The impact and value of uni- and multimodal intraoperative neurophysiological monitoring (IONM) on neurological complications during spine surgery: a prospective study of 2728 patients.

PURPOSE: We compared the value of different uni- and multimodal intraoperative neurophysiological monitoring (IONM) methods on the detection of neurological complications during spine surgery. METHODS: IONM data derived from sensory spinal and cortical evoked potentials combined with continuous electromyography monitoring, motor evoked potentials and spinal recording were evaluated in relation to subsequent post-operative neurological changes. Patients were categorised based on their true-positive or true-negative post-operative neurological status. RESULTS: In 2728 consecutive patients we had 909 (33.3%) IONM alerts. We had 8 false negatives (0.3%) with post-operative radicular deficit that completely recovered within 3 months, except for one. There was no false negative for spinal cord injury. 107 were true positives, and 23 were false positives. Multimodal IONM sensitivity and specificity were 93.0% and 99.1%, respectively. The frequency of neurological complications including minor deficits was 4.2% (n = 115), of which 0.37% (n = 10) were permanent. Analysis of the single IONM modalities varied between 13 and 81% to detect neurological complications compared with 93% when using all modalities. CONCLUSION: Multimodal IONM is more effective and accurate in assessing spinal cord and nerve root function during spine surgeries to reduce both neurological complications and false-negative findings compared to unimodal monitoring. We recommend multimodal IONM in all complex spine surgeries. These slides can be retrieved from Electronic Supplementary Material.

Biomechanical Modeling of Pterygium Radiation Surgery: A Retrospective Case Study.

Pterygium is a vascularized, invasive transformation on the anterior corneal surface that can be treated by Strontium-/Yttrium90 beta irradiation. Finite element modeling was used to analyze the biomechanical effects governing the treatment, and to help understand clinically observed changes in corneal astigmatism. Results suggested that irradiation-induced pulling forces on the anterior corneal surface can cause astigmatism, as well as central corneal flattening. Finite element modeling of corneal biomechanics closely predicted the postoperative corneal surface (astigmatism error -0.01D; central curvature error -0.16D), and can help in understanding beta irradiation treatment. Numerical simulations have the potential to preoperatively predict corneal shape and function changes, and help to improve corneal treatments.

Back pain in patients with degenerative spine disease and intradural spinal tumor: what to treat? when to treat?

BACKGROUND: Back pain is common in industrialized countries and one of the most frequent causes of work incapacity. Successful treatment is, therefore, not only important for improving the symptoms and the quality of life of these patients but also for socioeconomic reasons. Back pain is frequently caused by degenerative spine disease. Intradural spinal tumors are rare with an annual incidence of 2-4/1,00,000 and are mostly associated with neurological deficits and radicular and nocturnal pain. Back pain is not commonly described as a concomitant symptom, such that in patients with both a tumor and degenerative spine disease, any back pain is typically attributed to the degeneration rather than the tumor. OBJECTIVE: The aim of the present retrospective investigation was to study and analyze the impact of microsurgery on back/neck pain in patients with intradural spinal tumor in the presence of degenerative spinal disease in adjacent spinal segments. METHODS: Fifty-eight consecutive patients underwent microsurgical, intradural tumor surgery using a standardized protocol assisted by multimodal intraoperative neuromonitoring. Clinical symptoms, complications and surgery characteristics were documented. Standardized questionnaires were used to measure outcome from the surgeon's and the patient's perspectives (Spine Tango Registry and Core Outcome Measures Index). Follow-up included clinical and neuroradiological examinations 6 weeks, 3 months and 1 year postoperatively. RESULTS: Back/neck pain as a leading symptom and coexisting degenerative spine disease was present in 27/58 (47 %) of the tumor patients, and these comprised to group under study. Patients underwent tumor surgery only, without addressing the degenerative spinal disease. Remission rate after tumor removal was 85 %. There were no major surgical complications. Back/neck pain as the leading symptom was eradicated in 67 % of patients. There were 7 % of patients who required further invasive therapy for their degenerative spinal disease. CONCLUSIONS: Intradural spinal tumor surgery improves back/neck pain in patients with coexisting severe degenerative spinal disease. Intradural spinal tumors seem to be the only cause of back/neck pain more often than appreciated. In these patients suffering from both pathologies, there is a higher risk of surgical overtreatment than undertreatment. Therefore, elaborate clinical and radiological examinations should be performed preoperatively and the indication for stabilization/fusion should be discussed carefully in patients foreseen for first time intradural tumor surgery.

Multimodal intraoperative monitoring (MIOM) during 409 lumbosacral surgical procedures in 409 patients.

