Murat Pehlivan

Electrodiagnostic methods for neurogenic dysphagia

OBJECTIVE Swallowing mechanisms and neurogenic dysphagia have not been systematically studied by the EMG technique. It is desirable to evaluate neurogenic dysphagia for diagnostic and possibly for therapeutic purposes using electrophysiological methods. METHODS The following methods were described: mechanical upward/downward movements of the larynx were detected using a piezoelectric sensor, while submental integrated EMG activity was recorded during dry and wet swallowing. The EMG activity of cricopharyngeal muscle of the upper oesophageal sphincter was also recorded in some normal subjects and patients. Piecemeal deglutition and the dysphagia limit were determined in all patients to detect dysphagia objectively. In this study 75 normal subjects and 177 neurological patients with various degrees of dysphagia were investigated. RESULTS Voluntarily triggered oropharyngeal swallowing was commonly pathological in the majority of patients, with or without overt dysphagia. The dysphagia limit appeared to be an objective measure of the degree of dysphagia in more than 90% of patients. Pathophysiological mechanisms were different in at least three groups of patients with neurogenic dysphagia. In the group of patients with muscular disorders, laryngeal elevators were involved while the CP-sphincter was intact. The second group included patients with the clinical signs of corticobulbar fibre involvement such as amyotrophic lateral sclerosis and pseudobulbar palsy. In these patients, there was incoordination between paretic laryngeal elevators and hyperreflexic CP-sphincter. In the third group (patients with Parkinsons disease), the swallowing reflex was delayed and prolonged. CONCLUSIONS EMG methods described in the present study are very useful for the diagnosis of neurogenic dysphagia, objectively and quickly. They are important to understand the physiological mechanisms for deglutition and its disorders.

The Ege Stroke Registry: A Hospital-Based Study in the Aegean Region, Izmir, Turkey

We present the profile of risk factors, etiologic and clinical data of 2,000 consecutive patients with first-ever-in-a-lifetime stroke (cerebral infarction, cerebral hemorrhage and subarachnoid hemorrhage), admitted to the Ege University Hospital between January 1, 1991, and September 31, 1995. This hospital-based registry is the first systematic epidemiologic report on the stroke profile of Turkish people. The Ege University Stroke Unit is the only tertiary medical care facility which is organized for patients with different stroke subtypes in İzmir, Turkey. A prospective hospital-based registry using systematic computer coding of data of all stroke patients has been used since January 1991. All patients were evaluated by clinical examination, CT and/or MRI, color duplex and specific cardiac investigations. They were followed up for at least 6 months. The mean age was 62.3 ± 12 years, and 44.4% were females. Ischemic stroke was found in 77%, primary intracerebral hemorrhage in 19% and subarachnoid hemorrhage in 4%. The major risk factor of ischemic stroke was hypertension (63%), followed by hypercholesterolemia (37%), diabetes mellitus (35%), ischemic heart disease (23%), atrial fibrillation (20%) and smoking (17%). The main cause of primary intracerebral hemorrhage was hypertension (88%), and the principal localization was the thalamus (38%), followed by putamen (28%), lobar (16%), pons (6%), cerebellar (4%), primary intraventricular hemorrhage (4%) and multiple hemorrhages (2%). The overall 30-day case-fatality rate was 19.7% and the higher mortality rate was found in patients with primary intracerebral hemorrhage (29%) than in those with ischemic stroke (17%). The Ege Stroke Registry allows to estimate the stroke-related problems in patients admitted to a stroke unit and to evaluate the risk factors, etiology and clinical manifestations of stroke in Turkey.

An Electronic Device Measuring the Frequency of Spontaneous Swallowing: Digital Phagometer

A new and protable electronic device called the “Digital Phagometer” is described for the time-based counting of spontaneous swallowing. This device is composed of a piezoelectric sensor and a digital event counter/recorder which can be downloaded to any IBM-compatible PC. The sensor of Digital Phagometer is placed and fixed on the coniotomy region between the cricoid and thyroid cartilage. In this way, it is capable of sensing each upward and downward movement of the larynx produced by spontaneous movement as a function of time. Spontaneous swallowing was measured 1–4 h after lunch in 21 normal subjects and 21 patients with Parkinsons disease (PD). The mean frequency of spontaneous swallowing was 0.8 counts/min in PD patients and 1.18 counts/min in normal subjects (p<0.05). During the intake of 200 ml water, the mean frequency of voluntary swallowing did not differ significantly between the two groups (24.6 counts/min in normals vs. 22.3 counts/min in PD patients), but the time necessary to swallow the same volume of water was longer in the PD group.

