Diagnostic accuracy of somatosensory evoked potential monitoring during scoliosis fusion

Diagnostic utility of different types of somatosensory evoked potential changes in pediatric idiopathic scoliosis correction surgery

PURPOSE

To evaluate the diagnostic accuracy of intraoperative somatosensory evoked potential (SSEP) monitoring and types of SSEP changes in predicting the risk of postoperative neurological outcomes during correction surgery for idiopathic scoliosis (IS) in the pediatric age group (≤ 21 years).

METHODS

Database review was performed to identify literature on pediatric patients with IS who underwent correction with intraoperative neuromonitoring. The sensitivity, specificity, and diagnostic odds ratio (DOR) of transient and persistent SSEP changes and complete SSEP loss in predicting postoperative neurological deficits were calculated.

RESULTS

Final analysis included 3778 patients. SSEP changes had a sensitivity of 72.9%, specificity of 96.8%, and DOR of 102.3, while SSEP loss had a sensitivity of 41.8%, specificity of 99.3%, and DOR of 133.2 for predicting new neurologic deficits. Transient and persistent SSEP changes had specificities of 96.8% and 99.1%, and DORs of 16.6 and 59, respectively.

CONCLUSION

Intraoperative SSEP monitoring can predict perioperative neurological injury and improve surgical outcomes in pediatric scoliosis fusion surgery.

LEVEL OF EVIDENCE

Level 2. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Lower Extremity Somatosensory Evoked Potentials Predict Functional Outcomes in Complete Traumatic Cervical Spinal Cord Injury

BACKGROUND

Traumatic cervical spinal cord injury (tCSCI) is often a debilitating injury, making early prognosis important for medical and surgical planning. Currently, the best early predictors of prognosis are physical examination, imaging studies, and patient demographics. Despite these factors, patient outcomes continue to vary significantly. The purpose of this study was to evaluate the prognostic value of somatosensory evoked potentials (SSEPs) with functional outcomes in tCSCI patients.

METHODS

A retrospective study was conducted on prospectively collected data from 2 academic institutions. Patients 18 years and older who had tCSCI and underwent posterior cervical decompression and stabilization with intraoperative neuromonitoring were reviewed. The outcomes of interest were the American Spinal Injury Association (ASIA) Impairment Scale (AIS) grade and ASIA motor score at follow-up. Outcomes measures were assessed via student t-tests, chi-squared tests, and multivariable regression analysis.

RESULTS

A total of 79 patients were included. In complete injuries, detectable lower extremity SSEPs were associated with higher ASIA motor scores at follow-up (P = 0.002), greater increases in ASIA motor scores at follow-up (P = 0.009), and a greater likelihood of clinically important improvement in ASIA motor score (P = 0.024). Incomplete, AIS grade C injuries has higher rates of grade conversion (P = 0.019) and clinically important improvement in ASIA motor score (P = 0.010), compared to AIS grade A or B injuries.

CONCLUSIONS

The detection of lower extremity SSEP signals during initial surgical treatment of tCSCI is associated with greater improvement in ASIA motor scores postoperatively. The association is most applicable to patients with complete injury.

Deformity angular ratio is associated with neuromonitoring changes without a vertebral column resection: spinal deformity is more influential than type of surgery

PURPOSE

The purpose of this study is to investigate the effect of the deformity angular ratio (DAR) on intra-operative neuromonitoring (IONM) signal changes during posterior spinal fusion (PSF) without vertebral column resection (VCR).

METHODS

Retrospective review of severe pediatric spinal deformity patients treated with PSF without VCR or three-column osteotomy from 2008 to 2018. Exclusion criteria were prior instrumentation, lack of IONM, and incomplete radiographic data. Coronal DAR (C-DAR), sagittal DAR (S-DAR), and total DAR (T-DAR) were calculated and compared between patients with IONM signal loss and those without.

RESULTS

Two hundred and fifty-three patients met inclusion criteria. Forty-seven of two hundred and fifty-three (19%) patients had IONM signal loss. Intra-operative wake-up test was performed in seven cases; three of seven (43%) had a neurological deficit on wake-up test. All neurological deficits resolved at a mean of 41 days postop. IONM loss was associated with increased kyphosis (p = 0.003) and was not associated with Cobb angle (p = 0.16). S-DAR (p = 0.03) and T-DAR (p = 0.005) were associated with IONM signal loss but C-DAR was not (p = 0.06). Increased incidence of IONM signal loss was seen with S-DAR > 7 (p = 0.02) or T-DAR > 27 (p = 0.02). Twenty-four of ninety-two (26%) patients with S-DAR > 7 had IONM signal loss compared to twenty-three of one hundred and sixty-one (14%) with S-DAR ≤ 7 (OR, 2.1; 95% CI, 1.1-4.0). Seven of sixteen (44%) patients with T-DAR > 27 had signal loss compared to forty of two hundred and thirty-seven (17%) patients with T-DAR ≤ 27 (OR, 3.8; 95% CI, 1.3-10.9).

