Visual snow syndrome (VSS) is an emerging clinical entity, mainly characterized by persistent, bilateral, whole-visual field, disturbing, small flickering dots or pixelation, floaters, palinopsia, nyctalopia, photopsia, and photophobia. Patients with VSS also describe associated symptoms such as tinnitus, concentration difficulty, lethargy, depression, anxiety, and irritability, all of which affect the patients' quality of life. The consistency of these visual and nonvisual symptoms has recently led to proposed criteria for VSS. The diagnosis relies on the exclusion of other ophthalmic or neuropsychiatric disorders. Interestingly, many patients may have a comorbid migraine, and the symptoms were previously attributed as a persistent visual phenomenon in migraine. VSS is listed in the International Classification of Headache Disorders-Third Edition Appendix as a complication of migraine; however, VSS is a new disease entity distinct from persistent migraine aura. Some patients with VSS recall exposure to illicit hallucinogenic drugs, amphetamines, cannabis, or Lysergic acid diethylamide (LSD). The stereotypic clinical characteristics of VSS are currently well defined, and the pathophysiology is under investigation. Due to the subjective perceptual descriptions of patients with VSS, objective electrophysiologic parameters and functional brain imaging studies using magnetic resonance imaging and positron emission tomography are warranted for defining the quantifiable and reliable outcome measures. Patients with migraine, idiopathic occipital epilepsies, patients with Alice in Wonderland syndrome, patients with Charles Bonnet syndrome, visual hallucinations in recovery from cortical blindness, and recreational 3,4-methylenedioxymethamphetamine/ecstasy users have been suggested to have occipital cortex hyperexcitability. VSS is attributed to involving a dysfunctional magnocellular pathway, thalamocortical dysrhythmia, dysfunctional central visual processing, and occipital cortex hyperexcitability as possible underlying mechanisms. This review will focus on the role of occipital cortex hyperexcitability in VSS and hopefully provide insight into its pathophysiology and therapeutic strategies.

Background: A single transcranial magnetic pulse over the motor cortex is known to generate repetitive descending activity along the corticospinal tract. With respect to the origin; the earliest volley is named direct wave and the subsequent activity forms indirect (I) waves. I waves are assumed to originate from corticocortical afferents; they can be modulated by several methods and are practical parameters for evaluating motor cortex excitability. Weak transcranial direct current stimulation (tDCS), which has been widely used in human studies since the early 2000s, is a noninvasive and painless modulatory method for studying cortical excitability. We aimed to investigate the modulatory effects of anodal and cathodal tDCS on I waves of healthy controls, as a component of the motor evoked potential response generator. Materials and Methods: Twelve healthy volunteers were enrolled in the study. One mA tDCS was applied for 10 min and; single motor unit (SMU) recording technique was used for the identification of I waves. Two conditions were analyzed for each SMU in both anodal and cathodal current polarities; before tDCS and after tDCS. Separate peristimulus time histograms were constituted for each condition. Total peak duration, early peak latency, early peak duration, and early peak discharge rate were calculated. Results: Total peak duration, early peak latency, and early peak duration did not differ between pre- and post-tDCS conditions in either polarity. However, I1 peak discharge rate was found to be significantly decreased after cathodal tDCS (P: 0.017) and increased after anodal tDCS (P: 0.003). Conclusion: Our results confirm polarity-specific effects of tDCS of the primary motor cortex on I waves. According to our knowledge, this is the first study evaluating modulatory effects of tDCS on I waves using SMU recording technique.

Introduction: Requesting repetition of an electrodiagnostic examination (EDX) for follow-up and/or diagnostic verification is common in the daily practice of a reference center. Objective: This study aimed to evaluate demographical and electrophysiological characteristics of the patients who were referred to a reference electrophysiology laboratory for reassessment, to explore the underlying reasons, and motives for ordering a reassessment. Methods: Patients who had at least one EDX study within the last year in one of the two different time periods (winter and summer) were included in the study. Their demographical features, preliminary diagnosis, and electrophysiological findings were assessed and compared with their previous EDX interpretations. Results: Thirty-five (14 female, 21 male) patients (7,7%) out of 457 patients from the winter period (November 11, 2018‒December 12, 2018) and 38 (20 female, 18 male) patients (7,8%) out of 487 patients from the summer period (July 01, 2019‒August 08, 2019) were included in the study. Age, gender, preliminary diagnosis, and the number of previous electrophysiologic tests were statistically similar between the two groups. The most common reason for reassessment was to verify or to follow-up on a diagnosis of motor neuron disease or polyneuropathy. Compared to the summer group, the patients who had previous EDX in a different center were more common in the winter group, mean duration between EDX studies was also shorter. Conclusion: In this study, we have inspected the patients referred to our laboratory within two different time frames in a year for a repeat EDX study. It was observed that the number of patients who underwent a repeat EDX was relatively low, and there was no significant difference not only in the preliminary diagnosis but also in the electrophysiological findings.

