Journal of neurosurgery. Spine
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Although postsurgical neurological outcomes in patients with tethered cord syndrome (TCS) are well known, the rate and development of neurological improvement after first-time tethered cord release is incompletely understood. The authors reviewed their institutional experience with the surgical management of adult TCS to assess the time course of symptomatic improvement, and to identify the patient subgroups most likely to experience improvement of motor symptoms. ⋯ In the authors' experience, pain and motor and urinary dysfunction improve postoperatively in the majority of patients. The rate of symptomatic improvement was greatest for pain resolution, followed by motor, and then urinary improvement. Patients who experienced improvement in any symptom had done so by 6 months after tethered cord release. Patients with asymmetrical motor symptoms or lower extremity hyperreflexia at presentation were most likely to experience improvements in motor symptoms. These findings may help guide patient education and surgical decision-making.
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Porcine spinal cords were mechanically injured at the thoracic level while recording muscle-derived electrically stimulated transcranial motor evoked potentials (TcMEPs) and electromyography (EMG) readings from the same electrode derivations. The authors postulated that midthoracic spinal cord injury caused by diverse methods can trigger hindlimb EMG activity. Early detection of hindlimb EMG activity may permit avoidance of motor conduction block (TcMEP loss). ⋯ Electromyographic activity (referred to as "EMG injury discharges" in the present study) can be elicited both by intramedullary manipulation and rapidly applied transaxial spinal cord compression. Preliminary observations suggest that these EMG injury discharges precede and may anticipate TcMEP loss. Presumably, rapid deformation of spinal motor tracts (which appear to lie within the lateral porcine spinal cord) generates descending volleys which can bring to firing threshold lumbar motor neurons (and recording of EMG injury discharges). Intraoperative neuromonitoring of high-risk spinal surgeries at the spinal cord level may benefit from the addition of EMG recording to tests of spinal cord motor conduction such as TcMEP. Further clinical trials are required to examine EMG efficacy in this context.