Low luminance/eyes closed and monochromatic stimulations reduce variability of flash visual evoked potential latency

Context:

Visual evoked potentials are useful in investigating the physiology and pathophysiology of the human visual system. Flash visual evoked potential (FVEP), though technically easier, has less clinical utility because it shows great variations in both latency and amplitude for normal subjects.

Aim:

To study the effect of eye closure, low luminance, and monochromatic stimulation on the variability of FVEPs.

Subjects and Methods:

Subjects in self-reported good health in the age group of 18-30 years were divided into three groups. All participants underwent FVEP recording with eyes open and with white light at 0.6 J luminance (standard technique). Next recording was done in group 1 with closed eyes, group 2 with 1.2 and 20 J luminance, and group 3 with red and blue lights, while keeping all the other parameters constant. Two trials were given for each eye, for each technique. The same procedure was repeated at the same clock time on the following day.

Statistical Analysis:

Variation in FVEP latencies between the individuals (interindividual variability) and the variations within the same individual for four trials (intraindividual variability) were assessed using coefficient of variance (COV). The technique with lower COV was considered the better method.

Results:

Recording done with closed eyes, 0.6 J luminance, and monochromatic light (blue > red) showed lower interindividual and intraindividual variability in P2 and N2 as compared to standard techniques.

Conclusions:

Low luminance flash stimulations and monochromatic light will reduce FVEP latency variability and may be clinically useful modifications of FVEP recording technique.Key Words: Eye closure, flash visual evoked potentials, latency variability, luminance, monochromatic light, visual evoked potentials     

Prevalence and association of lifestyle factors with extracranial carotid atherosclerosis in non-cardioembolic anterior circulation strokes in adult males less than 50 years: One year cross-sectional study

Background:

Data is scarce on prevalence of extracranial carotid atherosclerosis (ECA) in strokes <50 years and its association with lifestyle factors.

Objective:

Study role of (a) ECA in non-cardio-embolic anterior circulation young strokes, and (b) smoking and alcohol in ECA.

Materials and Methods:

Cardiovascular risk factors and evidence of ECA on carotid doppler ultrasound (CDUS) was evaluated in an one-year preliminary cross-sectional study of consecutive strokes between 20 years and 49 years. Females were excluded.

Results:

There were 46 male strokes (mean age 38.26 yrs), 17.39% had hypertension, 2.23% had coronary artery disease; none was diabetic. Tobacco users and alcohol consumers were 24/46 (52.17%) cases each. ECA was found in 14/46 (30.44%) cases. Seven of these 14 (50%) i.e., 7/46 cases (15.21%) had carotid occlusion, four had <50%, three had >70% stenosis. ‘Smoking and smokeless tobacco use’ was found in 71.42% (10/14) symptomatic carotid lesions compared to 43.75% (14/32) strokes without carotid lesions. Prevalence odds ratio for tobacco use and ECA was 3.21 (95% CI: 0.83-12.44) while that of alcohol and ECA was 1.33 (95% CI: 0.38-4.72).

Conclusion:

Prevalence of ECA in strokes <50 years was high due to lifestyle factors which predispose to atherosclerosis at younger age.Key Words: Alcohol, extracranial carotid atherosclerosis, lifestyle factors, smoking, young stroke     

Primary sleep disorders seen at a Neurology service-based sleep clinic in India: Patterns over an 8-year period

There is an increasing awareness for recognition of sleep disorders in India; however, there is still a huge gap in the number of people suffering from various sleep disorders, in the community versus those visiting hospital clinics for the same. Ours is a neurology services-based sleep disorders clinic, which has evolved successfully over the last decade. In this study, we aimed to evaluate the changes in referral patterns and distribution of various sleep disorders in the patients presenting to the clinic.

