Bi-allelic variants in neuronal cell adhesion molecule cause a neurodevelopmental disorder characterized by developmental delay, hypotonia, neuropathy/spasticity.

Cell adhesion molecules are membrane-bound proteins predominantly expressed in the central nervous system along principal axonal pathways with key roles in nervous system development, neural cell differentiation and migration, axonal growth and guidance, myelination, and synapse formation. Here, we describe ten affected individuals with bi-allelic variants in the neuronal cell adhesion molecule NRCAM that lead to a neurodevelopmental syndrome of varying severity; the individuals are from eight families. This syndrome is characterized by developmental delay/intellectual disability, hypotonia, peripheral neuropathy, and/or spasticity. Computational analyses of NRCAM variants, many of which cluster in the third fibronectin type III (Fn-III) domain, strongly suggest a deleterious effect on NRCAM structure and function, including possible disruption of its interactions with other proteins. These findings are corroborated by previous in vitro studies of murine Nrcam-deficient cells, revealing abnormal neurite outgrowth, synaptogenesis, and formation of nodes of Ranvier on myelinated axons. Our studies on zebrafish nrcamaΔ mutants lacking the third Fn-III domain revealed that mutant larvae displayed significantly altered swimming behavior compared to wild-type larvae (p < 0.03). Moreover, nrcamaΔ mutants displayed a trend toward increased amounts of α-tubulin fibers in the dorsal telencephalon, demonstrating an alteration in white matter tracts and projections. Taken together, our study provides evidence that NRCAM disruption causes a variable form of a neurodevelopmental disorder and broadens the knowledge on the growing role of the cell adhesion molecule family in the nervous system.

Automatic detection of F waves and F-MUNE in two types of motor neuron diseases.

INTRODUCTION/AIMS: Motor unit number estimation by F waves (F-MUNE) is an uncommonly used MUNE technique. Our aim in this study was to assess the sensitivity of F-MUNE values elicited with newly developed software in motor neuron diseases. METHODS: F waves were recorded by 300 submaximal stimuli from abductor digiti minimi and abductor pollicis brevis muscles of 35 patients with amyotrophic lateral sclerosis, 18 with previous poliomyelitis, and 20 controls. The software determined the surface motor unit action potentials (sMUAPs) and calculated the F-MUNE values. Compound muscle action potential scans were also recorded to obtain MScanFit. RESULTS: The sMUAP amplitudes were higher and F-MUNE values were lower in both muscles of the patients when compared with controls. F-MUNE values could distinguish patients from controls. Significant correlations were found between F-MUNE and MScanFit in the patient groups. DISCUSSION: The new F-MUNE software offered promising results in revealing motor unit loss caused by motor neuron diseases.

Reduced expression of inflammasome complex components in cluster headache.

BACKGROUND: The involvement of inflammation in the pathophysiology of cluster headache (CH) has been suggested, with a role implied for interleukin (IL)-1ß. We aimed to measure peripheral blood expression levels of IL-1ß-inducing systems, the inflammasome complex, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling, and investigate their values as putative biomarkers in CH. METHODS: In this cross-sectional study conducted in the Headache Unit of Istanbul University, Turkey, blood mononuclear cells (PBMCs) and sera were collected from 30 patients with episodic migraine, 4 with chronic CH, and 47 healthy individuals. Levels of inflammasome complex components (NLRP1, NLRP3, caspase 1, and ASC), end products of inflammasome complex activity (IL-1ß, IL-18, and nitric oxide synthase isoforms), neuron-specific enolase, other inflammatory factors (NF-κB, HMGB1, and s100b), and anti-inflammatory IL-4 were measured by real-time quantitative polymerase chain reaction and/or enzyme-linked immunosorbent assay. RESULTS: NLRP3 expression levels were significantly reduced in PBMC samples of patients with CH, obtained during CH attacks (n = 24) or headache-free (out of cycle) episodes (n = 10). CH-attack patients showed greater expression levels of IL-1ß (2-ΔΔCT median [25th-75th percentile], 0.96 [0.66-1.29 vs. 0.52 [0.43-0.73]) and NF-κB (1.06 [0.66-3.00] vs. 0.62 [0.43-1.19]) in PBMCs but not in sera compared with headache-free CH patients. However, these differences did not attain statistical significance (p = 0.058 and p = 0.072, respectively). Moreover, NLRP1 (52.52 [35.48-67.91] vs. 78.66 [54.92-213.25]; p = 0.017), HMGB1 (11.51 [5.20-15.50] vs. 13.33 [8.08-18.13]; p = 0.038), S100b (569.90 [524.10-783.80] vs. 763.40 [590.15-2713.00]; p = 0.013), NSE (11.15 [6.26-14.91] vs. 13.93 [10.82-19.04]; p = 0.021), nNOS (4.24 [3.34-12.85] vs. 12.82 [4.52-15.44]; p = 0.028), and eNOS (64.83 [54.59-91.14] vs. 89.42 [61.19-228.40]; p = 0.034) levels were lower in patients with three or more autonomic manifestations (n = 9). No correlation was found between inflammation factors and clinical parameters of CH. CONCLUSION: Our results support the involvement of the IL-1ß system in attacks of CH. However, the components of the inflammasome complex are suppressed in the peripheral blood and do not appear to play a role in the pathophysiology of CH. These findings argue against a potential biomarker value of the inflammasome complex in CH.

