PS-25-4 Parallel increase of increment threshold and post-adaptation threshold to blue test light in Parkinson's disease and neuroleptic treatment; reduced transient tritanopia in Huntington's chorea

Postersession 25. Parkinson'sdisease and Parkinsonism PS-25. PARKINSON'S DISEASE AND PARKINSONISM

I PS-25-1 ] Effects of musical stimuli in Parkinson's disease Kazuko Aoto, Kazuko Hasegawa, Hisayuki Kowa, Chikaf umi Shoshi 1. Department of Neurology, Kitasato University, School

of Medicine, Sagamihara, 228 Japan; 1Division of Laboratory Medicine, Kitasato University, School of Medicine, Sagamihara, 228 Japan Efficacy of musical stimuli on improvement of cerebral function such as hemispacial agnosia are reported. Major symptoms of Parkinson's disease (PD) are based on disturbance of rhythm formation, such as gait, speech and so on. So, we attempted to determine the effects of musical stimuli in patients with PD. Subjects; 13 right-handed patients with PD and five age-matched controls. Methods: The stimulus conditions were our original. All subjects were studied with a routine E E G and contingent negative variation (CNV). Analytical methods were follows. (A) Topogram; We obtained topographic E E G using a topogram system (ATAMAP) and measured the relative variations (%): (power values under a musical stimulus - - power values at silent)/power values at silent. We analysed the relative variations in alpha (8-13 Hz) frequency band using ANOVA. (B) CNV; We measured area of CNV at vertex from 450 msec after warning stimulus to imperative stimulus and analysed using ANOVA. Results: (A) Musical stimuli increased power values in the alpha band. The relative variations were significantly increased in value in the conditions of a familiar Japanese classical song compared with march and symphony. Right hemisphere predominancy of the relative variations was presented in controls, however, that predominancy was absent in patients with PD. (B) The area of CNV weren't shown any changes obviously under any musical stimuli. Conclusions: We didn't recognise right hemisphere predominancy in patients with PD. The emotional music might activate cerebral cortex.

IPS-25-21

Giant sensory evoked potentials in both patients with Parkinson's disease and multiple system atrophy

Chikafumi Shoshi 1, Kazuko Aoto, Yoshikazu Mizoi, Kazuko Hasegawa, Hisayuki Kowa. Department of Neurology,

Kitasato University School of Medicine, Sagamihara, 228, Japan; 1Division of Laboratory Medicine, Kitasato University School of Medicine, Sagamihara, 228, Japan In several neurodegenerative disorders, giant sensory evoked potentials (giant-SEPs) were evoked. We evaluated frequency of giant-SEPs and relationship between giant-SEPs and clinical features. Subjects and Methods: Forty-nine cases of Parkinson's disease and 65 cases of spinocerebellar degeneration (SCD) and 160 normal subjects were examined. Evoked methods of SEPs were according to conventional methods. Results: 1. No one evoked giant-SEPs in normal controls. 2. Forty percent patients with Parkinson's disease were revealed giantSEPs. In Parkinson's disease, giant-SEPs were significantly highly evaluated in frequency in the patients group onset of age over 60 (28 cases) compared with the patients whose onset of age were under 60 (21 cases). 3. In SCD, frequency of giant-SEPs were variable in various based disease types; 21% in so called olivo-pontocerebellar atrophy (OPCA), 33% in late cerebellar cortical atrophy

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(LCCA), 25% in multiple system atrophy. However, in autosomal dominant type SCD, no one showed giant-SEPs. Conclusions: 1. There were some relationship in patients with Parkinson's disease between age of onset and frequency of giantSEPs. 2. In SCD group, frequency of giant-SEps was defferent in disease type.

I PS-25-31 Olfactory evoked potentials in Parkinson's disease Kenji Sakuma, Kenji Nakashima, Kazuro Takahashi. Division of Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, Japan Decreased ability to smell is present in patients with Parkinson's disease (PD). Olfactory evoked potential (OEP) recordings were carried out by using amyl acetate stimulation in 20 PD subjects and in 10 age-matched normal subjects. The odor or odorless air stimuli were ejected by pressure in a syringe by means of a motor. Single stimulation lasted for 600 msec. The amount of the air used as stimuli was 12 ml. OEPs were recorded from three positions (Fz, Cz and Pz) of the 10/20 system referred to A1 + A2. We obtained waves produced by odorant air and those produced by odorless air. The potentials produced by odorless air were subtracted from those produced by amyl acetate, thus we obtained the OEPs attributed only to stimulation of the olfactory nerve. In normal subjects, three components were observed in 81%, 68% and 81% of subjects. Mean latencies were 309 + 46 ms, 484 461 ms and 710 4- 55 ms, respectively. In patients with PD, the three components could be observed only in 20%, 35% and 35% subjects, respectively. The components were rarely detected in spite of whether the patients complained of dysosmia or not. W h e n we examined PD subgroups, the components appearance rate did not depend on disease duration, first symptom appearance age or anticholinergic drug administration.

