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Introduction: The aim of the study is to determine the role of upper motor neuron (UMN) or lower motor neuron (LMN) dysfunction as the primary initiator of distal-proximal and lateral-medial gradients of muscle involvement in amyotrophic lateral sclerosis (ALS). Methods: Concentric needle electromyography recordings were performed in deltoid, abductor digiti minimi, and first dorsal interosseous (FDI) muscles in patients with ALS and controls during slight voluntary contraction needed to activate two motor units (MU). Five motor unit potential (MUP) pairs were recorded from each muscle. Motor unit potential analyses were performed offline using Multi-MUP analysis program. Quantitative MUP parameters, MU firing rate (FR), FR variability (FRV), and mean consecutive difference (MCD) were calculated. Motor-evoked potentials and the triple stimulation technique (TST) were performed to evaluate UMN involvement. Results: Twenty patients with ALS along with 20 age and sex-matched healthy volunteers were enrolled. Quantitative MUP parameters compatible with denervation and reinnervation were found in patients with ALS, who also showed higher FR, FRV, and MCD values, most prominently in FDI. First dorsal interosseous FRV was lower in patients with abnormal central motor conduction time (CMCT). Firing rate and FRV were negatively correlated with CMCT, but not with TST. Conclusion: Distal limb muscles, particularly FDI, revealed more prominent FR abnormalities in patients with ALS in parallel with the distal-proximal and lateral-medial gradients of the selective muscle involvement pattern which seems predominantly to be correlated with LMN dysfunction. Reduced FRV may be associated with the presence of UMN dysfunction in ALS. [ABSTRACT FROM AUTHOR]

Ring chromosome 20 syndrome is a rare genetic disorder characterized by non-convulsive status epilepticus (NCSE) attacks, leading to prolonged confusional states of varying intensity. It is often accompanied by electroencephalography (EEG) changes, such as long-lasting slow waves and occasional spikes, primarily over the frontal lobes, as well as focal seizures with visual hallucinations, cognitive impairment, and behavioral problems. Although clinical suspicion, typical EEG abnormalities, and network disorders revealed by functional neuroimaging method aid in diagnosis, karyotyping remains essential. Seizures are typically drug-resistant although some limited success has been reported with certain anti-seizure drugs. In this report, we present the case of a patient with previously frequent drug-resistant NCSE periods characterized by prolonged confusional states and frightening visual hallucinations. Treatment with lacosamide partially decreased the frequency of seizures. In addition, positron emission tomography/computed tomography (PET/CT) imaging revealed hypometabolism in the frontal and parietal regions of the brain. In patients with drug-resistant and early frightening hallucinations, consideration of the ring 20 chromosome anomaly is crucial. PET/CT imaging may demonstrate hypometabolism in the parietal and frontal lobes, potentially associated with the hallucinations and epileptogenesis of the syndrome. Lacosamide may be a viable option for reducing seizures in Ring chromosome 20 syndrome. [ABSTRACT FROM AUTHOR]

After the outbreak of Coronavirus disease 19 (COVID-19), several case reports and case series of Guillain-Barré syndrome (GBS) associated with COVID-19 have been published to unravel the possible causal link between GBS and COVID-19. In this brief report, the epidemiological data from regions in different countries was reviewed. Some studies report an increase in the incidence of GBS during the pandemic while the others do not. The clinical features of GBS associated with COVID-19 was older age, male predominance, and typical sensorimotor variant responding well to treatments. The most common electrodiagnostic subtype was demyelinating. Despite the high effort, the causal relation between COVID-19 and GBS remains controversial. Case-control studies with high number of patients are needed to understand the relation between GBS and COVID-19. [ABSTRACT FROM AUTHOR]

The autosomal recessive spastic ataxia of CharlevoixSaguenay (ARSACS), presenting with spinocerebellar ataxia, dysarthria, nystagmus, and spastic paraparesis, is a gradually progressive hereditary disease. Sensorimotor polyneuropathy may also accompany the symptoms. Herein, we present the electrophysiologic findings of a Turkish family with ARSACS in combination with clinical and genetic features to better describe the characteristics of the polyneuropathy in ARSACS. Regarding the electrophysiologic findings, however, the demyelinating characteristics were prominent and there were findings compatible with secondary axonal degeneration. Rare hereditary diseases such as ARSACS must be suspected in the presence of polyneuropathies with demyelinating characteristics accompanying pyramidal findings and ataxia. [ABSTRACT FROM AUTHOR]

