Electrodiagnostic methods to verify Guillain-Barré syndrome subtypes in Istanbul: A prospective multicenter study.

BACKGROUND AND AIMS: This study aimed to identify the clinical characteristics and electrodiagnostic subtypes of Guillain-Barré syndrome (GBS) in Istanbul. METHODS: Patients with GBS were prospectively recruited between April 2019 and March 2022 and two electrodiagnostic examinations were performed on each patient. The criteria of Ho et al., Hadden et al., Rajabally et al., and Uncini et al. were compared for the differentiation of demyelinating and axonal subtypes, and their relations with anti-ganglioside antibodies were analyzed. RESULTS: One hundred seventy-seven patients were included, 69 before the coronavirus disease 2019 pandemic (April 2019-February 2020) and 108 during the pandemic (March 2020-March 2022), without substantial changes in monthly frequencies. As compared with the criteria of Uncini et al., demyelinating GBS subtype diagnosis was more frequent according to the Ho et al. and Hadden et al. criteria (95/162, 58.6% vs. 110/174, 63.2% and 121/174, 69.5%, respectively), and less frequent according to Rajabally et al.'s criteria (76/174, 43.7%). Fourteen patients' diagnoses made using Rajabally et al.'s criteria were shifted to the other subtype with the second electrodiagnostic examination. Of the 106 analyzed patients, 22 had immunoglobulin G anti-ganglioside antibodies (14 with the axonal subtype). They had less frequent sensory symptoms (54.5% vs. 83.1%, p = 0.009), a more frequent history of previous gastroenteritis (54.5% vs. 22.9%, p = 0.007), and a more severe disease as compared with those without antibodies. INTERPRETATION: Serial electrodiagnostic examinations are more helpful for accurate subtype diagnosis of GBS because of the dynamic pathophysiology of the disease. We observed no significant increase in GBS frequency during the pandemic in this metropolis.

Blink reflex excitability in patients with Hemifacial spasm exhibiting different abnormal discharge patterns: from early isolated discharges to later grouped bursts or tonic spasms.

OBJECTIVE: We studied blink reflex (BR) and BR excitability recovery (BRER) in patients with hemifacial spasm (HFS) exhibiting different abnormal discharge patterns. We hypothesized that patients with groups of clonic or tonic burst activities appear later in the disease course and may have more excitability of the BR circuit at the brainstem compared to patients with isolated twitchings, which occur earlier. METHODS: We included 124 patients with botulinum toxin-naive HFS (mean age 50.6 ± 13.3 years) and 40 healthy subjects. We performed surface polymyography on facial muscles in patients and classified them according to the abnormal discharge pattern: isolated discharges, grouped bursts forming random sequences, tonic spasms, and a combination of these activities. Then, we recorded BR and BRER at 200, 600, and 1000 ms interstimulus intervals. We compared disease duration, R1 and R2 latencies, R2 area-under-the-curve (AUC), and BRER% (i) between healthy subjects and patients and (ii) among groups of patients with different abnormal discharge patterns. RESULTS: There were isolated discharges in 28 patients, grouped bursts forming random sequences in 42, and continuous muscle activity with tonic spasms in one. The remaining patients had combinations. Mean R1 and R2 latencies were significantly longer, and mean R2 AUC was significantly higher on the symptomatic side of patients compared to healthy subjects. The mean BRER was enhanced on both sides in patients than in healthy subjects (p < 0.001). However, it was similar among patient groups with different abnormal discharge patterns (p > 0.05). The mean disease duration in patients with isolated discharges was shorter (3.3 ± 2.0 years) than those with grouped bursts or tonic spasms (p = 0.002; Kruskal-Wallis test). CONCLUSION: Our study observed that excitability at the brainstem was similar in HFS patients with different abnormal discharge patterns, suggesting that the difference in discharge patterns in HFS may be due to a reason other than the difference in BR excitability.

Segmental Reflex, Long Latency Reflex, and Mixed Nerve Silent Period in Dystonia.

