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Editorial

Sacral tumors

Michael G. Fehlings and Sean R. Smith

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Editorial

Spinal deformity

Michael G. Fehlings and George M. Ibrahim

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Michael G. Fehlings and Neilank K. Jha

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Michael G. Fehlings and Reza Mobasheri

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Editorial

Interspinous ligamentoplasty

Michael G. Fehlings and Soo Yong Chua

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Editorial

Occipital cervical fusion: an evolution of techniques

Michael G. Fehlings and David W. Cadotte

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Editorial

Treatment options for lumbar spinal stenosis

Michael G. Fehlings and Soo Yong Chua

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Editorial

High-grade intramedullary astrocytomas: what is the best surgical option?

Michael G. Fehlings and Sorin C. Craciunas

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David W. Cadotte, Patrick W. Stroman, David Mikulis and Michael G. Fehlings

Object

Since the first published report of spinal functional MRI (fMRI) in humans in 1996, this body of literature has grown substantially. In the present article, the authors systematically review all spinal fMRI studies conducted in healthy individuals with a focus on the different motor and sensory paradigms used and the results acquired.

Methods

The authors conducted a systematic search of MEDLINE for literature published from 1990 through November 2011 reporting on stimulation paradigms used to assess spinal fMRI scans in healthy individuals.

Results

They identified 19 peer-reviewed studies from 1996 to the present in which a combination of different spinal fMRI methods were used to investigate the spinal cord in healthy individuals. Eight of the studies used a motor stimulation paradigm, 10 used a sensory stimulation paradigm, and 1 compared motor and sensory stimulation paradigms.

Conclusions

Despite differences in the results of various studies, even when similar stimulation paradigms were used, this body of literature underscores that spinal fMRI signals can be obtained from the human spinal cord. The authors intend this review to serve as an introduction to spinal fMRI research and what it may offer the field of spinal cord injury research.

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Andrei V. Krassioukov, Roger Sarjeant, Homan Arkia and Michael G. Fehlings

Object. The purpose of this study was to examine the neurological outcomes after complex lumbosacral surgery in patients undergoing multimodality neurophysiological monitoring.

Methods. Sixty-one patients were consecutively enrolled in this study. These patients underwent complex intra- and extradural lumbosacral procedures with concomitant intraoperative electromyography (EMG) monitoring of the lower-limb muscles, external anal and urethral sphincters (EAS and EUS), and lower-limb somatosensory evoked potentials (SSEPs). Long-term (minimum 2-year) clinical follow-up data were obtained in all cases.

Most patients were treated for spinal/spinal cord tumors (61%) or adult tethered cord syndrome (25%). Recordable lower-extremity SSEPs were reported in 54 patients (89%). New postoperative neurological deficits occurred in only three patients (4.9%), and remained persistent in only one patient (1.6%) at long-term follow-up examination. In only one of these cases was a significant decrease in SSEP amplitude detected. Spontaneous EMG activity was observed in the lower-extremity muscles and/or EAS and EUS in 51 cases (84%). Intraoperatively, EMG demonstrated activity only in the EUS in 5% of patients and only in the EAS in 28%. In seven patients (11%) spontaneous intraoperative EMG activity was observed in both the EAS and the EUS; however, in only three of these cases was EMG activity recorded in both sphincters simultaneously. In addition to spontaneously recorded EMG activity, electrically evoked EMG activity was also used as an intraoperative adjunct. A bipolar stimulating electrode was used to identify functional neural tissue before undertaking microsurgical dissection in 58 individuals (95%). In the majority of these patients, evoked EMG activity occurred either in one (33%) or in two muscles (9%) simultaneously. The presence of electrically evoked EMG activity in structures encountered during microdissection altered the plan of treatment in 24 cases (42%).

Conclusions. The authors conclude that the combined SSEP and EMG monitoring of lower-limb muscles, EAS, and EUS is a practical and reliable method for obtaining optimal electrophysiological feedback during complex neurosurgical procedures involving the conus medullaris and cauda equina. Analysis of the results indicates that these intraoperative adjunctive modalities positively influence decision making with regard to microsurgery and reduce the risk of perioperative neurological complications. Validation of the clinical value of these approaches, however, will require further assessment in a larger prospective cohort of patients.