies" or "controlled clinical trial" or "systematic literature review" or "meta-analysis" or "review" or "overview") and ("complications"). From 01/1985 to 12/2019, we searched MEDLINE, PubMed, EMBASE, and Cochrane, Centre for Reviews and Dissemination, reference lists and journals. The PRISMA checklist was adopted to evaluate reporting quality. Two reviewers independently selected studies and extracted data. Statistical analysis was conducted to assess the probability of evoked potential tests performed on random samples, with the assumption of normal distribution of the populations from which they were derived and knowledge of the parametric variance.

RESULTS

Five articles fulfilled eligibility criteria.

CONCLUSION

Evoked potential tests can quickly and accurately detect imminent neurological impairment during surgery of acetabular and pelvic ring injuries. This results in significantly better surgical outcomes, although in some cases the irreversible nature of the injury cannot be prevented.

The effect of loco-regional anaesthesia on motor activity induced by direct stimulation of the sciatic nerve in dogs

A prospective, randomised, blinded, case-controlled clinical study was designed using client-owned dogs undergoing unilateral pelvic limb orthopaedic surgery, to determine the effect on induced motor activity by electrical stimulation of the sciatic nerve distal to the site of local anaesthetic administration. Dogs were administered 0.5% bupivacaine either extradurally or via a femoral and transgluteal sciatic electrolocation-guided nerve block prior to pelvic limb surgery. Motor response to electrical stimulation of branches of the sciatic nerve was tested and the minimum current required to induce muscle twitch was recorded prior to bupivacaine administration. Provided sensory blockade had been deemed successful intraoperatively, testing was repeated postoperatively, with each dog acting as its own control. Paired t-tests were performed to compare pre- and postoperative minimum currents. Eleven dogs administered extradural and 11 dogs administered femoral and sciatic perineural bupivacaine were eligible for post-operative testing. All dogs displayed normal motor response to electrical stimulation of the sciatic nerve at both sites tested before and after bupivacaine administration. There was no significant difference in the minimum current required to induce muscle twitch between pre- and post-operative testing (P = 0.31 sciatic site, P = 0.36 peroneal site), nor between the two groups using different loco-regional anaesthetic techniques (minimum P = 0.13). This study shows that stimulation of the sciatic nerve distal to the site of bupivacaine administration induces motor activity, despite adequate sensory blockade. This is relevant in surgical cases where mechanical stimulation of the sciatic nerve might be expected and needs to be recognised to avoid postoperative neurapraxia.

Somatosensory evoked potential monitoring of peripheral nerves during external fixation for limb lengthening and correction of deformity in children

We undertook a retrospective analysis of 306 procedures on 233 patients, with a mean age of 12 years (1 to 21), in order to evaluate the use of somatosensory evoked potential (SSEP) monitoring for the early detection of nerve compromise during external fixation procedures for limb lengthening and correction of deformity. Significant SSEP changes were identified during 58 procedures (19%). In 32 instances (10.5%) the changes were transient, and resolved once the surgical cause had been removed. The remaining 26 (8.5%) were analysed in two groups, depending on whether or not corrective action had been performed in response to critical changes in the SSEP recordings. In 16 cases in which no corrective action was taken, 13 (81.2%, 4.2% overall) developed a post-operative neurological deficit, six of which were permanent and seven temporary, persisting for five to 18 months. In the ten procedures in which corrective action was taken, four patients (40%, 1.3% overall) had a temporary (one to eight months) post-operative neuropathy and six had no deficit. After appropriate intervention in response to SSEP changes, the incidence and severity of neurological deficits were significantly reduced, with no cases of permanent neuropathy. SSEP monitoring showed 100% sensitivity and 91% specificity for the detection of nerve injury during external fixation. It is an excellent diagnostic technique for identifying nerve lesions when they are still highly reversible.