Normative data of F-wave measures in China

Clinical Features and Classification of Neuronal Intranuclear Inclusion Disease

Background and Objectives

Neuronal intranuclear inclusion body disease (NIID) is a neurodegenerative disease with highly heterogeneous clinical manifestations. The present study aimed to characterize clinical features and propose a classification system based on a large cohort of NIID in China.

Methods

The Chinese NIID registry was launched from 2017, and participants' demographics and clinical features were recorded. Brain MRI, skin pathologies, and the number of GGC repeat expansions in the 5′ untranslated region of theNOTCH2NLCgene were evaluated in all patients.

Results

In total, 223 patients (64.6% female) were recruited; the mean (SD) onset age was 56.7 (10.3) years. The most common manifestations were cognitive impairment (78.5%) and autonomic dysfunction (70.9%), followed by episodic symptoms (51.1%), movement disorders (50.7%), and muscle weakness (25.6%). Imaging markers included hyperintensity signals along the corticomedullary junction on diffusion-weighted imaging (96.6%), white matter lesions (98.1%), paravermis (55.0%), and focal cortical lesions (10.1%). The median size of the expanded GGC repeats in these patients was 115 (range, 70–525), with 2 patients carrying >300 GGC repeats. A larger number of GGC repeats was associated with younger age at onset (r= −0.329,p< 0.0001). According to the proposed clinical classification based on the most prominent manifestations, the patients were designated into 5 distinct types: cognitive impairment-dominant type (34.1%, n = 76), episodic neurogenic event-dominant type (32.3%, n = 72), movement disorder-dominant type (17.5%, n = 39), autonomic dysfunction-dominant type (8.5%, n = 19), and neuromuscular disease-dominant type (7.6%, n = 17). Notably, 32.3% of the episodic neurogenic event-dominant type of NIID has characteristic focal cortical lesions on brain MRI presenting localized cortical edema or atrophy. The mean onset age of the neuromuscular disease-dominant type was 47.2 (17.6) years, younger than the other types (p< 0.001). There was no significant difference in the sizes of GGC repeats among the patients in the 5 types (p= 0.547, Kruskal-Wallis test).

Discussion

This observational study of NIID establishes an overall picture of the disease regarding clinical, imaging, and genetic characteristics. The proposed clinical classification of NIID based on the most prominent manifestation divides patients into 5 types.

Association of peripheral neuropathy with subclinical left ventricular dysfunction in patients with type 2 diabetes

OBJECTIVES

The impacts of diabetic peripheral neuropathy (DPN) on clinical manifestations of left ventricular (LV) function in patients suffering from type 2 diabetes mellitus (T2DM) and the preserved LV ejection fraction (LVEF) lack a full evaluation. This study was carried out to investigate the correlation of peripheral neuropathy with subclinical LV systolic dysfunction, accompanied by the exploration of the relevant clinical features of peripheral neuropathy in these patients.

METHODS

A retrospective analysis was conducted depending on the data of 101 consecutive inpatients with T2DM and preserved LVEF (all ≥ 50 %), without coronary artery disease and other histories of heart disease. All subjects received both a nerve conduction assessment and a speckle-tracking echocardiography examination. Global longitudinal strain (GLS) was conducted to assess the subclinical LV systolic function.

RESULTS

Forty-six (46 %) patients were diagnosed as DPN according to electrophysiological examination and clinical assessment. A significant difference was revealed in GLS between patients with and without DPN (16.5 ± 2.8 vs. 19.3 ± 3.4, p < 0.001). Multiple logistic regression analysis indicated GLS as one of the independent determinative factors for DPN (odds ratio, 0.68; P < 0.001). In addition, motor-sensory nerve conduction exhibited a significant positive correlation with GLS, which may not be revealed between the types of peripheral nerve damage.

CONCLUSIONS

Despite the preserved LVEF, the subclinical LV myocardial dysfunction may have occurred in T2DM patients with DPN. Peripheral nerve conduction was significantly correlated with GLS. An early assessment of nerve conduction may exert a dual warning significance for the progression of subclinical LV dysfunction in asymptomatic patients with T2DM.

