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Advanced Neurologyurology
Advanced Ne Evoked potential response in parkinsonian syndromes

1. Introduction 50 patients per group. Detailed neurological examinations
were performed. HCs were only recruited if their clinical
Idiopathic Parkinson’s disease (IPD) is a neurodegenerative examination results were normal. The study participants
disorder affecting old and late middle-aged populations. were required to provide all relevant information related to
The characteristic clinical features of IPD include tremors, this study. Informed consent was obtained before recruiting
muscular rigidity, bradykinesia, and impairment of them. This study was approved by the institutional ethics
postural reflexes [1,2] . In addition, IPD is characterized by committee.
several defining pathological features, such as specific
degeneration of nigral and other pigmented brain stem Inclusion criteria of this study are as follows:
nuclei and inclusion of Lewy bodies in the nerve cells . (i). All IPD cases were diagnosed in adherence with the
[3]
UK Parkinson’s Disease Society Brain Bank Clinical
Atypical parkinsonian syndromes (APS) represent [5]
Diagnostic Criteria .
a group of heterogeneous degenerative neurological (ii). All APS cases were diagnosed using the validated
disorders that differ from the classical IPD in terms of the clinical criteria [6-9] .
associated clinical features. Progressive supranuclear palsy
(PSP), multiple system atrophy (MSA), and dementia Exclusion criteria of this study are as follows:
with Lewy body disease (DLB) are common disorders. (i). Cases of secondary parkinsonism
Less frequent disorders include corticobasal ganglionic (ii). Patients with previously known ophthalmological
degeneration (CBD), frontotemporal dementia with disorders (uncorrected refractive errors, glaucoma,
chromosome 17 (FTDP-17), Pick’s disease, and the retinopathies, etc.) and hearing difficulties after
parkinsonian-dementia complex of Guam . Evoked thorough evaluation by ophthalmologist and
[3]
potentials, or evoked responses such as visual evoked otorhinolaryngologist, respectively.
potentials (VEPs), short-latency somatosensory evoked 2.2. Study design
potentials (SSEP), short-latency brainstem auditory
evoked response (BAER), are measurements used to assess This is a cross-sectional, observational study. The flowchart
the electrophysiologic responses of the nervous system to of the study is depicted in Figure 1.
a variety of stimuli.
2.3. Parameters for evaluation
Based on the positive correlation between latency and
disease severity discovered by Gawel et al., VEP proves Evoked potentials were recorded using Nihon Kohden
Neuropack II plus.
valuable in the assessment of Parkinson’s disease . The
[4]
SSEP test could show the sensory electrical signals from 2.3.1. VEPs
the different organs to the brain or spinal cord. On the
other hand, waves III and V in the BAER test reflect the Patients and normal controls with no ocular pathology
postsynaptic activity in structures such as superior olive and a visual acuity of not more than 6/9 were selected. The
and colliculus. Therefore, the postsynaptic changes caused recording was made with Nihon Kohden Neuropack II
by these diseases could be corroborated with the BAER plus for Checkboard patterned reversal VEP (CBPR VEP).
study. At present, evoked potentials in APS have not been VEP was recorded from each eye separately with surface
evaluated thoroughly. This study was designed under the electrodes, with the reference electrode placed on Fz, the
hypothesis that APS presents altered evoked potentials, active electrode on Oz, and other electrodes in O1 and O2
which provides a new avenue for differentiating between as per the International 10-20 system. The analysis time
IPD and APS. was 500 msec, and 256 sweeps were averaged. N75 latency,
P100 latency, and P100 amplitude were recorded. P100
2. Materials and methods latency is the interval between the stimulus and the peak
of the major positive component.
2.1. Study subjects
This is a cross-sectional, observational study conducted 2.3.2. Brainstem auditory evoked potential
in the inpatient and outpatient clinics of the Department Auditory evoked responses were obtained by brief acoustic
of Neurology in a multispecialty teaching hospital from click stimuli delivering monophasic square pulses of
September 2017 to August 2020. We enrolled patients 100-msec duration to headphones with a monoaural
of both genders of various age groups. Healthy controls stimulus intensity of 60 – 65 dB HL. Given that there
(HCs) were selected from age and gender-matched were many patients experiencing subclinical hearing loss
asymptomatic medical college staff. The study participants in this sample, we resorted to gradually increasing the
were categorized into IPD, APS, and HC groups, with decibel if a BAER waveform was not obtained. The patients

Volume 2 Issue 4 (2023) 2 https://doi.org/10.36922/an.1907