Motor nerve conduction velocity

Endocr = endocrine F = female Gastro = gastrointestinal Gd = gestational day Hemato = hematological hr = hour(s) LOAEL = lowest-observed-adverse-effect level M = male Metab = metabolic MCV = motor nerve conduction velocity mo = month(s) Musc/skel = musculoskeletal NOAEL = no-observed-adverse-effect level Resp = respiratory wk = week(s) yr = year(s)... 

A decrease in the amplitude of the sensory nerve action potential has also been observed in a group of 20 asymptomatic workers exposed to -hexanc (Pastore et al. 1994). The subjects of this study were selected on the basis of urinary levels of the n-hexane metabolite 2,5-hexanedione (See Sections 2.3 and 2.7) exceeding 5 mg/L and compared to a group of unexposed laboratory workers. Mean years worked was 8.13 (range, 1.5—23 years). Sensory and motor nerve conduction velocities and distal latencies were normal in all nerves tested. However, significant decreases were found in sensory nerve action potential amplitude in the median, sural, and ulnar nerves. Neither the level of 2,5-hexanedione in urine nor age correlated with the changes in amplitude however, there was a significant correlation between years worked and amplitude. 

It is not entirely clear whether the acetone co-exposure in the Sanagi et al. (1980) study contributed to the observed effects. Indirect evidence from an occupational study (Cardona et al. 1996) showed that workplace acetone concentrations had a statistical correlation with the ratio of urinary -hexane metabolites to /i-hcxanc air concentration, although it did not correlate with measured urinary metabolites. No animal studies are available describing the effects of inhalation co-exposure to acetone and -hexane, although there are several studies which report interactions between acetone and the neurotoxic metabolite of -hexane 2,5-hexanedione (See Section 2.4, Mechanisms of Action). Oral administration of acetone has been reported to potentiate the neurotoxicity caused by oral exposure to the neurotoxic u-hexane metabolite 2,5-hexanedione in rats (Ladefoged et al. 1989, 1994). Oral exposure to acetone alone in rats at 650 mg/kg/day resulted in a statistically significant decrease in motor nerve conduction velocity after 6 weeks co-exposure to acetone and 2,5-hexanedione resulted in greater effects... 

A chronic-duration inhalation MRL of 0.6 ppm has been derived by ATSDR, based on a LOAEL of 58 ppm for reduced motor nerve conduction velocity in occupationally exposed workers (Sanagi et al. 1980). 

CVSF = conduction velocity of slow = motor fibers dSCV = distal sensory nerve conduction velocity MAP k/a = proximal to distal amplitude ratio of muscle action potentials MMCV = maximal motor nerve conduction velocity MNCV = mixed nerve conduction velocity RL = residual latency of motor nerve conduction... 

Pankow D, Glatzel W, Tietze K, et al. 1975. Motor nerve conduction velocity after carbon monoxide or m-dinitrobenzene poisoning following elimination of the poisons. Arch Toxicol 18 325-330. 

Compared to controls, 41 MEK workers with an average of 14 years exposure exhibited significantly lower motor nerve conduction velocities in the median, ulnar, and peroneal nerves irritation of the eyes and upper respiratory tract and a neurotoxic syndrome characterized by mood disorders, irritability, memory difficulties, sleep disturbances, headache, and numbness were also more prevalent in the exposed workers/... 

Coppey, L. J., Gellett, J. S., Davidson, E. P., Dunlap, J. A., Lund, D. D., and Yorek, M. A. 2001. Effect of antioxidant treatment of streptozotocin-induced diabetic rats on endoneurial blood flow, motor nerve conduction velocity, and vascular reactivity of epineurial arterioles of the sciatic nerve. Diabetes 50 1927-1937. 

In streptozotocin-induced diabetic rats, OPB-9195 improved delayed motor-nerve conduction velocity by 60%, reduced stress-related DNA damage in the periphery of sciatic nerves, and reduced serum-AGE levels, but did not affect body weight, blood glucose levels, and glycated haemoglobin.600... 

Neurotoxicity has been observed both preclinically and clinically with some platinum drugs including cisplatin and tetraplatin (Ormaplatin ). For example, in rats after 6 weeks of treatment with cisplatin twice weekly at 2 mg/kg, a significant decrease (17%) in sensory nerve conduction velocity was observed while the motor nerve conduction velocity was unaffected. Tetraplatin at 1 mg/kg twice weekly caused a 14% decrease in sensory nerve conduction velocity. In parallel experiments in the rat, twice weekly treatment with JM216 at 25 mg/kg did not affect the sensory nerve conduction velocity [24],... 

Lithium also impairs the function of the peripheral nervous system, reducing motor nerve conduction velocity (Faravelli et al., 1999). It causes many metabolic adverse effects, resulting in hypothyroidism, hyperthyroidism (rare), hyperparathyroidism, and diabetes insipidus (Livingston et al., 2006). 

Fatigue is one of the prime symptoms that everyone who has CMT seems to experience. Scoliosis and other spinal deformities are often diagnosed in people who show CMT at an early age and some people experience hip and knee dislocations while some are bom with deformed hip sockets. Diagnosis can also be made by doing an electromyogram (EMG) that measures the irritability and function of muscles and motor nerve-conduction velocity (MNC V) tests that establish the ability of nerves to send and receive impulses. 

In a cross-sectional study, nerve conduction velocities were determined in 59 workers employed in press proofing factories in Taipei. Workers were divided into exposure categories on the basis of air concentrations of -hexane ( 100, 50-99, and <50 ppm) and -hexane concentrations in the cleaning solvent used ( 50, 49-10, and <10%). Lifteen members (25%) of the study group were found to have polyneuropathy. In one factory where all six employees developed polyneuropathy, the air concentration of -hexane was determined to be 190 ppm. In other factories, workers exposed to n-hexane at levels of <100 ppm showed significant decreases in motor nerve conduction velocities. 

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