- Email: [email protected]
47. Effects of leg pedaling on cutaneous reflexes in the upper limb muscles
Society Proceedings / Clinical Neurophysiology 120 (2009) e147–e180
made the powers suitable for the brain signal. In this way, we eventually obtained 100% of the estimated precision. Our BCI, hence, can be a useful instrument in controlling cursor movements on a screen. doi:10.1016/j.clinph.2009.02.048
43. The effect of supramaximal conditioning stimuli on the Fwave in median nerve—Tatsuya Abe, Akiko Hishinuma, Tetsuo Komori, Hiroki Ohshima, Akihiko Unaki, Sayaka Kondo, Yasuko Oe, Nobuo Araki (Saitama Medical University, Saitama, Japan) F response is known as the indicator for excitability of spinal motor neuron. To know how much influence double stimulation has on spinal motor neuron excitability, F response was investigated on median nerve in 8 normal subjects using paired supramaximal stimuli with the inter-stimulus intervals (ISI) ranging from 5 to 500 ms. A hundred pair stimuli at 1 Hz interval were delivered to median nerve at the wrist in each session. F-wave was recorded from thenar muscles. Persistence of F-wave and mean amplitude of Fwave were examined. F-wave persistence was markedly decreased at ISI from 20 to 50 ms, and was increased at ISI from 150 to 200 ms. Mean F-wave amplitude showed no obvious change. Supramaximal conditioning stimulus includes some kinds of sensory input through posterior rami and antidromic invasion to the motor neuron through motor fibers. All such input may make inhibitory and facilitatory effects. Father conditioning stimulus of different intensity should be needed to clear the mechanism happened in spinal cord.
e157
To assess motor functions of proximal arm muscles, we have analyzed target-reaching movements in patients with cervical myelopathy, and detected obvious motor function impairments. In the current study, we examined if the reaching performance reflected functional recovery after surgery. Sixteen patients with cervical myelopathy (9 males and 7 females; age 63 13ðmean SDÞ) participated experiments before and after operation. They sat 40 cm in front of a board, to reach for a lighted LED (target) in its center after sound GO signal. After the movement onset, the center target was sometimes extinguished, and a new left or right target was lit. In these target jump trials, patients had to adjust ongoing movements rapidly to touch the new target. As reported previously, touch positions were more inaccurate and movement adjustment to new target was slower in patients before operation, compared with agematched control. However, the two parameters were improved significantly after operation. Weakness of proximal muscles was rarely detected in MMT score, even before operation. The results suggest that the reaching movement analysis provide good indices to assess motor function impairments and recovery in patients with cervical myelopathy, which could not be reflected in muscle strength assessment. doi:10.1016/j.clinph.2009.02.051
46. The adaptation process of postural control for maintaining upright stance in subjects with hemiparesis—Kimitaka Hase, Yasuhiro Kiyota, Satoshi Imai, Toshiyuki Fujiwara, Tetsuya Tsuji, Meigen Liu, Akio Kimura (Keio University, Tokyo, Japan)
doi:10.1016/j.clinph.2009.02.049
44. The influences of sub-motor threshold conditioning stimuli on F-wave in median nerve—Akihiko Unaki, Tatsuya Abe, Tetsuo Komori, Akiko Hishinuma, Hiroki Ohshima, Sayaka Kondo, Yasuko Oe, Nobuo Araki (Saitama Medical University, Saitama, Japan) F response is known as the indicator for excitability of spinal motor neuron. To know how much influence double stimulation has on spinal motor neuron excitability, F response was investigated on median nerve in 8 normal subjects using paired stimuli with the inter-stimulus intervals (ISI) ranging from 5 to 500 ms. We investigated the effect of sub-motor threshold stimuli, means pure sensory fibers were stimulated, as conditioning stimulus of F-wave elicited by supramaximal test stimulus. A hundred pair stimuli at 1 Hz interval were delivered to median nerve at the wrist in each session. F-wave was recorded from thenar muscles. Persistence of F-wave and mean amplitude of F-wave were examined. The persistence of F-wave was not altered on the ISI from 20 to 50 ms, shown clear inhibition when supramaximal conditioning stimuli were delivered, and were increased in ISI from 200 to 300 ms. Mean F-wave amplitude showed no obvious change. These results suggested that the inhibitory response of F wave during the ISI between 20 and 50 ms, when the supramaximal conditioning stimuli was given, may not be related to sensory conditioning input. doi:10.1016/j.clinph.2009.02.050
