Influence of L-DOPA/carbidopa on pattern reversal VEP: behavioural difference in primary and secondary parkinsonism

Data obtained from a total of 246 monocular VEPs performed on 46 patients, 35 with Parkinson's disease and 11 with arteriosclerotic parkinsonism, classed in the first 3 stages on the Hohen and Yahr disability scale, are reported. Our data show a delay of mean P100 latency in the primary parkinsonian group during the period of washout from L-DOPA therapy as well as in the secondary parkinsonian group. But the interocular mean difference in VEP P100 results significantly increased in primary parkinsonism only. A more important different behaviour between primary and secondary parkinsonism concerns a possible reduction of VEP delay related to L-DOPA/carbidopa treatment. An improvement of P100 delay can be noticed after acute and after chronic DOPA therapy in primary parkinsonism only. The above data confirm previous reports concerning VEP delays in Parkinson's disease, suggesting monitoring of different pharmacological sensitivity in idiopathic and arteriosclerotic parkinsonian patients as a useful method.