We hypothesized that "long latency reflexes" (LLRs), associated segmental reflex (SR), and mixed nerve silent periods (MnSPs) recorded on the distal upper extremity muscles would behave differently in patients with cervical dystonia and focal hand dystonia. We enrolled patients with cervical dystonia, generalized dystonia, focal hand dystonia, and healthy individuals. We recorded SR, LLRs, and MnSPs. The mean amplitude of SR on the affected side of focal hand dystonia was significantly lower (p = 0.010). The parameters related to LLRs and MnSPs were not different between groups. We suggest, using SR, LLRs, and MnSPs, we could not show an electrophysiological signature specific to dystonia.

An unusual cause of posterior interosseous nerve palsy and contribution of ultrasonography to electromyography in a patient with neurofibroma.

Neurofibroma, a benign peripheral nerve sheath tumor, represents a rare cause of posterior interosseous nerve syndrome. Electrodiagnostic studies may not identify the exact site of nerve compression, a possible lesion that compresses the nerve and do not provide information about the morphological changes. Ultrasound is a cost-effective, practical modality that provides the opportunity for dynamic tracking in the peripheral nerves, and it is widely considered as the initial imaging modality for peripheral nerves. Herein, we report a case of posterior interosseous nerve palsy in a 13-year-old boy with neurofibroma of posterior interosseous nerve diagnosed with ultrasound. The benefit of ultrasound in localizing and determining the etiology of the posterior interosseous nerve palsy is emphasized in this case report. A meticulous ultrasound examination is recommended in suspected peripheral nerve lesions, regardless of the results of electrophysiological and imaging modalities.

Late Component of the Trigemino-Cervical Reflex: Clinical and Neuroradiological Correlations.

INTRODUCTION: The authors aimed to analyze the possible relationship of the late response of trigemino-cervical reflex (TCR) with various clinical conditions having brainstem lesions and lesion localizations in the brainstem. METHODS: The authors enrolled 30 healthy subjects, 16 patients with stroke, 14 patients with multiple sclerosis (MS), and 9 patients with neuro-Behçet disease. All patients had at least one MRI, and lesion localization was classified into midbrain, pons, medulla oblongata, or their combinations. The TCR was recorded simultaneously from bilateral sternocleidomastoid and splenius capitis muscles. RESULTS: There was no significant difference based on lesion localization within the brainstem. Trigemino-cervical reflex latency was significantly longer in patients with MS compared with all other groups (P < 0.005 for each comparison). The Receiver Operating Characteristic curve analysis of sternocleidomastoid showed a cut-off value of 76.9 ms with 44% sensitivity and 92.7% specificity to predict MS. Similarly, the authors determined a cut-off value of 61.5 ms of splenius capitis latency with 38.5% sensitivity and 91.5% specificity to predict MS. CONCLUSIONS: This study showed that TCR might be abnormal in a given patient with one brainstem lesion, independently from the lesion localization. This may be attributed to a broad network of TCR at the brainstem. Thus, abnormally delayed TCR responses can be used as a tool for the discrimination of MS among other brainstem lesions.

The Thalamic and Intracortical Inhibitory Function of Somatosensory System Is Unchanged in Mesial Temporal Lobe Epilepsy With Hippocampal Sclerosis.

PURPOSE: In mesial temporal lobe epilepsy with hippocampal sclerosis, there is parietal atrophy and cognitive involvement in related domains. In this context, we hypothesized that inhibitory input into somatosensory cortex and thalamus may be increased in these patients, which could improve after epilepsy surgery. Thus, we analyzed the inhibitory function of somatosensory system by studying surround inhibition (SI) and recovery function of somatosensory evoked potentials in patients with mesial temporal lobe epilepsy with hippocampal sclerosis. METHODS: Nine patients with unoperated mesial temporal lobe epilepsy with hippocampal sclerosis, 10 patients who underwent epilepsy surgery, and 12 healthy subjects were included. For SI of somatosensory evoked potentials, we recorded somatosensory evoked potentials after stimulating median or ulnar nerve at wrist separately and after median and ulnar nerves simultaneously and calculated SI% in all participants. For recovery function of somatosensory evoked potentials, paired stimulation of median nerve at 40- and 100-millisecond intervals was performed. We compared the findings among groups. As a secondary analysis, we determined the outliers in the patient group and analyzed the relation to the clinical findings. RESULTS: The mean SI% or recovery function was similar among three groups. However, there were five patients with SI loss on normal side in the patient group, which was related to the antiseizure drugs. CONCLUSIONS: In contrast to our hypothesis, both intracortical (SI) and thalamic/striatal (recovery function) inhibitory modulation of the somatosensory cortex was not altered in mesial temporal lobe epilepsy with hippocampal sclerosis and did not differ in surgical and nonsurgical groups.