Olfactory dysfunction in patients with cluster headache.

OBJECTIVE: Cluster headache (CH) is a primary headache characterized by strictly unilateral, short-lasting severe headache attacks accompanied by at least one ipsilateral autonomic symptom. Our study aimed to determine whether CH patients had olfactory dysfunction and to correlate it with clinical characteristics. MATERIALS AND METHODS: Twenty patients and 57 healthy volunteers were included in the study. All participants were examined in the otorhinolaryngology outpatient clinics to exclude other clinical problems causing olfactory dysfunction. The Sniffin' Sticks test was performed, and threshold (T), discrimination (D), identification (I) scores, and TDI global olfactory score were evaluated. RESULTS: The CH patients had significantly lower threshold scores than healthy controls (6.9 ± 1.70 vs. 7.8 ± 1.08, p = 0.007). The mean threshold scores of CH patients during in-bout (n = 9) were significantly lower than CH patients during out-of-bout (n = 11) in subgroup analysis (5.9 ± 1.16 vs. 7.6 ± 1.76, p = 0.038). CH patients with left-sided headache had significantly lower discrimination scores compared to CH patients with right-sided headache (12.8 ± 1.24 vs. 14.4 ± 1.51, p = 0.03). CONCLUSION: There is marked impairment in olfactory function in CH patients compared to healthy controls.

Compound muscle action potential scan and MScanFit motor unit number estimation during Wallerian degeneration after nerve transections.

BACKGROUND: Compound muscle action potential (CMAP) scan and MScanFit have been used to understand the consequences of denervation and reinnervation. This study aimed to monitor these parameters during Wallerian degeneration (WD) after acute nerve transections (ANT). METHODS: Beginning after urgent surgery, CMAP scans were recorded at 1-2 day intervals in 12 patients with ANT of the ulnar or median nerves, by stimulating the distal stump (DS). Stimulus intensities (SI), steps, returners, and MScanFit were calculated. Studies were grouped according to the examination time after ANT. Results were compared with those of 27 controls. RESULTS: CMAP amplitudes and MScanFit progressively declined, revealing a positive correlation with one another. SIs were higher in WD groups than controls. Steps appeared or disappeared in follow-up scans. The late WD group had higher returner% than the early WD and control groups. CONCLUSIONS: MScanFit can monitor neuromuscular dysfunction during WD. SIs revealed excitability changes in DS.

Headache characteristics in COVID-19 pandemic-a survey study.

BACKGROUND: Headache is the most common COVID-19-related neurological symptom. We aimed to reveal diagnostic clues of headache for COVID-19 infection and to investigate the course of primary headaches during the pandemic. METHODS: We developed a detailed web-based questionnaire screening the characteristics and course of headaches besides clinical COVID-19 features. The participants were grouped according to being diagnosed with COVID-19 infection or not, and having previous or new-onset headaches. The COVID-19 related headache features and their associations with other clinical features were investigated. A binary logistic regression model was performed to differentiate the characteristics of headache related to COVID-19. FINDINGS: A total of 3458 participants (2341 females;67.7%, 1495 healthcare workers;43.2%) with a mean age of 43.21 ± 11.2 years contributed to the survey. Among them, 262 participants had COVID-19 diagnosis and 126 (48.1%) were male. The rate of males in the group without COVID-19 was 31% (991 out of 3196 participants) showing significant gender difference between groups (p < 0.000). COVID-19 related headaches were more closely associated with anosmia/ageusia and gastrointestinal complaints (p < 0.000 and p < 0.000), and showed different characteristics like pulsating, pressing, and even stabbing quality. Logistic regression analyses showed that bilateral headache, duration over 72 h, analgesic resistance and having male gender were significant variables to differentiate COVID-19 positive patients from those without COVID-19 (p = 0.04 for long duration and p < 0.000 for others). A worsening of previous primary headaches due to the pandemic-related problems was not reported in the majority of patients. INTERPRETATION: Bilateral, long-lasting headaches, resistance to analgesics and having male gender were more frequent in people with COVID-19 in conjunction with anosmia/ageusia and gastrointestinal complaints. These features may be helpful for diagnosing the headache related to COVID-19 during the pandemic.