A prospective study on 409 patients who received multimodel intraoperative monitoring (MIOM) during lumbosacral surgical procedures between March 2000 and December 2005 was carried out. The objective of this study was to determine the sensitivity and specificity of MIOM techniques used to monitor conus medullaris, cauda equina and nerve root function during lumbosacral decompression surgery. MIOM has increasingly become important to monitor ascending and descending pathways, giving immediate feedback information regarding any neurological deficit during the decompression and stabilisation procedure in the lumbosacral region. Intraoperative spinal- and cortical-evoked potentials, combined with continuous EMG- and motor-evoked potentials of the muscles, were evaluated and compared with postoperative clinical neurological changes. A total of 409 consecutive patients with lumbosacral spinal stenosis with or without instability were monitored by MIOM during the entire surgical procedure. A total of 388 patients presented true-negative findings while two patients presented false negative and 1 patient false-positive findings. Eighteen patients presented true-positive findings where neurological deficit after the operation was intraoperatively predicted. Of the 18 true-positive findings, 12 patients recovered completely; however, 6 patients recovered only partially. The sensitivity of MIOM applied during decompression and fusion surgery of the lumbosacral region was calculated as 90%, and the specificity was calculated as 99.7%. On the basis of the results of this study, MIOM is an effective method of monitoring the conus medullaris, cauda equina and nerve root function during surgery at the lumbosacral junctions and might reduce postoperative surgical-related complications and therefore improve the long-term results.

The diagnostic value of multimodal intraoperative monitoring (MIOM) during spine surgery: a prospective study of 1,017 patients.

A prospective study of 1,017 patients who received MIOM during spine surgery procedures between March 2000 and December 2005. To determine the sensitivity and specificity of MIOM techniques used to monitor spinal cord and nerve roots function during spine surgery. MIOM has become a widely used method of monitoring neural function during spine surgery. Several techniques only monitor either ascending or descending pathways and thus may not provide sensitive or specific results. MIOM aims to monitor both ascending and descending pathways therefore giving immediate feedback information regarding any neurological deficits during the operation. Intraoperative sensory spinal and cortical evoked potentials, combined with monitoring of EMG and motor evoked potentials recorded from the spinal cord and muscles elicited by electrical motor cortex, spinal cord, cauda equina and nerve root stimulation, was evaluated and compared with post-operative clinical neurological changes. One thousand and seventeen consecutive patients underwent a total of 4,731 h of MIOM to evaluate any neural deficits that may have occurred during spine surgery. Of these, 935 were true negative cases, 8 were false negative cases, 66 were true positive cases and 8 were false positive cases, resulting in a sensitivity of 89% and a specificity of 99%. Based on the results of this study, MIOM is an effective method of monitoring the spinal cord functional integrity during spine surgery and therefore can lead to reduction of neurological deficit and consequently improve postoperative results.

The validity of multimodal intraoperative monitoring (MIOM) in surgery of 109 spine and spinal cord tumors.

In a prospective study of 109 patients with tumor of the spine MIOM was performed during the surgical procedure between March 2000 and December 2005. To determine the sensitivity and specificity of MIOM techniques used to monitor spinal cord and nerve root function during surgical procedure of spinal tumors. MIOM become an integrated procedure during surgical approach to intramedullar and extramedullar spine tumors. The combination of monitoring ascending and descending pathways may provide more sensitive and specific results than SEP alone giving immediate feedback information regarding any neurological deficit during the operation. Intraoperative sensory spinal and cerebral evoked potential combined with EMG recordings and motor evoked potential of the spinal cord and muscles were evaluated and compared with postoperative clinical neurological changes. One hundred and nine consecutive patients with spinal tumors of different aetiologies were monitored by the means of MIOM during the entire surgical procedure. Eighty-two patients presented true negative findings while two patients monitored false negative, one false positive and 24 patients true positive findings where neurological deficits after the operation were present. All patients with neurological deficit recovered completely or to pre-existing neurological situation. The sensitivity of MIOM applied during surgery of spinal tumors has been calculated of 92% and specificity 99%. Based upon the results of the study MIOM is an effective method of monitoring the spinal cord and nerve root function during surgical approach of spinal tumors and consequently can reduce or prevent the occurrence of postoperative neurological deficit.

Multimodal intraoperative monitoring (MIOM) during surgical decompression of thoracic spinal stenosis in 36 patients.

A prospective study of 36 patients who received multimodal intraoperative monitoring (MIOM) during decompression of thoracic spinal stenosis between March 2000 and December 2005 was chosen as the study design. The objective was to determine the sensitivity and specificity of MIOM techniques used for monitoring spinal cord during surgical thoracic decompression. The background data revealed that the surgical decompression for thoracic spinal stenosis is less frequent than in other regions of the spine. However, due to the relative narrow spinal canal, neurological complications could be severe. The combination of monitoring ascending and descending pathways may provide an early alert to the surgeon in order to alter the surgical procedure, and avoid neurological complications. The methods involved evaluation of intraoperative somatosensory spinal and cerebral evoked potentials and motor evoked potentials of the spinal cord and muscles that were compared with post operative clinical neurological changes. 36 consecutive patients with thoracic spinal stenosis of different aetiologies were monitored by the means of MIOM during the surgical procedure. 31 patients had true negative while one patient had false positive findings. Three patients had true positive and one patient had false negative findings. This indicates a sensitivity of 75% and a specificity of 97%. The one case of false negative findings recovered completely within 3 months. In conclusion, the MIOM is an effective method of monitoring the spinal cord during surgical decompression of the thoracic spine.

