Dynamically evoked, discrete-threshold electromyography in the extreme lateral interbody fusion approach

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Because the psoas muscle, which contains nerves of the lumbar plexus, is traversed during the extreme lateral interbody fusion (XLIF) approach, appropriate nerve monitoring is needed to avoid nerve injury during surgery and prevent approach-related neural deficit. This study was performed to assess the effectiveness of dynamically evoked electromyography (EMG) to detect and prevent neural injury during the XLIF approach.</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>One hundred two patients undergoing XLIF at L3–4 and/or L4–5 were enrolled in a prospective, multicenter, nonrandomized clinical study. The EMG threshold values for each of the 3 successive dilators were recorded at the surface of the psoas muscle, mid-psoas, and on the spine. At each location, the dilators were rotated 360°, taking recordings immediately posterior, superior, anterior, and inferior. For each dilator, the authors noted the rotational position (the angle in degrees) at which the lowest threshold was found. Findings of pre- and postoperative neurological examinations were also recorded.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Nerves were identified within proximity of the dilators (alert-level EMG feedback) in 55.7% of all cases during the XLIF approach. Although nerves were more commonly identified in the posterior margin (63%), there was significant variability in the location of nerves identified. Despite the fact that the posterior half of the disc space was targeted in 90% of cases, no significant long-lasting neural deficits were identified in any case; 27.5% experienced new iliopsoas/hip flexion weakness and 17.6% experienced new postoperative upper medial thigh sensory loss. Transient motor deficits were identified in 3 patients (2.9%), and all had resolved by the 6-month follow-up visit.</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>The ability to identify and report a discrete, real-time EMG threshold during the transpsoas approach helps to avoid nerve injury and is required for the safe performance of the XLIF procedure. Additionally, nerve location is variable, thus reinforcing the need for real-time directional and proximity information.</jats:p></jats:sec>

Neurologic deficit following lateral lumbar interbody fusion

“…Tohmeh demonstrated that dynamically evoked, discrete-threshold electromyography reduces the risk of nerve injury during LLIF. However, even in this study, all cases with transient deficits had no concerning changes during intra-operative neuromonitoring assessment [12]. Furthermore, a case report by Houten shows two cases that had post-operative motor deficits following the transpsoas approach although the intra-operative monitoring did not detect anything [19].…”

“…Surgeons have theorized that this may be related to direct cutaneous nerve neuropraxia or an indirect mechanism via a psoas muscle inflammatory response due to mechanical dissection. The incidence of this varies considerably in the literature from 1 to 75% [2,[10][11][12]. Several studies have reported on post-operative neurologic deficits following LLIF.…”

“…Overall, the number of postoperative neurologic events ranges in literature between 0.6 and 33.6% after LLIF [10,11,[13][14][15][16]. In a study by Tohmeh et al [12] 28% of patients experienced a new iliopsoas weakness and 18% claimed of sensory loss at the upper medial thigh although intra-operative real-time monitoring was used to prevent neurologic deficits after LLIF. In a prospective multicenter trial similar numbers were reported, with 33% experiencing some motor weakness after surgery [13].…”

Complications of the Lateral Transpsoas Approach for Lumbar Interbody Arthrodesis: A Case Series and Literature Review

“…Studies from our systematic review that have characterized the complications of lateral transpsoas approaches (Table 2) included adverse medical outcomes (ileus, pneumonia, renal, pulmonary embolus, cardiac [26,27], anemia, volvulus [27], rhabdomyolysis [7], pleural effusion, sepsis [12]) and surgery-specific complications (vertebral fracture [14,26,27,32], end plate fracture [27], iatrogenic herniated nucleus pulposus [27], graft subsidence [7], sensory disturbance [14-16, 20, 26, 32, 33], Yes XLIF = extreme lumbar interbody fusion; ALIF = anterior lumbar interbody fusion; TDR = total disc replacement; fx = fracture; DDD = degenerative disc disease; HNP = herniated nucleus pulposus; EP = endplate; VB = vertebral body; OP = osteophyte; MI = myocardial infarction; DVT = deep venous thrombosis; PE = pulmonary embolism; A fib = atrial fibrillation; CSF = cerebrospinal fluid. motor deficits [12, 14-16, 20, 26, 27, 32, 33], incisional hernias [4,26], hardware failures [12,27], loss of fixation [15], malpositioned cage, retroperitoneal hemorrhage [32], hematoma [27],wound infection [12,20], durotomy, pneumothorax, and peritoneum perforation [33]). Second, none of the literature reviewed was of high quality.…”

Prevention of neurological complications using a neural monitoring system with a finger electrode in the extreme lateral interbody fusion approach

“…6,12,18,20,23,25 Therefore, neural monitoring is required for XLIF. 15,19,23 A dilator equipped with an electrode is inserted toward the vertebral region through the psoas major muscle while the threshold displayed on the monitor is observed. 19 Such surgery should be suspended when the insertion route is close to the lumbar plexus because of the invasive risk to the lumbar plexus.…”