IPS-25-41

Parallel increase of increment threshold and post-adaptation threshold to blue test light in Parkinson's disease and neuroleptic treatment; reduced transient tritanopia in Huntington's chorea

Bernhard A. Haug 1,3, Eva-Maria Hermsteiner 1, Borvin Bandelow 2, Walter Paulus 1. 1Dept. of Neurology and

Clinical Neurophysiology, ZDept. of Psychiatry, Georg August University, G6ttingen, Germany; 3Dept. of Brain Pathophysiology, Kyoto University, Kyoto, Japan Transient tritanopia is a p h e n o m e n o n of the human retina describing the momentary loss of sensitivity to blue test lights, when a yellow adaptation light is switched off. The blue cone inhibition is mediated by GABAergic horizontal cells from adjacent depolarizing g!utamatergic cones with medium/long wave sensitivity. A Maxwellian view system was used to display a 3 ° diameter 440 nm wave length test light of adjustable intensity on a 10° 600 nm background. For the increment threshold, the stimulus was superimposed concentrically on the adaptation field (background) for 50 ms every 6 s. To measure the time course of the sensitivity in the post-adaptation phase, when the transient tritanopia occurs, the stimulus was applied at different time intervals within a 2 s pause of background illumination. Fifteen Parkinson patients had both elevated increment thresholds (p < 0.001) and postadaptation thresholds (significance levels scattered around p < 0.01). Fifteen patients on phenothiazine or butyrophenone depot injections showed similar, less significant deficits (p < 0.01 and

Postersession 25. Parkinson's disease and Parkinsonism

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less). Three patients with Huntington's chorea showed elevated increment thresholds, but normal post-adaptation thresholds, which could be an indicator of diminished transient tritanopia. We speculate that the general loss of blue cone sensitivity in patients with dopaminergic deficiency is due to a lack of inhibitory inputs from dopaminergic interplexiform cells to GABAergic horizontal cells, which in turn increase their inhibitory effects on blue cones. The isolated elevation of the increment threshold in patients with Huntington's chorea may reflect an unbalanced retinal glutamate/GABA ratio in systemic G A B A deficit.

IPS-25-51

I

Contractile properties of single motor units in Parkinson's disease

J.M. Elek, K. Wohlfarth, M. Schubert, R. Dengler. Department of

Neurology, Medical University of Hannover, Germany Alterations of contractile properties of motor units (MUs) have been discussed in the pathophysiology of increased muscle tone (Watts et al. 1986). Changes in histochemical muscle properties have been described in both upper motor lesions and Parkinson's disease (PD) (Edstr6m, 1970). Correspondingly changes in contractile properties of muscle could be demonstrated in spasticity (Young & Mayer, 1982), findings in rigidity, however, are controversial (Watts et al., 1986, Hufschmidt et al. 1991). We therefore investigated twitch parameters of single MUs in PD-patients with rigidity using the technique of low-rate (1 Hz) intramuscular microstimulation (Taylor & Stephens, 1976). The following twitch parameters were assessed: twitch force, maximal rate of rise of force, contraction time and half-relaxation time. 97 MUs were collected in 11 PD-patients (4 females, 7 males, age 63 + 14 yrs.) and compared to a sample of 92 MUs from 8 age-matched controls (3 females, 5 males, age 59 4- 14 yrs.). Statistical comparison of twitch parameters did not show significant differences between both groups. Maximal rates of rise of force, however, tended to be lower in the PD-group (median in PD: 0.51 N/s, controls 0.61 N/s, p = 0.059). We conclude that contractile properties of MUs are not significantly altered in rigidity. The tendency towards lower maximal rates of rise of force in PD may indicate a subtle slowing of MU contraction which would fit to histochemical data describing an atrophy of white, fast fibers and a hypertrophy of red, slow fibers in muscles of PD-patients (Edstr6m, 1970).

