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Motor unit number estimates and quantitative muscle strength measurements in amyotrophic lateral sclerosis
2OP 59.
Society proceedings/
Electroencephalography
Motor unit number estimates and quantitative muscle strength measurements In amyotrophic lateral sclerosis. - C. Armon, M.E. Brandstater and G.W. Peterson (Loma Linda University, Loma Linda, CA)
Introduction: Measures of disease progression, other than survival, may enable trials of therapeutic interventions in amyotrophic lateral sclerosis (ALS) to be completed in shorter time. Objectives: To compare motor unit number estimates (MUNE) with quantitative tests of muscle strength at a single point in time in 21 patients with ALS. Methods: MUNE of thenar, hypothenar and extensor digitorum brevis (EDB) muscles were obtained according to the manual method of McComas. Chip and foot dorsiflexion (FD) strengths were measured within the Tufts Quantitative Neuromuscular Exam (TQNE). The measures were compared using analysis of variance (ANOVA) techniques. Results: The joint variance (R2> and P values were: grip strength/thenar MUNE: 0.448.0.0009; grip strength/hypothenar MUNE: 0.3, 0.0102; FD strength/EDB MUNE: 0.401, 0.0048. Joint variance of upper extremity versus lower extremity measures was not statistically significant. Conclusions: Quantitative tests of muscle strength and MUNE, when measured in the same body region, are significantly associated. However, the joint variance accounts for less than 50% of the overall variance of these measures. We conclude that these are separate and complementary measures of disease progression in ALS. The authors acknowledge Sherry May and Kim Riddle for performing the TQNEs, and Dharmaseeli Moses, R.N., for assisting with patient management and data collection. Supported in part by the Syntex/Synergen Neuroscience Joint Venture. 60. Selected paraspinal amyotrophy with normal limb magnetic resonance imaging, EMG and biopsy findings. - T.E. Bertorini ’ and H. Halford ’ (” University of Tennessee, Memphis, TN; ’ Methodist Hospitals, Memphis, TN) A 56-year-old black female patient developed progressive weakness in the trunk muscles, abnormal gait and mild diffuse back pain after a minor fall on her knees when she slipped on a wet floor. Examination revealed a marked lordosis with paraspinal muscle atrophy and weakness, mainly in the thoracic and lumbar areas, and mild neck extensor weakness. Limb muscles, reflexes and sensory examination were nonal. No fasciculations were present. Magnetic resonance imaging (MRI) showed a selective, profound atrophy of the paraspinal muscles, EMG showed diffuse denervation in all paraspinal muscles, mostly thoracic and lumbar, with normal limb examination. Nerve conduction tests were normal. Creadne kinase was twice normal. Repeated MRI and EMG 2 years later showed similar findings. Spinal fluid, blood chemistries and acetylcholine receptor antibodies were all normal. A muscle biopsy showed severe neurogenic atrophy in paraspinal muscles, but the quadriceps muscle was normal. This case represents a unique, selective, paraspinal amyotrophy without limb involvement that might be a variant of the benign focal amyotrophies. Study supported by Methodist Hospital and Methodist Foundation, University of Tennessee, Memphis, TN. 61. Corticomotoneuron counts in normal subjects and in amyotrophic lateral sclerosis. - A.A. Eiaen, M. Entezari-Taher and H. Stewart (Vancouver General Hospital, Vancouver, BC, Canada) Objective: Estimate the number of corticomotoneurons (CM& facilitating a single spinal motor neuron (SMN) in normal subjects and amyotrophic lateral sclerosis (ALS).