Materials and Methods:

This is a retrospective chart review-based study on all patients seen over an 8-year period, divided into 2 groups comprising of patients seen during the first 4 years versus those seen over the next 4 years. Only those patients who had the sleep disorder as their presenting manifestation and those who had been formally interviewed with a pre-structured questionnaire detailing about the main features of the common sleep disorders according to the ICSD-R were included. Patients, in whom the sleep disorder could be clearly attributable to another neurological or systemic disorder, were excluded. Statistical analysis was carried out to identify the differences between the two groups as regards the distribution of various sleep disorders and other clinical data.

Results:

Among 710 patients registered in the clinic, 469 were included for analysis and 222 patients formed group 1 while 247 formed group 2. The main differences observed were in the form of a clear increase in the percentage of patients with sleep-related breathing disorders, sleep-related movement disorder, and the hypersomnias on comparison of distribution over the first 4 years versus the last 4 years; while a clear decline was seen in the number of patients with insomnia and parasomnias. A 3-fold increase was observed in the number of patients in whom polysomnography was obtained.

Conclusion:

The distribution of various sleep disorders as seen in a neurology service-based sleep clinic is demonstrated in this study. Increasing referrals for sleep-disordered breathing, restless legs syndrome, and fewer referrals for insomnia and parasomnias might reflect on changing physician and patient awareness in our community.     

Lacosamide-Induced Valproic Acid Toxicity

Valproic acid is commonly used in the treatment of both focal and generalized epilepsies and is often well tolerated. There are many reported cases of hyperammonemic encephalopathy and other well-known side effects reported during use of valproic acid either alone or in combination with other antiepileptics. This case report demonstrates valproic acid toxicity in the presence of lacosamide, which has not previously been reported. Full recovery occurred after withdrawal of both valproic acid and lacosamide.     

Restoration of facial symmetry in a patient with bell palsy using a modified maxillary complete denture: a case report

Permanent facial paralysis can be devastating for a patient. Modern society's emphasis on appearance and physical beauty contributes to this problem and often leads to isolation of patients embarrassed by their appearance. Lagophthalmos with ocular exposure, loss of oral competence with resultant drooling, alar collapse with nasal airway obstruction, and difficulties with mastication and speech production are all potential consequences of facial paralysis. Affected patients are confronted with both a cosmetic defect and the functional deficits associated with loss of facial nerve function. In this case history report, a modified maxillary complete denture permitted a patient with Bell palsy to carry on daily activities with minimal facial distortion, pain, speech difficulty, and associated emotional trauma.     

ZnO thin film-nanowire array homo-structures with tunable photoluminescence and optical band gap

The growth and optical behavior of ZnO thin film-nanowire array homo-structures is reported. The ZnO films are deposited on glass substrates by thermal evaporation and subjected to heat treatment at 400 °C for 2 h to achieve crystallinity and stoichiometry. The surface comprises spherical grains or elongated flakes depending on thickness of films. These films are introduced in to a hydrothermal reactor in a medium of zinc acetate and HMTA to realize the nanostructures. The process results in the formation of ZnO nanowires with dimensions that are strongly dependent on the surface microstructure of the ZnO films. The role of temperature (90–180 °C) and duration (10 min to 10 h) of hydrothermal processing is investigated in detail. It is demonstrated that low temperature and short duration are ideal for producing nanowires with diameter < 100 nm, while longer durations and higher temperatures lead to large diameter and long length nanowires. Interestingly, all wires converge to a hexagonal shape with increase in duration or temperature. The lowest diameter of the vertically aligned nanowires is 50 nm and length upto 10 μm is achieved. Optical band gap of the homo-structures is of the order of 3.4–3.5 eV. Raman and photoluminescence spectra indicate the presence of defects in the films. The thin films exhibit a strong defect related photoluminescence peak centred around 550 nm. The nanowires grown on the films display both the UV-near band edge peak as well as the defect related peak. However, the intensity of the defect peak decreases with increase in length of the nanowires indicating that the photoluminescence of the homo-structures can be tuned by changing the surface microstructure of the films and also the aspect ratio of the nanowires.

ZnO homo-structures with tunable photoluminescence and band gap.