Overdoses of local anesthetics (LA) are well-known to induce neurological or cardiologic symptoms such as convulsions, confusion, cardiac arrhythmia and cardiac failure. In most cases, LA diffuse out of a catheter used for loco-regional administration into the bloodstream. Severe side effets are observed when blood concentrations reach toxic levels. We report a case of neurological syndrome after epidural administration of lidocaine and ropivacaine at usual doses for a caesarian section. The symptoms fortunately resolved. A few minutes after the beginning of the incident, a blood sample was taken to assay the LA levels.

The patient was a 37-year-old woman, primipara, with a history of Crohn's disease and endometriosis. The pregnancy was normal, bit the decision to perform a ceasarian section was made after an episode of fetal bradycardia. Regional anesthesia on D1 at 5:45 pm, with epidural LA: ropivacaine 0.2%, 10mL and lidocaine 2%, 15mL. The procedure took place normally without evidence of extravasation. The child was born with normal behavior (Apgar score 10/10 at 1 and 5min). after the birth, the mother complained of dysarthria, dusfunction of taste and labial dysesthesia. The, she exhibited dizziness and e few upper limb clonic seizures, immediately followed by relative agitation without loss of consciousness. A blood sanple was taken just before the injection of Intralipid^® (soybena oil) and analyzed by GC-MS.

Serum lidocaine concentration was 1.5mg/L and ropivacaine 0.10mg/L. The lidocaine concentration range considered as non-toxic in cardiology is 1.5–6mg/L. Intralipid^® perfusion accelerated the rapid regression of symptoms. No other cardiac or vascular sign was reported. An MRI was done, which was normal and ruled out a stroke.

The elimination half-life (T1/2^e) of lidocaine (α=0.5h; ß=1–2h) and ropivacaine (1.8h) could not explain higher blood concentrations at the time of surgery. Reported toxic blood concentrations for lidocaine are>6mg/L. Unfortunately, we did not assay the LA-fractions. There was non-associated medication, including sedatives, morphinomimetics, antibiotics and NSAIDS that could have increased the LA-free fraction after IV injection. Other authors found various cases of LA side effects with the usual dosage and in the absence of extravasation [1Fuzier R., e al. Adverse drug reactions to local anesthetics: a review of the French pharmacovigilance database Drug Saf 2009 ;  32 : 345-356 [cross-ref]

Cliccare qui per andare alla sezione Riferimenti]. The LA levels were also within the therapeutic range [2Alexandre J., e al. Cardiac arrests associated with low plasma and tissue levels of local anesthetics Drug Saf 2015 ; [In Press].

Cliccare qui per andare alla sezione Riferimenti].

The acute neurological side effects induced by LA could occur at the therapeutic dosage, with blood concentrations within the usual therapeutic values.