45. Functional recovery assessments of proximal arm muscles by target-reaching in postoperative patients with cervical myelopathy—Kazutaka Igarashi, Satoshi Shibuya, Hideto Sano, Masahito Takahashi, Kazuhiko Satomi, Yukari Ohki (School of Medicine, Kyorin University, Tokyo, Japan)
The standing postural control in process of being reorganized after stroke was analyzed in 9 subjects with hemiparesis, who have never maintained upright stance by themselves in the rehabilitative treatments (8 males: aged 48–68 years: 5 right hemiparesis: 6– 19 days after stroke). They were asked to stand on the forceplates for 60 s without any help, with his or her bare feet placed 10 cm apart. The standing trials were repeated five times with a few minutes interval. The ground reaction force and electromyographic data from the both lower limbs were recorded. During the standing tasks, any other instruction with respect to postural managements was not provided. In the early trails for standing, the subjects balanced themselves by loading equal weights onto each leg, while using increased muscular activities of the non-paretic leg. The center of pressure displacements in the anterior–posterior direction gradually decreased in the later standing trials ðP < :05Þ. The experience-related changes were achieved by shifting the center of body-sway to the side of the non-paretic foot ðP < :05Þ. The asymmetric weight-bearing for standing seemed to provide reduced biceps femoris muscular activity ðP < :01Þ as well as a tendency of reduced tibialis anterior muscular activity in the non-paretic leg. doi:10.1016/j.clinph.2009.02.052
47. Effects of leg pedaling on cutaneous reflexes in the upper limb muscles—Syusaku Sasada 1, Toshiki Tazoe 2, Tsuyoshi Nakajima 3, Tomoyoshi Komiyama 2 (1 Tokyo Gakugei University, Tokyo, Japan, 2 Chiba University, Chiba, Japan, 3 National Rehabilitation Center, Saitama, Japan) The present study investigated the effects of rhythmic leg pedaling on the amplitude of cutaneous reflexes (peak latency of 30– 70 ms) in the upper limb muscles. The subjects sat in an armchair and performed leg pedaling. The cutaneous reflexes were evoked
e158
Society Proceedings / Clinical Neurophysiology 120 (2009) e147–e180
by stimulating the superficial radial nerve (2–2.5 PT, 3 pulses, 333 Hz) while performing weak isometric contraction of the upper limb muscles. Cutaneous reflexes were recorded while the leg was at rest, performing pedaling, isometric contraction of the knee extensors and a one shot-like discrete pedaling motion. The magnitude of the cutaneous reflex in the flexor carpi radialis (FCR), biceps brachii and posterior deltoid (PD) was significantly modulated during leg pedaling compared to that during rest. Modulation of cutaneous reflexes in the FCR and PD strongly depended on the level of isometric contraction of the muscles tested and cadence of pedaling, but did not depend on the pedaling phase or contraction level of the knee extensors. Moreover, cutaneous reflexes were not significantly modulated by discrete leg pedaling. These findings suggest that activity of the rhythm generating system in the spinal cord would affect the excitability of cutaneous reflex pathways in the upper limbs. doi:10.1016/j.clinph.2009.02.053
48. Brain mechanisms of auditory temporal assimilation—Takako Mitsudo, Yoshitaka Nakajima, Gerard B. Remijn, Yoshinobu Goto, Shozo Tobimatsu (Kyushu University, Fukuoka, Japan) We recorded event-related potentials (ERPs) to elucidate the mechanisms of human auditory temporal assimilation. Stimulus patterns consisted of two neighboring time intervals marked by three successive tone bursts (20 ms, 1000 Hz), where the first time interval (T1) varied from 80 to 320 ms, while the second time interval (T2) was fixed at 200 ms. Four dummy stimuli, combinations of T1 and T2 differed from the others, were also used. Participants judged whether T1 and T2 had the same duration or not by pressing a button. They judged the two neighboring time intervals as the same when 80 ðT 1 T 2Þ þ40 (ms). The ERP results are summarized as follows: (a) a slow negative component in the frontal area emerged at approximately 300 ms after the 1st marker, and lasted until 300–400 ms after the 3rd marker, (b) the responses of the right frontal electrodes were greater than those of the left, and (c) the frontal areas’ activation was smaller when the temporal assimilation occurred. We consider that the attenuation of the frontal negativity immediately after the stimuli correlates with the perceptual assimilation of auditory temporal patterns. doi:10.1016/j.clinph.2009.02.054
