Nevin Gürgör

Orbicularis oculi muscle activation during swallowing in humans

Intraoral trigeminal afferents elicit EMG activity from the lower facial muscle, orbicularis oris (OR) during swallowing. The upper facial muscles and especially orbicularis oculi (OC) were not previously known to be associated with deglutitional events. Nevertheless, given the large area of intraoral mucosa and teeth innervated by the trigeminal nerve afferents, a connection between OC motoneurons and deglutition may theoretically be expected, which we sought to evaluate in this study. Healthy controls were investigated for the possible synchronization of orbicularis OC and OR muscles during deglutition by the following methods: EMG activities were recorded during voluntary dry, 3-, 10-, 20-ml discrete wet swallowing, and sequential swallowing from a cup, concurrent with respiratory recording. A polygraphic recording was obtained from these muscles to determine whether they were synchronously activated during spontaneous swallowing. The polygraphic recording during spontaneous swallowing demonstrated that the OC and OR muscles were synchronously activated in all subjects. This synchronous activation was less prominent in voluntary discrete swallowing. It is proposed that this might be based on trigemino-solitarii-facial pathways with weaker connection to OC muscles. The synchronization of OC muscle activity with deglutition may be an evolutionary process that should be rudimentary in higher mammals including humans. The swallowing-induced cranial muscle activities could potentially explain some movement disorders, such as craniofacial dystonias.

Diagnostic value of lumbar root stimulation at the early stage of Guillain-Barré syndrome.

OBJECTIVE The aim of this study is to investigate diagnostic value of electrical lumbar root stimulation (RS) at the laminar level in the early stage of Guillain-Barré syndrome (GBS). METHODS Fifteen patients (30 sides) and nine controls (17 sides) were included in the study. Conventional nerve conduction studies, needle electromyography, F responses and electrical lumbar RS were obtained from both groups. The needle electrical stimulation was performed at the L2-3 intervertebral level. Vastus lateralis, tibialis anterior and soleus muscles were investigated bilaterally and simultaneously in the first and fourth weeks. RESULTS In all patients, the amplitudes elicited by lumbar RS were significantly attenuated while the conventional electrophysiological findings were normal and/or not diagnostic in 6 of 15 patients (40%) within the first week. Motor latencies by the lumbar RS were prolonged in the patients, compared to the controls, but the results were not statistically significant. CONCLUSIONS M-responses elicited by lumbar RS appear to be helpful in disclosing proximal conduction abnormalities of GBS early in the course. SIGNIFICANCE Lumbar RS seems to be a useful method in making the diagnosis of GBS early and there is no considerable side effect of this particular method.

Diagnostic value of cauda equina motor conduction time in lumbar spinal stenosis

OBJECTIVE Lumbar spinal stenosis (LSS) is a chronic degenerative disease with pain in the back, buttocks and legs aggrevated by walking and relieved after rest without associated vascular disease of lower extremities observed in patients between 50 and 60 years. Several studies, using different methods indicated an association between slowing or blocking of root-nerve conduction and LSS. None of the previous research had applied the more conceivable methods such as recording the cauda equina potentials from the lumbar level or stimulating the spinal roots within the canal using either leg nerves or muscles. In this study, electrical lumbar laminar stimulation was used to demonstrate prolongation of cauda equina motor conduction time in lumbar spinal stenosis. METHODS Twenty-one LSS patients and age matched 15 normal control subjects were included in the study. Lumbar laminar electrical stimulation from L1 and L5 vertebra levels were applied by needle electrodes. Compound muscle action potential (CMAP) from gastrocnemius muscles were recorded bilaterally. Latency difference of CMAPs obtained from L1 and L5 spine levels were accepted as the cauda equina motor conduction time (CEMCT). RESULTS CEMCT was significantly longer in patient group when compared to normal controls. Mean latency difference was 3.59 ± 1.07 msec on the right side, 3.49 ± 1.07 msec on the left side in LSS group, it was 1.45 ± 0.65 msec on the right side, 1.35 ± 0.68 msec on the left side on normal control group (p<0.0001). CONCLUSIONS The prolongation of CEMCT was statistically and individually significant in patient group. This may indicate that lower lumbosacral motor roots were locally and chronically compressed due to lumbar spinal stenosis. Lumbar spinal stenosis may have induced local demyelination at the cauda equina level. SIGNIFICANCE Since the prolongation of CEMCT was found only in patients with LSS, the method of laminar stimulation can be chosen for patients with uncertain diagnosis of LSS.

Focal status epilepticus induced by hyperbaric oxygen therapy.

