Intraoperative improvements of somatosensory evoked potentials in predicting the clinical outcome of the surgery for cervical spondylosis

Xinyu YANG; Shugang LI; Xisheng WENG; Guixing QIU

ABSTRACT

BACKGROUND:

Spinal somatosensory evoked potential(SEP) monitoring is widely used intraoperatively due to the easiness to operate and its reliability.

OBJECTIVE:

This study was designed to assess the significance of improving SEP signals in intraoperative spinal monitoring on predicting the post-operative spinal function.

DESIGN:

A non-randomized concurrent controlled study was conducted on selected patients.

SETTING:

This study was conducted at the Orthopedic Department of Peking Union Medical College Hospital.

PARTICIPANTS:

Totally 34 patients with cervical spondylosis underwent surgical treatment at the Orthopaedic Department of Peking Union Medical College Hospital were selected from January to October in 2001. Of all the patients, 24 underwent anterior decompression and fusion, 3 single door operation and 7 double door operation. According to the variance of intraoperative SEP, the patients were divided into the improvement group(12 cases)and the non-improvement group(22 cases).

METHODS:

All the patients' neurologic deficits were assessed according to the Japanese Orthopaedic Association scoring system(JOA score), prior to operation and postoperative week 1, 2, and 4 and month 3, 6. Each patient received the intraoperative spinal SEP monitoring. The variance of SEP signals in amplitude and latency were classified as improvement(an increase in amplitude of 50% or more, or a decrease in latency of 10% or more), decrease(a decrease in amplitude of 50% or more, or an increase in latency of 10% or more), and no improvement.MAIN OUTCOME

MEASURES:

JOA scores were calculated in two groups in the study at all time points.

RESULTS:

All the 34 patients entered the statistical analysis procedure. In postoperative week 1 and week 2, the improvement group showed a larger increase in JOA score than the non-improvement group did[improvement group(14.08±1.44), (14.17±1.11) points; no improvement group( 12.73 ± 1.42), ( 12.86 ± 1.28)points, P ＜ 0.05]. In postoperative week 4, month 3 and month 6, both groups showed an increase in JOA scores [improvement group (14.00±1.04), (13.58±1.08), (13.68±1.61)points; no improvement group (13.82 ± 1.01), (13.41 ± 1.22), (13.41± 1.47)points], but there was no significant difference( P ＞ 0.05).

CONCLUSION:

Improvement of intraoperative SEP can be used to predict the good early clinical outcomes in surgery for cervical spondylosis.