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Development of neurographic and electroencephalographic functions after cessation of a chronic exposure to organic solvents
$60 ments are performed at 200 uV detection level during a light voluntary contraction. A potential exceeding the detection level triggers the measurement of the numbers of spikes during two consecutive 10 msec epochs. The difference in the numbers of spikes during the epochs gives the number of spikes time-locked to the first potential. The statistical result is expressed as 'computerized fibre density' (cFD; single fibre electrode) or as 'computerized fraction density' (cFrD; concentric needle). The measurements are done with a small microprocessor programmed for the purpose. The results are printed on paper immediately after the on-line measurements. The investigation ,ff a single muscle takes only a few minutes. In healthy subjects cFD and cFrD are quite similar. The mean cFD for extensor digitorum communis is 1.17. The results are independent of the contraction force. The method is also sensitive in the detection of pathology in myopathic and neurogenic disorders.
W!3.12 QUANTITATIVE AUTOMATIC ANALYSIS OF M O T O R UNIT POTENTIALS IN M Y O T O N I C DYSTROPHY. B. F a h ' k
(Turk{l, Finland) Individual motor unit potentials (MUPs) were recorded from 12 patients with myotonic dystrophy using a two-channel EMG electrode. The electrode has two recording surfaces: one SFelectrode and a coaxial electrode. The coaxial electrode is used to record individual MUPs, which are averaged. The MUPs were analyzed automatically. Since several of the parameters are related to age and sex the results are given as standard deviations (SD) from the reference values. In the deltoid muscle the total duration was 1.1 sd shorter than in the reference material and the amplitude was 0.8 sd smaller; the spike part duration and the number of turns were within normal limits. In the anterior tibial muscle the total duration was shortened by 0.9 sd, the amplitude 0.8 sd smaller, thc number of phases and turns were increased by 3.2 sd and 3.7 sd respectively and the duration of the spike part was prohmged by 0.8 sd. The abnormalities were positively correlated with the clinical state of the patient. The slight decrease in total duration and amplitude indicate that the number of muscle fibres in the motor unit may be decreased in their diameter. Increase in the spike part duration indicates that there is increased temporal dispersion of the action pc,tentials within the motor unit. The independent behaviour of the total duration and the spike part duration indicate that they reflect different physiological phenomena.
ELECTROPHYSIOLOGICAL SEQUELAE OF EXPOSURE TO TOXIC AGENTS W14.01 T R I G E M I N A L E V O K E D P O T E N T I A L C H R O N I C TRICHLORETHYLENE INTOXICATION.
IN
S. Garrel
(Grenoble, France} Industrial intoxication by trichlorethylene (solvent) can produce neurological disturbance of the trigeminal nerve. We have investigated this disturbance by recording the somatosensory evoked potential following stimulation of the trigeminal nerve (SEPt) We have obtained the following results in 1(/9 patients. 35 patients had abnormal SEPts as follows: 24 patients had delayed SEPt (10 of them with bilateral delay), 11 patients had amplitude modifications of SEPt (6 with reduced amplitude and 5 with increased amplitude). Both anomalies occurred in 7 patients. In most cases these anomalies of SEPt were connected with an abnormal clinical examination (facial hypoesthesia, anomalies of corneal, oculopalpebral and nasopal pebral reflexes). Sometimes, however, although the clinical examination was normal, SEPt perturbations revealed a toxic trigeminal lesion. This demonstrates the value of SEPt in this toxic pathology.
WI4.02 DEVELOPMENT OF NEUROGRAPHIC AND ELECTROENCEPHALOGRAPHIC F U N C T I O N S AFTER CESSATION OF A C H R O N I C EXPOSURE I"O ORGANIC SOLVENTS. 1. Rosi, n, P. Orbaek and Birgitta Haeger-Aronsen
{Lund, Sweden) A large number of neurographic variables and EEG (quantified by FFT analysis) were recorded from: 1) 50 asymptomatic workers in a paint factory long exposed to a mixture of organic solvents: 2) 65 painters exposed for many years with complaints indicating a psycho-organic syndrome; 3) 20 patients with chronic alcoholism:; 4)'normal-exposed' controls. 30 of the patients in group 2 were examined at the time of diagnosis and again 20-60 months after cessation of exposure to the organic solvent. All exposed groups differed from controls in having increased EEG power in all frequency bands and, also, relatively less EEG activity over anterior, as compared with posterior, parts of the brain. The amount of beta activity was larger in groups exposed to organic solvents. Group 2 differed from normal controls in a number of neurographic variables particularly in having low amplitude, temporally-dispersed sensory nerve action potentials. Other exposed groups showed only minor deviations from the normal. The follow-up study showed a significant decrease of EEG
St~ 1 power in all frequency bands. Patients below 50 also showed a significant increase in their sensory nerve action potentials. This was not seen in patients over 50. The ~tudy demonstrates effects of long-term organic solvent exposure on CNS and PNS. The improvement after cessation of exposure corroborate the notion that the effects observed are of neurotoxic origin.