CONCLUSION

Patients with S-DAR > 7 or T-DAR > 27 have a higher risk of IONM loss during pediatric PSF even in the absence of a VCR or three-column osteotomies.

LEVEL OF EVIDENCE II

Intraoperative Optical Monitoring of Spinal Cord Hemodynamics Using Multiwavelength Imaging System

The spinal cord is a major structure of the central nervous system allowing, among other things, the transmission of afferent sensory and efferent motor information. During spinal surgery, such as scoliosis correction, this structure can be damaged, resulting in major neurological damage to the patient. To date, there is no direct way to monitor the oxygenation of the spinal cord intraoperatively to reflect its vitality. This is essential information that would allow surgeons to adapt their procedure in case of ischemic suffering of the spinal cord. We report the development of a specific device to monitor the functional status of biological tissues with high resolution. The device, operating with multiple wavelengths, uses Near-InfraRed Spectroscopy (NIRS) in combination with other additional sensors, including ElectroNeuroGraphy (ENG). In this paper, we focused primarily on aspects of the PhotoPlethysmoGram (PPG), emanating from four different light sources to show in real time and record biological signals from the spinal cord in transmission and reflection modes. This multispectral system was successfully tested in in vivo experiments on the spinal cord of a pig for specific medical applications.

Diagnostic Accuracy of SSEP Changes During Lumbar Spine Surgery for Predicting Postoperative Neurological Deficit: A Systematic Review and Meta-Analysis

STUDY DESIGN

This study is a meta-analysis of prospective and retrospective studies identified in PubMed, Web of Science, and Embase with outcomes of patients who received intraoperative somatosensory-evoked potential (SSEP) monitoring during lumbar spine surgery.

OBJECTIVE

The objective of this study is to determine the diagnostic accuracy of intraoperative lower extremity SSEP changes for predicting postoperative neurological deficit. As a secondary analysis, we evaluated three subtypes of intraoperative SSEP changes: reversible, irreversible, and total signal loss.

SUMMARY OF BACKGROUND DATA

Lumbar decompression and fusion surgery can treat lumbar spinal stenosis and spondylolisthesis but carry a risk for nerve root injury. Published neurophysiological monitoring guidelines provide no conclusive evidence for the clinical utility of intraoperative SSEP monitoring during lumbar spine surgery.

METHODS

A systematic review was conducted to identify studies with outcomes of patients who underwent lumbar spine surgeries with intraoperative SSEP monitoring. The sensitivity, specificity, and diagnostic odds ratio (DOR) were calculated and presented with forest plots and a summary receiver operating characteristic curve.

RESULTS

The study cohort consisted of 5607 patients. All significant intraoperative SSEP changes had a sensitivity of 44% and specificity of 97% with a DOR of 22.13 (95% CI, 11.30-43.34). Reversible and irreversible SSEP changes had sensitivities of 28% and 33% and specificities of 97% and 97%, respectively. The DORs for reversible and irreversible SSEP changes were 13.93 (95% CI, 4.60-40.44) and 57.84 (95% CI, 15.95-209.84), respectively. Total loss of SSEPs had a sensitivity of 9% and specificity of 99% with a DOR of 23.91 (95% CI, 7.18-79.65).

CONCLUSION

SSEP changes during lumbar spine surgery are highly specific but moderately sensitive for new postoperative neurological deficits. Patients who had postoperative neurological deficit were 22 times more likely to have exhibited intraoperative SSEP changes.Level of Evidence: 2.

What is the predictive value of intraoperative somatosensory evoked potential monitoring for postoperative neurological deficit in cervical spine surgery?-a meta-analysis

BACKGROUND CONTEXT

Cervical decompression and fusion surgery remains a mainstay of treatment for a variety of cervical pathologies. Potential intraoperative injury to the spinal cord and nerve roots poses nontrivial risk for consequent postoperative neurologic deficits. Although neuromonitoring with intraoperative somatosensory evoked potentials (SSEPs) is often used in cervical spine surgery, its therapeutic value remains controversial.

PURPOSE

The purpose of the present study was to evaluate whether significant SSEP changes can predict postoperative neurologic complications in cervical spine surgery. A subgroup analysis was performed to compare the predictive power of SSEP changes in both anterior and posterior approaches.

STUDY DESIGN

The present study was a meta-analysis of the literature from PubMed, Web of Science, and Embase to identify prospective/retrospective studies with outcomes of patients who underwent cervical spine surgeries with intraoperative SSEP monitoring.

PATIENT SAMPLE

The total cohort consisted of 7,747 patients who underwent cervical spine surgery with intraoperative SSEP monitoring.

METHODS

Inclusion criteria for study selection were as follows: (1) prospective or retrospective cohort studies, (2) studies conducted in patients undergoing elective cervical spine surgery not due to aneurysm, tumor, or trauma with intraoperative SSEP monitoring, (3) studies that reported postoperative neurologic outcomes, (4) studies conducted with a sample size ≥20 patients, (5) studies with only adult patients ≥18 years of age, (6) studies published in English, (7) studies inclusive of an abstract.