Parameters derived from compound muscle action potential scan for discriminating amyotrophic lateral sclerosis-related denervation.

INTRODUCTION: The objective of this study was to determine compound muscle action potential (CMAP) scan parameters and MScanFit motor unit number estimation (MUNE) in patients with amyotrophic lateral sclerosis (ALS) and to compare the results in the abductor pollicis brevis (APB) to those in the abductor digiti minimi (ADM). METHODS: CMAP scans were recorded from the APB and ADM in 35 patients with ALS and 21 controls. MScanFit MUNE, neurophysiological index (NI), step%, returner%, and D50 were calculated. RESULTS: CMAP scan parameters including the returner%, MScanFit MUNE, and NI can distinguish ALS with high sensitivity and specificity. The electrophysiological parameters, with the exception of D50 (the number of largest consecutive differences of recorded responses generating 50% of maximum CMAP), showed more pronounced changes in the APB than in the ADM, even though most of the patients had normal APB/ADM amplitude ratios. DISCUSSION: CMAP scan parameters and MScanFit MUNE can be used in the evaluation of denervation and reinnervation and may herald the "split hand" in ALS.

Assessment of the Olfactory Function in Patients With Idiopathic Intracranial Hypertension Using the Sniffin' Sticks Test: A Case-Control Study.

OBJECTIVE: Despite the lack of recognition in clinical practice, there is increasing evidence that patients with idiopathic intracranial hypertension may suffer from hyposmia. The current case-control study aims to evaluate olfactory dysfunction in a large series of patients with idiopathic intracranial hypertension. METHODS: All subjects, 44 idiopathic intracranial hypertension patients and 57 healthy controls, underwent olfactory function assessment using standardized "Sniffin' Sticks" test at a tertiary referral center of a university hospital. Threshold, discrimination, identification, and total threshold-discrimination-identification scores have been determined and analyzed statistically. RESULTS: Idiopathic intracranial hypertension patients had significantly lower threshold (6.5 [3.69] vs 8 [1.88], P < .001, 95% CI [-2.250, -0.750]) and threshold-discrimination-identification scores (29.75 [5.56] vs 32.5 [5.25], P = .003, 95% CI [-4.250, -0.750]). Twenty-five patients (57%) were diagnosed with hyposmia. Test scores of patients with active idiopathic intracranial hypertension (n = 18) were not statistically different from patients with inactive disease (n = 26), except for discrimination score (14 [2.50] vs 11 [2.25], P = .005, 95% CI [-3.000, -1.000]). Although idiopathic intracranial hypertension patients with a cerebrospinal fluid opening pressure of ≥330 mmH2 O had lower test scores, the difference was significant only for total threshold-discrimination-identification scores (28.5 [5.50] vs 30.5 [4.38], P = .044, 95% CI [0.750, 5.500]). Multiple regression analysis revealed that test scores were related to disease activity, cerebrospinal fluid opening pressure, papilledema, headache, and medication. CONCLUSION: Our clinical study revealed significant olfactory dysfunction in patients with idiopathic intracranial hypertension compared with healthy controls. Future research should employ larger samples to search for usability of olfactory testing in clinical management of patients with idiopathic intracranial hypertension.

Analysis of motor unit firing characteristics in patients with motor neuron diseases.

This study was designed to evaluate firing rate variability in patients with upper/lower motor neuron disorders. Twenty healthy subjects and 19 patients with motor neuron disorders participated in the study. Consecutive motor unit action potential pairs from extensor digitorum communis (EDC) muscle were recorded from each subject with trigger-delay line mode. Patients with motor neuron disorders (17.7 ± 10.8 ms) showed significantly higher mean time variability of interpotential interval value than healthy volunteers (10.3 ± 0.1 ms) (p < 0.001).

