---

Background and Aim: In this study, we investigated : 1) The effect of diferent lengths of Abd. policis brevis muscle on variations EMG frequency spectrum. 2) The effect of muscle contractions on frequency spectrum and 3) The effect of different lengths of muscle on local muscle fatigue.

Material and Method: 20 normal subjects participated in this study. (with range of 20 - 34 years old). Each test carried out in four steps. Every person performed 3 minutes of isometric contraction in Abd. policis brevis muscle and EMG signals were saved for 5 seconds before and after the test. Then the  same procedure was performed while individual did 6 minutes free dynamic contraction and 6 minutes high speed dynamic contraction and 6 minutes forceful dynamic contraction respectively.

Results:This study showed that when the individual performed muscle contraction in short length, median and mean frequency increased (P = % 0) and fatigue test caused a decrease in frequency charactristics that was more in dynamic contractions in compare with isometric contraction (it was more obvious in forceful dynamic contraction). These parameters didn't change in different lengths (P = %9, P = %4, P= %3 for 0 - 45, 0 -90 and 45 - 90 degrees respectively).

Conclusion and discussion:This study showed that different muscle lengths and muscle contractions affect on frequency spectrum and it also showed the effect of different muscle lengths and muscle contractions on local muscle fatigue.

---

Background and aim: The presence of the flexion relaxation phenomenon (FRP) during trunk flexion represents myoelectric  silence consistent with increased load sharing of the posterior discoligamentous passive structures. A number of studies have shown differences in the FRP between patients with chronic low back pain and healthy individuals, Persistent activation of the lumbar erector spinae musculature among patients with back pain may represent the body's attempt to stabilize injured spinal structures via reflexogenic ligamentomuscular activation for protecting them from further injury and avoiding pain.

Materials and methods: Two groups of female subjects ((20 - 40 years old) were participated in this study. First group consisted of 10 subjects with chronic low back pain (CLBP) and second group consisted of 10 healthy ones as control group. Both groups have performed 5 cycles of trunk flexion - extension . The speed of the movement repetition controlled by an electronic metronome . The EMG signals recorded from T12 and L3 paravertebral muscles and bisepse femoris on the right side. The lumbar flexion motion degree has been measured by the digital flexible goniometry.  All subjects have done Sorenson Back Endurance test in prone laying position. The subjects have extended their trunk up to the horizontal position and sustained in this position up to fatigue level .The subjects leave the table and asked to do 5 more cycle of trunk flexion - extension.

Results:  In patients group there is an increment and significant differences in lumbar flexion degree at the time of muscle EMG off  in comparison with healthy subjects after fatigue test (p<0.05). In both groups, the myoelectric silence period showed a significant change with respect to the pre- fatigue (p<0.05). The median frequencies shifted to lower frequencies after fatigue protocol (p<0.05).

Conclusion: Muscle reflexive responses would change following fatigue protocol. Therefore, the muscle activity will increase after the fatigue period. In the other hand, in patient group the role of the muscles as a stabilizer seems to be increased to enhance the stability at the injured segment after fatigue protocol .This protects the segment against pain and disability.

---

Background and Aim: Aphasia is common symptom after acute stroke with a prevalence in earlier studies between 21 - 38% .In Iran unfortunately no investigation has been reported on the prevalence of aphasia .So the main aim of this study was to investigate the frequency of aphasia after stroke at hospitals affiliated to Tehran University of medical sciences (TUMS).

 aterials and Methods: This study is a cross-sectional design and has been done on 30 patients with brain injury who admitted to TUMS hospitals during three months. The Mississippi Aphasia Screening Test (MAST) was used to screening aphasia patients.

Results: The descriptive results indicated, from 22 patients with CVA five cases (22.7%) were aphasic. Mean age of aphasic patients (69.6 years) was more than non-aphasic patients (49.24 years) and of five aphasic patients, three cases (60%) were male and two of them (40%) were female. Also, regarding background diseases, four of five (80%) aphasic patients had history of high blood pressure and diabetes. 

Conclusion: Results of this study was consistent with prevalence of aphasia in last studies. Also results of this study confirmed other studies based on that etiology of lesion, age, and high blood pressure and diabetes history of the patients plays an important role in prevalence of aphasia.

---

Background and Aim: Knee joint injuries are the most common injuries in routine life and stirring sports. The most common injuries in knee joint are meniscus injuries, anterior cruciate ligament rupture and kind of tears of above structures. Diagnosis of meniscus tear is generally clinically and by magnetic resonance imaging (MRI: Magnetic Resonance Imaging). In this study, meniscuc tear was recognized by recorded the knee vibration signals (VAG: Vibroarthrography).

Materials and Methods: Forty subjects (20 normal and 20 abnormal) with meniscus tear were selected and recorded the signals by electrostethoscope, 3 times in 15 sec. Testimonial form was taken from all of participants. 

Results: After recording, the signals were processed and reduced the noise by singular value decomposition algorithm (SVD: Singular Value Decomposition), four parameters of these signals were extracted in energy and frequency domain. These were included energy parameter (EP: Energy Parameter), energy spread parameter (ESP: Energy Spread Prameter), frequency parameter (FP: Frequency Parameter) and frequency spread parameter (FSP: Frequency Spread Parameter). Mean and standard deviation of each feature were considered and analyzed eight features of the signals. Statistical analyzes showed the P-Value less than 0.05 ( ) for each feature. Three methods for data classification were used. ) Mean and standard deviation of the parameters were obtained as below: Multi Layer Perceptron (MLP: Multi Layer Perceptron), Support Vector Machine (SVM: Support Vector Machine) and K- Nearest Neighbor (KNN: K-Nearest Neighbor) with ( ), ( ) and ( . K-nearest neighbor method (K=5) has the highest percentage of accuracy.

Conclusion: Knee signals processing (VAG signals) is a suitable and non-invasive method for diagnosis of meniscus tear which can save the time and reduce the costs.

Keywords: Articular pathology, Meniscus tear, VAG signals, Singular Value Decomposition (SVD), Time- frequency distribution.