IntroductionGeneralized tonic clonic (GTC) seizure activity because of central nerve system oxygen toxicity is a rare but recognized effect of HBOT (hyperbaric oxygen therapy). Almost all case reports and database analyses about the relationship between seizure activity and HBOT point out that GTC seizures and status epilepticus are more likely to occur as a result of the treatment and there are only few reports demonstrating partial seizures. Case ReportAn 87-year-old male patient was admitted to our clinic because of tonic-clonic contractions on his left arm. He was under HBOT because of a decubitis ulcer. After repeated exposures to hyperbaric oxygen, he had contractions on his left arm. He was diagnosed as focal motor status. There was no evidence of acute ischemia or mass lesion on brain magnetic resonance imaging. IV phenytoin (diphenylhydantoin) 20 mg/kg was given over 30 minutes and continued orally with phenytoin at a dose of 300 mg/d. He had no subsequent seizures. ConclusionGTC seizures or status epilepticus as a result of GTC seizures are more common than focal seizures as neurologic complications of HBOT. Partial seizures as a neurologic complication of HBOT have rarely been reported and to our knowledge, this is the first case which is characterized by focal status epilepticus induced by HBOT.

Motor evoked responses from the thigh muscles to the stimulation of the upper limb nerves in patients with late poliomyelitis

OBJECTIVES To demonstrate a clear-cut M response recorded from the severely affected thigh muscles to the stimulation of the upper limb nerves in a serial of patients with late poliomyelitis. METHODS Fifteen patients with late poliomyelitis, 7 patients with spinal cord disorders and 11 control subjects were included. Evoked muscle responses were investigated in quadriceps femoris and/or thigh adductor muscles to the stimulation of the brachial plexus, median and ulnar nerves. RESULTS Evoked muscle responses were obtained from the thigh muscles in all 12 late polio patients with proximal lower extremity involvement. The response could not be recorded from the thigh muscles neither in the 3 polio patients with upper extremity involvement nor in the healthy control subjects and in patients with other spinal cord disorders of anterior horn cell. CONCLUSIONS It is proposed that the electrical stimulation of the arm nerves produce interlimb descending muscle responses in the severely affected atrophic thigh muscles of the patients with late polio. This finding suggests that there might be a focal and/or specific loss of inhibitory interneurons between injured and normal motor neurons and increased facilitatory synaptic action at the end of long propriospinal descending fibers in the case of late poliomyelitis.

Electrophysiological association of spontaneous yawning and swallowing.

Abstract Yawning and swallowing are fundamental physiological processes that are present from fetal stages throughout life and that involve sequential motor activities in the oropharyngo-larynx making it likely that they may share neuroanatomical pathways. We postulate that yawning and swallowing are controlled by a distributed network of brainstem regions including the central pattern generator of swallowing, and therefore spontaneous swallowing is frequently associated with spontaneous yawning. In this study, we sought to test this hypothesis by evaluating the elementary features of yawning in the facial, masseter and submental muscles, together with laryngeal movement sensor and respiratory recordings for spontaneous swallowing. We investigated 15 healthy, normal control subjects, 10 patients with Parkinson’s disease (PD) and 10 patients with brainstem stroke (BSS). Apart from four subjects with PD and two with BSS, who had dysphagia, none of the other study subjects were dysphagic by published criteria. Twenty-five subjects (10 control, 10 BSS, 5 PD) were evaluated by 1-h polygraphic recording, and 10 (5 control, 5 PD) underwent whole-night sleep recordings. One hundred thirty-two yawns were collected, 113 of which were associated with spontaneous swallows, a clear excess of what would be considered as coincidence. The yawns related with swallows could be classified into the following three categories. The characteristics or the duration of swallows and yawns were similar between controls and disease subjects, with the exception of increased duration of yawning in subjects with BSS. Our findings support the presence of common neuroanatomico-physiological pathways for spontaneous swallows and yawning.

The Effects of Botulinum Toxin a on Ephaptic Transmission in Idiopathic Hemifacial Spasm

Objective: Lateral spreading and synkinetic responses of blink reflex are a sign of ephaptic transmission in idiopathic hemifacial spasm (HFS). The aim of this study was to evaluate the effect of botulinum toxin A (Btx A) on ephaptic transmission in idiopathic HFS. Methods: Thirty-three patients with idiopathic HFS were investigated. Btx A was injected only into the affected orbicularis oculi (OC) muscle. Electrophysiological studies were performed before and three weeks after the Btx A injection. Results: After Btx A, the latencies of motor response and blink reflexes elicited from the OC muscle were significantly increased. The lateral spreading was not obtained in the OC muscle, while the orbicularis oris muscle response was not changed. There were no significant differences in the synkinetic responses of blink reflex. During needle EMG examination, positive sharp waves and fibrilation potentials were observed due to chemodenervation only in the OC muscle. Conclusion: Btx A affects only the neuromuscular junctions of the injected muscle and has no effect upon ephaptic transmission.

