The spinocerebellar evoked response as an option of monitoring for inferior cerebellar peduncle dysfunction

本研究旨在发展一种术中监测下小脑脚(Inf.C.Ped)功能的方法。由于脊髓小脑束背核(SCT)位于Inf.C.Ped内，我们研究了利用刺激脊髓背小脑束诱发的诱发电位来评估Inf.C.Ped功能的可能性。电刺激诱发单侧股四头肌收缩。从同侧小脑和对侧初级感觉皮质表面记录诱发电位。从同侧小脑半球获得的高度重复性的电位称为脊髓小脑诱发电位(SCEP)。SCEP为1个负峰，潜伏期为11.7±0.3毫秒(N11)。对侧初级感觉皮层记录到短潜伏期躯体感觉诱发电位(SSEP)，潜伏期为19.1±0.6毫秒。电凝同侧Inf.C.Ped导致SCEP N11消失或明显减少，但不改变SSEP。另一方面，切断同侧背柱导致SSEP消失，但不影响SCEP N11。电刺激股四头肌可从大鼠小脑半球记录到可重复的SCEP。我们推测，SCEP不同于通过背柱上升的SSEP，它是由位于Inf.C.Ped的背侧SCT传导的。我们的结果表明，在小脑手术期间监测患者的Inf.C.Ped是可能的。

The aim of this study was to develop a new method for the intraoperativemonitoring of inferior cerebellar peduncle (Inf.C.Ped) function. As the dorsal spinocerebellar tract (SCT) is located in the Inf.C.Ped, we studied the possibility of using the evoked potential elicited by stimulation of the dorsal SCT and recorded from the cerebellar surface to assess the Inf.C.Ped function.The experimental study was performed in rats. Unilateral muscular contractions of quadriceps femoris muscle were elicited by electrical stimulation. The evoked potentials were recorded from the surface of the ipsilateral cerebellum and the contralateral primary sensory cortex. The highly reproducible potentials obtained from the ipsilateral cerebellar hemisphere were named spinocerebellar evoked potentials (SCEP). The SCEP exhibited one negative peak with a latency of 11.7 ± 0.3 msec (N11). Short latency somatosensory evoked potential (SSEP) was recorded from the contralateral primary sensory cortex with a latency of 19.1 ± 0.6 msec. Coagulation of the ipsilateral Inf.C.Ped caused disappearance or marked reduction of the SCEP N11 but it did not change the SSEP. On the other hand, sectioning of the ipsilateral dorsal column resulted in the disappearance of the SSEP but it did not affect the SCEP N11.Reproducible SCEP was recorded from the rat cerebellar hemisphere by electrical stimulation of the quadriceps femoris muscle. We posit that the SCEP differs from the SSEP which ascends via the dorsal column and that it is conducted by the dorsal SCT located in the Inf.C.Ped. Our results suggest that it may be possible to monitor the Inf.C.Ped in patients during cerebellar surgery.