Session Information
Date: Wednesday, June 22, 2016
Session Title: Parkinson's disease: Neuroimaging and neurophysiology
Session Time: 12:00pm-1:30pm
Location: Exhibit Hall located in Hall B, Level 2
Objective: We attempted to find an objective tool by assessing the variability of levodopa induced change in the blink reflex recovery to differentiate Parkinsonian syndromes.
Background: Parkinson’s disease (PD) is primarily diagnosed by clinical examination. Of all the Parkinsonian conditions, progressive supranuclear palsy (PSP) patients are hard to differentiate from PD before the classical clinical signs appear. Blink reflex recovery abnormality due to hyperexcitability of brainstem interneurons has been demonstrated by Jun Kimura (1973). In 1987 Agostino etal demonstrated R2 recovery cycle became similar to that of normal subjects after fluctuation from "off" to "on" period in PD patients. No comparison has been made to date, of the effect of levodopa on blink reflex recovery in various Parkinsonian syndromes.
Methods: 24 clinically probable PD, 8 clinically probable PSP, 3 clinically probable MSA, 1 clinically probable CBD, 4 drug induced parkinsonism, 2 vascular parkinsonism patients underwent the study. Institutional ethics comittee approval and written consent were obtained. Three sets of two electrical test stimuli of equal intensity were applied at interstimulus intervals of 500ms and 1000ms after a conditioning stimulus. The test was done in "off" and "on" states (90 min after per oral administration of 100mg levodopa). During offline analysis we multiplied the largest peak to peak amplitude of ipsilateral R2 response with its total duration. The mean and standard deviation of recovery indices (R2 test/R2 condition) in both states were calculated. For correlation analysis, we used the student’s paired t test to calculate the significance of alteration of recovery index. The level of significance was taken as p<0.05.
Results: In PD patients the mean R2 decreased from 1.16 (500 ms off state) to 0.88 (500 ms on state) and 1.09 (1000ms off state) to 0.81 (1000ms on state). In PSP, there was no significant change in mean between two states. MSA patients showed an increase in R2 mean during on period.
| Interstimulus interval | "Off" state (Mean±SD) | "On" state (Mean±SD) | |
| PD (n=24) | 500ms | 1.16±0.46 | 0.88±0.36 |
| 1000ms | 1.09±0.5 | 0.81±0.32 | |
| PSP (n=8) | 500ms | 1.09±0.35 | 1.07±0.59 |
| 1000ms | 1.03±0.42 | 1.03±0.53 | |
| MSA (n=3) | 500ms | 0.8±0.35 | 0.99±0.37 |
| 1000ms | 0.75±0.73 | 1.02±0.32 | |
| CBD (n=1) | 500ms | 0.67±0.3 | 0.59±0.28 |
| 1000ms | 0.66±0.09 | 0.47±0.27 | |
| Drug induced parkinsonism (n=4) | 500ms | 1.32±0.95 | 1±0.56 |
| 1000ms | 1.20±0.77 | 1.13±0.7 | |
| Vascular parkinsonism (n=2) | 500ms | 0.99±0.69 | 0.49±0.26 |
| 1000ms | 1.08±1.08 | 0.38±0.15 |
| At interstimulus interval of 500ms | At interstimulus interval of 1000ms | |
| PD | p<0.0001 | p<0.0001 |
| PSP | p=0.8798 | p=0.9678 |
| MSA | p=0.3728 | p=0.4402 |
| CBD | p=0.7240 | p=0.2389 |
| Drug induced parkinsonism | p=0.2197 | p=0.8022 |
| Vascular parkinsonism | p=0.1998 | 0.1996 |
Conclusions: Levodopa responsiveness of blink reflex recovery index can be an effective tool to differentiate PD from other Parkinsonian syndromes.
Indian academy of neurology conference: 2013.
To cite this abstract in AMA style:
C. Gaddipati, M. Umaiorubahan, C.U. Velmurugendran, V. Shankar. Effectiveness of Levodopa responsiveness of Blink reflex recovery: An objective method to differentiate Parkinsonian syndromes [abstract]. Mov Disord. 2016; 31 (suppl 2). https://www.mdsabstracts.org/abstract/effectiveness-of-levodopa-responsiveness-of-blink-reflex-recovery-an-objective-method-to-differentiate-parkinsonian-syndromes/. Accessed May 17, 2025.« Back to 2016 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/effectiveness-of-levodopa-responsiveness-of-blink-reflex-recovery-an-objective-method-to-differentiate-parkinsonian-syndromes/