Long latency trigemino-cervical reflex in restless legs syndrome.

OBJECTIVE: The trigemino-cervical complex (TCC) seems under dopaminergic inhibitory control and the abnormalities of trigemino-cervical reflex (TCR) have been reported in disorders associated with the dopaminergic system and various pain disorders. If the inhibitory response in TCC is likely dopaminergic, we hypothesized that TCR, which has never been evaluated in restless legs syndrome (RLS) patients before, would be also abnormal. METHODS: TCR was recorded from bilateral sternocleidomastoid and splenius capitis muscles in consecutive 15 drug-naive RLS patients and 16 age- and sex-matched healthy subjects. The right and left infraorbital branches of the trigeminal nerve were stimulated by percutaneous electrical stimulation separately. The presence rates, onset latencies, amplitudes, and durations of responses were measured and compared between patients with RLS and controls. RESULTS: The presence rates, onset latencies and amplitudes of TCR responses were similar between RLS patients and controls, however, the durations of responses were bilaterally longer in RLS patients compared to healthy volunteers. CONCLUSIONS: Hyperexcitability of TCR suggests defective sensory processing in the brainstem probably due to impairment of descending inhibitory dopaminergic system in RLS. The sensitization of TCC in RLS patients may also be a possible factor that might explain the association of RLS and pain disorders.

[Comparison of long-latency reflex and mixed nerve silent period responses in various hypokinetic movement disorders]. / A hosszú latenciájú reflexválaszoknak és a kevert idegek csendes periódusainak összehasonlítása különbözo hipokinetikus mozgási rendellenességekben.

Background and purpose: Long-latency reflex and mixed nerve silent period responses are electrophysiological methods to study the sensorimotor functions of the central nervous system. Here we aimed to study long-latency reflexes and mixed nerve silent period responses in different types of hypokinetic movement disorders in order to find an electrophysiological landmark to distinguish them. Methods: We included 39 patients with idiopathic Parkinson's disease (IPD), 12 patients with multiple system atrophy (MSA), 10 patients with corticobasal syndrome (CBS), 5 patients with progressive supranuclear palsy (PSP) and 26 healthy participants. We recorded the segmental reflex, the long-latency reflexes and the mixed nerve silent period responses for each participant. Results: C reflex, long-latency reflex-I and long-latency reflex-III responses were not obtained in any patients with PSP. Long-latency reflex amplitude/ F amplitude ratio was significantly lower in patients with IPD and PSP compared to healthy individuals (p=0.036, p=0.006 respectively). The mixed nerve silent period end latencies were significantly longer in IPD, MSA, CBS groups compared to the healthy individuals (p=0.026, p=0.050, p=0.008 respectively). Conclusion: We suggest that recording long-latency reflex, particularly C reflex responses may provide promising results in distinction of CBS and MSA from PSP. Prospective studies with clinical findings and brainstem reflexes may offer more information.

Cutaneous silent period modulation by tooth clenching, tonic and phasic limb movements in healthy subjects.

