H reflex and F wave latencies to soleus normal values and side-to-side differences

Significance of EMG and ENMG in the Diagnosis and Treatment of Degenerative-Dystrophic Diseases of the Spine (Literature Review)

The article presents the review of domestic and foreign literature on the use of neurophysiological diagnostic methods – electroneuromyography (ENMG) and electromyography (EMG) in degenerative-dystrophic diseases of the spine. The ENMG method is of great importance for theoretical neurology, obtaining new data on the structural and functional organization of the central and peripheral nervous system in the process of individual development. Electromyography as a diagnostic method studies the electrical activity of the peripheral apparatus of the nervous system. With these methods we directly evaluate both voluntary bioelectric activity of muscles at rest and during their activation (EMG), and caused by stimulation (ENMG). Most authors believe that modifications of stimulation electromyography are objective diagnostic methods that allow to assess the functional state of the peripheral nervous system. Interesting is the fact that changes in EMG and ENMG parameters for osteochondrosis of the spine are recorded even in the absence of external manifestations of the disease. At the same time, for patients with myofascial syndrome in lumbar osteochondrosis, a bilateral decrease in the direct and reflex excitability of motoneurons is characteristic, a slowing down of the pulse along the arc of the H-reflex on the side of the pain and a two-sided local acceleration of the pulse on the distal part of the efferent part of the H-reflex arc from the popliteal pits to soleus muscle. Noteworthy is the fact that the pathological process in the nervous tissue according to ENMG in patients with osteochondrosis of the spine with unilateral radicular syndromes is bilateral. The work of our clinic has shown that diagnostic electroneuromyography can be considered as a medical procedure – electropuncture, according to its results, tactics of both surgical and conservative treatment can be determined. Data of EMG and EMG, carried out after the end of any of the listed types of treatment, serve as an objective control of their effectiveness.

H-reflex and clinical examination in the diagnosis of diabetic polyneuropathy

OBJECTIVES

To determine among adult patients with type-2 diabetes mellitus the proportion diagnosed with diabetic polyneuropathy (DPN) by clinical evaluation and by the Hoffmann reflex (H-reflex). In addition, the predictive value of the H-reflex in the diagnosis of DPN was evaluated.

METHODS

Studies were carried out on 150 adult patients referred for neuropathy screening. Diagnostic criteria for DPN were at least two abnormalities in clinical neurophysiological examinations and electrophysiological testing (H-reflex and nerve conduction velocity). Logistic regression analysis was performed to identify unique contributions of study characteristics to positive versus negative outcomes.

RESULTS

H-reflex was absent in 39.3% (59/150) and latency was prolonged in 43.3% (65/150) of patients. Ulnar nerve motor branch nerve conduction showed prolonged latency in 9.3% (14/150) of patients. Logistic regression analysis indicated that the H-reflex was significantly associated with positive outcomes.

CONCLUSION

The H-reflex could have a predictive value in DPN, providing more quantitative information regarding diagnosis than conventional nerve conduction studies.

The reliability of a method for measuring the anterior cruciate ligament-hamstring reflex: an objective assessment of functional knee instability

Anterior cruciate ligament (ACL) rupture leads to mechanical and functional knee instability. Functional instability is likely attributable to a sensorimotor deficit. In previous studies, a method has been introduced which allows this deficit to be objectively assessed using ACL-hamstring reflex measurements. There is evidence that subjectively stable and unstable patients with ACL rupture can be objectively distinguished by this method. This study on 34 men was conducted to investigate the reliability of this method on the basis of several factors (intra-individual reproducibility, side-to-side differences, inter-examiner reliability, audiovisual stimuli, fatigue, height, weight, physical fitness, and level of activity at work). The role of gender was assessed in 20 men and 20 women. None of the factors had a relevant influence on reflex responses. The tests were reproducible and reliable. The method described here can thus be used for further research and the clinical diagnosis of functional instability following ACL rupture.

Factors influencing F-wave latency detection of lumbosacral root lesions using a detection theory based model

OBJECTIVE

To evaluate the F-wave dilution hypothesis; which implies that absolute F-wave latencies obscure the much smaller delay associated with slow intra-lesion conduction, such is caused by nerve root compression in lumbosacral radiculopathy. A corollary objective is to determine how F-wave measurement and pathological factors influence diagnostic accuracy.

METHODS

An analytical model is developed based on signal detection theory and a number of simplifying assumptions. Diagnostic accuracy, quantified by the area under the receiver operating characteristic (ROC) curve, is determined for various model realizations derived from the clinical and experimental neurophysiology literature. A preliminary experimental validation of model predictions is also performed.

RESULTS

Absolute F-wave latency does not influence the accuracy of focal lesion detection. F-wave latency variance and lesion pathology are the determinant factors. F-wave latencies and distal latencies are estimated to have qualitatively similar detection characteristics, although distal latencies have quantitatively better diagnostic efficacy for comparable focal pathology. Preliminary experimental results support the modeled dependence of diagnostic accuracy on latency variance and lesion severity.

CONCLUSIONS

Absolute F-wave latency does not dilute slow conduction within focal lesions, such as in lumbosacral radiculopathy. The dominant measurement factor is F-wave latency variance.

SIGNIFICANCE

To maximize the diagnostic utility of F-wave latencies, focus must be placed on reducing latency variance, such as through correction for demographic covariates. This model calls into question the F-wave dilution hypothesis.

Effects of age and leg length upon central loop of the gastrocnemius-soleus H-reflex latency

Background

central loop of the gastrocnemius-soleus H-reflex latency (T_c) that looks promising in the diagnosis of S1 radiculopathy; has been investigated in a few studies and only two of them have focused on the constitutional factors affecting it. Although leg length has been shown to contribute to the T_c, the role of age is controversial. More confusing, none of the previously performed studies have used strict criteria to rule out subclinical neuropathy, so the results could be misleading. This study has been performed to determine the influence of leg length and age on T_c among a carefully selected group of healthy volunteers.

Methods

after screening forty six volunteers by taking history, physical examination and a brief electrophysiologic study; forty of them were selected to enroll into the study. T_c was obtained in all the study subjects and leg length and age were recorded for correlational analyses.

Results

this group was consisted of 26 males (65%) and 14 females (35%) with the age range of 19–65 years (Mean ± SD: 37 ± 10.7) and leg length range of 29.5–43 centimeters (36.4 ± 3.4).

Mean ± SD for T_c was 6.78 ± 0.3. We found a significant correlation between T_c and leg length (p value= 0.003, r = 0.49 and confidence interval 95% = 0.59–0.88), no significant correlation was found between age and T_c (p value= 0.48, r = 0.11), also we obtained the regression equation as: T_c = 0.04L + 5.28

Conclusions

in contrast to leg length, age was not correlated with T_c. Future studies are required to delineate other contributing factors to T_c.

An instance of an atypical intraspinal cyst presenting as S1 radiculopathy: a case report and brief review of pathophysiology

Intraspinal cysts are rare, but typically they originate from a degenerate zygapophyseal joint. These cysts have been commonly referred to as juxtafacet cysts and occur concomitantly with lumbar and occasionally lower-limb radicular pain. Documented cases have shown pseudoarthroses developing from nonhealing pars defects. Histologic analyses have found synovial tissue within these fibrocartilaginous accumulations. We present a case of S1 radiculopathy indicated by an intraspinal pseudocyst arising as a complication of a chronic spondylolytic defect. A brief review of the related pathophysiology is also included.