and clinical Neurophysiology
98 (1996) 8P-40P
Background: Peristimulus time histograms (PSTHs) can be used lo measure the firing probability of a voluntary recruited SMN. Concurrent magnetic stimulation of the motor cortex increases the firing probability of the unit. The size of the increase reflects the magnitude of the excitatory postsynaptic potential (EPSP) which measures the number of CMs facilitating the SMN under study. Methods: PSTHs were derived from voluntary activated wrist extensor SMNs. Two hundred subthreshold magnetic stimuli were delivered at 2-5 Hz during the activity. We studied 30 patients with ALS (aged 60.7 f 12.5) and 23 aged-matched control subjects (aged 58.2 f 13.7). Results: Age showed a significant negative linear correlation with EPSP magnitude (r = -0.653, P < 0.001)). The normal mean EPSP measured 2.45 mV compared to 1.50mV in the ALS patients (P < 0.0 1). In 16 patients, there was either no measurable EPSP (N = 5) or a value < 1 mV (N = 11). In 6 patients, EPSP was greater than predicted for age. Eight had normal values. Conclusion: ‘Ihe reduced or absent EPSPs in ALS reflects a loss of CMs. High values likely reflect a stage of glutamate induced excitotoxicity. 62. Golseth Young Investigator Award Winner!. The effects of lithium on muscle contractile function in humans - M.A. Tarnopolsky, A. Hicks and K. Winegard (McMaster University, Hamilton, Ont., Canada) Introduction:Patients treatedwith lithium (Li+) experience symptoms of muscle fatigue. Li+ can decrease inositol triphosphate (IP,) accumulation in some cell systems and IP, may play a role in excitation-contraction (E-C) coupling of skeletal muscle. Objectives: We sought to examine whether therapeutic doses of Li+ would impair muscle contractile function and/or the ability to recruit motor units in 12 young, healthy male subjects. These data may increase our understanding of the role of IP, in E-C coupling. Methods: We studied the effects of Li+ carbonate (600 mg b.i.d. X 6 days; randomized, double blind) upon muscle contractile function of tie dorsiflexors: peak twitch torque @‘IT), time to PlT (TPT), half-relaxation time (1 /2aT). maximal voluntary contraction strength (MVC), percent motor unit activation (% MUA), compound muscle action potential (M-wave) characteristics, and tetanic torque (3 min @ 15 and 50 Hz). Results and conclusions: Li+ treatment resulted in a significant decrease in tetanic torque at both frequencies (P < 0.001); resting and post-tetanic MVC and resting P’IT (P < 0.05). There was no effect of Li+ on % MUA, TPT, l/2, or M-wave characteristics. These data suggested that Li+ had a direct negative effect upon E-C coupling (no effect upon M-wave) and did not affect central motor unit recruitment. Study supported by N.S.E.R.C. (Canada). 63. Lateral antebrachial cutaneous neuropathy revisited. - E.J. Angus and B.K. Ahmad (Henry Ford Hospital, Detroit, MI) Over a 4 year period, we have identified 7 cases of lateral antebrachial cutaneous (LABC) neuropathy out of 14,000 patients seen in our EMG lab. Four patients were male and 3 female. They ranged in age from 25 to 71 years. All complained of numbness in the lateral forearm and had sensory deficit in the territory of the LABC nerve. In 2 cases, the LABC sensory nerve action potential (SNAP) was recordable but of significantly reduced amplitude (50-60% drop compared to the contralateral side). In both, the etiology was clumsy venipuncture. In the other 5 cases, the SNAP was unobtainable. Etiologies in these included forearm gunshot wound, rupture and/or repair of biceps tendon, and secondary to an arteriovenous tistula in the antecubital fossa. In one patient, the neuropathy was of apparently spontaneous onset. This is a rare mononeuropathy but presents a distinctive clinical and electrodiagnostic picture. The causes are more varied than previously reported. In our cases the lesions were axonal rather than demyelinating.
Society proceedings/
Electroencephalography
Motor unit number estimates and quantitative muscle strength measurements In amyotrophic lateral sclerosis. - C. Armon, M.E. Brandstater and G.W. Peterson (Loma Linda University, Loma Linda, CA)
Introduction: Measures of disease progression, other than survival, may enable trials of therapeutic interventions in amyotrophic lateral sclerosis (ALS) to be completed in shorter time. Objectives: To compare motor unit number estimates (MUNE) with quantitative tests of muscle strength at a single point in time in 21 patients with ALS. Methods: MUNE of thenar, hypothenar and extensor digitorum brevis (EDB) muscles were obtained according to the manual method of McComas. Chip and foot dorsiflexion (FD) strengths were measured within the Tufts Quantitative Neuromuscular Exam (TQNE). The measures were compared using analysis of variance (ANOVA) techniques. Results: The joint variance (R2> and P values were: grip strength/thenar MUNE: 0.448.0.0009; grip strength/hypothenar MUNE: 0.3, 0.0102; FD strength/EDB MUNE: 0.401, 0.0048. Joint variance of upper extremity versus lower extremity measures was not statistically significant. Conclusions: Quantitative tests of muscle strength and MUNE, when measured in the same body region, are significantly associated. However, the joint variance accounts for less than 50% of the overall variance of these measures. We conclude that these are separate and complementary measures of disease progression in ALS. The authors acknowledge Sherry May and Kim Riddle for performing the TQNEs, and Dharmaseeli Moses, R.N., for assisting with patient management and data collection. Supported in part by the Syntex/Synergen Neuroscience Joint Venture. 60. Selected paraspinal amyotrophy with normal limb magnetic resonance imaging, EMG and biopsy findings. - T.E. Bertorini ’ and H. Halford ’ (” University of Tennessee, Memphis, TN; ’ Methodist Hospitals, Memphis, TN) A 56-year-old black female patient developed progressive weakness in the trunk muscles, abnormal gait and mild diffuse back pain after a minor fall on her knees when she slipped on a wet floor. Examination revealed a marked lordosis with paraspinal muscle atrophy and weakness, mainly in the thoracic and lumbar areas, and mild neck extensor weakness. Limb muscles, reflexes and sensory examination were nonal. No fasciculations were present. Magnetic resonance imaging (MRI) showed a selective, profound atrophy of the paraspinal muscles, EMG showed diffuse denervation in all paraspinal muscles, mostly thoracic and lumbar, with normal limb examination. Nerve conduction tests were normal. Creadne kinase was twice normal. Repeated MRI and EMG 2 years later showed similar findings. Spinal fluid, blood chemistries and acetylcholine receptor antibodies were all normal. A muscle biopsy showed severe neurogenic atrophy in paraspinal muscles, but the quadriceps muscle was normal. This case represents a unique, selective, paraspinal amyotrophy without limb involvement that might be a variant of the benign focal amyotrophies. Study supported by Methodist Hospital and Methodist Foundation, University of Tennessee, Memphis, TN. 61. Corticomotoneuron counts in normal subjects and in amyotrophic lateral sclerosis. - A.A. Eiaen, M. Entezari-Taher and H. Stewart (Vancouver General Hospital, Vancouver, BC, Canada) Objective: Estimate the number of corticomotoneurons (CM& facilitating a single spinal motor neuron (SMN) in normal subjects and amyotrophic lateral sclerosis (ALS).