W14.03 EEG FINDINGS IN H U M A N EXPERIMENTAL E X P O S U R E TO XYLENE. Anna M. Seppidi~inen, A. Laine and E. Verkkala
mg to within normal range; others had no significant changes in their VEPs. Since restarting DFO therap',, VEPs in 5 ,~f these patients have increased again bewmd m~rmal limits, as did the VEPs in 6 patients who had normal basehne tests. Most of the 105 patients have VEPs that are slab]e and normal: however, a significant sub-group have variable, abnormal VEPs that appear sensitive to administration of DFO and may reflect a vulnerability to DFO toxicit'i. The Vt~P, appear to detect subclinical toxic effects and hence can bc u~eful in monitoring I)FO therapy.
W14.05 VISUAL E L E C T R O P H Y S I O L O G I C ~ L STUDS" IN PATIENTS ON H I G H - D O S E DESFERRIOXAMINE.
( Helsinki, Finland) Several EEG samples were recorded in 9 young men during experimental exposure to m-xylene. During exposure subjects were either sedentary or had two periods of exercise at 100 W for 10 rain. Subjects participated from different exposure situations and 2 control situations, each lasting 3 h 40 rain. Of the EEGs 18 one-minute periods were computer analyzed off-line for each subject and exposure day. The exposure to stable and to fluctuating peak-concentrations combined with exercise induced a quick rise of alpha frequency from 9.8 cps to 10.15 cps. This did not occur on the control days or during sedentary exposure. Also, after exercise, the alpha frequency tended to stay higher up to 1 hour into the exposure. The percent time alpha rose in the exposure with exercise condition. In sedentary situations, the percent time alpha was higher in the early phases of exposure than on the control day. During a 20 minute continuous EEG recording, the percent time alpha decreased in the control situations, but it did not fall in exposure to peak ~:oncentrations. Exposure to xylene thus seemed to counteract the lowering of vigilance.
W!4.04 LONGITUDINAL EVOKED POTENTIAL STUDIES IN PATIENTS O N DESFERRIOXAMINE (DFO). M.J. -Fa!,.lor, N.K. Keenan, W.J. Logan and M. Freedman
li gugnoli, E. Granieri, G. Serra, A. di Pahna. ~. lncor',aia and A. Sebastiani (Ferrara, Italy) In 1983 Davies et ah and in 1984 Borgna-Pignatti et al. described ocular complications in patient~ alfected by betaThalassaemia mttjor treated with high-dose I)esferrioxamine. Following these observations we studied flash electroretinogram (FERG), early retinal oscillator 5 D~tentials lOP), pattern electroretinogram (PERG) and xisual ew)ked potential (VEP) with checks of 60 and 15 rain of arc m 16 asymptomatic patients affected by beta-Thalassaemia major during prolonged high-dose De:sferrioxamine treatment (2 intravenously and 14 subcutaneously) in order to study any drug-linked ocular con> plications. Four patients presented mild PERG amplitude abnormalities and two showed minimal FF, RG amplitude reduction. No VEP or OP impairments were found. The minimal ctectrophysiological abnormalities may well be related to prolonged anaemia or siderosis rather than to ocular toxicity caused by high-dose Desferrioxamine. Our observations indicate that Desferrioxamine therapy is quite safe even at high dose in spite of the sporadic ocular complications described in the literature, but a possible role of Desferrioxamine cannot be completely excluded. In order to avoid ocular complications it is advisable to increase the dosage gradually and monitor visual function by electrophysiological examinations.