Assessment of effects of pinealectomy and exogenous melatonin administration on rat sciatic nerve suture repair: an electrophysiological, electron microscopic, and immunohistochemical study

SummaryBackground. Collagen scar formation at the cut end of a nerve, an important problem in clinical practice for neurosurgeons in peripheral nerve surgery, obstructs sprouting of axons into appropriate distal fascicles, and thereby limits nerve regeneration. Researchers attempt to control collagen accumulation in the formation of neuroma by various physical and chemical methods, but these have yielded only limited functional success. This is the first experimental study investigating the effects of melatonin (MLT) on nerve repair and neuronal regeneration in rat sciatic nerve suture repair.Methods. The hypothesis that exogenous MLT administration may inhibit the formation of neuroma in peripheral nerve surgery was investigated in rat sciatic nerve model. In this study, a total of 80 rats were used for control groups (Groups Ia, Ib, IIa, and IId), MLT group (Group Ic), surgical pinealectomy (Px) groups (Groups IIb and IIc), and group of MLT treatment following Px procedure (Group IIe). All animals underwent a surgical intervention consisting of bilateral sciatic nerve section and primary suture repair. At 8 weeks after repair, the animals were killed following completion of recording of nerve action potentials (NAPs). Then, unilateral sciatic nerve specimens including the suture repair region were carefully removed and the excised segments were processed for electron microscopy examination. Afterwards, contralateral sciatic nerve specimens from two animals from each group were removed and stained for immunohistochemical analysis.Results. Results of morphometric analysis revealed that Px procedure caused an elevation of collagen content of the sciatic nerve and macroscopic neuroma formation, and that there was a statistically significant reduction in collagen content of the same region in pinealectomized animals treated with MLT (p<0.001). Accordingly, electrophysiological findings demonstrated that the stimulus intensities required to excite a NAP response were increased in surgical Px group, but the presence of a reduced threshold response was found in the group treated with MLT following Px procedure (p<0.01). Immunohistochemical staining for Type I collagen and Type III collagen was markedly more intense in the epineurium of animals after Px. Virtually no or only weak staining was observed in animals in control groups and the MLT treatment group. Results of immunohistochemical analysis revealed that surgical Px procedure caused a strong immunoreactivity for Type I collagen and Type III collagen in all connective tissue planes of the nerve, especially in the epineurium, and there was a statistically significant reduction in immunoreactivity of the repair region in animals receiving MLT treatment after Px procedure (p<0.001).Conclusion. This study demonstrates that exogenous MLT administration significantly inhibits collagen accumulation in the formation of neuroma in the suture repair site and thereby improves nerve regeneration. From a clinical standpoint, the positive effect of MLT administration on neuroma formation and nerve regeneration seems a particularly attractive treatment option. Therefore, we believe that nerve repair with addition of MLT may be a worthwhile option in addition to other treatment modalities in case of MLT deficiency, such as aging. However, further experimental and clinical studies using functional analysis warranted to confirm this result in future.

Nonlinear analysis of heart rate variability

This article reports nonlinear analysis of ECG R-R interval time-series obtained from healthy individuals and some cardiac patients. The R-R interval time-series data from 6 healthy individuals and 3 cardiac patients were transformed into multidimensional phase-space vectors by time-delay embedding. The largest Lyapunov exponent and correlation dimension (CD) were calculated. Nonlinearity was tested by comparing the CDs obtained from the original data with those obtained from surrogate data sets. Results are discussed with reference to results obtained in previous studies.

Effects of sibutramine on thermogenesis in obese patients assessed via immersion calorimetry

Glucose utilization studies show that sibutramine-induced thermogenesis is mediated via selective sympathetic activation of brown adipose tissue. The goal of the present study was to use a new calorimetry method in which resting metabolic rate is enhanced to evaluate the effects of sibutramine treatment on thermogenesis. Sixty obese women were included in the study. Subjects were divided into 2 equal groups-the placebo and sibutramine treatment groups. The sibutramine group was given sibutramine 10 mg daily for 12 wk. At baseline and at the end of the 12-wk treatment period, thermogenic measurements were taken with the use of water immersion calorimetry. Subjects were examined at weeks 4, 8, and 12 of treatment to identify adverse effects. Body mass index, measured at 31.5±2.05 kg/m2 in the placebo group, decreased to 30.4±2.94 kg/m2 after 12 wk (P=.07). In the sibutramine group, it decreased from 33.5±4.1 kg/m2 to 30.9±4.8 kg/m2 (P < .05). In the sibutramine group, mean thermogenic response changed from a baseline value of 1.27±0.29 kcal/kg/h to 1.44±0.13 kcal/kg/h after 12 wk of treatment. In the placebo group, the baseline value was 1.56±0.27 kcal/kg/h; it changed to 1.33±0.36 kcal/kg/h at the end of 12 wk. The findings of this study suggest that sibutramine treatment promotes thermogenesis, thus facilitating weight loss. Calorimetry enhances resting metabolism through more efficient heat transfer from the body.

