Effects of Nerve Root Retraction in Lumbar Discectomy
Effects of Nerve Root Retraction in Lumbar Discectomy
The authors studied whether the amount of retraction pressure applied to a compromised nerve root during lumbar discectomy has an impact on intra- or postoperative outcome.
Methods: The authors conducted a prospective analysis of 20 patients. There were 12 men and 12 women whose mean age (± standard deviation [SD]) was 42.25 years ± 15 years (range 21-65 years). During intraoperative electromyography (EMG) monitoring, measurements were obtained during routine retraction of the affected nerve root by using a specially designed and constructed nerve root retractor connected to a reconfigured personal computer for this specific purpose. Follow-up results were assessed in the immediate postoperative period and at up to 1 year. The maximum measured force applied during random periods of time was 9.85 N/second (mean 6.95 ± N/second [± SD]). The mean retraction time was 39.5 ± 21 (SD). No intraoperative EMG-detected irritation was noted during or after routine retraction. In four of 20 patients, sensory changes occurred at the ipsilateral nerve root level, which resolved at the time of discharge.
Conclusions: The authors found that routine nerve root retraction does not cause nerve root irritation, as demonstrated by EMG monitoring, nor was patient outcome affected in this series.
Despite the evolution of technology in neurosurgery, lumbar discectomy continues to be the most common operative procedure performed by neurosurgeons in North America. Unfortunately, for a variety of reasons, the surgery-related success of such procedures is far from perfect, particularly in those patients in whom multiple lumbar procedures have been performed.
Many different operative variables have been proposed to explain such an imperfect surgery-related outcome. Of consequence, the "timed force" exerted against the involved nerve root as it is retracted during decompressive surgery has attracted considerable attention. Our study was designed to focus on the dynamics of such retraction.
The authors studied whether the amount of retraction pressure applied to a compromised nerve root during lumbar discectomy has an impact on intra- or postoperative outcome.
Methods: The authors conducted a prospective analysis of 20 patients. There were 12 men and 12 women whose mean age (± standard deviation [SD]) was 42.25 years ± 15 years (range 21-65 years). During intraoperative electromyography (EMG) monitoring, measurements were obtained during routine retraction of the affected nerve root by using a specially designed and constructed nerve root retractor connected to a reconfigured personal computer for this specific purpose. Follow-up results were assessed in the immediate postoperative period and at up to 1 year. The maximum measured force applied during random periods of time was 9.85 N/second (mean 6.95 ± N/second [± SD]). The mean retraction time was 39.5 ± 21 (SD). No intraoperative EMG-detected irritation was noted during or after routine retraction. In four of 20 patients, sensory changes occurred at the ipsilateral nerve root level, which resolved at the time of discharge.
Conclusions: The authors found that routine nerve root retraction does not cause nerve root irritation, as demonstrated by EMG monitoring, nor was patient outcome affected in this series.
Despite the evolution of technology in neurosurgery, lumbar discectomy continues to be the most common operative procedure performed by neurosurgeons in North America. Unfortunately, for a variety of reasons, the surgery-related success of such procedures is far from perfect, particularly in those patients in whom multiple lumbar procedures have been performed.
Many different operative variables have been proposed to explain such an imperfect surgery-related outcome. Of consequence, the "timed force" exerted against the involved nerve root as it is retracted during decompressive surgery has attracted considerable attention. Our study was designed to focus on the dynamics of such retraction.
