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PO1.14 Origin of the Premotor Potentials Preceding APB and Second Lumbrical CMAPs
S36 PO1.13 Motor Nerve Conduction Study of the Anterior Interosseous Nerve: Normative Data in the Korean Chang Hyo Yoon *, Jung Im Seok, Dong Kuck Lee Dept. of Neurology, School of Medicine, Catholic University of Daegu, Korea E-mail address: [email protected] Background: Anterior interosseous nerve (AIN) syndrome is a clinical entity characterized by paresis of the pronator quadratus, the flexor pollicis longus (FPL), and the flexor digitorum profundus. Previous study described a nerve conduction study using surface electrode by recording compound muscle action potentials from FPL. The purpose of this study was to determine the normal motor conduction values for the AIN in the Korean. Methods: Nerve conduction studies of the AIN were performed on 100 healthy subjects (51 women and 49 men, aged 26 to 60 years). The median nerve was stimulated supramaximally in antecubital fossa, just medial to the pulsation of the brachial artery. The active surface recording electrode was positioned over the belly of the flexor pollicis longus, 6 8 cm proximal to the radial styloid, and moved so as to obtain a negative takeoff. And, we applied the normative data to a patient with the AIN syndrome. Results: In 100 normal controls (200 different AIN studies), mean CMAP amplitude and area were 9.8±1.4 mV and 34.0±4.2 mV.ms. Mean CMAP onset latency was 3.7±0.4 ms. and mean velocity was 46.0±4.1 m/s. In patient with AIN syndrome, the CMAP amplitude and onset latency were 6.5 mV and 3.1 ms. (13.3 mV and 3.0 ms in asymptomatic side) Conclusions: Normative data has been established in the Korean and the CMAP amplitudes were larger than that of previous study and onset latency was similar. This normative data may be used to assess AIN syndrome. PO1.14 Origin of the Premotor Potentials Preceding APB and Second Lumbrical CMAPs Masayuki Ohira1 *, Masahiro Sonoo2 , Katsumi Kurokawa3 , Teruo Shimizu4 , Norio Suzuki1 1 Neurology Keio University School of Medicine, Japna, 2 Neurology, Teikyo University School of Medicine, Japan, 3 Neurology, Hiroshima City Asa Hospital, Japan, 4 Neurology, Teikyo University School of Medicine, Japan E-mail address: [email protected] Background: Premotor potentials (PMPs) are small deflections preceding a compound muscle action potential (CMAP), and are now considered to be of the sensory nerve origin. Park and Del Toro (1995) suggested that PMPs are divided into early and late components, and that the farfield potential (FFP) is the origin of the latter. In the present study, we investigated the origin of PMPs preceding the abductor pollicis brevis (APB) and the second lumbricalis (2L) using two new methods: usage of a proximal reference best suited to investigate FFPs, and the selective sensory nerve stimulation. Methods: We examined five healthy volunteers. Recording electrodes were placed over the belly of APB or 2L, as electrode arrays along the thumb (for APB) or index finger (for 2L), and over the forearm as a proximal reference. In addition to the ordinary supramaximal stimulation, we tried to selectively stimulate sensory nerves by manipulating the position of the stimulating electrode. Results: Positive-negative travelling waves were recoreded over the thumb or index finger with forearm reference, representing the nearfield recording of the sensory nerve action potentials (SNAPs) of the digital nerve. The late PMP peak in the routine APB-thumb recording corresponded to the initial positive peak of the digital nerve SNAP recorded at the reference electrode when proximal thumb references were used. When thumb references were placed distally, the late PMP peak purely corresponded to the positive FFP peak recorded in the thumb tip-forearm lead. In contrast to APB, the index finger tip-foream lead registered only small FFPs, which did not contribute to the PMPs preceding the 2L CMAP. The large PMP peak just corresponded to the median SNAP at the palm. Conclusions: Besides FFPs, the NFPs recorded at the reference electrode must also be considered for the late PMP origin. FFPs contributed little to the PMPs preceding the 2L CMAP.
