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. Author manuscript; available in PMC: 2012 Jan 3.
Published in final edited form as: Anesth Analg. 2009 Sep;109(3):817–821. doi: 10.1213/ane.0b013e3181b086bd

Figure 1.

Figure 1

SSEP changes in the left median nerve in Case 1. Somatosensory evoked potentials (SSEPs) from bilateral median nerves were recorded using needle electrodes placed at Erb's point over the brachial plexus, for assessing peripheral conduction and on the scalp at CP3 and CP4 locations, for assessing central conduction. Time in minutes is recorded on the y axis. From the start of the recordings (time = 1 minute), there is a unilateral decrease in the amplitude of the left median nerve recordings compared to the right median nerve. This difference exists at both peripheral (Erb’s) and central (CP3 and CP4) recordings, suggesting a peripheral mechanism. With repositioning of the shoulder, the amplitude increases on the left side with time in central and peripheral recordings, approaching the amplitude on the right side.