• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.85-98
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• 1991

The aim of this study was to investigate the effect of low - power laser used in the medical field for various purposes to suppress pain responses evoked by noxious electrical or mechanical stimuli. After both inferior alveolar nerves and the left anterior digastric muscle of cats under general anesthesia were exposed, a recording electrode for the jaw opening reflex was inserted into the anterior digastric muscle. The right inferior alveolar nerve was dissected under a surgical microscope until the response of the functional single nerve could be evoked by the electrical stimulation of the dental pulp or oral mucosa. The electrical stimulus was applied with a rectangular pulse of 10 ms duration for measuring the threshold intensity of a single nerve fiber in the inferior alveolar nerve which responds to stimulation of dental pulp and oral mucosa. Then a pulse of 1 ms duration was applied for determination of conduction velocity. A noxious mechanical stimulus to the oral mucosa was applied by clamping the receptive field with an arterial clamp. The Ga-As diodide laser(wave length, 904 nm ; frequency, 1,000 Hz) was irradiated to the prepared tooth cavity, inferior alveolar nerve and oral mucosa as a pulse wave of 2 mW for 6 minutes. This was followed by a continuous wave of 15 mW for 3 minutes. The action potential of the nerve and EMG of the digastric muscle evoked by the noxious electrical stimulus and nerve response to noxious mechanical stimulus were compared at intervals of before, immediately after, and at 5, 10, 20, 40, 60 minutes after laser irradiation. The results were as follows: The conduction velocity of the intrapulpal $A{\delta}$- nerve fiber recorded from the inferior alveolar nerve before irradiation had a mean value of $6.68{\pm}2.07m/sec$. The laser irradiation did not affect the conduction velocity of the AS - nerve fiber and did not change the threshold intensity or amplitude of the action potential either. The EMG of the digastric muscle evoked by noxious electrical stimulation to the tooth was not changed by the laser irradiation, whether in latency, threshold intensity or amplitude. The laser irradiated to the receptive field of the oral mucosa which was subjected to noxious stimuli did not affect the amplitude of the action potential or the frequency either.

• Journal of Korean Biological Nursing Science
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• v.10 no.1
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• pp.88-95
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• 2008

Purpose: The purpose of this study was to examine the effect of neuropathic pain by peripheral nerve injury on mass and Type I and II fiber cross-sectional areas on hindlimb muscles of the neuropathic pain model rat. Method: Adult male Sprague-Dawley rats (body weight 200-220 g) were assigned to one of two groups: a neuropathic pain group (n=7) that had a ligation of the left L5 spinal nerve, a control group (n=5), a naive rat without any procedures. Withdrawal threshold, activity, body weight and food intake were measured daily. At 8 days after neuropathic pain, all rats were anesthetized and the soleus and plantaris muscles were dissected from the both hindlimbs. Body weight, food intake, muscle weight and Type I and II fiber cross-sectional area of the dissected muscles were determined. Result: The neuropathic pain group showed a significant decreases (p<.05) as compared with the control rats, in diet intake, body weight, muscle weight and Type II fiber cross-sectional area of the left (affected side) soleus and plantaris muscles, and the right (unaffected side) muscle weight of plantaris and Type II fiber cross-sectional area of the soleus muscle. Conclusion: The hindlimb muscle atrophy occurs in both affected and unaffected side due to neuropathic pain by the peripheral nerve injury. The hindlimb muscle atrophy of the affected side is more pronounced than that of the unaffected side.

• Restorative Dentistry and Endodontics
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• v.21 no.2
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• pp.505-516
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• 1996

The effects of application of dentin desensitizer containing glutaraldehyde (Gluma Desensitizer) and dentin adhesive system (All Bond 2) to the exposed dentin on the intradental nerve activity (INA) and the occluding aspects of dentinal tubules were investigated in cat canine teeth. Single pulp nerve units were dissected from the inferior alveolar nerve and indentified as $A{\delta}$-fiber units. The INAs elicited by 4M NaCl before and after the application of each experimental agent were compared. The morphological changes of exposed dentin surfaces and dentinal tubules in the dentin specimens used to record INAs were observed by SEM. The results obtained were as follows. 1. Eight $A{\delta}$-fiber units (conduction velocity: $8.0{\pm}4.0m$/sec) were identified. 4M NaCl evoked an irregular burst of action potentials which ceased immediately after washing. 2. In 4 $A{\delta}$-fiber units, the change of INA after the application of Gluma Desensitizer was $133.9{\pm}80.7%$ when it was compared with the INA before the application of the same agent. 3. In 4 $A{\delta}$-fiber units, application of All Bond 2 completely abolished the INA induced by 4M NaCl. 4. In specimens applied with Gluma Desensitizer, the formation of hybrid layer as well as the identification of resin penetration and reaction products with proteins in dentinal tubules were not clearly observed in interface between dentin and adhesive resin. In specimens applied with All Bond 2, the gap width of 2-$3{\mu}m$ was formed between exposed dentin and adhesive resin, and the hybrid layer and resin tags were not clearly formed either.