Migraine incidence in 5 years: a population-based prospective longitudinal study in Turkey.

BACKGROUND: The incidence of migraine has been investigated only in a few studies worldwide and it is not known in our country. We, therefore, aimed to estimate the migraine incidence in a previously accomplished population-based prevalence study sample of 5323 individuals in the year 2008. METHODS: The former Turkish headache prevalence study has been completed as a nationwide, randomized, home-based study of face-to-face examination by physicians trained for headache diagnosis by using ICHD criteria. Five years after this study an optimized survey including 50 questions was performed to estimate the migraine incidence in migraine-free individuals in the previous study, with a 56.4 % responder rate. Two validation studies for this survey were performed prior and after the study each in 100 subjects by comparing the gold standard of expert diagnosis of headache, showing high rate of reliability (Crohnbach alpha: 0.911 and 0.706, respectively). RESULTS: Migraine incidence was estimated as 2.38 % (2.98 % in women and 1.93 % in men) per year in 2563 migraine-free individuals; if the population at risk is defined as the group without any headaches, the migraine incidence decreased to 1.99 %. The chronic migraine (CM) incidence [without medication overuse (MOH)] was 0.066 % and that of MOH was 0.259 %. We found a significant burden of the disease on the occupational functionality as well as on social and family life, even in the early years of the migraine. The family history of headaches especially in the fathers could be useful to predict new cases of migraine, besides the well-known risk factor, diagnosis of depression, whereas income and education did not seem to relate to migraine onset. CONCLUSIONS: Our study with a large population-based nation-wide sample, using ICHD-II criteria, with structured headache interviews as well as blinded re-validation of the questionnaire diagnoses showed a 2.38 % incidence rate of migraine in Turkey, higher than most of the other previous reports; a finding which could be related to genetic factors and also to the methodological differences in the study designs. Moreover the incidence of CM was found to be 0.066 %.

Aquaporin-4 antibodies are not present in patients with idiopathic intracranial hypertension.

OBJECTIVES: We aimed to investigate anti-aquaporin-4 (AQP-4) water channel antibodies, affecting cerebrospinal fluid (CSF) secretion and absorption, in idiopathic intracranial hypertension (IIH) patients. METHODS: Patients fulfilling the modified Dandy's diagnostic criteria for IIH were included and their clinical features and CSF findings were reviewed. Their serum samples and control groups were investigated by immunofluorescence and a cell-based assay for anti-AQP-4 antibodies and by immunohistochemistry for IgG binding patterns. RESULTS: Twenty-nine patients diagnosed with IIH were investigated. We could not detect any anti-AQP-4 antibodies in our series. However, we identified different serum IgG binding patterns in 11 IIH patients. CONCLUSION: There is only one report investigating the anti-AQP4 antibodies in IIH. Our study with a larger sample confirmed the results of this report and indicated that AQP4 antibodies did not have a primary role in IIH pathogenesis, but provided some support for the contribution of inflammatory mechanisms in IIH.

Near-tendon single-fiber electromyography in patients with myopathy.

We investigated how properties of single-fiber action potentials (SFAP) and jitter changed in different recording sites in patients with myopathy and controls. SFAP and jitter were recorded using a disposable single-fiber electrode in the biceps brachii muscle of three patients and controls in two sites: i) near the end-plate zone (EPZ), ii) near the tendon. SFAP and spike duration were longer in patients than in controls. Moving the needle away from the EPZ did not change the electrophysiologic parameters. Longer SFAP duration may reflect slow velocity in muscle fibers and serve as an indicator for small fiber size in myopathy.

Cluster Analysis Revealed Two Hidden Phenotypes of Cluster Headache.