and clinical Neurophysiology
98 (1996) 8P-40P
Background: Peristimulus time histograms (PSTHs) can be used lo measure the firing probability of a voluntary recruited SMN. Concurrent magnetic stimulation of the motor cortex increases the firing probability of the unit. The size of the increase reflects the magnitude of the excitatory postsynaptic potential (EPSP) which measures the number of CMs facilitating the SMN under study. Methods: PSTHs were derived from voluntary activated wrist extensor SMNs. Two hundred subthreshold magnetic stimuli were delivered at 2-5 Hz during the activity. We studied 30 patients with ALS (aged 60.7 f 12.5) and 23 aged-matched control subjects (aged 58.2 f 13.7). Results: Age showed a significant negative linear correlation with EPSP magnitude (r = -0.653, P < 0.001)). The normal mean EPSP measured 2.45 mV compared to 1.50mV in the ALS patients (P < 0.0 1). In 16 patients, there was either no measurable EPSP (N = 5) or a value < 1 mV (N = 11). In 6 patients, EPSP was greater than predicted for age. Eight had normal values. Conclusion: ‘Ihe reduced or absent EPSPs in ALS reflects a loss of CMs. High values likely reflect a stage of glutamate induced excitotoxicity. 62. Golseth Young Investigator Award Winner!. The effects of lithium on muscle contractile function in humans - M.A. Tarnopolsky, A. Hicks and K. Winegard (McMaster University, Hamilton, Ont., Canada) Introduction:Patients treatedwith lithium (Li+) experience symptoms of muscle fatigue. Li+ can decrease inositol triphosphate (IP,) accumulation in some cell systems and IP, may play a role in excitation-contraction (E-C) coupling of skeletal muscle. Objectives: We sought to examine whether therapeutic doses of Li+ would impair muscle contractile function and/or the ability to recruit motor units in 12 young, healthy male subjects. These data may increase our understanding of the role of IP, in E-C coupling. Methods: We studied the effects of Li+ carbonate (600 mg b.i.d. X 6 days; randomized, double blind) upon muscle contractile function of tie dorsiflexors: peak twitch torque @‘IT), time to PlT (TPT), half-relaxation time (1 /2aT). maximal voluntary contraction strength (MVC), percent motor unit activation (% MUA), compound muscle action potential (M-wave) characteristics, and tetanic torque (3 min @ 15 and 50 Hz). Results and conclusions: Li+ treatment resulted in a significant decrease in tetanic torque at both frequencies (P < 0.001); resting and post-tetanic MVC and resting P’IT (P < 0.05). There was no effect of Li+ on % MUA, TPT, l/2, or M-wave characteristics. These data suggested that Li+ had a direct negative effect upon E-C coupling (no effect upon M-wave) and did not affect central motor unit recruitment. Study supported by N.S.E.R.C. (Canada). 63. Lateral antebrachial cutaneous neuropathy revisited. - E.J. Angus and B.K. Ahmad (Henry Ford Hospital, Detroit, MI) Over a 4 year period, we have identified 7 cases of lateral antebrachial cutaneous (LABC) neuropathy out of 14,000 patients seen in our EMG lab. Four patients were male and 3 female. They ranged in age from 25 to 71 years. All complained of numbness in the lateral forearm and had sensory deficit in the territory of the LABC nerve. In 2 cases, the LABC sensory nerve action potential (SNAP) was recordable but of significantly reduced amplitude (50-60% drop compared to the contralateral side). In both, the etiology was clumsy venipuncture. In the other 5 cases, the SNAP was unobtainable. Etiologies in these included forearm gunshot wound, rupture and/or repair of biceps tendon, and secondary to an arteriovenous tistula in the antecubital fossa. In one patient, the neuropathy was of apparently spontaneous onset. This is a rare mononeuropathy but presents a distinctive clinical and electrodiagnostic picture. The causes are more varied than previously reported. In our cases the lesions were axonal rather than demyelinating.