Temporary Occlusion of Common Carotid Arteries Does Not Evoke Total Inhibition in the Activity of Corticospinal Tract Neurons in Experimental Conditions.

Temporary occlusion of the common cervical artery is the reason for ischemic stroke in 25% of patients. Little data is provided on its effects, especially regarding neurophysiological studies verifying the neural efferent transmission within fibers of the corticospinal tract in experimental conditions. Studies were performed on 42 male Wistar rats. In 10 rats, ischemic stroke was evoked by permanent occlusion of the right carotid artery (group A); in 11 rats, by its permanent bilateral occlusion (B); in 10 rats, by unilateral occlusion and releasing after 5 min (C); and in 11 rats, by bilateral occlusion and releasing after 5 min (D). Efferent transmission of the corticospinal tract was verified by motor evoked potential (MEP) recordings from the sciatic nerve after transcranial magnetic stimulation. MEPs amplitude and latency parameters, oral measurements of temperature, and verification of ischemic effects in brain slides stained with hematoxylin and eosin staining (H + E) were analyzed. In all groups of animals, the results showed that five minutes of uni- or bilateral occlusion of the common carotid artery led to alterations in brain blood circulation and evoked changes in MEP amplitude (by 23.2% on average) and latency parameters (by 0.7 ms on average), reflecting the partial inability of tract fibers to transmit neural impulses. These abnormalities were associated with a significant drop in the body temperature by 1.5 °C on average. Ten minutes occlusion in animals from groups A and B resulted in an MEP amplitude decrease by 41.6%, latency increase by 0.9 ms, and temperature decrease by 2.9 °C of the initial value. In animals from groups C and D, five minutes of recovery of arterial blood flow evoked stabilization of the MEP amplitude by 23.4%, latency by 0.5 ms, and temperature by 0.8 °C of the initial value. In histological studies, the results showed that ischemia was most prominent bilaterally in sensory and motor areas, mainly for the forelimb, rather than the hindlimb, innervation of the cortex, putamen and caudate nuclei, globulus pallidus, and areas adjacent to the fornix of the third ventricle. We found that the MEP amplitude parameter is more sensitive than the latency and temperature variability in monitoring the ischemia effects course following common carotid artery infarction, although all parameters are correlated with each other. Temporary five-minute lasting occlusion of common carotid arteries does not evoke total and permanent inhibition in the activity of corticospinal tract neurons in experimental conditions. The symptoms of rat brain infarction are much more optimistic than those described in patients after stroke, and require further comparison with the clinical observations.

Neurophysiological Evaluation of Neural Transmission in Brachial Plexus Motor Fibers with the Use of Magnetic versus Electrical Stimuli.

The anatomical complexity of brachial plexus injury requires specialized in-depth diagnostics. The clinical examination should include clinical neurophysiology tests, especially with reference to the proximal part, with innovative devices used as sources of precise functional diagnostics. However, the principles and clinical usefulness of this technique are not fully described. The aim of this study was to reinvestigate the clinical usefulness of motor evoked potential (MEP) induced by a magnetic field applied over the vertebrae and at Erb's point to assess the neural transmission of brachial plexus motor fibers. Seventy-five volunteer subjects were randomly chosen to participate in the research. The clinical studies included an evaluation of the upper extremity sensory perception in dermatomes C5-C8 based on von Frey's tactile monofilament method, and proximal and distal muscle strength by Lovett's scale. Finally, 42 healthy people met the inclusion criteria. Magnetic and electrical stimuli were applied to assess the motor function of the peripheral nerves of the upper extremity and magnetic stimulus was applied to study the neural transmission from the C5-C8 spinal roots. The parameters of compound muscle action potential (CMAP) recorded during electroneurography and MEP induced by magnetic stimulation were analyzed. Because the conduction parameters for the groups of women and men were comparable, the final statistical analysis covered 84 tests. The parameters of the potentials generated by electrical stimulus were comparable to those of the potentials induced by magnetic impulse at Erb's point. The amplitude of the CMAP was significantly higher following electrical stimulation than that of the MEP following magnetic stimulation for all the examined nerves, in the range of 3-7%. The differences in the potential latency values evaluated in CMAP and MEP did not exceed 5%. The results show a significantly higher amplitude of potentials after stimulation of the cervical roots compared to potentials evoked at Erb's point (C5, C6 level). At the C8 level, the amplitude was lower than the potentials evoked at Erb's point, varying in the range of 9-16%. We conclude that magnetic field stimulation enables the recording of the supramaximal potential, similar to that evoked by an electric impulse, which is a novel result. Both types of excitation can be used interchangeably during an examination, which is essential for clinical application. Magnetic stimulation was painless in comparison with electrical stimulation according to the results of a pain visual analog scale (3 vs. 5.5 on average). MEP studies with advanced sensor technology allow evaluation of the proximal part of the peripheral motor pathway (between the cervical root level and Erb's point, and via trunks of the brachial plexus to the target muscles) following the application of stimulus over the vertebrae.