Responses of human soleus motor units to low-threshold stimulation of the tibial nerve

The peristimulus frequencygram (PSF) has recently been shown to illustrate postsynaptic potentials of motoneurones much more reliably than the peristimulus time histogram (PSTH). The aim of this investigation was to examine the profile of the postsynaptic potential (PSP) in soleus motoneurones in response to an H-reflex with and without accompanying M waves of different magnitude by using PSTH and PSF profiles of single motor units. Nine men and five women healthy subjects participated in this study. Electrical stimuli were delivered to the tibial nerve in the popliteal fossa. The reflex response of the soleus muscle was recorded using both surface electromyogram and single motor unit potentials. The PSTH analysis demonstrated that there were four different synaptic events following low-intensity stimulation of the tibial nerve: primary enhancement in firing probability (H-reflex or E1), primary reduction in firing probability (primary silent period or SP1), secondary reduction in firing probability (secondary silent period or SP2), and secondary enhancement in firing probability (E2). On the other hand, the PSF analysis indicated only two reflex responses, long-lasting enhancement in discharge rate including the H-reflex (LLE) and long-lasting decrease in discharge rate (LLD). The results of the two analyses methods are compared and contrasted. While the PSTH demonstrated that there was a silent period (SP1) immediately following the H-reflex, the PSF indicated an increase in discharge rate during the same period. The PSF also indicated that, during SP2 and E2, the discharge rate actually decreased (LLD). It was therefore suggested that LLD involved activation of several inhibitory pathways including the autogenic inhibition of units via the Golgi tendon organs. It was concluded that the PSF could indicate the details of the postsynaptic potentials and is very useful for bringing out previously unknown effects of electrical stimulation of muscle nerves.

The comparison of therapeutic effects of atropine and pralidoxime on cardiac signs in rats with experimental organophosphate poisoning

Organophosphate poisoning causes disturbances in cardiac conduction and potentially fatal severe cardiac rhythm abnormalities. This study investigated the cardiac effects of atropine and pralidoxime in the treatment of organophosphate poisoning in rats. Three groups of 10 adult male Wistar rats were anesthetized with an intraperitoneal injection of ketamine 100 mg/kg and xylazine 10mg/kg and connected to a computerized electrocardiographic monitor. Each rat was then injected intraperitoneally with the pesticide dichlorvos 70 mg/kg. Sixty seconds after the injection, 10 rats were injected with saline, 10 with pralidoxime mesylate 20 mg/kg, and 10 with atropine 10 mg/kg. During the computerized electrocardiographic monitoring, each rat’s heart rate and QTc intervals were recorded and analyzed as the injections were administered. The heart rates in all 3 groups did not differ before the dichlorvos was administered, nor at 60 seconds afterward, but in the atropine group, the time elapsed before the first decline in heart rate was significantly longer than that in the control group (P< .05). In addition, the interval before death was significantly longer in the atropine group than in either the control group or the pralidoxime group (P< .05 for both). The QTc was almost identical in each of the groups. Atropine has beneficial effects on the heart rate, prolongs the time before the heart rate declines, and delays death but has no effect on the QTc interval. Further research about the toxic effects of organophosphate compounds on myocardial cells is warranted.

Analysis of the corneal reflex with air puff: normal controls and patient groups.

Though there are several reports published about the corneal reflex elicited by different methods, a standardized electrophysiologic study with air puff in man has not been published. The aim of this study is to standardize the corneal reflex elicited by air puff to cornea. The authors studied the corneal reflex with air puff and direct touch by using a standardized method in patients with thalamic hemorrhage (n = 15), hemispheric infarction (n = 9), brainstem infarction (n = 9), multiple sclerosis (n = 12), and Bells palsy (n = 12) and in normal control subjects (n = 21). The conventional blink reflex (BR) was also studied. The reflex responses were recorded from both orbicularis oculi muscles by air puff and direct touch to cornea in addition to the electrical stimulation of the supraorbital nerve. No statistical difference could be detected between the responses elicited by air puff or direct touch to cornea (P > 0.05). Corneal reflex responses were statistically different from the R2 response of the BR (P < 0.005). Because the responses elicited by direct touch and air puff to cornea are identical, air puff to cornea can be used confidently to study the corneal reflex.

Effect of tibial tubercle elevation on patellofemoral compressive force in patellofemoral arthrosis.

Abstract In this study, the effect of tibial tubercle elevation on the patellofemoral compressive force (PFCF) was investigated in patients with patellofemoral arthrosis. Fifteen (11 women and 4 men) patients who had undergone tibial tubercle elevation were included in the study. The average follow-up was 4.5 years. The mean age of the patients was 59 years (range 34–71 years). They were able to maintain a normal pain-free daily life. Maximal isometric quadriceps force (Q) was calculated by equating the moment generated by this force to the moment of the force measured at the ankle by a modified hand dynamometer. PFCF was calculated from the quadriceps and patellar tendon forces. Statistical analyses were then applied to the measured and calculated quantities. The mean quadriceps force in the operated knee decreased by 20%. Likewise, the mean PFCF was found to be reduced by 30% in the operated knees as compared with the asymptomatic contralateral knees. The above differences in Q and PFCF between the operated knee and the asymptomatic knee were statistically significant (P < 0.05). Therefore, the results of this study do not agree with the previously held view that Q and PFCF increase due to the removal of pain after the elevation operation. It is our contention that comparison of the forces measured preoperatively in a painful joint with the forces that can be attained postoperatively in the pain-free joint can lead to errors in biomechanical evaluations.