Posters: PO1. Nerve Conduction Studies PO1.15 The Changes in the Mixed Nerve Conduction with Age in the Medial and Lateral Plantar Nerves Kyung Seok Park1 *, Beom Joon Kim1 , Se Ho Oh1 , Yoon-Ho Hong3 , Seong-Ho Park1 , Kwang-Woo Lee2 1 Dept. of Neurology, Seoul National University Bundang Hospital, Korea, 2 Dept. of Neurology, Seoul National University Hospital, Korea, 3 Dept. of Neurology, Seoul Boramae Municipal Hospital, Korea E-mail address: [email protected] Background: The purpose of this study was to determine the changes in the mixed nerve conduction with age in the medial and lateral plantar nerves in Korean. Methods: We studied mixed nerve conduction in the medial and lateral plantar nerves of 58 normal subjects between the ages of 20 to 79, using the technique described by Saeed and Gatens in 1982. The recording surface electrode was placed on the posterior tibial nerve proximal to the flexor retinaculum. The medial and lateral plantar nerves were stimulated orthodromically with a bipolar surface stimulator at a distance of 14 cm. Orthodromic latency and amplitude of compound nerve action potentials (CNAP) were measured and analyzed according to each decade. Results: The mean distal latency of CNAP of the medial and lateral plantar nerves ranged from 2.6 2.8 ms and 2.8 3.0 ms respectively. The amplitude ranged from 4 36 mV and 3 19 mV respectively. No significant differences were noted in the mean latency among the age groups. However, in the 70 79-year-old group compared with other age groups, there was a significant decrease in the amplitude. Conclusions: The changes in the mixed nerve conduction with age in the medial and lateral plantar nerves seem to be accelerated after the early 70s. The changes are more prominent in the amplitude of CNAP. These data can also be used usefully as normal values of mixed nerve conduction in the plantar nerves in the future Korean studies. PO1.16 Origin of the Far-Field Potentials (FFPs) in the Ulnar-Nerve Compound Muscle Action Potential (CMAP) Masahiro Sonoo1 *, Mana Higashihara2 , Katsumi Kurokawa3 , Yuki Hatanaka1 , Hiroko Kurono1 , Teruo Shimizu1 1 Dept. of Neurology, Teikyo University School of Medicine, Japan, 2 Dept. of Neurology, Graduate School of Medicine, the University of Tokyo, Japan, 3 Dept. of Neurology, Hiroshima City Asa Citizens Hospital, Japan E-mail address: [email protected] Background: Recent studies documented contribution of the potentials recorded at the reference electrode to the CMAP, especially for tibial and ulnar nerves, and FFPs have been postulated for their origin. For the ulnar nerve, the major contribution of interosseus muscles to FFPs has been suggested, although direct proof has been lacking. In the present study, we investigated this issue by two new methods: first, the identification of individual motor unit potentials (MUPs) during weak voluntary contraction, and second, the investigation of patients with ulnar neuropathy at the wrist (UNW). Methods: 1. Voluntary MUPs were investigated in six healthy volunteers. We placed recording electrodes at several sites including over the bellies of abductor digitti minimi (ADM) and dorsal and palmar interossei, and at the ordinary distal reference over the little finger (dref). Common proximal reference (pref) was placed at forearm, and FFPs were evaluated by the dref-pref lead. 2. We investigated FFPs in two UNW patients diagnosed as having a selective deep motor branch lesion sparing hypothenar muscles. Results: 1. FFPs of the ulnar-nerve CMAP was composed of negative (N1) positive (P1) negative (N2) triphasic waves. The comparison between CMAP and MUPs revealed that ADM contributed to P1 N2 components of FFP, although there was significant intersubject variation. The N1 component was solely derived from a muscle, possibly IOP3, which also contributed to P1 and N2. Other ulnar interossei may also contribute mainly to P1. 2. In the patient 1, FFPs were almost completely lost. In the patient 2, N1 and steep earlier P1 components were lost, while delayed P1 and N2 components remained. Conclusions: The two different studies indicated almost the same conclusions. Muscles other than hypothenar muscles such as interossi significantly contribute to FFPs, especially to N1. ADM may contribute to P1 and N2 to a lesser extent, with significant intersubject variation.