Objective: To investigate the possible subgroups of patients with Cluster Headache (CH) by using K-means cluster analysis. Methods: A total of 209 individuals (mean (SD) age: 39.8 (11.3) years), diagnosed with CH by headache experts, participated in this cross-sectional multi-center study. All patients completed a semi-structured survey either face to face, preferably, or through phone interviews with a physician. The survey was composed of questions that addressed sociodemographic characteristics as well as detailed clinical features and treatment experiences. Results: Cluster analysis revealed two subgroups. Cluster one patients (n = 81) had younger age at diagnosis (31.04 (9.68) vs. 35.05 (11.02) years; p = 0.009), a higher number of autonomic symptoms (3.28 (1.16) vs. 1.99(0.95); p < 0.001), and showed a better response to triptans (50.00% vs. 28.00; p < 0.001) during attacks, compared with the cluster two subgroup (n = 122). Cluster two patients had higher rates of current smoking (76.0 vs. 33.0%; p=0.002), higher rates of smoking at diagnosis (78.0 vs. 32.0%; p=0.006), higher rates of parental smoking/tobacco exposure during childhood (72.0 vs. 33.0%; p = 0.010), longer duration of attacks with (44.21 (34.44) min. vs. 34.51 (24.97) min; p=0.005) and without (97.50 (63.58) min. vs. (83.95 (49.07) min; p = 0.035) treatment and higher rates of emergency department visits in the last year (81.0 vs. 26.0%; p< 0.001). Conclusions: Cluster one and cluster two patients had different phenotypic features, possibly indicating different underlying genetic mechanisms. The cluster 1 phenotype may suggest a genetic or biology-based etiology, whereas the cluster two phenotype may be related to epigenetic mechanisms. Toxic exposure to cigarettes, either personally or secondarily, seems to be an important factor in the cluster two subgroup, inducing drug resistance and longer attacks. We need more studies to elaborate the causal relationship and the missing links of neurobiological pathways of cigarette smoking regarding the identified distinct phenotypic classes of patients with CH.

Evaluation of Patients with Post-Traumatic Hearing Loss: A Retrospective Review of 506 Cases.

OBJECTIVES: The purpose of the study is to evaluate the audiological, radiological, and examination findings of patients who have been treated for hearing loss (HL) due to head trauma and evaluated in terms of causality to reveal current data, and to highlight the steps to be taken. METHODS: We retrospectively reviewed the reports of cases that had applied for disability with HL due to head injury and had been evaluated by the Forensic Medicine Institute between January 01, 2009 and January 01, 2019. RESULTS: Of the total cases of head trauma, 52.42% were not vehicle-related, and cases were observed to be concentrated in the age range of 19-40 (55.92%; n = 283). Although otorrhagia/otorrhea was the most common finding in all types of trauma, TM perforation was the most common finding in blast-type injuries. While the rate of newly developed unilateral HL was 84.2%, 72.7% of the patients had sensorineural hearing loss (SNHL) . Temporal bone fractures were detected in 59.3% of the cases, and 60.2% of them were of the longitudinal type. Facial paralysis (FP) was detected in 28.6% of the cases, and there was no statistically significant difference between the groups in terms of HL compared to those without FP. Other nerve palsy was detected in 4.9% of the cases, and N. Abducens paralysis was the most common. CONCLUSION: Accompanying intracranial nerve injury, temporal fracture, and intracranial pathologies are considerably high in patients who develop HL following head trauma. The first examination requires a multidisciplinary approach to guide future disability applications.

Corticomotor Excitability in Two Kinds of Motor Neuron Diseases: A Study on the Patients With Amyotrophic Lateral Sclerosis and Poliomyelitis Survivors.

PURPOSE: To examine upper motor neuron functions comparatively in patients with amyotrophic lateral sclerosis (ALS) and poliomyelitis survivors using transcranial magnetic stimulation (TMS) methods. METHODS: Single- and paired-pulse TMS with conventional methods and the triple-stimulation technique were performed by recording from the abductor digiti minimi and abductor pollicis brevis muscles in 31 patients with ALS, 18 patients with poliomyelitis survivors, and 21 controls. Nine patients were diagnosed as having postpoliomyelitis syndrome after a 6-month follow-up. RESULTS: Triple-stimulation technique and some of conventional TMS studies were able to distinguish ALS from both poliomyelitis survivors and controls. A reduced ipsilateral silent period in abductor pollicis brevis muscles was the only parameter to show a significant difference when comparing thenar and hypothenar muscles in ALS. No significant difference was present in any TMS parameters between the postpoliomyelitis syndrome and non-postpoliomyelitis syndrome groups. CONCLUSIONS: Conventional TMS and particularly triple-stimulation technique studies are helpful in disclosing upper motor neuron dysfunction in ALS. The results of this study might favor the cortical hypothesis for split hand in ALS, but they revealed no significant indication for upper motor neuron dysfunction in postpoliomyelitis syndrome.

Electrophysiological Findings of Subclinical Lower Motor Neuron Involvement in Degenerative Upper Motor Neuron Diseases.