Clinical and Physiological Significance of F-Wave in Spinocerebellar Ataxia Type 3

Objective: To evaluate the characteristics of F-wave in spinocerebellar ataxia type 3 (SCA3) patients and preclinical carriers of SCA3 gene mutation (PreSCA3), and explore the relationship between disease severity and F-wave parameters and evaluate F-wave parameters as potential biomarkers for monitoring of disease progression in SCA3. Methods: We performed F-wave recordings in median, ulnar and tibial nerves of 39 SCA3 patients, 20 PreSCA3, and 27 healthy controls, and compared F-wave parameters between them. Results: In all nerves studied, the mean F-wave amplitude, maximum F-wave amplitude, and F/M amplitude ratio were significantly increased in the SCA3 patients in comparison with the normal controls. And the minimal F-wave latency of SCA3 patients was significantly prolonged and the F-wave persistence (%) was significantly decreased in the median nerve. For the PreSCA3, the maximum F-wave amplitude was significantly higher than normal controls for both median, ulnar, and tibial nerves. The mean F-wave amplitude and F/M amplitude ratio in all nerves were comparable between PreSCA3 and normal controls. The frequency of giant F-wave and frequency of patients with giant F-wave were similar between PreSCA3 and SCA3. The values of F/M amplitude ratio in both median, ulnar, and tibial nerves were correlated positively with disease severity and disease duration. Conclusion: Significant F-wave abnormalities occur in patients with SCA3, even in PreSCA3. F-wave may therefore reveal subclinical alterations and provide objective parameters for evaluating the progression of SCA3.

Age-related characteristics and normative values of F waves in healthy infants

OBJECTIVE

To establish age-related characteristics and normative values of F waves in healthy Chinese infants.

METHODS

We studied median, ulnar and tibial nerves on one side distally in 229 healthy Chinese infants (108 males) ranging from 1 to 12 months old.

RESULTS

Minimal F-wave latencies (Fmin) showed a strong negative correlation to the age for median, ulnar and tibial nerves (P < 0.01) but no correlation to the height. Statistical analyses revealed a significant (P < 0.01) decrease of Fmin during the second month of life and no change (P > 0.05) thereafter. Dividing the infants into 1 month old (Group 1) and 2-12 months old (Group 2), normal values (Mean ± SD ms) of Fmin for tibial, median and ulnar nerves consisted of 23.38 ± 1.68, 17.19 ± 0.95 and 16.47 ± 1.06 for Group 1 and 21.42 ± 1.25, 14.50 ± 1.15 and 14.52 ± 0.90 for Group 2.

CONCLUSION

F-wave latencies shorten in the 2nd month of life and change little thereafter when age-related maturation counters the concomitant growth of the nerve length.

SIGNIFICANCE

F waves can assess infantile neuropathies as a reliable measure, complementing the technically difficult conventional nerve conduction study in short limbs.

Establishing Normal Values for F-Wave Latencies in Diagnosing Peripheral Neuropathies for the Pediatric Population

PURPOSE

We present a unique technique applying F-wave latencies to assist in the diagnosis of peripheral neuropathy within the pediatric age group.

METHODS

We calculated an F-wave estimated deviance adjusted for limb length measurements, distal motor conduction velocity, and distal motor latencies. We compared the F-wave estimated deviance from the normal subjects with those with peripheral neuropathy (both axonal and demyelinating) to establish diagnostic accuracy in pediatric patients.

RESULTS

The normal range for the F-wave estimated deviance in the upper limb was -1 to +6 ms and in the lower limb was -8 to +5 ms. When compared with 82 subjects with peripheral neuropathy, there was a significant difference between the normal subjects and those with neuropathy (P values between 0.002 and 0.0005 for each of the individual nerves tested).

CONCLUSIONS

The F-wave estimated deviance is independent of age and can be accurately applied to the electrodiagnostic testing of pediatric patients with suspected neuropathy.

