May 1998

Transient Neurologic Symptoms after Spinal Anesthesia. A Lower Incidence with Prilocaine and Bupivacaine than with Lidocaine.
Hampl KF, Heinzmann-Wiedmer S, Luginbuehl I, Harms C, Seeberger M, Schneider MC, Drasner K; Anesthesiology 1998;88:629-33.
[ see abstract below ]

Despite its long record of safety, there have recently been reports that transient neurologic symptoms (TNS) occur after lidocaine spinal anesthesia. Clinicians are seeking alternative agents. For long surgical procedures, bupivacaine is a good alternative, but for brief procedures a short acting alternative local anesthetic needs to be identified.

Prilocaine is an amide local anesthetic with a duration of action similar to lidocaine. This prospective, double-blinded study compared prilocaine with lidocaine and bupivacaine, evaluating duration of action as well as the occurrence of TNS. Ninety ASA 1-2 patients scheduled for short gynecologic procedures under spinal anesthesia were randomly assigned to receive either 2.5% ml lidocaine in 7.5% glucose, 2% prilocaine in 7.5% glucose, or 0.5% bupivacaine in 7.5% glucose. All of these patients were to remain in the hospital overnight and therefore could be evaluated on postoperative days.

There was a similar incidence of technical problems associated with the spinal puncture in all groups and satisfactory surgical anesthesia was achieved in all patients. Recovery times to regression, to S2, complete recovery from motor block, and time to void were similar after lidocaine and prilocaine (127 vs 128, 155 vs 165, and 238 vs 253, respectively). The recovery times were, however, significantly longer for patients who received bupivacaine (172, 200 and 299 minutes, respectively).

TNS were evaluated using a standardized symptom check list including pain and/or dysesthesia in the legs or buttocks, starting after recovery from spinal anesthesia; localized pain at the site of puncture was by definition not considered a TNS. These authors found that the incidence of TNS on postoperative day one was 10% with lidocaine, which was statistically greater than the incidence of 3% with prilocaine and 0% with bupivacaine. Most TNS persisted for 2 postoperative days and all had resolved by postoperative day 5. The time to onset of TNS after regression of sensory block to S2 was similar for both agents, 140 or 150 minutes, and the location of the symptoms was primarily in the buttocks and back of thighs. These authors also recorded pain at the site of puncture (not TNS). The incidence of puncture site pain was similar, 10% with lidocaine, 17% with prilocaine and 17% with bupivacaine.

There were 2 other articles with different incidences of TNS in the same journal. Martinez-Bourio et al.¹ reported a comparison of hyperbaric 5% lidocaine or hyperbaric 5% prilocaine. The incidence of TNS in both groups was lower and a difference was not found: 4% with lidocaine and 1% with prilocaine. In another study by Liguori et al.², comparison was made between 46 ml 1.5% mepivacaine or 60 ml 2% lidocaine. None of the mepivacaine patients developed TNS whereas 22% of lidocaine patients did. The times to regression to the L5 sensory level and complete resolution of motor block were similar in both groups.

A point not addressed by these studies, but which should be noted, concerns discharge readiness. The time to void would correlate with discharge readiness from ambulatory surgical facilities in this country. In Hampl et al. the time to void was 238-253 minutes for lidocaine and prilocaine, after surgery lasting 16 to 19 minutes. While these authors did find that 0.5% bupivacaine had significantly longer recovery, neither lidocaine nor prilocaine as used provide a satisfactory recovery duration for ambulatory surgery. Further work may need to be done to determine if a lower dose or concentration of either lidocaine or prilocaine would retain satisfactory anesthesia but yet permit an earlier discharge.

1. Incidence of Transient Neurologic Symptoms after Hyperbaric Subarachnoid Anesthesia with 5% Lidocaine and 5% Prilocaine. Martinez-Bourio R, Arzuaga M, Quintana JM, Aguilera L, Aguirre J, S�ez-Eguilaz JL, Ar�zaga A; Anesthesiology 1998; 88(3):624-8.
   
   
2. Transient neurologic symptoms after spinal anesthesia with mepivacaine and lidocaine. Liguori GA, Zayas VM, Chisholm MF; Anesthesiology 1998; 88(3):619-23.
   
   

ABSTRACT BACKGROUND: Recent evidence suggests that transient neurologic symptoms (TNSs) frequently follow lidocaine spinal anesthesia but are infrequent with bupivacaine. However, identification of a short-acting local anesthetic to substitute for lidocaine for brief surgical procedures remains an important goal. Prilocaine is an amide local anesthetic with a duration of action similar to that of lidocaine. Accordingly, the present, prospective double-blind study compares prilocaine with lidocaine and bupivacaine with respect to duration of action and relative risk of TNSs. METHODS: Ninety patients classified as American Society of Anesthesiologists physical status I or II who were scheduled for short gynecologic procedures under spinal anesthesia were randomly allocated to receive 2.5 ml 2% lidocaine in 7.5% glucose, 2% prilocaine in 7.5% glucose, or 0.5% bupivacaine in 7.5% glucose. All solutions were provided in blinded vials by the hospital pharmacy. Details of spinal puncture, extension and regression of spinal block, and the times to reach discharge criteria were noted. In the evening of postoperative day 1, patients were evaluated for TNSs by a physician unaware of the drug administered and the details of the anesthetic procedure. RESULTS: Nine of 30 patients receiving lidocaine experienced TNSs, 1 of 30 patients receiving prilocaine (P = 0.03) had them, and none of 30 patients receiving bupivacaine had TNSs. Times to ambulate and to void were similar after lidocaine and prilocaine (150 vs. 165 min and 238 vs. 253 min, respectively) but prolonged after bupivacaine (200 and 299 min, respectively; P < 0.05). CONCLUSIONS: Prilocaine may be preferable to lidocaine for short surgical procedures because it has a similar duration of action but a lower incidence of TNSs.