49. Effects of prosthetic gait training for individuals with hemiparesis—Junichi Shoji, Kimitaka Hase, Etsuko Suzuki, Ken Kobayashi, Michiyo Kamisako, Meigen Liu (Keio University Hospital, Tokyo, Japan) The common motor strategy of hemiparetic gait is based on coactivations of flexor and extensor muscles in the lower limbs. We analyzed the changes of electromyographic co-activation pattern after two different hemiparetic gait trainings. Fourteen hemiparetic subjects who could independently walk 10 m without a cane and orthosis participated in the gait training programs either using the treadmill or below-knee prosthesis. The former was carried out at a speed around maximum gait velocity for each patient (mean training number;12:1 2:5 days). The other is a newly developed method to induce the forced use of the paretic leg by applying the prosthesis to the non-paretic leg (mean training number;11:8 1:6 days). We measured the surface electromyographic activity of the vastus medialis (VM), biceps femoris (BF), tibialis
anterior (TA), and soleus (Sol) muscles before and after each training and calculated the percentage of co-activation duration for the stance phase of gait cycle. The amounts of the paretic VM-BF and non-paretic TA–Sol co-activation were significantly decreased after the prosthetic gait training. On the other hand, there was no significant difference after the treadmill gait training. The results suggest that the prosthetic gait training may provide a possible improvement of hemiparetic gait pattern. doi:10.1016/j.clinph.2009.02.055
50. Repetitive transcranial magnetic stimulation for intractable neuropathic pain—Koichi Hosomi, Youichi Saitoh, Haruhiko Kishima, Masayuki Hirata, Satoru Oshino, Tetsu Goto, Takufumi Yanagisawa, Toshiki Yoshimine (Osaka University, Suita, Japan) The objective of this retrospective study was to confirm the pain relief with repetitive transcranial magnetic stimulation (rTMS) in neuropathic pain. Subject were 86 patients with neuropathic pain who underwent 5 Hz-rTMS over the primary motor cortex and evaluation of that efficacy with visual analogue scale (VAS). Forty-three of eighty-six patients underwent both real and sham rTMS. The real rTMS reduced pain in all the patients and the mean reduction rate in VAS was 23.3% and 28 patients (32.6%) showed 30% pain reduction in VAS. In the 43 patients who underwent both real and sham rTMS, the real rTMS was more effective than the sham stimulation (mean reduction rates of VAS; 30.3%, 14.4%, p = 0.0003), and 21 patients (48.8%) showed 30% pain reduction after real rTMS, while six patients (14.0%) after sham (p = 0.0005). These results confirmed that 5 Hz-rTMS over the primary motor cortex could provide pain relief in patients with neuropathic pain. doi:10.1016/j.clinph.2009.02.056
51. A pitfall in sensory conduction study of the lateral antebrachial cutaneous nerve (LAC): Spread to the median nerve— Chizuko Oishi 1, Masahiro Sonoo 2, Teruo Shimizu 2, Atsuro Chiba 1 (1 Faculty of Medicine, Kyorin University, Tokyo, Japan, 2 Teikyo University School of Medicine, Tokyo, Japan) Antidromic sensory-nerve conduction study (SCS) of the LAC nerve is a diagnostic test mainly employed for the evaluation of plexopathy. We recently reported a previously-undescribed pitfall for this test, the spread of the stimulus to the radial nerve at the elbow, which may be a reason for the reported large amplitude variation of the sensory nerve action potential (SNAP) of this nerve. In the present study, we report another new pitfall for LAC SCS that the same stimulation spreads to the median nerve. We examined 78 nerves of 39 normal subjects. We judged whether the spread occurred by recording SNAPs of the median nerve (middle finger and thumb) and the radial nerve (thumb and over the extensor pollicis longus tendon) at distal sites. Among 78 nerves investigated, the spread to the median nerve was observed for 8 nerves, causing up to 2-fold apparent enlargement of the SNAP. However, it was difficult to distinguish whether the spread occurred solely to the median nerve or both to the median and radial nerves. The influence of the spread to the median nerve was assumed to be smaller than that of the radial nerve because the median nerve ran deeper in the forearm. doi:10.1016/j.clinph.2009.02.057