Muscle Activity Detectors-Surface Electromyography in the Evaluation of Abductor Hallucis Muscle.

Despite the high availability of surface electromyography (sEMG), it is not widely used for testing the effectiveness of exercises that activate intrinsic muscles of foot in people with hallux valgus. The aim of this study was to assess the effect of the toe-spread-out (TSO) exercise on the outcomes of sEMG recorded from the abductor hallucis muscle (AbdH). An additional objective was the assessment of nerve conduction in electroneurography. The study involved 21 patients with a diagnosed hallux valgus (research group A) and 20 people without the deformation (research group B) who performed a TSO exercise and were examined twice: before and after therapy. The statistical analysis showed significant differences in the third, most important phase of TSO. After the exercises, the frequency of motor units recruitment increased in both groups. There were no significant differences in electroneurography outcomes between the two examinations in both research groups. The TSO exercise helps in the better activation of the AbdH muscle and contributes to the recruitment of a larger number of motor units of this muscle. The TSO exercises did not cause changes in nerve conduction. The sEMG and ENG are good methods for assessing this exercise but a comprehensive assessment should include other tests as well.

Standard neurophysiological studies and motor evoked potentials in evaluation of traumatic brachial plexus injuries - A brief review of the literature.

PURPOSE: Traumatic damage to the brachial plexus is associated with temporary or permanent motor and sensory dysfunction of the upper extremity. It may lead to the severe disability of the patient, often excluded from the daily life activity. The pathomechanism of brachial plexus injury usually results from damage detected in structures taking origin in the rupture, stretching or cervical roots avulsion from the spinal cord. Often the complexity of traumatic brachial plexus injury requires a multidisciplinary diagnostic process including clinical evaluation supplemented with clinical neurophysiology methods assessing the functional state of its structures. Their presentation is the primary goal of this paper. METHODS: The basis for the diagnosis of brachial plexus function is a clinical examination and neurophysiology studies: electroneurography (ENG), needle electromyography (EMG), somatosensory evoked potentials (SEPs) and motor evoked potentials (MEPs) assessing the function of individual brachial plexus elements. CONCLUSIONS: The ENG and EMG studies clarify the level of brachial plexus damage, its type and severity, mainly using the Seddon clinical classification. In contrast to F-wave studies, the use of the MEPs in the evaluation of traumatic brachial plexus injury provides valuable information about the function of its proximal part. MEPs study may be an additional diagnostic in confirming the location and extent of the lesion, considering the pathomechanism of the damage. Clinical neurophysiology studies are the basis for determining the appropriate therapeutic program, including choice of conservative or reconstructive surgery which results are verified in prospective studies.

The study of surface electromyography used for the assessment of abductor hallucis muscle activity in patients with hallux valgus.

BACKGROUND: Hallux valgus is a common foot disorder. In patients with hallux valgus, the anatomy and biomechanics of foot is subject to alterations. OBJECTIVE: The aim of this clinical and neurophysiological study is to compare the activity of abductor hallucis (AbdH) muscle between the group of patients with hallux valgus and control group of healthy people, with the use of surface electromyography. METHODS: The study involved 44 feet with diagnosed hallux valgus (research group) and 42 feet without deformation (control group). The X-ray images, measurements of range of motion in the first metatarsophalangeal joint and in hallux interphalangeal joint, and the surface electromyography study recorded from AbdH muscle were performed. RESULTS: Considering the amplitude of motor unit action potential, study participants with hallux valgus demonstrate significantly less activity of AbdH muscle than people without hallux valgus deformity. This activity is not dependent on the severity of valgus, age, or range of motion. CONCLUSIONS: It is speculated that the changes of the AbdH function may occur in the period before clinical appearance of hallux valgus deformity, or at the onset of distortion development. Further studies are needed for a comprehensive assessment of AbdH muscle in patients with hallux valgus.

