A 43 year old man underwent spinal cord surgery for removal of filum terminale lipoma. Intraoperative somatosensory evoked potentials (SSEP) monitoring showed a transient loss of response on simultaneous bilateral posterior tibial nerve (PTN) stimulation that recovered within 20 minutes. The patients exhibited paralysis and abnormal proprioceptive perception in the right leg postoperatively, when SSEP recordings revealed abnormal response to right PTN and normal response to bilateral PTN stimulation. In order to avoid false negative intraoperative responses, stimulation of each leg independently in an alternative fashion is recommended.
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MizrahiE.M., and CrawfordE.S., Somatosensory evoked potentials during reversible spinal cord ischemia, Electroenceph. clin. Neurophysiol., 58:120–26, 1984.
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AllenA., StarrA., and NudlemanK., Assessment of sensory function in the operating room utilizing cerebral evoked potentials: A study of fifty-six surgically anesthesized patients, Clin. Neurosurg., 28:457–81, 1981.
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NordwallA., AxelgoardJ., HaradaY., ValenciaP., McNealD., and BrownJ., Spinal cord monitoring using evoked potentials recorded from feline vertebral bone, Spine, 4:486–94, 1979.
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GibsburgH.H., ShetterA.G., and Raud-ZensP.A., Postoperative paraplegia with preserved intraoperative somatosensory evoked potentials, case report, J. Neurosurg., 63:296–300, 1985.
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NashC.L., LoringR.A., SchatzingerL.A., and BrownR.H., Spinal cord monitoring during operative treatment of the spine, Clin. Orthop., 126:100–105, 1977.
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WorthR.M., MarkandO.N., DeRosaG.P., and WattenC.H., Intra-operative somatosensory evoked response monitoring during spinal cord surgery, In: COURJONJ., MAU-GUIEREF., and REVOLM., (eds): Clinical Application of Evoked Potentials in Neurology, Raven Press, New York, pp. 367–73, 1982.
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ShimizuH., MaruyamaY., EndoH., ShimojiK., HormaT., and TakahashiH., Spinal cord monitoring by means of evoked electrospinogram in spinal surgery, Electroenceph. clin. Neurophysiol., 52:75P, 1981.
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MaconJ.B., PolettiC.E., SweetW.H., OjemannR.G., and ZervasN.T., Conducted somatosensory evoked potentials during spinal surgery, Part 2: Clinical Applications J. Neurosurg., 57:354–59, 1982.