made the powers suitable for the brain signal. In this way, we eventually obtained 100% of the estimated precision. Our BCI, hence, can be a useful instrument in controlling cursor movements on a screen. doi:10.1016/j.clinph.2009.02.048
43. The effect of supramaximal conditioning stimuli on the Fwave in median nerve—Tatsuya Abe, Akiko Hishinuma, Tetsuo Komori, Hiroki Ohshima, Akihiko Unaki, Sayaka Kondo, Yasuko Oe, Nobuo Araki (Saitama Medical University, Saitama, Japan) F response is known as the indicator for excitability of spinal motor neuron. To know how much influence double stimulation has on spinal motor neuron excitability, F response was investigated on median nerve in 8 normal subjects using paired supramaximal stimuli with the inter-stimulus intervals (ISI) ranging from 5 to 500 ms. A hundred pair stimuli at 1 Hz interval were delivered to median nerve at the wrist in each session. F-wave was recorded from thenar muscles. Persistence of F-wave and mean amplitude of Fwave were examined. F-wave persistence was markedly decreased at ISI from 20 to 50 ms, and was increased at ISI from 150 to 200 ms. Mean F-wave amplitude showed no obvious change. Supramaximal conditioning stimulus includes some kinds of sensory input through posterior rami and antidromic invasion to the motor neuron through motor fibers. All such input may make inhibitory and facilitatory effects. Father conditioning stimulus of different intensity should be needed to clear the mechanism happened in spinal cord.
e157
To assess motor functions of proximal arm muscles, we have analyzed target-reaching movements in patients with cervical myelopathy, and detected obvious motor function impairments. In the current study, we examined if the reaching performance reflected functional recovery after surgery. Sixteen patients with cervical myelopathy (9 males and 7 females; age 63 13ðmean SDÞ) participated experiments before and after operation. They sat 40 cm in front of a board, to reach for a lighted LED (target) in its center after sound GO signal. After the movement onset, the center target was sometimes extinguished, and a new left or right target was lit. In these target jump trials, patients had to adjust ongoing movements rapidly to touch the new target. As reported previously, touch positions were more inaccurate and movement adjustment to new target was slower in patients before operation, compared with agematched control. However, the two parameters were improved significantly after operation. Weakness of proximal muscles was rarely detected in MMT score, even before operation. The results suggest that the reaching movement analysis provide good indices to assess motor function impairments and recovery in patients with cervical myelopathy, which could not be reflected in muscle strength assessment. doi:10.1016/j.clinph.2009.02.051
46. The adaptation process of postural control for maintaining upright stance in subjects with hemiparesis—Kimitaka Hase, Yasuhiro Kiyota, Satoshi Imai, Toshiyuki Fujiwara, Tetsuya Tsuji, Meigen Liu, Akio Kimura (Keio University, Tokyo, Japan)
doi:10.1016/j.clinph.2009.02.049
44. The influences of sub-motor threshold conditioning stimuli on F-wave in median nerve—Akihiko Unaki, Tatsuya Abe, Tetsuo Komori, Akiko Hishinuma, Hiroki Ohshima, Sayaka Kondo, Yasuko Oe, Nobuo Araki (Saitama Medical University, Saitama, Japan) F response is known as the indicator for excitability of spinal motor neuron. To know how much influence double stimulation has on spinal motor neuron excitability, F response was investigated on median nerve in 8 normal subjects using paired stimuli with the inter-stimulus intervals (ISI) ranging from 5 to 500 ms. We investigated the effect of sub-motor threshold stimuli, means pure sensory fibers were stimulated, as conditioning stimulus of F-wave elicited by supramaximal test stimulus. A hundred pair stimuli at 1 Hz interval were delivered to median nerve at the wrist in each session. F-wave was recorded from thenar muscles. Persistence of F-wave and mean amplitude of F-wave were examined. The persistence of F-wave was not altered on the ISI from 20 to 50 ms, shown clear inhibition when supramaximal conditioning stimuli were delivered, and were increased in ISI from 200 to 300 ms. Mean F-wave amplitude showed no obvious change. These results suggested that the inhibitory response of F wave during the ISI between 20 and 50 ms, when the supramaximal conditioning stimuli was given, may not be related to sensory conditioning input. doi:10.1016/j.clinph.2009.02.050