Objective: To decompose a part of the nerve action potential (NAP), mainly originating from large-myelinated sensory fibers, from mixed NAPs by using a stimulus with long duration during surface recordings. Materials and Methods: Median and ulnar mixed NAPs were elicited using submaximal stimulus intensities with 0.5 and 1.0-ms stimulus duration, which were adjusted to just below the threshold to activate motor fibers as detected visually through muscle twitch in hand muscles, by stimulating the median and ulnar nerves at the wrist and elbow and recording from the median and ulnar nerves at both the elbow and axilla, respectively. Healthy controls and patients with demyelinating neuropathy and/or motor conduction block were included in the study. Results: Mixed NAPs were recorded in 24 healthy subjects and three patients who had multifocal motor neuropathy (MMN), acute motor axonal neuropathy (AMAN), and ulnar entrapment neuropathy (UEN). Reference values were calculated in the healthy subjects. In patients with AMAN and MMN, mixed NAPs were normal, whereas in UEN, ulnar mixed NAPs had prolonged latencies. Conclusion: Mixed NAPs elicited by stimuli with long duration and low strength in the upper limbs can be used to detect sensory involvement at segments where motor conduction block exists and might help to classify demyelinating neuropathies. [ABSTRACT FROM AUTHOR]

Introduction: The present study is an examination of possible subclinical involvement of lower motor neuron (LMN) in patients with primary lateral sclerosis (PLS) and hereditary spastic paraparesis (HSP) electrophysiologically. Methods: Nine PLS patients and 5 HSP patients were prospectively analyzed. Jitter measurement with concentric needle electrode (25 mm, 30 G) (CN-jitter) recorded from right extensor digitorum muscle during voluntary contraction with 1 kHz high-pass frequency filter set. European Myelopathy Score (EMS) was used to evaluate disability. The relationship between disability score and jitter values was investigated. Results: HSP patients had suffered from the disease for longer period of time (p<0.001). Mean jitter values of patients with PLS and HSP were 26.5±12.1 µs and 30.8±34.8 µs, and the number of individual high jitters (>43 microseconds) observed in the PLS and HSP groups was 16/180 and 9/100, respectively without a significant intergroup difference. The ratio of patients with an abnormal jitter study were higher in HSP group (60%) compared to PLS (22%) (p<0.05). Potential pairs with blocking were present in HSP group (7 of 100 potential pairs) but not seen in PLS patients. EMS values were significantly lower in patients having potential pairs with high jitter and blocking compared to those without high jitter and blocking. Conclusion: The present study has demonstrated that early signs of LMN dysfunction can be detected electrophysiologically by CN-jitter in patients with UMN involvement. These electrophysiological findings in these patients with longer disease duration and lower clinical scores may be explained by spreading of the disease to LMNs or transsynaptic degeneration and its contribution in disease progression. [ABSTRACT FROM AUTHOR]

Some respiratory viruses have long been known to cause neurological involvement. A novel coronavirus, leading to severe acute respiratory syndrome, also called coronavirus disease 19 (COVID-19), seems to be a new member of neuroinvasive viruses. While severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) keeps on spreading around the world rapidly, reports about the neurological manifestations associated with SARS-CoV-2, increases day by day. It is reported that a variety of symptoms and syndromes such as headache, dizziness, confusion, ataxia, epilepsy, ischemic stroke, neuropathic pain and myopathy are common especially in more severe COVID-19 patients. It is also suggested that the development of neurological complications is strongly associated with a poor outcome. On the other hand, hyposmia can be the unique symptom in COVID-19 carriers and this can serve as a marker for identifying the otherwise asymptomatically infected patients. It is thought that SARSCoV- 2 may cause neurological symptoms through direct or indirect mechanisms. Nevertheless, neuroinvasion capability of SARS-CoV2 is confirmed by the presence of the virus, in the cerebrospinal fluid of a COVID-19 patient with encephalitis, and this is proven by gene sequencing. In conclusion, during the COVID-19 pandemic, it is crucial to be aware of the possible neurological complications of the disease. Therefore, in this review, we aimed to report neurological manifestations associated with SARS-CoV-2 and possible underlying pathophysiological mechanisms. Due to the high homology of SARS-CoV-2 with other human coronaviruses such as SARS-CoV or Middle East Respiratory Syndrome (MERS)-CoV, reviewing the neurological involvement also associated with these coronaviruses will provide an idea about the longterm complications of COVID-19. [ABSTRACT FROM AUTHOR]