IPS-25-61

Muscle relaxation relates to clinical impairment in Parklnson's disease

J.C. Rothwell 1, C.M. Chen 1, N.P. Quinn 1, D.M. Corcos 1.2

l MRC Human Movement & Balance Unit and Department of Neurology, The National Hospital for Neurology & Neurosurgery, London WC1N 3BG; 2 University of lllinois at Chicago, Chicago, IL, 60608 This study determined the relationship between objective measures of motor control and the degree of clinical impairment in patients with Parkinson's disease as assessed by the Unified Parkinson's Disease Rating Scale. Nine patients were tested in three movement tasks on and off antiparkinsonian medication. In the first task, they performed maximal isometric connections to determine their strength. In the second task they were instructed to generate a 50% maximal voluntary contraction as fast as possible, hold the contraction and then relax. In the third task, they were again instructed to generate a 50% maximal voluntary contraction as fast as possible, hold the contraction and then return the force to baseline as quickly as possible. Removing medication resulted in a decrease in muscle strength and an increase in all measures of con-

traction time. These measures were then correlated with changes in UPDRS score on and off medication. The highest correlation (r = 0.90) was between change in U P D R S score and change in relaxation time. We suggest that changes in the time it takes patients to relax muscle activity is a very sensitive indicator of change in clinical status.

I PS-25-7 ] Reciprocal inhibition in early onset Parkinsonism Chung-Hao Tsai, Rou-Shayn Chen, Chin-Song Lu. Department of Neurology, Chang Gung Memorial Hospital, Taipei, Taiwan We studied the inhibition of median H-reflex by conditioning stimuli on the radial nerve in 14 normal controls, 2 patients with unilateral and 1 patient with predominantly left sided early onset parkinsonism (onset age < 40 years). In normal controls, the electrophysiological studies were performed on their right hands, yet both hands were examined in patient group. The subjects were awake and lying supine with arms resting parallel to the body. In all experiments, the surface electromyogram was recorded with disc electrodes from the bellies of the flexor carpi radialis and the extensor digitorum communis. The electrical stimuli were delivered with constant-current stimulators (Nicolet model $403) at a frequency of 0.2 Hz and 1 msec in duration. Stimuli delivered to the median nerve at the antecubital fossa were defined as "test stimuli". Stimuli delivered to the radial nerve at the spiral groove were defined as "conditioning stimuli". Various time intervals were designed between test and conditioning stimuli. The delays used were - 1, -0.5, 0, 0.5, 1, 2, 4, 5, 10, 20, 30, 50, 70, 100, 200, and 500 msec. Positive delay indicated that the test stimuli were delivered after the conditioning stimuli, whereas negative delay indicated the opposite. Trials of "test H-reflex" (recorded with test stimuli only) and "conditioned H-reflexes" (recorded with test stimuli plus conditioning stimuli) were alternated. At each delay, we averaged 10 test H-reflexes and 10 conditioned H-reflexes. The averaged peakto-peak amplitude of conditioned H-reflexes was compared with that of the test H-reflexes and expressed as a percentage of the size of the amplitude of the test H-reflexes at every delay. In the controls, we identified three inhibitory phases, with maximal inhibition at conditioning-test intervals of 0 msec (41.66 4- 4.73%), 20 msec (45.19 + 4.33%), and 100 msec ((44.55 -4- 6.84%), respectively. In the less or asymptomatic side of the patient group, the inhibitory patterns are similar to those of the controls (ANOVA, p = 0.987). However, in the symptomatic arms, loss of inhibition, or even mild potentiation, was observed in the third inhibitory phase (ANOVA, p = 0.000). Our results provide another aspect for the understanding of parkinsonian rigidity and suggest the perturbation of the polysynaptic long latency reflex pathway may somehow play a role in the rigidity pathogenesis.

I PS-25-8 j Dissociation of midline component of contingent negative variation (CNV) and bereitschaftspotenUal (BP) in Parkinson's disease Akio lkeda 1 Hiroshi Shibasaki 1, Kiyohito Terada 1, Takashi Nagamine 1, Ryuji Kaji 2, Jun Kimura 2. 1Department of

Brain Pathophysiology, Kyoto University School of Medicine, Japan; z Department of Neurology, Kyoto University School of Medicine, Japan As opposed to BP representing cortical activity of self-paced voluntary movements, CNV reflects sensorimotor association in externally-paced movement. Subdural recording from epilepsy pa-