• Korean Journal of Head & Neck Oncology
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• v.16 no.1
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• pp.69-72
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• 2000

The neurilemmoma is a relatively uncommon benign neoplasm which is known to be originated from the schwann sheath of the nerve fiber. Parapharyngeal neurilemmomas may originate from any nerve traversing this space, but the vast majority arise from the vagus nerve and sympathetic chain. The neurilemmomas arising from the extracranial portion of the hypoglossal nerve are extremely rare. To our knowledge, the case we present is the ninth one to be reported occurring in the parapharyngeal space. Recently we experienced a case of parapharyngeal neurilemmoma arising from the hypoglossal nerve and so we report our case with a brief review of literatures.

• Applied Microscopy
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• v.36 no.3
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• pp.183-194
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• 2006

The threadlike structures of fascia were examined by tight and electron microscopy. In order to distinguish its tissue organization, we used staining methods including hematoxylin-eosin, Masson's trichrome, Van Gieson's collagen fiber stain and Kluver-Barrera's luxol fast blue for nerve stain. Under the light microscope, the threadlike structures were composed of many collagen fibers and nerve. In higher magnification, they looked like as the bundle of tubular structures. Many myoid cell-spindle nuclei were observed in the tissue, which were taken from the fascia. It was identical with Bonghan duct known as one of meridian network theory. In the early 1960's the North Korean Bong-Han Kim showed the anatomical structures of the acupuncture points, and explained the meridian system as the concrete duct network system. According to Bonghan theory the Bonghan ducts spread throughout the body Because it is believed that the duct could have the role of signal pathway, the theory was reinvestigated in these days. All of the threadlike structures isolated from fascia shows the abundance of collagen fibers. The electron microscope examination (TEM) could confirm the well arranged collagen fiber and nerve. This investigation reveals that superficial Bohghan duct are nerve fiber parallel running with collagen fibers. We conjectured that the intermingled structure of collagen fiber, blood vessel and nerve fiber might have the role of meridian system. And the more, regardless of histological research, the study on collagen fiber as response transmitter in acupuncture treatment are in need.

• The Korean Journal of Physiology
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• v.19 no.2
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• pp.227-232
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• 1985

Previously, we had reported that the electrical stimulation of peripheral nerve with stimlatory parameters of 20 V strength and 2 Hz frequency for 60 min resulted in reducing the pain reaction. The present study was performed to evaluate if the pain reaction was affected by the peripheral nerve stimulation with different stimulatory parameters in the decerebrated cat. The flexion reflex was used as an index of the pain reaction. The reflex was elicited by stimulating the sural nerve (stimulus strength of 20 $V\;\times\;0.5$msec) and recorded as a compound action potential from the motor nerve innervated to the posterior biceps femoris muscle. The common perneal nerve was selected as a peripheral nerve on which the electrical stimulation of various intensities and frequencies was applied. The results are summarized as follows : 1) The peripheral nerve stimulation with 100 mV strength, regardless of frequencies, did not affect the pain reaction induced by the sural nerve stimulation. 2) When the stimulus of 1V intensity and slow frequency (2 Hz) was applied to the peripheral nerve for 30 min or 60 min, the pain reaction was significantly reduced comparing to the control. However, this reduced pain reaction by the peripheral nerve stimulation was not reversed by the injection of naloxone (0.02 mg/kg) 3) High frequency stimulus (60 Hz) of 1V intensity for 30 or 60 min did not show any effects of affecting the pain reaction. These results suggest that the stimulus of relatively high intensity (at least 1V) and low frequency (2 Hz) is needed to elicite the analgesic effect by the peripheral nerve stimulation. By the 1V stimulus, $A\delta$ nerve fiber is activated. Therefore, an $A\delta$ or smaller nerve fibers must be activated for showing analgesia by the peripheral nerve stimulation. However, the mechanism of analgesia by the $A\delta$ nerve activation alone was not related to the endogeneous morphine system since the reduced pain reaction by the $A\delta$ fiber activation alone was not reversed by the treatment of naloxone.

• Archives of Plastic Surgery
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• v.32 no.5
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• pp.613-618
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• 2005