OBJECTIVE: We aimed to examine the modulation of the cutaneous silent period (CSP) by tooth clenching and contralateral tonic dorsiflexion of lower limb and phasic voluntary movements of upper limb. METHODS: In 18 healthy subjects, we recorded CSP on right thenar muscle after painful stimulation of index finger during mild contraction at six conditions: baseline, maximum tooth clenching, contralateral tonic dorsiflexion of foot, as well as at the beginning (RT1), in the middle (RT2) and at last part (RT3) of the contralateral phasic wrist extension. We measured latency and duration and calculated suppression indices. RESULTS: During tooth clenching, the suppression index of second inhibitory phase (I2) was significantly higher than that at baseline condition. The suppression index of first inhibitory phase (I1) was reduced in tonic dorsiflexion. The I2 durations in RT2 and RT3 were longer than that at baseline. The I2 suppression indices during RT1, RT2, and RT3 were significantly higher than that at baseline condition (p < 0.05). CONCLUSION: The tooth clenching has an inhibitory effect on CSP. The contralateral phasic hand movements caused higher suppression index. The CSP is modulated by remote influences differently depending on the type of muscle contraction (tonic vs. phasic) and/or where it is realized (tooth, upper or lower limb).

ADCY5 gene mutation: a case report.

BACKGROUND: ADCY5 mutation is a clinical condition that has been described in limited numbers in the literature, causing hyperkinetic movement disorder, and may be sporadic or familial. PATIENT DESCRIPTION: This report looks at the involuntary movements that started early in life in a 5-year-old girl. RESULTS: Patient's electroensephalogram and cranial magnetic resonance imaging were normal. Metabolic scans were normal. ADCY5 mutation was found in whole exome sequencing of the patient who did not have a similar family history. CONCLUSION: Some features such as the worsening of involuntary movements after sleep and the presence of hypotonia in our patient suggested this mutation. Our patient is resistant to more than one drug. With this report, we aimed to pave the way for better understanding of the gene and the discovery of different treatment options.

Myoclonus and tremor in chronic inflammatory demyelinating polyneuropathy: a multichannel electromyography analysis.

BACKGROUND: Information regarding involuntary movements in chronic inflammatory polyneuropathy (CIDP) is gradually increasing. Our goal is to identify the types of involuntary movements in CIDP. METHODS: All patients who were followed with the diagnosis of CIDP were invited for clinical and electrophysiological evaluations. Demographic and clinical findings (age, gender, duration of illness, diagnosis, treatments) were noted. Clinical examination and multichannel surface electromyography were done. We also performed routine upper and lower extremity peripheral nerve conduction studies, F-waves, long latency reflexes, blink reflex, mixed nerve silent period and cutaneous silent period in all patients. RESULTS: Twenty-two patients accepted the invitation. Eleven patients with CIDP had involuntary movements. Ten (45.5%) patients with CIDP had tremor and seven (31.8%) had short-duration and high-amplitude myoclonus. Regarding demographic, clinical and electrophysiological features, there was no significant difference between patients with and without tremor. The latencies of R1, R2 and R2c components of BR were longer among CIDP patients without tremor compared to CIDP patients with tremor. Presence of myoclonus (p = 0.007) and delayed F-waves (p = 0.008) were associated with the presence of tremor. CONCLUSION: Tremor and myoclonus were frequent in CIDP. The fact that myoclonus was detected in the majority of patients only by multichannel surface EMG who were clinically evaluated as pure tremor suggests that a more detailed electrophysiological evaluation is required. There was no difference in the medications used or other clinical features between patients with and without tremor.

Postural tremor in L-2-hydroxyglutaric aciduria is associated with cerebellar atrophy.

OBJECTIVE: In this study, we performed analysis of brainstem reflexes and movement disorders using surface polymyogram in L-2-hydroxyglutaric aciduria (L2HGA). We also reviewed all cases in the literature with detailed clinical and radiological description to analyze the anatomical correlates of involuntary movements. PATIENTS AND METHOD: We performed surface electromyography of appropriate muscles, long-loop reflexes, and somatosensory evoked potentials and analyzed the neuroimaging findings in patients with L2HGA and recorded blink reflex (BR), auditory startle response (ASR), and startle response after somatosensory stimuli (SSS) in patients and healthy subjects. We also performed a systematic literature search to identify the association of neuroimaging findings and movements disorders in previous patients with L2HGA. RESULTS: Thirteen patients were enrolled in the study. Among them, ten had low-amplitude postural tremor with a frequency between 4 and 7 Hz. The tremor was predominant on distal parts of the upper extremities. Postural tremor was accompanied by negative myoclonus in one-third. The BR, ASR, and SSS, all, were hypoactive. There was a close association of postural tremor with cerebellar atrophy in patients who participated in this study and by the analysis of the previously reported patients. CONCLUSIONS: Low-amplitude postural tremor is common in L2HGA. It is related with cerebellar atrophy. Although the neuroimaging shows no overt lesions at the brainstem, there is a functional inhibition at this level.