(Toronto, Canada) Visual and auditory brain-stem evoked potentials (VEPs, ABRs) have been studied in 105 patients (2-28 yrs, ~ ' = 11 yrs) with chronic transfusion-dependent anaemia (eg, Thalassemia major). These patients are treated with DFO to prevent iron accumulation in vital organs, yet DFO itself can have toxic effects on the auditory and visual systems. DFO therapy was stopped in all patients to obtain baseline assessment of sensor5 function. In creased VEP latencies ( > 2.5 sd) were found in 24%, but few had observable ocular abnormalities. ABR studies showed 23% with raised thresholds, all confirmed with audio-. logical testing. Only 4 patients had increased ABR conduction times. Patients with abnormal VEPs remained off DFO and after 3- 6 months half showed improvement, with VEPs return-
WI4.06 S P I N D L E COMA IN BENZODIAZEPINE TOXICITY. Mary M. Mouradian and Patrt~la E. Pcm};'ttch (Cincinnati, OH, USA) A 42-year-old woman with alcoholic li~er cirrhosis and bleedmg oesophageal varices developed delerium tremens on the third hospital day. Her examination had been significant for tachypnea, tachycardia, systolic ejection murmur, hepatosplenomegaly and normal neurological examination. Abnormal admission laboratory values were haemoglobin 5.6 gm/dl, PT
W!3.12 QUANTITATIVE AUTOMATIC ANALYSIS OF M O T O R UNIT POTENTIALS IN M Y O T O N I C DYSTROPHY. B. F a h ' k
(Turk{l, Finland) Individual motor unit potentials (MUPs) were recorded from 12 patients with myotonic dystrophy using a two-channel EMG electrode. The electrode has two recording surfaces: one SFelectrode and a coaxial electrode. The coaxial electrode is used to record individual MUPs, which are averaged. The MUPs were analyzed automatically. Since several of the parameters are related to age and sex the results are given as standard deviations (SD) from the reference values. In the deltoid muscle the total duration was 1.1 sd shorter than in the reference material and the amplitude was 0.8 sd smaller; the spike part duration and the number of turns were within normal limits. In the anterior tibial muscle the total duration was shortened by 0.9 sd, the amplitude 0.8 sd smaller, thc number of phases and turns were increased by 3.2 sd and 3.7 sd respectively and the duration of the spike part was prohmged by 0.8 sd. The abnormalities were positively correlated with the clinical state of the patient. The slight decrease in total duration and amplitude indicate that the number of muscle fibres in the motor unit may be decreased in their diameter. Increase in the spike part duration indicates that there is increased temporal dispersion of the action pc,tentials within the motor unit. The independent behaviour of the total duration and the spike part duration indicate that they reflect different physiological phenomena.
ELECTROPHYSIOLOGICAL SEQUELAE OF EXPOSURE TO TOXIC AGENTS W14.01 T R I G E M I N A L E V O K E D P O T E N T I A L C H R O N I C TRICHLORETHYLENE INTOXICATION.
IN
S. Garrel
(Grenoble, France} Industrial intoxication by trichlorethylene (solvent) can produce neurological disturbance of the trigeminal nerve. We have investigated this disturbance by recording the somatosensory evoked potential following stimulation of the trigeminal nerve (SEPt) We have obtained the following results in 1(/9 patients. 35 patients had abnormal SEPts as follows: 24 patients had delayed SEPt (10 of them with bilateral delay), 11 patients had amplitude modifications of SEPt (6 with reduced amplitude and 5 with increased amplitude). Both anomalies occurred in 7 patients. In most cases these anomalies of SEPt were connected with an abnormal clinical examination (facial hypoesthesia, anomalies of corneal, oculopalpebral and nasopal pebral reflexes). Sometimes, however, although the clinical examination was normal, SEPt perturbations revealed a toxic trigeminal lesion. This demonstrates the value of SEPt in this toxic pathology.
WI4.02 DEVELOPMENT OF NEUROGRAPHIC AND ELECTROENCEPHALOGRAPHIC F U N C T I O N S AFTER CESSATION OF A C H R O N I C EXPOSURE I"O ORGANIC SOLVENTS. 1. Rosi, n, P. Orbaek and Birgitta Haeger-Aronsen
{Lund, Sweden) A large number of neurographic variables and EEG (quantified by FFT analysis) were recorded from: 1) 50 asymptomatic workers in a paint factory long exposed to a mixture of organic solvents: 2) 65 painters exposed for many years with complaints indicating a psycho-organic syndrome; 3) 20 patients with chronic alcoholism:; 4)'normal-exposed' controls. 30 of the patients in group 2 were examined at the time of diagnosis and again 20-60 months after cessation of exposure to the organic solvent. All exposed groups differed from controls in having increased EEG power in all frequency bands and, also, relatively less EEG activity over anterior, as compared with posterior, parts of the brain. The amount of beta activity was larger in groups exposed to organic solvents. Group 2 differed from normal controls in a number of neurographic variables particularly in having low amplitude, temporally-dispersed sensory nerve action potentials. Other exposed groups showed only minor deviations from the normal. The follow-up study showed a significant decrease of EEG
St~ 1 power in all frequency bands. Patients below 50 also showed a significant increase in their sensory nerve action potentials. This was not seen in patients over 50. The ~tudy demonstrates effects of long-term organic solvent exposure on CNS and PNS. The improvement after cessation of exposure corroborate the notion that the effects observed are of neurotoxic origin.