Activity of facial and swallowing muscles during water and sour bolus deglutition in healthy adult humans

There are very close relationships among deglutition, taste sensations, and facial expressions in humans. However, the associations among mimicking, swallowing, and the suprahyoid/submental muscle group (SM) during deglutition events have yet to be investigated using electrophysiological techniques to elucidate taste sensation and facial expression further. Thus, this study used surface EMG to evaluate synchronous electromyography activity in the facial and swallowing muscles during the swallowing of water and sour boluses in 20 normal healthy adults. All participants were instructed to swallow four bolus volumes (5, 10, 15, and 20 ml) each of a water bolus and a sour bolus (lemon juice) in a neutral head position. EMG recordings were obtained from the orbicularis oculi (OC; a mimic muscle), orbicularis oris (OR; a mimic and swallowing muscle), and SM (deglutition muscles) to determine whether these muscles were synchronously activated during voluntary oropharyngeal swallowing. The mimic (OC and OR) and swallowing muscles (SM) were synchronously activated in more than 90% of participants during water swallowing. Swallowing lemon juice increased the number of spontaneous swallows after the first deglutition and significantly shortened the duration of a single swallowing apnea. The present findings indicate that both taste and the intraoral trigeminal afferents of water and sour boluses excite facial neurons via the nucleus tractus solitarius and/or a central pattern generator. Additionally, sour boluses produced stronger and safer oropharyngeal swallowing in conjunction with increases in facial expressions due to the activation of facial mimic muscles.

P28-10 Cauda equina motor conduction time in lumbar spinal stenosis

The analysis of C5-C6 root conduction is one of the problems of neurophysiology. We tried to perform the complex T-reflex study to diagnose the radiculopathy on this level. The bicipital and carporadial reflexes at the same electrodes position on the biceps were studied. 38 patients were examined, 20 of them were the control group. 18 patients had the clinical signs of radiculopathy. The analysis of latencies revealed that the normal latency of the bicipital reflex was 17÷13 ms, the one of the carporadial reflex was 18.8÷14.4 ms. The latency difference was 0.7÷2.6 ms. The study of the patients with the cervical radiculopathy and pain syndrome indicated hardly reliable change of latency of reflex responses. The comparison of the reflex responses of injured and healthy sides were used for the analysis. The data analysis revealed the following. In sensory radiculopathy at C7C8 level the latency of carporadial reflex and the latency difference of reflex responses increased reliably. In motor radiculopathy at C5-C6 level the latency of both reflex responses at the injured side increased. In sensory radiculopathy at C5-C6 level the latency of bicipital reflex increased and the difference of the reflex responses decreased. Conclusion: The complex study of bicipital and carporadial reflexes allows analyzing the injury of C5-C6, C7-C8 root system. Moreover, it is possible to study sensory and motor root conduction separately.

P13-20 Wide receptive field of cremasteric reflex (CMR) in human adult males

Introduction: Because motor unit action potentials (MUAPs) of human striated cremaster muscle (CM) have not been analysed previously, we examined the MUAPs of the CM to learn more about the physiology of this unusual muscle that works mostly without voluntary control. Method: In this study, MUAPs of human CM were investigated in 31 normal subjects. MUAPs were elicited by either a voluntarily contraction effort or a reflex response to tactile stimulation of the inner thigh. Singlefiber electromyography (SF EMG) using a disposable concentric needle electrode (CNE) was also performed in 10 normal subjects. Results: The total number of MUAPs was 288. Approximately 40% of all MUAPs were classified as simple MUAPs, and the remainder were polyphasic potentials. During tactile stimulation, the MUAPs longer than 20 ms sometimes grouped as a single long potential or as different subgroups with time intervals between them. In SF EMG only 29 potential pairs were obtained. SF EMG using a CNE revealed an increase in jitter and intermittent blocking. The average of mean consecutive differences (MCD) was 73.5ms. Discussion: These results were similar to those obtained from patients with chronic neurogenic disorders despite the fact that the CMs studied were clinically and functionally normal in our healthy male subjects. These findings suggest that the CM is an embryogenic striated muscle with polyneural innervation both at the muscle fiber and spinal cord level.