Intra-operative spinal cord monitoring in orthopaedics

Macri, Shiela; Monte, Amato De; Greggi, Tiziana; Parisini, P.; Zanoni, Andrea; Merlini, Lorenzo

doi:10.1038/sj.sc.3100973

Cited by 15 publications

(12 citation statements)

References 33 publications

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“…To manage this limitation, the Stagnara wake up test is recommended, which, however, reveals inherent serious disadvantages like delayed diagnostic information, time-consuming procedure and discomfort for the patient. [4][5][6] To overcome these problems, somatosensory evoked potentials (SSEP) have been introduced for neurological investigation and monitoring of the integrity of the neural pathways during surgical procedures. This technique allows an on-line surveillance and early diagnosis of spinal cord dysfunction and aims to provide warning signals before an irreversible damage has occurred.…”

Section: Introductionmentioning

confidence: 99%

Reliability of perioperative SSEP recordings in spine surgery

et al. 2003

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Objective: The reproducibility and clinical reliability of perioperative somatosensory-evoked potentials (SSEP) were prospectively evaluated in uneventful scoliosis surgery. The influence of anesthesia owing to induction of total intravenous anesthesia (TIVA) upon preoperative SSEP and the variability of intraoperative SSEP were calculated. The potential effect of spine surgery was assessed by comparing pre-to postoperative SSEP. Methods: A total of 2143 pre-, intra-and postoperative tibial and median SSEP recorded in 25 patients undergoing spine surgery owing to idiopathic scoliosis were analyzed. The anesthesia protocol consisted of a computerized target controlled infusion (TCI) device for propofol and intravenous application of an opioid. Results: Anesthesia induced a significant and comparable prolongation of the tibial SSEP onset, P40 and P60 latencies, while the N50 latency was less changed. Throughout anesthesia, latencies of median (onset, N20, P25 and N35) and tibial (onset, P40, N50 and P60) SSEP showed mean variations of less than 6%. The intraoperative SSEP amplitudes were less stable with a relative standard deviation of 30-40%. In uneventful spine surgery, the postoperative tibial SSEP were not significantly changed in comparison to preoperative recordings. Conclusions: By using a standardized anesthesia protocol, the impact of anesthesia on preoperative SSEP can be predicted. Furthermore, the controlled application of sedatives and analgesics allows recording of stable SSEP parameters for intraoperative monitoring purposes. As in uneventful spine surgery pre-to postoperative SSEP are unchanged the latter comparison can be applied as an additional perioperative neuromonitoring procedure to assess the influence of spine surgery or other invasive interventions on spinal cord function.

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Section: Introductionmentioning

confidence: 99%

Reliability of perioperative SSEP recordings in spine surgery

et al. 2003

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“…An amplitude loss of SEP of 4 50% or an increase of latency over 10% is generally considered meaningful. 13 However, some researchers argue that the change of amplitude alone is not adequate to be the criterion for SCI, and the duration of the change should also be taken into account. 13 In the studies of Kawahara 6 and Modi, 7 the fluctuation of SEP amplitude alone was set as the signal of SCI.…”

Section: Discussionmentioning

confidence: 99%

“…13 However, some researchers argue that the change of amplitude alone is not adequate to be the criterion for SCI, and the duration of the change should also be taken into account. 13 In the studies of Kawahara 6 and Modi, 7 the fluctuation of SEP amplitude alone was set as the signal of SCI. Whereas, in our study, the amplitude and latency were examined quantitatively and over time, which would lead to a more sensible and reliable judgement of SCI, especially of incomplete injury.…”