When a large peripheral nerve defect occurs, an autologous nerve graft is the most ideal method of recinstruction. But an autologous nerve graft has many limitations due to donor site morbidities. Many previous focused on finding the ideal nerve conduit. Among them, $Gore-Tex^{(R)}$ has several advantages over other conduits. It can be manipulated to a suitable size, does not collapse easily, and it is a semi- permeable material that contain pores. A round shaped nerve can be newly formed because of its smooth inner surface. The purpose of this study was to evaluate the availability of $Gore-Tex^{(R)}$ tube as a nerve conduit at the peripheral nerve defect in the rat sciatic nerve. The 10 mm nerve gap was made in each group. A $Gore-Tex^{(R)}$ tube filled with skeletal muscle was inserted and autologous nerve graft was harvested, respectively. In the experimental group, we placed a 0.5 mm thickness, $30{\mu}m$ pored, 1.8 mm in diameter and 14 mm length tube with skeletal muscle inserted inside. In the control group, the nerve gap was inserted with a rat sciatic nerve. We estimated the results electrophysiologically and histologically to 16 weeks postoperatively. Results in the nerve conduction velocity, total myelinated axon count, myelin sheath thickness and mean nerve fiber diameter, the experimental group was substantially lower than that of the control group, but the statistic difference was not significant (p<0.05). The morphology was very similar in both groups, microscopically. From the above results, We conclude that $Gore-Tex^{(R)}$ qualifies as an ideal nerve conduit. It is suggested that $Gore-Tex^{(R)}$ tube filled with skeletal muscle may, substitute for an autologous nerve graft.

• Journal of Korean Neurosurgical Society
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• v.66 no.2
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• pp.183-189
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• 2023

Objective : The facial nerve trace on the ipsilateral side of the vestibular schwannoma was reconstructed by diffusion tensor imaging tractography to identify the adjacent relationship between the facial nerve and the tumor, and to improve the level of intraoperative facial nerve protection. Methods : The clinical data of 30 cases of unilateral vestibular schwannoma who underwent tumor resection via retrosigmoid approach were collected between January 2019 and December 2020. All cases underwent magnetic resonance imaging examination before operation. Diffusion tensor imaging and anatomical images were used to reconstruct the facial nerve track of the affected side, so as to predict the course of the nerve and its adjacent relationship with the tumor, to compare the actual trace of the facial nerve during operation, verify the degree of coincidence, and evaluate the nerve function (House-Brackmann grade) after surgery. Results : The facial nerve of 27 out of 30 cases could be displayed by diffusion tensor imaging tractography, and the tracking rate was 90% (27/30). The intraoperative locations of facial nerve shown in 25 cases were consistent with the preoperative reconstruction results. The coincidence rate was 92.6% (25/27). The facial nerves were located on the anterior middle part of the tumor in 14 cases, anterior upper part in eight cases, anterior lower part in seven cases, and superior polar in one case. Intraoperative facial nerve anatomy was preserved in 30 cases. Among the 30 patients, total resection was performed in 28 cases and subtotal resection in two cases. The facial nerve function was evaluated 2 weeks after operation, and the results showed grade I in 12 cases, grade II in 16 cases and grade III in two cases. Conclusion : Preoperative diffusion tensor imaging tractography can clearly show the trajectory and adjacent position of the facial nerve on the side of vestibular schwannoma, which is beneficial to accurately identify and effectively protect the facial nerve during the operation, and is worthy of clinical application and promotion.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.4
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• pp.369-372
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• 2000

The purpose of this study was to investigate the distribution pattern of CGRP immunoreactive nerve fibers in the healing mucosa of extracion wound. Maxillary 1st molars of rats were extracted. All extraction sites and adjacent tissues of 3 groups of rats(1-week, 2-week and 4-week groups) were removed en bloc and processed for immunostaining and were subjected to light microscopic examination. The results obtained were as follows; In 1-week group, there was no difference in the distribution pattern of CGRP immunoreactive nerve fiber between epithelial margin adjacent to extraction socket and normal gingival epithelium. In 2-week group, some CGRP-immunoreactive nerve fibers were seen in epithelial layer. In 4-week group, many intercellular CGRP immunoreactive nerve fibers were abundant in all layers of immature epithelium characterized by scab on the mucosa and thick keratinized cell layer with irregular surface. Intraepithelial CGRP immunoreactive nerve fibers were reduced to normal level in adjacent mature epithelium. These results suggest that density of CGRP immunoreactive nerve fibers are increased transiently in epithelium during reepithelialization process and CGRP released from these nerve fibers may play an important role in the reepithelialization in the wound healing.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.17 no.4
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• pp.317-330
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• 1995

The purpose of this study is to observe the stimulant effect of the isolated nerve segment on the peripheral nerve regeneration using silicone tube in rats. Sprague-Dawley female albino rats were used as experimental animals and nerve defects were made by resection of 14 mm-long segment of right sciatic nerves. In control group, the defects were bridged with the silicone tubes. In experimental group, the defects were bridged with the same manner and additionally, 2mm-long nerve segments were inserted at the center of the silicone tubes. 3 months later, the regenerated nerve tissue within the silicone tubes were examined by histologic study. Axonal diameters and numbers of axons were measured and all data were analyzed by using SAS package program. The results obtained were as follows : 1. The experimental group was increased than the control group in general diameters of the regenerated nerve fiber.(P<0.05) 2. The diameters of axons were increased in the experimental group compare to the control group.(P<0.05) 3. The numbers of axons were increased in the experimental group compare to the control group.(P<0.05)