Reassessment of Split-Leg Signs in Amyotrophic Lateral Sclerosis: Differential Involvement of the Extensor Digitorum Brevis and Abductor Hallucis Muscles

Background: The muscle patterns involved in the “split-leg” syndrome of amyotrophic lateral sclerosis (ALS) remains controversial. We sought to evaluate and reassess the pattern of the extensor digitorum brevis (EDB) and the abductor hallucis (AH) muscles' involvement in split-leg syndrome in ALS.

Methods: We recruited 60 consecutive patients with ALS and 25 healthy controls (HCs). Compound muscle action potentials (CMAPs) and F-waves were recorded over the EDB and AH muscles in all subjects. For comparison, we classified patients into two categories based on the presence or absence of lower limbs symptoms.

Results: The EDB/AH CMAP amplitude ratio was significantly reduced in patients with affected legs (0.33 ± 0.21, P = 0.007), whereas patients with unaffected legs had a ratio similar to that of the HCs. The EDB/AH ratios for the F-wave latencies, mean F-wave amplitude, mean F/M amplitude ratio, and the persistence of the total repeater F-wave shapes (index Freps) of the EDB-AH, were significantly increased in the affected leg group, whereas the EDB/AH ratio for F-wave persistence was significantly reduced. These findings indicated a greater loss of lower motor neurons (LMNs) innervating the EDB and dysfunction of spinal motoneurons innervating the EDB. In the unaffected leg group, the EDB, but not the AH, F-wave latencies, mean and maximal F/M amplitude ratios, and index Freps were significantly altered. Receiver operating characteristic curve analysis suggested that the EDB F-wave latencies, mean F/M amplitude ratios, and index Freqs (area under the curve [AUC] > 0.8) more strongly differentiated patients with ALS from the HCs compared to the EDB/AH CMAP amplitude ratio (AUC = 0.61). Notably, the EDB maximal F-wave latency and index Freqs reliably differentiated patients with unaffected legs (HCs), with AUCs of 0.83 (95% CI 0.76–0.91) and 0.81 (95% CI 0.72–0.89), sensitivities of 76 and 78%, and specificities of 76 and 78%, respectively.

Conclusions: These results suggest preferential EDB compared to AH involvement in the split-leg syndrome of ALS. The EDB maximal F-wave latency and index Freqs robustly differentiated patients with ALS from HCs, which might facilitate an earlier identification of ALS.

F wave, A wave, H reflex, and blink reflex

Late responses include F waves, A waves, H reflex, and the blink reflex. These responses help enhance routine nerve conduction studies. Despite the use of F waves in multiple clinical applications, their studies can technically challenge even the most experienced electromyographers. They vary in latency, amplitude, and configuration, whereas A waves show no change in latency or morphology. Electrical stimulation of the supraorbital branch of the trigeminal nerve on one side results in a reflexive activation of the facial nucleus causing contraction of the orbicularis oculi muscle, short latency R1 ipsilaterally, and long latency R2 bilaterally. F waves can help determine the presence of a polyneuropathy. A waves can reflect axonal damage. H reflexes provide nerve conduction measurements along the entire length of the nerve, demonstrating abnormalities in neuropathies and radiculopathies. Abnormalities in the blink reflex can suggest the presence of an acoustic neuroma or a demyelinating polyneuropathy, which can affect the cranial nerves. This reflex, which also needs appropriate technical expertise, helps to assess cranial nerves V and VII along with their connections in the pons and medulla. The blink reflex, the electrical version of the corneal reflex, represents a polysynaptic reflex.

F-waves of peroneal and tibial nerves in the differential diagnosis and follow-up evaluation of L5 and S1 radiculopathies

PURPOSE

To investigate F-wave as a method to identify a specific root lesion of L5 or S1 and to quantitatively evaluate the severity and progression of motor root lesions in lumbosacral radiculopathies (LR).

METHODS

Both peroneal and tibial F-waves were performed bilaterally in 142 patients with unilateral L5 or S1 radiculopathies and 37 controls along with Medical Research Council (MRC) evaluation, and soleus H-reflexes were tested bilaterally in 78 of these 142 cases. Both F-wave and MRC were re-evaluated approximately 1 year after initial examination in 65 patients.