45. Functional recovery assessments of proximal arm muscles by target-reaching in postoperative patients with cervical myelopathy—Kazutaka Igarashi, Satoshi Shibuya, Hideto Sano, Masahito Takahashi, Kazuhiko Satomi, Yukari Ohki (School of Medicine, Kyorin University, Tokyo, Japan)
The standing postural control in process of being reorganized after stroke was analyzed in 9 subjects with hemiparesis, who have never maintained upright stance by themselves in the rehabilitative treatments (8 males: aged 48–68 years: 5 right hemiparesis: 6– 19 days after stroke). They were asked to stand on the forceplates for 60 s without any help, with his or her bare feet placed 10 cm apart. The standing trials were repeated five times with a few minutes interval. The ground reaction force and electromyographic data from the both lower limbs were recorded. During the standing tasks, any other instruction with respect to postural managements was not provided. In the early trails for standing, the subjects balanced themselves by loading equal weights onto each leg, while using increased muscular activities of the non-paretic leg. The center of pressure displacements in the anterior–posterior direction gradually decreased in the later standing trials ðP < :05Þ. The experience-related changes were achieved by shifting the center of body-sway to the side of the non-paretic foot ðP < :05Þ. The asymmetric weight-bearing for standing seemed to provide reduced biceps femoris muscular activity ðP < :01Þ as well as a tendency of reduced tibialis anterior muscular activity in the non-paretic leg. doi:10.1016/j.clinph.2009.02.052
47. Effects of leg pedaling on cutaneous reflexes in the upper limb muscles—Syusaku Sasada 1, Toshiki Tazoe 2, Tsuyoshi Nakajima 3, Tomoyoshi Komiyama 2 (1 Tokyo Gakugei University, Tokyo, Japan, 2 Chiba University, Chiba, Japan, 3 National Rehabilitation Center, Saitama, Japan) The present study investigated the effects of rhythmic leg pedaling on the amplitude of cutaneous reflexes (peak latency of 30– 70 ms) in the upper limb muscles. The subjects sat in an armchair and performed leg pedaling. The cutaneous reflexes were evoked
e158
Society Proceedings / Clinical Neurophysiology 120 (2009) e147–e180
by stimulating the superficial radial nerve (2–2.5 PT, 3 pulses, 333 Hz) while performing weak isometric contraction of the upper limb muscles. Cutaneous reflexes were recorded while the leg was at rest, performing pedaling, isometric contraction of the knee extensors and a one shot-like discrete pedaling motion. The magnitude of the cutaneous reflex in the flexor carpi radialis (FCR), biceps brachii and posterior deltoid (PD) was significantly modulated during leg pedaling compared to that during rest. Modulation of cutaneous reflexes in the FCR and PD strongly depended on the level of isometric contraction of the muscles tested and cadence of pedaling, but did not depend on the pedaling phase or contraction level of the knee extensors. Moreover, cutaneous reflexes were not significantly modulated by discrete leg pedaling. These findings suggest that activity of the rhythm generating system in the spinal cord would affect the excitability of cutaneous reflex pathways in the upper limbs. doi:10.1016/j.clinph.2009.02.053
48. Brain mechanisms of auditory temporal assimilation—Takako Mitsudo, Yoshitaka Nakajima, Gerard B. Remijn, Yoshinobu Goto, Shozo Tobimatsu (Kyushu University, Fukuoka, Japan) We recorded event-related potentials (ERPs) to elucidate the mechanisms of human auditory temporal assimilation. Stimulus patterns consisted of two neighboring time intervals marked by three successive tone bursts (20 ms, 1000 Hz), where the first time interval (T1) varied from 80 to 320 ms, while the second time interval (T2) was fixed at 200 ms. Four dummy stimuli, combinations of T1 and T2 differed from the others, were also used. Participants judged whether T1 and T2 had the same duration or not by pressing a button. They judged the two neighboring time intervals as the same when 80 ðT 1 T 2Þ þ40 (ms). The ERP results are summarized as follows: (a) a slow negative component in the frontal area emerged at approximately 300 ms after the 1st marker, and lasted until 300–400 ms after the 3rd marker, (b) the responses of the right frontal electrodes were greater than those of the left, and (c) the frontal areas’ activation was smaller when the temporal assimilation occurred. We consider that the attenuation of the frontal negativity immediately after the stimuli correlates with the perceptual assimilation of auditory temporal patterns. doi:10.1016/j.clinph.2009.02.054
