Electrical stimulation threshold in chronically compressed lumbar nerve roots: Observational study.
OBJECTIVE
Intraoperative neuromonitoring (IONM) is a common practice in spinal surgery, mostly during pedicle screw placement. However, there is not enough information about the factors that can interfere with IONM data. One of these factors may be existing damage of the nerve root whose function must be preserved. The main purpose of the present study is to evaluate the effect of chronic compression in lumbar nerve roots in terms of stimulation thresholds during direct nerve stimulation.


METHODS
Direct electrical stimulation was performed in 201 lumbar nerve roots during lumbar spinal procedures under general anaesthesia in 80 patients with different lumbar spinal pathologies. Clinical and radiological data were reviewed in order to establish the presence of chronic compression.


RESULTS
Chronically compressed nerve roots showed a higher stimulation threshold than non compressed nerve roots (11.93 mA vs. 4.33 mA). This difference was confirmed with intra-subject comparison (paired sample t test, p=0.012). No other clinical factors were associated with this higher stimulation threshold in lumbar nerve roots.


CONCLUSIONS
A higher stimulation threshold is present in compressed lumbar nerve roots than non compressed roots. This needs to be taken into consideration during pedicle screw placement, where intraoperative neurophysiological monitoring is being used.
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain. Electronic address: jplata5@hotmail.com.
Julio
J
Plata-Bello
Hospital Universitario de Canarias, Intraoperative Neurophysiologic Monitoring Unit, S/C de Tenerife, Spain.
Pedro Javier
PJ
Pérez-Lorensu
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain.
Liberto
L
Brage
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain.
Vanessa
V
Hernández-Hernández
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain.
Ayoze
A
Dóniz
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain.
Héctor
H
Roldán-Delgado
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain.
Pablo
P
Febles
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain.
Mario
M
García-Conde
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain.
Luis
L
Pérez-Orribo
Hospital Universitario de Canarias, Department of Neurosurgery, S/C de Tenerife, Spain.
Víctor
V
García-Marín
D000328:Adult; D000368:Aged; D002908:Chronic Disease; D015331:Cohort Studies; D004558:Electric Stimulation; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement; D064795:Intraoperative Neurophysiological Monitoring / Q000379:methods*; D008159:Lumbar Vertebrae / Q000293:injuries / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D065289:Pedicle Screws; D011446:Prospective Studies; D011843:Radiculopathy / Q000503:physiopathology*; D012600:Scoliosis / Q000601:surgery; D013122:Spinal Diseases / Q000601:surgery*; D016103:Spinal Fractures / Q000601:surgery; D013125:Spinal Neoplasms / Q000601:surgery; D013126:Spinal Nerve Roots / Q000503:physiopathology*; D013130:Spinal Stenosis / Q000601:surgery; D013168:Spondylolisthesis / Q000601:surgery
Direct stimulation; Intraoperative neuromonitoring; Nerve compression; Nerve damage; Nerve root; Spinal surgery