ABSTRACT
The aim of the study was to evaluate the cholinergic deficiency in Alzheimer's (AD) and Parkinson's disease (PD). For this purpose, pupil size changes and mobility were assessed using a fast-video pupillometer (263 frames/s). Twenty-three (23) patients with probable AD and twenty-two (22) patients with PD (eleven with cognitive impairment and eleven without) entered the study. A full record of the pupil's reaction to light was registered. From this data ten (10) parameters were measured and reported. Comparison of those parameters in both group of subjects followed. Patients with probable AD had abnormal pupillary function compared to healthy ageing. All the Pupil Light Reflex (PLR) variables significantly differed between the two groups (p<0.005) except the Baseline Pupil Diameter after 2-min dark adaptation (D1) and the Minimum Pupil Diameter (D2). Maximum Constriction Acceleration (ACmax) was the best predictor in classifying a subject as normal or as an AD with a perfect classification ability (AUC=1, p<0.001). ACmax and Maximum Constriction Velocity (VCmax) were significantly lower in PD patients without and with coexisting cognitive impairment compared to normal subjects (p<0.001). Patients with cognitive impairment had significantly lower levels of ACmax, VCmax and amplitude (AMP=D1-D2) than patients with no cognitive deficits. ACmax and secondarily VCmax were the best predictors in classifying a subject as normal or as a PD patient with or without cognitive impairment. Cognitive and memory impairment, which reflects a cholinergic deficit, may be a crucial pathogenetic factor for the decrease in the aforementioned pupillometric parameters. VCmax and ACmax can be considered as the most sensitive indicators of this cholinergic deficiency.
Subject(s)
Alzheimer Disease/complications , Autonomic Nervous System Diseases/etiology , Parkinson Disease/complications , Reflex, Pupillary/physiology , Aged , Alzheimer Disease/diagnosis , Alzheimer Disease/physiopathology , Area Under Curve , Autonomic Nervous System Diseases/diagnosis , Autonomic Nervous System Diseases/physiopathology , Cognition Disorders/complications , Cognition Disorders/diagnosis , Cognition Disorders/physiopathology , Female , Humans , Light , Male , Middle Aged , Parkinson Disease/diagnosis , Parkinson Disease/physiopathologyABSTRACT
The aim of this study is to investigate the effect of Myasthenia Gravis (MG) on the Central Nervous System (CNS) and/or the smooth muscles of the iris through pupillometry. Sixteen recently diagnosed Myasthenic and sixteen non-Myasthenic subjects of matching age and gender underwent a pupillometric study of the effects of single flash stimuli of 24.6 candelas/m2 intensity and 20 msec duration. A significant decrease in Amplitude (p < 0.001), Maximum Constriction Velocity (p < 0.001) and especially Maximum Constriction Acceleration with a perfect discrimination ability (AUC= 1, p < 0.001). was observed in the Myasthenic compared to the non-Myasthenic subjects. In contrast, no significant difference was observed in Baseline Pupil Radius (R1) and 3.5 secs Percentage Recovery-Redilatation (R%) (p = 0.051 and p = 0.517, respectively). Of the parameters that are studied, R1 and R% are governed mainly by the action of the Sympathetic Nervous System (SNS) and the rest by the Parasympathetic Nervous System (ParNS), through Acetylcholine. The analysis of these parameters demonstrates that the SNS remains unaltered while the ParNS may be affected in MG. This post-synaptic cholinergic receptors' deficit may be central, within the CNS, or peripheral, related to the Neuromuscular Junction of the iris' sphincter.
Subject(s)
Electrodiagnosis/methods , Myasthenia Gravis/physiopathology , Pupil/physiology , Reflex, Abnormal/physiology , Reflex, Pupillary/physiology , Female , Humans , Image Processing, Computer-Assisted , Male , Middle Aged , Myasthenia Gravis/complications , Photic Stimulation , Reaction Time , Sensitivity and SpecificityABSTRACT
PURPOSE: The aim of this study was to provide a data base for the measurement of various parameters of the pupil light reflex in normal subjects using a fast video pupillometry device (262 frames/sec). METHOD: One hundred healthy subjects took part in the study aged 44.31+/-18.11 years. Subjects were divided in two (2) groups according to age: 18-50 years of age (group 1) and 51-81 years of age (group 2). All subjects were examined between 09.00 and 15.00 and the re-test examination was repeated exactly 24 hours later. All variables showed satisfactory test-retest reliability (Pearson test-retest showed values over 0. 70 for all parameters besides Time for Maximum Constriction (T3. 0.62) and Recovery (R%: 0.57)). RESULTS: The Latency of pupil reaction to light (Ti) was not affected by Age. Baseline Pupil Radius (RI) after 2 min of dark adaptation was statistically smaller in the elderly group p < 0.001; Maximum Constriction Velocity (VCmax), Maximum Constriction Acceleration (ACmax) and Amplitude (AMP) were significantly smaller in the elderly group (p < 0.001) when compared to group 1. When all parameters were studied their correlation showed a statistical significant difference for R1, R2, VCmax, ACmax and AMP when related to Age. However when Age was taken into account through the use of partial correlation, the relation between R1, R2 and AMP remained unaltered, but the relations between R1 and VCmax and ACmax were dramatically reduced from -0.39 to -0.21 and from -0.45 to -0.09 respectively indicating that the relation observed between Ri and VCmax and ACmax was due mainly to the Age of the subjects. CONCLUSION: The results suggest that age influences Baseline Pupil Size, Maximum Constriction Velocity (VCmax) and Acceleration (ACmax), while the Latency of the light reflex remains unaltered.