Progression of myoclonus subtypes in subacute sclerosing panencephalitis.

OBJECTIVES: Diagnostic criteria of subacute sclerosing panencephalitis (SSPE) include myoclonus, a well-recognized clinical feature. Here, we studied the electrophysiological features of myoclonus with regards to disease staging in SSPE patients. METHODS: We included 10 patients diagnosed with SSPE between 2010 and 2018, along with 21 healthy subjects. All participants had detailed electrophysiological evaluation including polymyographic analysis, blink reflex after trigeminal stimulation, auditory startle response, startle response after somatosensory stimuli, F-waves, and long-loop reflexes. Clinical findings were retrieved from the medical records. RESULTS: Patients were categorized into Gascon stage 2B (n = 5, 50%), 2A (n = 2, 20%), 3B (n = 2, 20%) and 4A (n = 1, 10%) at the time of electrophysiological evaluation. Two patients had cortical myoclonus, four had possible cortico-subcortical myoclonus, and four had brainstem myoclonus. Patients were categorized into Gascon stages 2a and 2b had possible cortico-subcortical myoclonus (85.7%). However, none of the patients with stage 3b or 4a had possible cortico-subcortical subtype but all had the brainstem subtype. CONCLUSION: Association was seen between subtypes of myoclonus and clinical staging in SSPE. This suggests that myoclonus in SSPE may primarily involve the cortex and cortico-subcortical structures such as the thalamus at earlier stages of disease, and then involve more caudal structures as the disease progresses.

Contribution of brainstem circuits in pathophysiology of NREM-sleep parasomnias.

OBJECTIVE: We aimed to investigate the brainstem circuits to reveal if there was any abnormality in these circuits in clinically diagnosed patients with NREM parasomnias during wakefulness. METHODS: Twelve patients with NREM-sleep parasomnia diagnosed according to ICSD-3 criteria and a control group of 16 healthy subjects were enrolled into our study. We analyzed the auditory startle reflex (ASR), blink reflex (BR), prepulse inhibition (PPI) of BR and recovery excitability of BR. RESULTS: There was a trend for longer responses from orbicularis oculi and sternocleidomastoid muscles after auditory stimulation in the patients compared to those in the healthy subjects. The recovery percentages at 200 ms and 300 ms showed a borderline significance in the patients. No significant difference was found in the R2-PPI between the patients and healthy subjects. CONCLUSIONS: Our results suggest a mildly enhanced ASR and relatively early facilitation of BR excitability in patients with NREM-sleep parasomnia during daytime. Although our findings suggest involvement of brainstem networks in NREM-sleep parasomnia during wakefulness, it would be better to study these networks at night and during daytime to see if there is any contribution.

The role of pedunculopontine nucleus in isolated REM sleep behavior disorder and REM sleep without atonia.

INTRODUCTION: The aim of this study was to analyze the functions of pedunculopontine nucleus (PPN) in isolated REM sleep behavior disorder (iRBD) and REM sleep without atonia (RSWA) to investigate the role of PPN in dream-enacting motor behaviors in RBD. We evaluated the activity of PPN through the prepulse modulation (PPM) together with other brainstem reflexes to investigate the differences in changes at brainstem. METHODS: We included nine patients with isolated RSWA and 10 patients with iRBD. For diagnosis, all patients underwent polysomnography. None of the patients had parkinsonism or dementia. We also included 17 healthy participants with similar age and sex. Blink reflex (BR), PPM of BR, recovery excitability of BR, and auditory startle reflex (ASR) were recorded in all participants. RESULTS: There was a prepulse inhibition deficit in iRBD and RSWA groups compared to healthy subjects. The BR-R2 recovery at 200 ms interval was also higher in patients with iRBD and RSWA. In ASR recordings, the response probabilities were higher in the RBD group compared to RSWA and control groups. CONCLUSION: The PPM was abnormal in both iRBD and RSWA whereas ASR was enhanced in iRBD. We suggest that there are certain similarities and differences in the pathophysiologies of iRBD and RSWA.