Multimodal intraoperative monitoring (MIOM) during cervical spine surgical procedures in 246 patients.

A prospective study of 246 patients who received multimodal intraoperative monitoring during cervical spine surgery between March 2000 and December 2005. To determine the sensitivity and specificity of MIOM techniques used to monitor spinal cord and nerve root function during cervical spine surgery. It is appreciated that complication rate of cervical spine surgery is low, however, there is a significant risk of neurological injury. The combination of monitoring of ascending and descending pathways may provide more sensitive and specific results giving immediate feedback information and/or alert regarding any neurological changes during the operation to the surgeon. Intraoperative somatosensory spinal and cerebral evoked potentials combined with continuous EMG and motor-evoked potentials of the spinal cord and muscles were evaluated and compared with postoperative clinical neurological changes. A total of 246 consecutive patients with cervical pathologies, majority spinal stenosis due to degenerative changes of cervical spine were monitored by means of MIOM during the surgical procedure. About 232 patients presented true negative while 2 patients false negative responses. About ten patients presented true positive responses where neurological deficit after the operation was predicted and two patients presented false positive findings. The sensitivity of MIOM applied during cervical spine procedure (anterior and/or posterior) was 83.3% and specificity of 99.2%. MIOM is an effective method of monitoring the spinal cord functional integrity during cervical spine surgery and can help to reduce the risk of neurological deficit by alerting the surgeon when monitoring changes are observed.

Multimodal intraoperative monitoring during surgery of spinal deformities in 217 patients.

A prospective study was performed on 217 patients who received MIOM during corrective surgery of spinal deformities between March 2000 and December 2005. Aim is to determine the sensitivity and specificity of MIOM techniques used to monitor spinal cord and nerve root function during corrective spine surgery. MIOM is becoming an increasingly used method of monitoring function during corrective spine surgery. The combination of monitoring of ascending and descending pathways may provide more sensitive and specific results giving immediate feedback information regarding any neurological deficits during the operation. Intraoperative somatosensory spinal and cerebral evoked potentials combined with continuous EMG and motor evoked potentials of the spinal cord and muscles were evaluated and compared with postoperative clinical neurological changes. A total of 217 consecutive patients with spinal deformities of different aetiologies were monitored by means of MIOM during the surgical procedure. Out of which 201 patients presented true negative findings while one patient presented false negative and three patients presented false positive findings. Twelve patients presented true positive findings where neurological deficit after the operation was predicted. All neurological deficits in those 12 patients recovered completely. The sensitivity of MIOM applied during surgery of spinal deformities has been calculated of 92.3% and the specificity 98.5%. Based upon the results of this study MIOM is an effective method of monitoring the spinal cord and nerve root function during corrective surgery of spinal deformities and consequently improves postoperative results. The Wake-up test for surgical procedure of spinal deformities became obsolete in our institution.

Multimodal intraoperative monitoring: an overview and proposal of methodology based on 1,017 cases.

To describe different currently available tests of multimodal intraoperative monitoring (MIOM) used in spine and spinal cord surgery indicating the technical parameters, application and interpretation as an easy understanding systematic overview to help implementation of MIOM and improve communication between neurophysiologists and spine surgeons. This article aims to give an overview and proposal of the different MIOM-techniques as used daily in spine and spinal cord surgery at our institution. Intensive research in neurophysiology over the past decades has lead to a profound understanding of the spinal cord, nerve functions and their intraoperative functional evaluation in anaesthetised patients. At present, spine surgeons and neurophysiologist are faced with 1,883 publications in PubMed on spinal cord monitoring. The value and the limitations of single monitoring methods are well documented. The diagnostic power of the multimodal approach in a larger study population in spine surgery, as measured with sensitivity and specificity, is dealt with elsewhere in this supplement (Sutter et al. in Eur Spine J Suppl, 2007). This paper aims to give a detailed description of the different modalities used in this study. Description of monitoring techniques of the descending and ascending spinal cord and nerve root pathways by motor evoked potentials of the spinal cord and muscles elicited after transcranial electrical motor cortex, spinal cord, cauda equina and nerve root stimulation, continuous EMG, sensory cortical and spinal evoked potentials, as well as direct spinal cord evoked potentials applied on 1,017 patients. The method of MIOM, continuously adapted according to the site, stage of surgery and potential danger to nerve tissues, proved to be applicable with online results, reliable and furthermore teachable.