5% hyperbaric lidocaine has lost its usefulness for same-day-surgery (SDS) anaesthesia
because it has been blamed responsible for the so-called transitory neurological syndrome
(TNS). This entity appears particularly in patients operated on lithotomy and knee
arthroscopy position and obese patients. It is a benign, moderately painful (grade 3-4 out of
10) and self-limited in time, but disturbing enough to be avoided in same-day-surgery cases.
Other local anesthetics are not competitive with general anesthesia in time to be discharged
home from the SDS unit. The magnesium ion is well-known for its protective properties on
cells with electrical activity. The objective is to confirm that the magnesium ion added as
adjuvant to intrathecal (IT) lidocaine may antagonize TNS incidence. If this hypothesis could
be confirmed, the practical and theoretical consequences would be far-reaching.
The method to achieve our objective would be a double-blinded randomized clinical trial
considering two groups of intrathecal lidocaine: with and without added IT magnesium.