RESULTS

Abnormal peroneal F-waves were found in 34 patients with L5 radiculopathy (34/67, 50.7%) along with normal tibial F-waves and soleus H-reflexes in all tested cases. By contrast, 27 patients with S1 radiculopathy presented abnormal tibial F-waves (27/76, 36.0%) along with normal peroneal F-waves in all 76 cases and abnormal soleus H-reflexes in 38 of 47 (80.9%) cases. There were significant differences in involved side F-duration among different MRC scales in both radiculopathy groups (P < 0.05). Follow-up analysis demonstrated slow progression of both F-wave abnormalities and muscle weakness in patients undergoing conservative treatment (P < 0.05).

CONCLUSIONS

Comparisons of F-waves between the same nerve on both sides and between peroneal and tibial nerves in the same leg may clearly increase the validity of F-waves for evaluating a specific motor root lesion of L5 or S1. Furthermore, a quantitative comparison of F-waves may provide additional information on the severity of individual root lesions and their progression even in the early stages of disease. These slides can be retrieved under Electronic Supplementary Material.

Creatine kinase level and its relationship with quantitative electromyographic characteristics in amyotrophic lateral sclerosis

OBJECTIVE

To explore the relationship between serum creatine kinase (CK) level and electromyographic characteristics in patients with amyotrophic lateral sclerosis (ALS).

METHODS

Two hundred thirty-eight consecutive ALS patients were enrolled. All patients underwent electrophysiological study with a consistent approach. We calculated a compound muscle action potential (CMAP) sum score, and spontaneous potentials were graded from 0 to 4 depending on their density and distribution. We tested for any independent correlation of the CK levels with CMAP sum score, mean spontaneous potential (MSP) score, F wave persistence or conduction velocity.

RESULTS

The median serum CK level was 151 U/L. Log CK was independently correlated with MSP score (β = 0.07, 95% CI: 0.01-0.14, p = 0.032) and F persistence (β = -0.0013, 95% CI: -0.00251 to -0.0002, p = 0.02) but not with CMAP sum score or F wave conduction velocity. When stratified by sex, the correlation of log CK with MSP score and F persistence was significant in male but not female patients.

CONCLUSIONS

The results support that lower motor neuron loss and muscle denervation are associated with elevated CK levels of ALS patients.

SIGNIFICANCE

The severity of lower motor neuron loss and denervation might be involved in pathophysiological mechanisms of CK elevation in ALS patients.

Differences in F-Wave Characteristics between Spinobulbar Muscular Atrophy and Amyotrophic Lateral Sclerosis

There is limited data on the differences in F-wave characteristics between spinobulbar muscular atrophy (SBMA) and lower motor neuron dominant (LMND) amyotrophic lateral sclerosis (ALS). We compared the parameters of F-waves recorded bilaterally from the median, ulnar, tibial, and deep peroneal nerves in 32 SBMA patients, 37 patients with LMND ALS, and 30 normal controls. The maximum F-wave amplitudes, frequencies of giant F-waves, and frequencies of patients with giant F-waves in all nerves examined were significantly higher in the SBMA patients than in the ALS patients and the normal controls. The mean F-wave amplitude, maximum F-wave amplitude, frequency of giant F-waves, and frequency of patients with giant F-waves in the median and deep peroneal nerves were comparable between the ALS patients and normal controls. Giant F-waves were detected in multiple nerves and were often symmetrical in the SBMA patients compared with the ALS patients. The number of nerves with giant F-waves seems to be the most robust variable for differentiation of SBMA from ALS, with an area under the curve of 0.908 (95% CI: 0.835–0.982). A cut-off value of the number of nerves with giant F-waves (≥3) for diagnosing SBMA showed high sensitivity and specificity: 85% sensitivity and 81% specificity vs. ALS patients. No significant correlations were found between the pooled frequency of giant F-waves and disease duration in the SBMA (r = 0.162, P = 0.418) or ALS groups (r = 0.107, P = 0.529). Our findings suggested that F-waves might be used to discriminate SBMA from ALS, even at early stages of disease.

