title: Prevention of neurological complications using a neural monitoring system with a finger electrode in the extreme lateral interbody fusion approach.
abstract: OBJECTIVE Extreme lateral interbody fusion (XLIF) is a minimally disruptive surgical procedure that uses a lateral approach. There is, however, concern about the development of neurological complications when this approach is used, particularly at the L4-5 level. The authors performed a prospective study of the effects of a new neural monitoring system using a finger electrode to prevent neurological complications in patients treated with XLIF and compared the results to results obtained in historical controls. METHODS The study group comprised 36 patients (12 male and 24 female) who underwent XLIF for lumbar spine degenerative spondylolisthesis or lumbar spine degenerative scoliosis at L4-5 or a lower level. Using preoperative axial MR images obtained at the mid-height of the disc at the treated level, we calculated the psoas position value (PP%) by dividing the distance from the posterior border of the vertebral disc to the posterior border of the psoas major muscle by the anteroposterior diameter of the vertebral disc. During the operation, the psoas major muscle was dissected using an index finger fitted with a finger electrode, and threshold values of the dilator were recorded before and after dissection. Eighteen cases in which patients had undergone the same procedure for the same indications but without use of the finger electrode served as historical controls. Baseline clinical and demographic characteristics, PP values, clinical results, and neurological complications were compared between the 2 groups. RESULTS The mean PP% values in the control and finger electrode groups were 17.5% and 20.1%, respectively (no significant difference). However, 6 patients in the finger electrode group had a rising psoas sign with PP% values of 50% or higher. The mean threshold value before dissection in the finger electrode group was 13.1 ± 5.9 mA, and this was significantly increased to 19.0 ± 1.5 mA after dissection (p < 0.001). A strong negative correlation was found between PP% and threshold values before dissection, but there was no correlation with threshold values after dissection. The thresholds after dissection improved to 11 mA or higher in all patients. There were no serious neurological complications in any patient, but there was a significantly lower incidence of transient neurological symptoms in the finger electrode group (7 [38%] of 18 cases vs 5 [14%] of 36 cases, p = 0.047). CONCLUSIONS The new neural monitoring system using a finger electrode may be useful to prevent XLIF-induced neurological complications.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine; and.|Spine Surgery and Related Research Center, Nantan General Hospital, Nantan City, Kyoto, Japan.
authors.forename: Wataru
authors.initials: W
authors.lastname: Narita
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine; and.
authors.forename: Ryota
authors.initials: R
authors.lastname: Takatori
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine; and.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine; and.
authors.forename: Masateru
authors.initials: M
authors.lastname: Nagae
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine; and.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Tonomura
authors.affiliation: Spine Surgery and Related Research Center, Nantan General Hospital, Nantan City, Kyoto, Japan.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Hayashida
authors.affiliation: Spine Surgery and Related Research Center, Nantan General Hospital, Nantan City, Kyoto, Japan.
authors.forename: Taku
authors.initials: T
authors.lastname: Ogura
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine; and.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine; and.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D004566:Electrodes; D005260:Female; D005385:Fingers / Q000503:physiopathology; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery; D064795:Intraoperative Neurophysiological Monitoring / Q000295:instrumentation / Q000379:methods*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D011183:Postoperative Complications / Q000517:prevention & control*; D016658:Psoas Muscles / Q000000981:diagnostic imaging; D012600:Scoliosis / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery; D013123:Spinal Fusion / Q000379:methods*; D013168:Spondylolisthesis / Q000150:complications / Q000000981:diagnostic imaging / Q000601:surgery
keywords: ALIF = anterior lumbar interbody fusion; BLN-VAS = VAS for gluteal and lower limb numbness; BLP-VAS= VAS for gluteal and lower-limb pain; BMI = body mass index; JOA = Japanese Orthopaedic Association; LBP-VAS = VAS for low-back pain; PP% = psoas position (expressed as a percentage); VAS = visual analog scale; XLIF; XLIF = extreme lateral interbody fusion; complications; extreme lateral interbody fusion; finger electrode; lumbar; minimally invasive spine stabilization; neural monitoring