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.

Sex Differences of Migraine: Results of a Nationwide Home-based Study in Turkey.

INTRODUCTION: The prevalence of migraine was found to be more than three-fold higher in women as compared with men, and in addition to differences in prevalence rates, the characteristics and associated features might also differ between the sexes. The aim of this study was to compare sex-specific features of migraine and demographic parameters in a nationwide population-based study in Turkey. METHODS: Among 5323 subjects, a total of 871 patients who were diagnosed as having definite migraine according to the diagnostic criteria of the International Classification of Headache Disorders-III (ICHD-III) were included in our study. The demographic characteristics, associated features, and triggers of migraine were examined with regard to sex. RESULTS: The study group comprised 640 women (73.5%) and 231 men (26.5%), with a female to male ratio of 2.8:1. Attack duration, mean migraine disability assessment scores (MIDAS), frequencies of nausea, vomiting, osmophobia, vertigo/dizziness, and allodynia were found significantly different between women and men. When we compared these parameters between men and postmenopausal women, all these parameters were still significant except nausea. Odor was statistically more frequent as a reported trigger in women, whereas excessive sleep was a statistically more frequent triggering factor in men. The rates of depression and allergy were significantly higher in women when compared with men. CONCLUSION: Longer attack duration, higher MIDAS scores, and the frequencies of nausea, vomiting, osmophobia, vertigo/dizziness, and allodynia were more significant in women and this variance in sex persisted after menopause. Also, some trigger factors and co-morbidities differed between the sexes. These findings might result from complex genetic factors besides sociocultural influences, biologic, and sociocultural roles. Future studies should continue to explore biologic and genetic factors with respect to sex in migraine.

Changes in motor unit bioelectrical activity recorded at two different sites in a muscle.

INTRODUCTION: The objective of this study was to compare the properties of bioelectrical signals of motor units recorded at different sites in the muscles of controls, patients with myopathy and patients with motor neuron disease (MND). METHODS: Five controls, 10 patients with myopathy and 11 patients with MND were included. Electrophysiologic tests were performed in the biceps brachii (BB) muscle from two recording sites. Site 1 was near the belly of the muscle and Site 2 was 5cm distal from Site 1, near the tendon. Multi-motor unit potential (MUP) analysis, jitter analysis, and peak number count were calculated from the signals recorded using a concentric needle electrode (CN). RESULTS: At Site 2, duration was longer, number of phases was higher and amplitudes were smaller in MUPs compared with those recorded at Site 1. This significant difference between recording site and patient groups was related to neurogenic muscles. Jitter analysis showed no significant difference except an intergroup difference between the patient groups and controls. The peak number calculated using the CN was greater when recorded from Site 1 in concordance with MUP analysis. CONCLUSION: Duration of MUP was longer and amplitude was smaller when the recording electrode was placed distally along the muscle near the tendon in neurogenic muscles, probably related to increased temporal dispersion. However, changing the position of the needle did not provide further information in distinguishing myogenic muscles.

Repeater F-waves in amyotrophic lateral sclerosis: Electrophysiologic indicators of upper or lower motor neuron involvement?

OBJECTIVE: To extract insight about the mechanism of repeater F-waves (Frep) by exploring their correlation with electrophysiologic markers of upper and lower motor neuron dysfunction in amyotrophic lateral sclerosis (ALS). METHODS: The correlations of Frep parameters with clinical scores and the results of neurophysiological index (NI), MScanfit MUNE, F/M amplitude ratio (F/M%), single and paired-pulse transcranial magnetic stimulation (TMS), and triple stimulation technique (TST) studies, recorded from abductor digiti minimi (ADM) and abductor pollicis brevis (APB) muscles of 35 patients with ALS were investigated. RESULTS: Frep parameters were correlated with NI and MScanfit MUNE in ADM muscle and F/M% in both muscles. None of the Frep parameters were correlated with clinical scores or TST and TMS measures. While the CMAP amplitudes were similar in the two recording muscles, there was a more pronounced decrease of F-wave persistence in APB, probably heralding the subsequent split hand phenomenon. CONCLUSION: Our findings suggest that the presence and density of Freps are primarily related to the degree of lower motor neuron loss and show no correlation with any of the relatively extensive set of parameters for upper motor neuron dysfunction. SIGNIFICANCE: Freps are primarily related to lower motor neuron loss in ALS.