Association of peripheral nerve conduction in diabetic neuropathy with subclinical left ventricular systolic dysfunction

BACKGROUND

Subclinical left ventricular (LV) longitudinal myocardial systolic dysfunction occurs in patients with diabetes mellitus (DM) and preserved LV ejection fraction (LVEF), and is closely related to DM-related complications. However, the association of diabetic neuropathy (DN) with subclinical LV systolic longitudinal dysfunction in such patients has not been fully clarified.

METHODS

The subjects of this study were 112 consecutive DM patients with preserved LVEF (all ≥50%) without coronary artery disease and overt heart failure (aged 59 ± 14 years; 60 women, 52 men). Global longitudinal strain (GLS) was determined as the average peak strain of 18 segments from the three standard apical views, and was expressed as an absolute value. DN was diagnosed by experienced diabetologists. Median, ulnar, and sural nerves were subjected to motor and sensory nerve conduction studies. F-wave latency was defined as the minimum F-wave latency after a total of 16 stimulations of the tibial nerve.

RESULTS

Forty-one (37%) patients were clinically diagnosed with DN. LV functions of DM patients with and without DN were similar except for GLS being significantly smaller in patients with than in patients without DN (18 ± 2% vs. 20 ± 2%, p < 0.001). It was noteworthy that, of the parameters for the nerve conduction study, only F-wave latency correlated with GLS (r = -0.34, p < 0.001), and also was identified as an independent determinative value of GLS in a multivariate linear regression model (β = -0.25, p = 0.001) even after adjustment for other closely related GLS factors.

CONCLUSIONS

Monitoring of F-wave latency may aid early detection of not only DN but also subclinical LV dysfunction. Joint planning of assessment by diabetologists and cardiologists is therefore advisable for better management of DM patients.

Sphincter electromyography in diabetes mellitus and multiple system atrophy

AIMS

Abnormalities of external anal sphincter electromyography (EAS-EMG) characterize multiple system atrophy (MSA) and focal cauda equina or conus medullaris lesions. This study is designed to determine whether and how diabetic polyneuropathy (DPN) affects EAS as compared to the abnormalities seen in MSA.

METHODS

We conducted multi-motor unit potential (MUP) analysis of EAS in 22 healthy controls, 32 diabetes mellitus (DM) patients without neuropathy, 38 DPN patients, and 68 MSA patients.

RESULTS

DPN patients had a significant (P < 0.01) increase in MUP mean duration, mean amplitude, percentage of long duration MUPs, and satellite rate, but to a lesser extent than MSA. Mean duration and satellite rate showed the least overlap among different groups in individual value distributions.

CONCLUSIONS

Compared with MSA, DPN affects EAS to a lesser degree as judged by neurogenic MUP abnormalities in EMG. Mean duration and satellite rate may serve as the most discriminating aspects in MUP analysis of EAS.

Proximally evoked soleus H-reflex to S1 nerve root stimulation in sensory neuronopathies (ganglionopathies)

INTRODUCTION

Sensory neuronopathy (SNN) mimics distal sensory axonopathy. The conventional H-reflex elicited by tibial nerve stimulation (tibial H-reflex) is usually abnormal in both conditions. We evaluated the proximally evoked soleus H-reflex in response to S1 nerve root stimulation (S1 foramen H-reflex) in SNN.

METHODS

Eleven patients with SNN and 6 with distal sensory axonopathy were studied. Tibial and S1 foramen H-reflexes were performed bilaterally in each patient.

RESULTS

Tibial and S1 foramen H-reflexes were absent bilaterally in all patients with SNN. In the patients with distal sensory axonopathy, tibial H-reflexes were absent in 4 and demonstrated prolonged latencies in 2, but S1 foramen H-reflexes were normal.

CONCLUSIONS

Characteristic absence of the H-reflex after both proximal and distal stimulation reflects primary loss of dorsal root ganglion (DRG) neurons and the distinct non-length-dependent impairment of sensory nerve fibers in SNN.