Relations between the results of complex clinical and neurophysiological examinations in patients with temporomandibular disorders symptoms.

OBJECTIVE: Reinvestigation of clinical importance of surface electromyography recordings (sEMG) from the masticatory, neck and shoulder girdle muscles in patients with various clinically detected temporomandibular disorders (TMDs). METHODS: Fifty women with myalgia diagnosis of Axis I DC/TMD and the same number of healthy female volunteers were studied clinically and neurophysiologically by means of sEMG. RESULTS: Unilateral more than bilateral complex symptoms of TMDs were related to the non-neurogenic masticatory rather than neck and shoulder girdle muscles dysfunctions at rest. A strong negative correlation between masticatory muscles activity at rest and during maximal contraction was found (rs = -0.778), mainly in the masseter muscle. CONCLUSION: sEMG is a suitable tool for prosthodontists because it provides objective results on the stomatognathic system muscles function. Pain and other temporomandibular symptoms detected mostly unilaterally significantly increase muscle tension of the masticatory muscles and diminish muscle motor units recruitment during maximal contraction. Effects may spread to the neck and shoulder girdle muscles.

Clinical and neurophysiological evaluation of persistent sensory disturbances in breast cancer women after mastectomy with or without radiotherapy.

PURPOSE: Breast cancer surgery or radiotherapy (RT) are potential causes of persistent pain syndrome. It remains to be clarified whether numbness or pain reported by patients after mastectomy and RT are conditioned by changes in nerve transmission. The aim of this study was to examine the potential relationship between subjective sensory complications and neurophysiological examinations in breast cancer survivors with post-mastectomy pain syndrome. METHODS: Sixty breast cancer survivors (30 patients only after mastectomy - group A; and 30 after mastectomy with RT - group B) complaining of pain and sensory disturbances in the brachial plexus area and 20 healthy women (group C) were studied with regard to sensory perception and pain intensity using the Visual Analogue Scale and electroneurography (ENG). RESULTS: There was a statistically significant decrease in the amplitudes in SCV recordings following stimulation of the ulnar (p = 0.04) and lateral cutaneous antebrachii nerves (p = 0.02) in group B in comparison to group C. Additionally, a significant decrease in the amplitude and conduction velocity parameters was detected in the sensory fibers of the median and medial cutaneous antebrachii nerves in group A (p = 0.00 and p = 0.02, respectively) in comparison to group C. CONCLUSIONS: The results of this pilot study suggest persistent post-mastectomy pain syndrome sometimes appears as a result of nerve injury in course of breast cancer surgery and RT. Therefore studies in nerve conduction may be added to the comprehensive patient assessment used in planning breast cancer patients' rehabilitation after oncological treatment has finished.

Saphenous vein stripping surgical technique and frequency of saphenous nerve injury.

OBJECTIVES: Saphenous nerve injury is the most common complication after surgical treatment of varicose veins. The aim of this study was to establish its frequency at great saphenous vein long stripping when four methods of surgery were applied. METHODS: Eighty patients were divided into four groups depending on different stripping methods. Sensory transmission in saphenous nerve and sensory perception of shank were examined before surgery and two weeks, three and six months afterwards with clinical neurophysiology methods. RESULTS: In 36% of patients, surgeries caused the injury of saphenous nerve mainly by proximal stripping without invagination (65%, group I). Transmission disturbances ceased completely after three months in patients undergoing distal stripping with invagination (group IV), while in group I they persisted for six months in 35%. Group IV patients were the least injured and group I the most. CONCLUSION: Neurophysiological findings may suggest that distal stripping with vein invagination gives the best saphenous nerve sparing.

Correlations between the clinical, histological and neurophysiological examinations in patients before and after parotid gland tumor surgery: verification of facial nerve transmission.