Electrophysiological investigation for autonomic dysfunction in patients with myasthenia gravis: A prospective study.

BACKGROUND AND PURPOSE: Myasthenia gravis (MG) is an autoimmune disorder of neuromuscular transmission. Autonomic dysfunction is not a commonly known association with MG. We conducted this study to evaluate autonomic functions in MG & subgroups and to investigate the effects of acetylcholinesterase inhibitors. METHODS: This study comprised 30 autoimmune MG patients and 30 healthy volunteers. Autonomic tests including sympathetic skin response (SSR) and R-R interval variation analysis (RRIV) was carried out. The tests were performed two times for patients who were under acetylcholinesterase inhibitors during the current assessment. RESULTS: The RRIV rise during hyperventilation was better (p=0.006) and Valsalva ratio (p=0.039) was lower in control group. The SSR amplitudes were lower thereafter drug intake (p=0.030). As much as time went by after drug administration prolonged SSR latencies were obtained (p=0.043).Valsalva ratio was lower in the AchR antibody negative group (p=0.033). CONCLUSION: The findings showed that both ocular/generalized MG patients have a subclinical parasympathetic abnormality prominent in the AchR antibody negative group and pyridostigmine has a peripheral sympathetic cholinergic noncumulative effect.

Modulation of the excitatory phase following the cutaneous silent period by vibration.

INTRODUCTION: The post-inhibition excitatory phase (E3) of the cutaneous silent period (CSP) is attributed to the resynchronization of motoneuron activity following the inhibitory period but there is also evidence that a somatosensory startle reflex may contribute to this phase. We hypothesized that the startle reflex component contained in E3 will decrease during vibration. METHODS: Sixteen healthy individuals were included in the study. CSP was recorded from slightly contracted right thenar muscles after painful index finger stimulation, before, during, and immediately after vibration. The values of the percentage change of E3 relative to pre-stimulus baseline (E3%) were compared before, during, and after vibration for each individual. RESULTS: There was a reduction in E3% during vibration and the values returned to normal immediately after vibration (153.1 ± 43.5%, 115.2 ± 30.2%, 154.9 ± 68.2%, respectively; p = 0.030). DISCUSSION: E3 is reduced during vibration in healthy individuals, presumably due to suppression of a reflex component, which is superimposed upon the known resynchronization of motoneurons.

Surround inhibition in patients with juvenile myoclonic epilepsy.

OBJECTIVE: In healthy subjects, there is a reduction in the amplitudes of somatosensory-evoked potentials (SEPs) after the simultaneous stimulation of two nerves compared to the sum of separate stimulations. This reduction is due to the inhibition of one area in the cortex after stimulation of the neighboring area, which results from the surround inhibition (SI) phenomenon. In this study, we aimed to investigate whether there was a decrease in SI of SEP in patients with juvenile myoclonic epilepsy (JME). METHODS: We included 17 patients with JME and 18 healthy subjects. Groups were similar in terms of age and gender. We recorded SEPs after stimulating (i) median nerve (mSEP), (ii) ulnar nerve (uSEP), (iii) median and ulnar nerves simultaneously (muSEP) at wrist. The arithmetic sum (aSEP) of amplitudes of mSEP and uSEP was compared with the amplitudes of muSEP. We also calculated SI%. RESULTS: The amplitudes of SEPs were significantly higher in the JME group than in the healthy subjects (mSEP, p = 0.005; uSEP, p = 0.032; muSEP, p = 0.014). In healthy subjects and the JME group, the amplitude of muSEP was significantly lower than the aSEP (p = 0.014; p = 0.001, respectively). However, SI% was significantly higher in the JME group (p = 0.010). SIGNIFICANCE: Although the SI is maintained in JME patients, the higher SI% indicates an impairment relative to healthy subjects.