Posters: PO1. Nerve Conduction Studies PO1.15 The Changes in the Mixed Nerve Conduction with Age in the Medial and Lateral Plantar Nerves Kyung Seok Park1 *, Beom Joon Kim1 , Se Ho Oh1 , Yoon-Ho Hong3 , Seong-Ho Park1 , Kwang-Woo Lee2 1 Dept. of Neurology, Seoul National University Bundang Hospital, Korea, 2 Dept. of Neurology, Seoul National University Hospital, Korea, 3 Dept. of Neurology, Seoul Boramae Municipal Hospital, Korea E-mail address: [email protected] Background: The purpose of this study was to determine the changes in the mixed nerve conduction with age in the medial and lateral plantar nerves in Korean. Methods: We studied mixed nerve conduction in the medial and lateral plantar nerves of 58 normal subjects between the ages of 20 to 79, using the technique described by Saeed and Gatens in 1982. The recording surface electrode was placed on the posterior tibial nerve proximal to the flexor retinaculum. The medial and lateral plantar nerves were stimulated orthodromically with a bipolar surface stimulator at a distance of 14 cm. Orthodromic latency and amplitude of compound nerve action potentials (CNAP) were measured and analyzed according to each decade. Results: The mean distal latency of CNAP of the medial and lateral plantar nerves ranged from 2.6 2.8 ms and 2.8 3.0 ms respectively. The amplitude ranged from 4 36 mV and 3 19 mV respectively. No significant differences were noted in the mean latency among the age groups. However, in the 70 79-year-old group compared with other age groups, there was a significant decrease in the amplitude. Conclusions: The changes in the mixed nerve conduction with age in the medial and lateral plantar nerves seem to be accelerated after the early 70s. The changes are more prominent in the amplitude of CNAP. These data can also be used usefully as normal values of mixed nerve conduction in the plantar nerves in the future Korean studies. PO1.16 Origin of the Far-Field Potentials (FFPs) in the Ulnar-Nerve Compound Muscle Action Potential (CMAP) Masahiro Sonoo1 *, Mana Higashihara2 , Katsumi Kurokawa3 , Yuki Hatanaka1 , Hiroko Kurono1 , Teruo Shimizu1 1 Dept. of Neurology, Teikyo University School of Medicine, Japan, 2 Dept. of Neurology, Graduate School of Medicine, the University of Tokyo, Japan, 3 Dept. of Neurology, Hiroshima City Asa Citizens Hospital, Japan E-mail address: [email protected] Background: Recent studies documented contribution of the potentials recorded at the reference electrode to the CMAP, especially for tibial and ulnar nerves, and FFPs have been postulated for their origin. For the ulnar nerve, the major contribution of interosseus muscles to FFPs has been suggested, although direct proof has been lacking. In the present study, we investigated this issue by two new methods: first, the identification of individual motor unit potentials (MUPs) during weak voluntary contraction, and second, the investigation of patients with ulnar neuropathy at the wrist (UNW). Methods: 1. Voluntary MUPs were investigated in six healthy volunteers. We placed recording electrodes at several sites including over the bellies of abductor digitti minimi (ADM) and dorsal and palmar interossei, and at the ordinary distal reference over the little finger (dref). Common proximal reference (pref) was placed at forearm, and FFPs were evaluated by the dref-pref lead. 2. We investigated FFPs in two UNW patients diagnosed as having a selective deep motor branch lesion sparing hypothenar muscles. Results: 1. FFPs of the ulnar-nerve CMAP was composed of negative (N1) positive (P1) negative (N2) triphasic waves. The comparison between CMAP and MUPs revealed that ADM contributed to P1 N2 components of FFP, although there was significant intersubject variation. The N1 component was solely derived from a muscle, possibly IOP3, which also contributed to P1 and N2. Other ulnar interossei may also contribute mainly to P1. 2. In the patient 1, FFPs were almost completely lost. In the patient 2, N1 and steep earlier P1 components were lost, while delayed P1 and N2 components remained. Conclusions: The two different studies indicated almost the same conclusions. Muscles other than hypothenar muscles such as interossi significantly contribute to FFPs, especially to N1. ADM may contribute to P1 and N2 to a lesser extent, with significant intersubject variation.