49. Effects of prosthetic gait training for individuals with hemiparesis—Junichi Shoji, Kimitaka Hase, Etsuko Suzuki, Ken Kobayashi, Michiyo Kamisako, Meigen Liu (Keio University Hospital, Tokyo, Japan) The common motor strategy of hemiparetic gait is based on coactivations of flexor and extensor muscles in the lower limbs. We analyzed the changes of electromyographic co-activation pattern after two different hemiparetic gait trainings. Fourteen hemiparetic subjects who could independently walk 10 m without a cane and orthosis participated in the gait training programs either using the treadmill or below-knee prosthesis. The former was carried out at a speed around maximum gait velocity for each patient (mean training number;12:1 2:5 days). The other is a newly developed method to induce the forced use of the paretic leg by applying the prosthesis to the non-paretic leg (mean training number;11:8 1:6 days). We measured the surface electromyographic activity of the vastus medialis (VM), biceps femoris (BF), tibialis
anterior (TA), and soleus (Sol) muscles before and after each training and calculated the percentage of co-activation duration for the stance phase of gait cycle. The amounts of the paretic VM-BF and non-paretic TA–Sol co-activation were significantly decreased after the prosthetic gait training. On the other hand, there was no significant difference after the treadmill gait training. The results suggest that the prosthetic gait training may provide a possible improvement of hemiparetic gait pattern. doi:10.1016/j.clinph.2009.02.055
50. Repetitive transcranial magnetic stimulation for intractable neuropathic pain—Koichi Hosomi, Youichi Saitoh, Haruhiko Kishima, Masayuki Hirata, Satoru Oshino, Tetsu Goto, Takufumi Yanagisawa, Toshiki Yoshimine (Osaka University, Suita, Japan) The objective of this retrospective study was to confirm the pain relief with repetitive transcranial magnetic stimulation (rTMS) in neuropathic pain. Subject were 86 patients with neuropathic pain who underwent 5 Hz-rTMS over the primary motor cortex and evaluation of that efficacy with visual analogue scale (VAS). Forty-three of eighty-six patients underwent both real and sham rTMS. The real rTMS reduced pain in all the patients and the mean reduction rate in VAS was 23.3% and 28 patients (32.6%) showed 30% pain reduction in VAS. In the 43 patients who underwent both real and sham rTMS, the real rTMS was more effective than the sham stimulation (mean reduction rates of VAS; 30.3%, 14.4%, p = 0.0003), and 21 patients (48.8%) showed 30% pain reduction after real rTMS, while six patients (14.0%) after sham (p = 0.0005). These results confirmed that 5 Hz-rTMS over the primary motor cortex could provide pain relief in patients with neuropathic pain. doi:10.1016/j.clinph.2009.02.056
51. A pitfall in sensory conduction study of the lateral antebrachial cutaneous nerve (LAC): Spread to the median nerve— Chizuko Oishi 1, Masahiro Sonoo 2, Teruo Shimizu 2, Atsuro Chiba 1 (1 Faculty of Medicine, Kyorin University, Tokyo, Japan, 2 Teikyo University School of Medicine, Tokyo, Japan) Antidromic sensory-nerve conduction study (SCS) of the LAC nerve is a diagnostic test mainly employed for the evaluation of plexopathy. We recently reported a previously-undescribed pitfall for this test, the spread of the stimulus to the radial nerve at the elbow, which may be a reason for the reported large amplitude variation of the sensory nerve action potential (SNAP) of this nerve. In the present study, we report another new pitfall for LAC SCS that the same stimulation spreads to the median nerve. We examined 78 nerves of 39 normal subjects. We judged whether the spread occurred by recording SNAPs of the median nerve (middle finger and thumb) and the radial nerve (thumb and over the extensor pollicis longus tendon) at distal sites. Among 78 nerves investigated, the spread to the median nerve was observed for 8 nerves, causing up to 2-fold apparent enlargement of the SNAP. However, it was difficult to distinguish whether the spread occurred solely to the median nerve or both to the median and radial nerves. The influence of the spread to the median nerve was assumed to be smaller than that of the radial nerve because the median nerve ran deeper in the forearm. doi:10.1016/j.clinph.2009.02.057