Postersession 5 7. Higherbrainfunctions and speech $235 both at 1 week (mean: 56.45 us) and at 2 weeks (mean: 60.95 us) postinjection. The jitter values were rate dependent, being larger at 1 Hz compared to 10 Hz stimulation. BTX is helpful in lubag especially in alleviating pain and focal lingual and foot dystonias. PS-56-11 J Paretic motor effects of intramuscular ] lidocaine in human extensor digitorum brevis (EDB) Francis O. Walker, Christopher H. Hunt. Department of Neurology, Bowman Gray School of Medicine, USA It has recently been suggested that intramuscular lidocaine selec- tively impairs afferent fibers following intramuscular injection, an effect of potential therapeutic benefit in dystonia. We investigated the paretic motor effects of intramuscular lidocaine in 9 subjects before and after injections of 0.5 ml of lidocaine into EDB. Injecting 1% lidocaine reduced EDB compound muscle action potential (CMAP) amplitudes by 40% in the first minute and 49% -F 8% [s.d.] by 14 minutes. Injection of 0.5% lidocaine demon- strated similar effects, but 0.25% lidocaine produced a rapidly reversible reduction in CMAPs. The injection of 1% lidocaine decreased the mean rectified voltage (MRV) of maximal volun- tary contraction of EDB more profoundly (59 = 13%) and longer (peak effect at 30 minutes) than it decreased CMAPs. Repetitive stimulation at 4 Hz produced increasing decrements over time, 5% at 1 minute and 11% at minutes. These findings suggest the presence of frequency dependent block. Despite only partial neuromuscular blockade, needle insertion became painless and evoked less insertional activity (7.5 mV ms to 4.5 mV ms) following lidocaine administration. Contralateral saline injections produced no significant change in measured vari- ables. Our findings indicate that intramuscular lidocaine impairs EDB motor function in a dose-dependent fashion, an effect magnified by frequency dependent block. Both muscle membranes and nerve fibers appear to be affected. Clinical sensory block tends to be more profound than motor block. Intramuscular lidocaine appears to have mixed effects on neuromuscular function, findings which may complicate the interpretation of clinical effects of this drug in dystonia. Further investigation of local anesthetic effects following intramuscular injections is warranted. [ PS-56-12 I Serial neurophysiological effects of intramuscular mivacurium Francis Walker 1, Michael Flanagan 2, John Butterworth 2. 1Department of Neurology, ~Department of Anesthesia, Bowman Gray School of Medicine, USA The use of local anesthetics for treating myofascial pain raises the question of their locus of action. Do they work through motor effects, sensory effects or both? The use of an agent that selec- tively blocks motor, but not sensory, function may help address this question. We recently investigated the effects of intramuscu- lar mivacurium, a potent neuromuscular junction blocker, to de- fine its onset, duration, and degree of motor blockade following intramuscular injection into extensor digitorum brevis (EDB). We studied EDB injections in 13 subjects following baseline nerve conduction studies. Following the injection of 0.1 mg of mi- vacurium CMAPs decreased 49% with a peak effect at 18 minutes. Unlike the systemic effects of mivacurium, which induces marked repetitive stimulation decrements shortly after intravenous admin- istration, we found only mild decrements that peaked 40 minutes after injection. Intravenous neostigmine reverses the intravenous effects of mivacurium. Paradoxically, however, intramuscular neostigmine, which alone produced no evidence of neuromuscular blockade, potentiated the neuromuscular blockade induced by intramuscular mivacurium. We speculate that neostigmine inhibition of acetyl- cholinesterase slowed the metabolism of mivacurium. Our findings indicate that 1) the effects of intramuscular admin- istration of neostigmine and mivacurium differ from those of intra- venous administration and 2) mivacurium potently inhibits local muscular contraction following intramuscular injection. Clinical trials of intramuscular mivacurium in the treatment of fibromyal- gia are warranted. I PS'56-13] Muscle afferent block by intramuscular injection of lidocaine and ethanol for the treatment of spasmodic torticollis Tamotsu Kubori 1, Ryuji Kaji 1, Marl Katayama 1, Takahiro Mezaki 1, Nobuo Kohara 1, Hiroshi Sibasaki 2, Jun Kimura 1. 1 Department of Neurology, 2 Department of Brain Pathophysiology, Kyoto University Faculty of Medicine, Japan We developed a new method by the intramuscular injection of li- docaine and ethanol for treating patients with dystonia (Kaji, et al. Ann Neuro11995). This method is distinct from nerve block, and is intended to produce muscle afferent block (MAB). In the present study, we evaluated the efficacy of this method for spasmodic tor- ticollis comparing with that of botulinum toxin A (BTX). Forty- nine patients with spasmodic torticollis were divided into three groups: 24 patients were enrolled for MAB, 11 patients were en- tered for medium-dose botulinum toxin (120 units/session) treat- ment, and 14 patients underwent high-dose of botulinum toxin (240 units/session) treatment. Patients for MAB had 2 injections a week with lidocaine (0.5%) and ethanol (99.5%), each injected into 2-3 muscles with increased activity. The ratio of lidocaine in volume to ethanol was 10 to 1. The dose of lidocaine and ethanol was limited to 50 ml and 5 ml respectively per one session. Patients of BTX group were injected with 120 or 240 units of botulinum toxin A at an interval of 1 month, divided into a fraction of 30- 120 units/muscle. We evaluated the efficacy of these treatments by objective score at 2 months after the initial injection. Objective score was obtained with the aid of video recordings, registering degrees of the neck deviation from the neutral position as follows: score 0; 0 °, 1; 0°~15 °, 2; 15°~-'30 °, 3; 30°~-'45°, 4; 45 °~. The efficacy was assessed by changes in objective score in patients before and after treatment; improvement in 71% of those for MAB, 73% for 120 units BTX and 79% for 240 units BTX. In conclusion, MAB proved useful for treating spasmodic torticollis with the efficacy comparable to medium-dose botulinum toxin treatment. PS-57. HIGHER BRAIN FUNCTIONS AND SPEECH [ PS-57-1' ] Comparative study of event-related potentials and pet activation during a paired associate memory paradigm Manabu Honda 1.3, Geoff Barrett 2, Nahoko Yoshimura 1, Norihiro Sadato 3, Yoshiharu Yonekura 1, Hiroshi Shibasaki 1. l Department of Brain Pathophysiology, Kyoto University School of Medicine, Kyoto, Japan; 2 Defence Research Agency, Alverstoke, Hants, UK; 3 NINDS, NIH, Bethesda, MD, USA Event-related potentials (ERP) and regional cerebral blood flow (rCBF) activation associated with retrieval and retention of mere-