Transient neurologic symptoms after spinal anaesthesia using isobaric 2% mepivacaine and isobaric 2% lidocaine

Transient Neurological Symptoms (TNS) syndrome following subarachnoid anaesthesia was initially associated with hyperbaric lidocaine 50 mg/ml, but has also been reported with most local anaesthetics, including hyperbaric mepivacaine 40 mg/ml. The aim of this study was to determine the incidence of TNS after subarachnoid anaesthesia using isobaric mepivacaine 20 mg/ml and isobaric lidocaine 20 mg/ml.

Eighty patients of both sexes, ASA class I-II, scheduled for elective minor orthopaedic surgery under subarachnoid anaesthesia, were prospectively included and randomly allocated to receive 40-60 mg of either isobaric mepivacaine 20 mg/ml (Group M) or isobaric lidocaine 20 mg/ml (Group L). Patients were evaluated on the first postoperative day by one investigator unaware of the grouping, looking for symptoms suggestive of TNS, such as pain or dysaesthesias in the buttocks or lower limbs with or without back pain.

TNS symptoms were observed in three patients (7.5%) of Group M and in one patient (2.5%) of Group L, without statistically significant differences between the groups. Symptoms had an abrupt onset and relief, lasted from 45 min to 24 h, and had a complete resolution without sequelae. The only statistically significant difference between groups was longer motor blockade in Group M (P=0.0031).

In this study TNS was associated with isobaric mepivacaine 20 mg/ml, with an incidence of 7.5%, and with isobaric lidocaine 20 mg/ml, with an incidence of 2.5%, in patients having orthopaedic procedures in the supine position.