The effect of spinal anesthesia on resting-state fMRI.

The influence of spinal injection on brain connectivity is not known. In this placebo-controlled randomized study healthy male right-handed volunteers will be injected wiht 3 mL bupivacaine 0.5% in the spinal space. Next resting-state fMRI will be obtained 1 and 2 hours after infection. The effect of deafferentiation on pain and sedation will be tested using heat pain tests and sedation self scoring and the Observer’s Assessment of Alertness/Sedation Scale (OAA/S).

1. The deafferentiation during spinal anesthesia changes the connectivity in resting-state networks in healthy volunteers;

2. The deafferentiation during spinal anesthesia changes pain perception and has sedetive effects.

1. Resting state fMRI: At baseline and at 1 and 2 hours after spinal infusion;

2. Heat pain tests: At baseline and at timepoint 15,30,45,90,105,150 minutes after spinal infusion;

3. Sedation scoring: At baseline and at timepoint 15,30,45,90,105,150 minutes after spinal infusion;

4. Block height: At baseline and at 10,20,30,45,90,105,150 minutes after spinal infusion.

Spinal anesthesia at the level of L3-L4 with 3 mL bupivacaine 0.5% after local anesthesia with lidocaine 1%. Placebo will exist of local anesthesia with lidocaine after which a punction will take place to mimic the spinal punction.



The spinal anesthesia will last 4-5 hours. fMRi and arterial spin labeling will be performed 1 and 2 hours after anesthesia. Betweens these scans, heat pain tests will be performed on the forearm to evaluate the effect of spinal anesthesia on pain perception in areas not affected by the anesthesia.