OUTCOME MEASURES

The sensitivity, specificity, diagnostic odds ratio (DOR), and likelihood ratios of overall SSEP changes, reversible SSEP changes, irreversible SSEP changes, and SSEP loss for predicting postoperative neurological deficit were calculated.

RESULTS

The total rate of postoperative neurological deficits was 2.50% (194/7,747) and the total rate of SSEP changes was 7.36% (570/7,747). The incidence of postoperative neurological deficit in patients with intraoperative SSEP changes was 16.49% (94/570) while only 1.39% (100/7,177) in patients without. All significant intraoperative SSEP changes had a sensitivity of 46.0% and specificity of 96.7% with a DOR of 27.32. Reversible and irreversible SSEP changes had sensitivities of 17.7% and 37.1% and specificities of 97.5% and 99.5%, respectively. The DORs for reversible and irreversible SSEP changes were 9.01 and 167.90, respectively. SSEP loss had a DOR of 51.39, sensitivity of 17.3% and specificity 99.6%. In anterior procedures, SSEP changes had a DOR of 9.60, sensitivity of 34.2%, and specificity of 94.7%. In posterior procedures, SSEP changes had a DOR of 13.27, sensitivity of 42.6%, and specificity of 94.0%.

CONCLUSIONS

SSEP monitoring is highly specific but weakly sensitive for postoperative neurological deficit following cervical spine surgery. The analysis found that patients with new postoperative neurological deficits were nearly 27 times more likely to have had significant intraoperative SSEP change. Loss of SSEP signals and irreversible SSEP changes seem to indicate a much higher risk of injury than reversible SSEP changes.

Unilateral Nerve Root Ligation for Multilevel Vertebral Column Resection After Fixed Post-infectious Deformity

Kyphotic deformity is a well-recognized complication of thoracic vertebral osteomyelitis, often requiring multi-level vertebral column resection for mobilization of the spine and reduction of the deformity. We present a case of severe post-infectious kyphosis treated with multi-level vertebral column resection via a unilateral approach. We obtained excellent decompression and deformity correction without neurologic decline. We review relevant literature regarding spinal cord blood supply and known potential complication of nerve root ligations.

Postsurgical Neuropathy: A Descriptive Review

Postsurgical neuropathies represent an infrequent but potentially devastating complication of surgery that may result in significant morbidity with medicolegal implications. Elucidation of this phenomenon has evolved over the past few decades, with emerging evidence for not only iatrogenic factors contributing to this process but also inflammatory causes. This distinction can be important; for instance, cases in which inflammatory etiologies are suspected may benefit from further investigations including nerve biopsy and may benefit from treatment in the form of immunotherapy. In contrast, postsurgical neuropathies due to perioperative causes including anesthesia, traction, compression, and transection will not benefit in the same manner. This article summarizes early and current literature surrounding the frequency of new neurologic deficits after various surgical types, potential causes including anatomical and inflammatory considerations, and roles for treatment. To capture the scope of the issue, a literature review was conducted for human studies in English via MEDLINE and EMBASE from January 1, 1988 to March 31, 2018. Search terms included anesthesia and/or surgical procedures, operative, peripheral nervous system diseases, trauma, mononeuropathy, polyneuropathy, peripheral nervous system, nerve compression, neuropathy, plexopathy, postoperative, postsurgical, perioperative, complication. We excluded case series with less than 10 patients and review papers. We then narrowed the studies to those presented highlighting key concepts in postsurgical neuropathy.

Benefit of Intraoperative Neurophysiological Monitoring in a Pediatric Patient with Spinal Dysmorphism, Split Cord Malformation, and Scoliosis

Intraoperative neurophysiological monitoring (IONM) consists of a group of neurodiagnostic techniques that assess the nervous system's functional integrity during surgical operations. A retrospective analysis of a pediatric female patient was conducted who underwent 12 operations for the correction of scoliosis, tethered cord, and split spinal cord wherein IONM played an important role. From age 3 to 6, she underwent six procedures including a release of the tethered cord, resection of the filum terminale, removal of a T11-T12 bony spur, release of L3 adhesions, repair of subcutaneous meningocele, and correction of scoliosis with a vertical expandable prosthetic titanium rod (VEPTR) technique without the use of IONM. However, a multimodality IONM protocol with somatosensory evoked potentials, transcranial electrical motor evoked potentials (TCeMEP), and an electromyogram was utilized during the later procedures. At age 6 (the seventh procedure), a VEPTR expansion was performed, with loss and recovery of the lower extremity motor evoked potentials. The postoperative magnetic resonance imaging (MRI) showed a partial split cord malformation with retethering of the spinal cord. We repaired her split cord malformation and tethered cord while employing IONM. Using IONM for her operation was crucial because a sudden significant loss of TCeMEP resulted in a cancellation of the procedure; the MRI showed a thick remnant attached to the spinal cord. If the procedure was performed without IONM, we could have missed the underlying pathology, an error that may have resulted in paraplegia. We strongly recommend using IONM during high-risk surgical procedures to help significantly reduce the risk of permanent postoperative complications.