Section: Discussionmentioning

confidence: 99%

Study on the safe range of shortening of the spinal cord in canine models

et al. 2012

Spinal Cord

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Study design: Experimental dog model of spinal cord shortening. Objectives: To clarify the relationship between the amount of shortening of the spinal cord and the degree of injury it may induce, and to determine the safe range of the shortening. Setting: Xi'an Jiaotong University, China. Methods: Thirty adult dogs were randomly allocated to five groups. Dogs in Group A (sham operation control) underwent spondylectomy to have two-thirds of the thirteenth thoracic segment (T13) resected, without bone-to-bone contact of the adjacent vertebral bodies. Those in Group B, C, D and E had one-third, half, two-thirds and total of their T13 resected, respectively, with boneto-bone contact. Somatosensory-evoked potentials (SEP) and spinal cord blood flow (SCBF) were detected. The histopathologic changes of spinal cord tissue were observed by hematoxylin and eosin stain and electron microscope. Results: The shortening of the spinal cord o half of a vertebral segment height caused a reversible change of SEP. Whereas, the changes resulted from the shortening of more than two-thirds of a vertebral segment height did not return to the normal level. SCBF increased temporarily when the shortening was within two-thirds of a vertebral segment height; whereas, it decreased progressively when the length of the shortening was equal to one vertebral segment height. More serious hemorrhage occurred as the shortening increased. INTRODUCTIONVertebrectomy is commonly performed in treating spinal deformity, tumors of the spinal column and other abnormal spinal conditions. [1][2][3] In this process, spinal shortening is a basic and commonly performed operation for the correction of spinal deformity and the fusion of osteotomy surface. 2,4,5 However, there exists the risk of neurologic complications induced by spinal cord injury (SCI) due to overshortened spinal cord. 2 These complications can be catastrophic for the patients and are very costly. Therefore, it is of great importance to clarify the pathophysiological changes of spinal cord shortening and determine the safe range of the shortening so as to prevent SCI.However, the safe range of shortening of the spinal column is still in debate. Two previous studies recognized the association between SCI and the range of spinal column shortening, but reached different conclusions in the safe range. 6,7 It seems that further research is necessary to confirm the safe shortening range. Besides, we have found no report about the serial changes of somatosensory-evoked potentials (SEP) and spinal cord blood flow (SCBF) over time with different amount of spinal shortening. The present study was therefore conducted, in which a modified animal model was used and detailed variations of SCBF and SEP were quantitatively recorded over a longer period of time at each stage of shortening. The obtained

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“…Several conventional models of electrophysiologic monitoring during spinal surgery are effective in the diagnosis and assessment of neurologic compromise resulting from spinal cord injury [7,14,18,20]; however, these models are limited in their ability to detect injury to a single nerve root. Cortical somatosensory evoked potential (CSEP), elicited by peripheral-nerve o r dermatomal stimulation, is unable to provide immediate information when a single root is injured [25].…”

Section: Introductionmentioning

confidence: 99%

Spinal somatosensory evoked potential evaluation of acute nerve‐root injury associated with pedicle‐screw placement procedures: An experimental study

Jou

Hsu

Chern

et al. 2003

Journal Orthopaedic Research

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Pedicle screws for spinal fixation risk neural damage because of the proximity between screw and nerve root. We assessed whether spinal somatosensory evoked potential (SSEP) could selectively detect pedicle-screw-related acute isolated nerve injury. Because pedicle screws are too large for a rat's spine, we inserted a K-wire close to the pedicle in 32 rats, intending not to injure the nerve root in eight (controls), and to injure the L4 or L5 root in 24. We used sciatic-nerve-elicited SSEP pre-and postinsertion. Radiologic, histologic, and postmortem observations confirmed the level and degree of root injury. Sciatic (SFI), tibia1 (TFI), and peroneal function indices (PFI) were calculated and correlated with changes in potential. Although not specific for injuries to different roots, amplitude reduction immediately postinsertion was significant in the experimental groups. Animals with the offending wire left in place for one hour showed a further non-significant deterioration of amplitude. Electrophysiologic changes correlated with SF1 and histologic findings in all groups. SSEP monitoring provided reliable, useful diagnostic and intraoperative information about the functional integrity of single nerve-root injury. These findings are clinically relevant to acute nerve-root injury and pedicle-screw insertion. If a nerve-root irritant remains in place, a considerable neurologic deficit will occur.

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Intra-operative spinal cord monitoring in orthopaedics

Cited by 15 publications

References 33 publications

Reliability of perioperative SSEP recordings in spine surgery

Reliability of perioperative SSEP recordings in spine surgery

Study on the safe range of shortening of the spinal cord in canine models

Spinal somatosensory evoked potential evaluation of acute nerve‐root injury associated with pedicle‐screw placement procedures: An experimental study

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