Parotid gland tumor surgery sometimes leads to facial nerve paralysis. Malignant more than benign tumors determine nerve function preoperatively, while postoperative observations based on clinical, histological and neurophysiological studies have not been reported in detail. The aims of this pilot study were evaluation and correlations of histological properties of tumor (its size and location) and clinical and neurophysiological assessment of facial nerve function pre- and post-operatively (1 and 6 months). Comparative studies included 17 patients with benign (n = 13) and malignant (n = 4) tumors. Clinical assessment was based on House-Brackmann scale (H-B), neurophysiological diagnostics included facial electroneurography [ENG, compound muscle action potential (CMAP)], mimetic muscle electromyography (EMG) and blink-reflex examinations (BR). Mainly grade I of H-B was recorded both pre- (n = 13) and post-operatively (n = 12) in patients with small (1.5-2.4 cm) benign tumors located in superficial lobes. Patients with medium size (2.5-3.4 cm) malignant tumors in both lobes were scored at grade I (n = 2) and III (n = 2) pre- and mainly VI (n = 4) post-operatively. CMAP amplitudes after stimulation of mandibular marginal branch were reduced at about 25 % in patients with benign tumors after surgery. In the cases of malignant tumors CMAPs were not recorded following stimulation of any branch. A similar trend was found for BR results. H-B and ENG results revealed positive correlations between the type of tumor and surgery with facial nerve function. Neurophysiological studies detected clinically silent facial nerve neuropathy of mandibular marginal branch in postoperative period. Needle EMG, ENG and BR examinations allow for the evaluation of face muscles reinnervation and facial nerve regeneration.

Pre- and postoperative evaluation of patients with lumbosacral disc herniation by neurophysiological and clinical assessment.

STUDY DESIGN: The application of complex neurophysiological examination including motor evoked potentials (MEP) for pre- and postoperative evaluation of patients experiencing acute sciatica. OBJECTIVE: The assessment of sensitivity and specificity of needle electromyography, MEP, and H-reflex examinations. The comparative analysis of preoperative and postoperative neurophysiological examination. SUMMARY OF BACKGROUND DATA: In spite of the fact that complex neurophysiological diagnostic tools seem to be important for interpretation of incompatible results of neuroimaging and clinical examination, especially in the patients qualified for surgical treatment, their application has never been completely analyzed and documented. METHODS: Pre- and postoperative electromyography, electroneurography, F-waves, H-reflex, and MEP examination were performed in 23 patients with confirmed disc-root conflict at lumbosacral spine. Clinical evaluation included examination of sensory perception for L5-S1 dermatomes, muscles strength with Lovett's scale, deep tendon reflexes, pain intensity with visual analogue scale, and straight leg raising test. RESULTS: Sensitivity of electromyography at rest and MEP examination for evaluation of L5-S1 roots injury was 22% to 63% and 31% to 56% whereas specificity was 71% to 83% and 57% to 86%, respectively. H-reflex sensitivity and specificity for evaluation of S1 root injury were 56% and 67%, respectively. A significant improvement of root latency parameter in postoperative MEP studies as compared with preoperative was recorded for L5 (P = 0.039) and S1 root's levels (P = 0.05). CONCLUSION: The analysis of the results from neurophysiological tests together with neuroimaging and clinical examination allow for a precise preoperative indication of the lumbosacral roots injury and accurate postoperative evaluation of patients experiencing sciatica. LEVEL OF EVIDENCE: 3.

[Intraoperative facial nerve monitoring for parotid gland surgery]. / Sródoperacyjne monitorowanie czynnosci nerwu twarzowego w chirurgii slinianki przyusznej.

INTRODUCTION: The route of the facial nerve in its extracranial part determines the technique of parotid gland surgery. Permanent facial nerve paralysis after parotidectomy is not rare. It is the most devastating complication for the patient and surgeon. Facial nerve monitoring by observing or palpating the face during the surgery is a long-standing practice. Using an EMG device is a standard procedure at present. AIM OF THE STUDY: Evaluation of the effectiveness of intraoperative facial nerve monitoring for parotid gland surgery. MATERIAL AND METHODS: Fifty three patients operated on due to parotid gland tumour in the Head and Neck Surgery and Laryngological Oncology Department of the Greater Poland Cancer Center in 2007-2008. All patients had been provided with EMG and ENG examinations of the facial nerve before the surgery and continuous facial nerve monitoring during the operation. Facial nerve function after surgery was assessed according to the House-Brackmann grading system. RESULTS: Six (12%) patients presented facial nerve dysfunction after surgery. Three (6%) patients had temporary paralysis grade III H-B with complete recovery in 6 weeks. Three (6%) patients with deep lobe tumour had grade V H-B with complete recovery in one patient after 3 months, and two (4%) patients had grade III H-B after one year since the surgery. CONCLUSIONS: Intraoperative facial nerve monitoring should be a standard procedure during parotid gland surgery in most clinical situations.