W14.03 EEG FINDINGS IN H U M A N EXPERIMENTAL E X P O S U R E TO XYLENE. Anna M. Seppidi~inen, A. Laine and E. Verkkala
mg to within normal range; others had no significant changes in their VEPs. Since restarting DFO therap',, VEPs in 5 ,~f these patients have increased again bewmd m~rmal limits, as did the VEPs in 6 patients who had normal basehne tests. Most of the 105 patients have VEPs that are slab]e and normal: however, a significant sub-group have variable, abnormal VEPs that appear sensitive to administration of DFO and may reflect a vulnerability to DFO toxicit'i. The Vt~P, appear to detect subclinical toxic effects and hence can bc u~eful in monitoring I)FO therapy.
W14.05 VISUAL E L E C T R O P H Y S I O L O G I C ~ L STUDS" IN PATIENTS ON H I G H - D O S E DESFERRIOXAMINE.
( Helsinki, Finland) Several EEG samples were recorded in 9 young men during experimental exposure to m-xylene. During exposure subjects were either sedentary or had two periods of exercise at 100 W for 10 rain. Subjects participated from different exposure situations and 2 control situations, each lasting 3 h 40 rain. Of the EEGs 18 one-minute periods were computer analyzed off-line for each subject and exposure day. The exposure to stable and to fluctuating peak-concentrations combined with exercise induced a quick rise of alpha frequency from 9.8 cps to 10.15 cps. This did not occur on the control days or during sedentary exposure. Also, after exercise, the alpha frequency tended to stay higher up to 1 hour into the exposure. The percent time alpha rose in the exposure with exercise condition. In sedentary situations, the percent time alpha was higher in the early phases of exposure than on the control day. During a 20 minute continuous EEG recording, the percent time alpha decreased in the control situations, but it did not fall in exposure to peak ~:oncentrations. Exposure to xylene thus seemed to counteract the lowering of vigilance.
W!4.04 LONGITUDINAL EVOKED POTENTIAL STUDIES IN PATIENTS O N DESFERRIOXAMINE (DFO). M.J. -Fa!,.lor, N.K. Keenan, W.J. Logan and M. Freedman
li gugnoli, E. Granieri, G. Serra, A. di Pahna. ~. lncor',aia and A. Sebastiani (Ferrara, Italy) In 1983 Davies et ah and in 1984 Borgna-Pignatti et al. described ocular complications in patient~ alfected by betaThalassaemia mttjor treated with high-dose I)esferrioxamine. Following these observations we studied flash electroretinogram (FERG), early retinal oscillator 5 D~tentials lOP), pattern electroretinogram (PERG) and xisual ew)ked potential (VEP) with checks of 60 and 15 rain of arc m 16 asymptomatic patients affected by beta-Thalassaemia major during prolonged high-dose De:sferrioxamine treatment (2 intravenously and 14 subcutaneously) in order to study any drug-linked ocular con> plications. Four patients presented mild PERG amplitude abnormalities and two showed minimal FF, RG amplitude reduction. No VEP or OP impairments were found. The minimal ctectrophysiological abnormalities may well be related to prolonged anaemia or siderosis rather than to ocular toxicity caused by high-dose Desferrioxamine. Our observations indicate that Desferrioxamine therapy is quite safe even at high dose in spite of the sporadic ocular complications described in the literature, but a possible role of Desferrioxamine cannot be completely excluded. In order to avoid ocular complications it is advisable to increase the dosage gradually and monitor visual function by electrophysiological examinations.
(Toronto, Canada) Visual and auditory brain-stem evoked potentials (VEPs, ABRs) have been studied in 105 patients (2-28 yrs, ~ ' = 11 yrs) with chronic transfusion-dependent anaemia (eg, Thalassemia major). These patients are treated with DFO to prevent iron accumulation in vital organs, yet DFO itself can have toxic effects on the auditory and visual systems. DFO therapy was stopped in all patients to obtain baseline assessment of sensor5 function. In creased VEP latencies ( > 2.5 sd) were found in 24%, but few had observable ocular abnormalities. ABR studies showed 23% with raised thresholds, all confirmed with audio-. logical testing. Only 4 patients had increased ABR conduction times. Patients with abnormal VEPs remained off DFO and after 3- 6 months half showed improvement, with VEPs return-
WI4.06 S P I N D L E COMA IN BENZODIAZEPINE TOXICITY. Mary M. Mouradian and Patrt~la E. Pcm};'ttch (Cincinnati, OH, USA) A 42-year-old woman with alcoholic li~er cirrhosis and bleedmg oesophageal varices developed delerium tremens on the third hospital day. Her examination had been significant for tachypnea, tachycardia, systolic ejection murmur, hepatosplenomegaly and normal neurological examination. Abnormal admission laboratory values were haemoglobin 5.6 gm/dl, PT