Safak Sahir Karamehmetoglu

Whole-body vibration-induced muscular reflex: Is it a stretch-induced reflex?

[Purpose] Whole-body vibration (WBV) can induce reflex responses in muscles. A number of studies have reported that the physiological mechanisms underlying this type of reflex activity can be explained by reference to a stretch-induced reflex. Thus, the primary objective of this study was to test whether the WBV-induced muscular reflex (WBV-IMR) can be explained as a stretch-induced reflex. [Subjects and Methods] The present study assessed 20 healthy males using surface electrodes placed on their right soleus muscle. The latency of the tendon reflex (T-reflex) as a stretch-induced reflex was compared with the reflex latency of the WBV-IMR. In addition, simulations were performed at 25, 30, 35, 40, 45, and 50 Hz to determine the stretch frequency of the muscle during WBV. [Results] WBV-IMR latency (40.5 ± 0.8 ms; 95% confidence interval [CI]: 39.0–41.9 ms) was significantly longer than T-reflex latency (34.6 ± 0.5 ms; 95% CI: 33.6–35.5 ms) and the mean difference was 6.2 ms (95% CI of the difference: 4.7–7.7 ms). The simulations performed in the present study demonstrated that the frequency of the stretch signal would be twice the frequency of the vibration. [Conclusion] These findings do not support the notion that WBV-IMR can be explained by reference to a stretch-induced reflex.

A quantitative skin impedance test to diagnose spinal cord injury

The purpose of this study was to develop a quantitative skin impedance test that could be used to diagnose spinal cord injury (SCI) if any, especially in unconscious and/or non-cooperative SCI patients. To achieve this goal, initially skin impedance of the sensory key points of the dermatomes (between C3 and S1 bilaterally) was measured in 15 traumatic SCI patients (13 paraplegics and 2 tetraplegics) and 15 control subjects. In order to classify impedance values and to observe whether there would be a significant difference between patient and subject impedances, an artificial neural network (ANN) with back-propagation algorithm was employed. Validation results of the ANN showed promising performance. It could classify traumatic SCI patients with a success rate of 73%. By assessing the experimental protocols and the validation results, the proposed method seemed to be a simple, objective, quantitative, non-invasive and non-expensive way of assessing SCI in such patients.

Vibration parameters affecting vibration-induced reflex muscle activity

Abstract Purpose: To determine vibration parameters affecting the amplitude of the reflex activity of soleus muscle during low-amplitude whole-body vibration (WBV). Materials and methods: This study was conducted on 19 participants. Vibration frequencies of 25, 30, 35, 40, 45, and 50 Hz were used. Surface electromyography, collision force between vibration platform and participant’s heel measured using a force sensor, and acceleration measured using an accelerometer fixed to the vibration platform were simultaneously recorded. Results: The collision force was the main independent predictor of electromyographic amplitude. Conclusion: The essential parameter of vibration affecting the amplitude of the reflex muscle activity is the collision force.

Alteration of Facet Joint Orientation and Asymmetry With Time in Lumbar Disc Herniation

In the previous studies, the facet tropism and its relation to the development of lumbar disc herniation (LDH) were investigated. However, these studies have shown inconsistent conclusions. The aim of this study was to investigate the alteration of facet joint angle and (a)symmetry in LDH. Fifty-four patients with LDH were included. In the first and second computed tomography images, all facet angles were measured from the similar axial slice by the same observer who was blinded with regard to the date of computed tomography scan. Total reproducibility of the variability was found to be ±1.85 degrees. Thirty-one patients had a change in the orientation of at least 1 facet joint. The mean rate of the change in the facet orientation varied from 2.69 to 3.63 degree/y. The most common observed change in the orientation was sagittalization. Females, taller patients, cases with median herniation, and patients with longer course of LDH had a higher risk of this change (P=0.011). The facet asymmetry was found to develop in 7 patients and to recover in 7 patients (P=0.002). The facet orientation could change and the facet asymmetry could develop or recover in the same patient with time in LDH. These results could explain contradictory results in the literature.

Use of Sildenafil in the Treatment of Erectile Dysfunction in Patients With Spinal Cord Injury

Erectile dysfunction (ED) is one of the major complications after spinal cord injury (SCI) that decreases the quality of life of the patients. Although many efforts have been made to decrease ED, they are frequently cumbersome, with a high failure rate. The aim of this study was to assess the effects of sildenafil citrate at several doses, an oral agent that has been shown to improve a broad spectrum of ED. Sixty male patients with SCI were divided into 2 groups and received 25 mg or 50 mg sildenafil citrate, respectively, during a 4-week treatment period 1 hour before sexual intercourse. Our results demonstrated that sildenafil citrate significantly improved reflexogenic erectile response in both groups (P=0.02 and P=0.01, respectively). Subjects receiving sildenafil citrate reported that treatment had significantly improved their erections, frequency of sexual intercourse, satisfaction, enjoyment, sexual desire, overall sex life, sexual relationship, and self-confidence in erections (P<0.05). There was no statistically significant difference between 2 groups regarding the dosage regimen (P>0.05). The authors concluded that sildenafil citrate might be used effectively for the treatment of ED in patients with SCI, even in a low-dose (25 mg) regimen.

Comparison of the Data Classification Approaches to Diagnose Spinal Cord Injury

In our previous study, we have demonstrated that analyzing the skin impedances measured along the key points of the dermatomes might be a useful supplementary technique to enhance the diagnosis of spinal cord injury (SCI), especially for unconscious and noncooperative patients. Initially, in order to distinguish between the skin impedances of control group and patients, artificial neural networks (ANNs) were used as the main data classification approach. However, in the present study, we have proposed two more data classification approaches, that is, support vector machine (SVM) and hierarchical cluster tree analysis (HCTA), which improved the classification rate and also the overall performance. A comparison of the performance of these three methods in classifying traumatic SCI patients and controls was presented. The classification results indicated that dendrogram analysis based on HCTA algorithm and SVM achieved higher recognition accuracies compared to ANN. HCTA and SVM algorithms improved the classification rate and also the overall performance of SCI diagnosis.