Context: Restless legs syndrome (RLS) is a neurological sleep disorder which causes an overwhelming urge to move the legs. However, this spinal excitability can be decreased through the use some motor movements such as walking or stretching. Aims: This study aimed to investigate the effect of motor imagery (MI) on spinal excitability in relation to the H reflex (HR). Settings and Design: In this study, 11 patients diagnosed with RLS (3 males and 8 females, mean age: 41.2) and 14 controls (8 males and 7 females, mean age: 38.4) were tested. HR was studied while participants in the supine position were imagining walking and also while imagining both dorsiflexion (DF) and plantar flexion (PF). Results: There was significant decrease in the Hmax/Mmax at 90° DF in both groups (p = 0.002, p = 0.001). There was no significant decrease in the RLS group on imagery; however, there was a significant decrease in the control group with movement imagination compared to the resting state (p = 0.021). There was no significant increase in Hmax/Mmax at 135° PF in both groups on movement and imagery. There was a decrease in the ratio on the imagery of walking in the RLS group (p = 0.038), but the same ratio increased in the control group (p = 0.010). Conclusion: As motor movements decrease corticospinal excitability in RLS, the imagery of movement mimicking the actmovement can relieve the symptoms of RLS. As a conclusion, further electrophysiological studies can be useful to gauge the effects of MI on spinal excitability in RLS.

Objective: Nonconvulsive status epilepticus (NCSE) is a challenge to diagnose in some cases, and recently, Salzburg consensus criteria for NCSE (SCC-NCSE) were developed to contribute to clinical practice. We aimed to investigate their validity and usefulness by reevaluating the electroencephalogram (EEG) examinations of our patients in this study. Materials and Methods: We retrospectively evaluated all EEG recordings of patients diagnosed with NCSE by experienced clinical neurophysiologists in our EEG laboratory over a period of 2 years. Two neurologists trained in EEG reanalyzed all EEG data and categorized these patients as NCSE, possible NCSE, or non-NCSE using the SCC-NCSE. Results: Twenty-nine patients with a mean age of 31.5 ± 25.9 were reanalyzed. According to the SCC-NCSE, 24 patients (82.7%) were diagnosed as NCSE. Eighteen patients (62%) who fulfilled all SCC-NCSE were diagnosed as NCSE, whereas six patients (20.7%) were diagnosed only as possible NCSE. Five patients (17.3%) did not fulfill SCC-NCSE; the reasons are the lack of additional secondary criteria in 2 patients with encephalopathy, the absence of full compliance with the criteria in other 2 patients, and a diagnosis of electrical status epilepticus during sleep in the last patient. Conclusion: The results of our study show that SCC-NCSE is highly consistent with clinical practice to decide for the diagnosis of NCSE. The evaluation of NCSE according to a set of new standardized criteria is thought to be difficult in practice, but it provides a more objective assessment. Therefore, we believe that its use should be encouraged to increase experience and the possibility of correct diagnosis.

Background: Depression is common among elderly and middle-aged individuals and is a reason for decreased quality of life. Depression may lead to impairments in cognitive abilities. The P300 potential is one of the most used event-related potentials (ERPs) to evaluate cognition. This study investigated the P300 amplitude differences between individuals with depressive symptoms and nondepressed healthy elderly individuals. Materials and Methods: The current study included twenty individuals with high depression scores (high DS, age: 64.80 ± 7.22, 6 M/14 F) and twenty demographically matched participants with low depression scores (low DS, age: 64.20 ± 6.21, 7 M/13 F). The Geriatric Depression Scale (GDS) was used to evaluate whether participants have depressive symptoms. All of the participants were underwent a comprehensive neuropsychological battery. The ERPs were recorded with a visual classical oddball paradigm. The P300 amplitudes were measured in the 250–550 ms time window. Results: High DS group had lower P300 amplitudes than low DS individuals regardless of electrode location. Correlation analyses showed that there was a significant correlation between GDS scores and the P300 amplitudes recorded from the F_z electrode. Conclusion: The current study showed the reduced P300 amplitudes on individuals with high GDS scores. The P300 potential may be a useful tool to determine possible changes or impairments due to subthreshold depressive symptoms.

