[Neurotoxicity of intrathecal lidocaine].

Lidocaine is a local anesthetic belonging to the amide group and has been administered intrathecally for over 40 years. Although no serious complications had been attributed to lidocaine before the 1990s, subarachnoid administration is now the subject of controversy following its implication in numerous cases of neurological complication. The clinical pictures described in the literature are cauda equina syndrome, which is mainly associated with continuous subarachnoid anesthesia through microcatheters, and transitory neurological symptoms, also termed radicular irritation syndrome and associated with single injections. The literature reveals a clearly higher incidence of transitory neurological symptoms with lidocaine than with other local anesthetics. Although the underlying mechanism remains unclear, the main hypotheses being the neurotoxicity of lidocaine itself or the malpositioning of the paravertebral musculature due to extreme relaxation. The various factors that can lead to neuropathy have been widely described in the many articles reporting complications. Arthroscopy and lithotomy positions are significantly related to the appearance of symptoms, as are early ambulation or the use of small-gauge needles or pencil-point needles. Further clinical studies should be undertaken. No consensus on subarachnoid administration of lidocaine has emerged, yet no alternative has been demonstrated to be safe and to offer similar pharmacological features (short latency, short duration of action and good muscle relaxation). Prilocaine, mepivacaine, articaine and bupivacaine at low doses have been suggested as alternatives.