Background: Insomnia and excessive daytime sleepiness (EDS) are frequently reported as sleep disorders, especially in patients with chronic migraine (CM). The main drive of conducting a study on the relationship of genes that regulate circadian rhythm is that migraine contains a robust genetic background, and it is known that migraine attacks have circadian characteristics. This study aims to evaluate the relationship of circadian locomotor output cycles kaput (CLOCK) rs1801260 and hypocretin receptor 1 (HCRTR1) rs2271933 gene-related circadian rhythm of patients with CM and sleep disorders. Methods: The present study was designed prospectively in the Mersin University Neurology Clinic. Volunteer individuals aged 18–75 were included in the study in three groups. Each group was made up of 100 individuals. The first group was created among the patients diagnosed with CM. The sleep disorders of patients were evaluated by Epworth Sleep Scale and Pittsburgh Sleep Quality Scale. The second group healthy first-degree relatives of patients. Finally, the third group was formed by the other healthy volunteers who did not have blood relations with the patients. Genotyping was performed for the CLOCK rs1801260 and HCRTR1 rs2271933 genes. Results: Eighty-seven (87%) of the patients, 56 (56%) of the control group 1, and 50 (50%) of the control group 2 consisted of female patients. Their mean ages were 41.1 ± 11.5, 45.7 ± 15.2, and 35.9 ± 10. EDS was detected in 27% of the patients, and poor sleep quality was detected in 67%. About 21% of the patients were found to be suffering from both EDS and poor sleep quality. The CLOCK rs1801260 AG genotype was 6.71 times higher than the AA genotype in the migraine patient group with EDS compared to the second control group (odds ratio [OR]: 6.71, 95% confidence interval [CI]: 0.819–54.992, P = 0.076). The GG genotype, according to the AA genotype, also was found 2.87 times higher in this group (OR = 2.87, 95% CI: 0.336–24.566, P = 0.335). In the group of patients with CM and insomnia, the CLOCK rs1801260 AG genotype was 17.763 times higher than the AA genotype compared to the second control (OR = 17.763, 95% CI: 2.242–140.740, P = 0.006). Conclusion: When CM patients were compared with control groups, CLOCK rs1801260 gene AG genotype was associated with both insomnia and EDS. However, there was no significant relationship between patients and control groups regarding the HCRTR1 rs2271933 gene.

Objective: To demonstrate the psychometric properties of the Turkish Fatigue Assessment Scale (FAS). Materials and Methods: A total of 104 patients were recruited. The patients were assessed twice, 1 week apart. Patients completed the FAS, Fatigue Severity Scale (FSS), EuroQol-5 dimensions-3 L (EQ-5D-3 L), and Beck Depression Scale (BDS) in the initial assessment. Thirty-four patients completed the FAS again in the second assessment. Results: The mean age of the patients with multiple sclerosis (MS) was 37.6 ± 10.1 years. The intraclass correlation coefficient (ICC) of the FAS was excellent (ICC = 0.812). The Cronbach alpha coefficient of the FAS was 0.914. The alpha of the FAS was excellent (>0.80). Standard error of measurement and minimal detectable change of the FAS were 3.51 and 9.73 respectively. The relationship between the FAS (test, retest) and the FSS was excellent (r₁ = 0.767, r₂ = 0.782, P < 0.01). The EQ-5D-3 L index score was both strongly related with FAS (test, retest) (r₁ = −0.500, r₂ = −0.745, P < 0.01). The EQ-5D-3 L Visual Analog Scale score was also highly correlated with FAS (test, retest) (r₁ = −0.536, r₂ = −0.764, P < 0.01). Besides, FAS (test, retest) scores were strongly correlated with BDS total scores (r₁ = 0.540, r₂ = 0.571, P < 0.01). Conclusions: The Turkish FAS is a reliable and valid scale for individuals with MS.