The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
Albert L. Rhoton - One of the best experts on this subject based on the ideXlab platform.
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The cochlea in skull base surgery: an anatomy study
Journal of Neurosurgery, 2016Co-Authors: Jian Wang, Fumitaka Yoshioka, Wonil Joo, Noritaka Komune, Vicent Quilis-quesada, Albert L. RhotonAbstract:OBJECTIVE The object of this study was to examine the relationships of the cochlea as a guide for avoiding both cochlear damage with loss of hearing in middle fossa approaches and injury to adjacent structures in approaches directed through the cochlea. METHODS Twenty adult cadaveric middle fossae were examined using magnifications of ×3 to ×40. RESULTS The cochlea sits below the floor of the middle fossa in the area between and below the labyrinthine segment of the facial Nerve and Greater Petrosal Nerve (GPN) and adjacent to the lateral genu of the petrous carotid. Approximately one-third of the cochlea extends below the medial edge of the labyrinthine segment of the facial Nerve, geniculate ganglion, and proximal part of the GPN. The medial part of the basal and middle turns are the parts at greatest risk in drilling the floor of the middle fossa to expose the Nerves in middle fossa approaches to the internal acoustic meatus and in anterior petrosectomy approaches. Resection of the cochlea is used selectively in extending approaches through the mastoid toward the lateral edge of the clivus and front of the brainstem. CONCLUSIONS An understanding of the location and relationships of the cochlea will reduce the likelihood of cochlear damage with hearing loss in approaches directed through the middle fossa and reduce the incidence of injury to adjacent structures in approaches directed through the cochlea.
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Microsurgical and endoscopic anatomy of the vidian canal.
Neurosurgery, 2009Co-Authors: Shigeyuki Osawa, Albert L. Rhoton, Askin Seker, Satoru Shimizu, Kiyotaka Fujii, Amin B. KassamAbstract:OBJECTIVE: The vidian canal, the conduit through the sphenoid bone for the vidian Nerve and artery, has become an important landmark in surgical approaches to the cranial base. The objective of this study was to examine the anatomic features of the vidian canal, Nerve, and artery, as well as the clinical implications of our findings. METHODS: Ten adult cadaveric specimens and 10 dried skulls provided 40 vidian canals for examination with x 3 to x 20 magnification and the endoscope. RESULTS: The paired vidian canals are located in the skull base along the line of fusion of the pterygoid process and body of the sphenoid bone. The canal opens anteriorly into the medial part of the pterygopalatine fossa and posteriorly at the upper part of the anterolateral edge of the foramen lacerum. The vidian Nerve, when followed posteriorly, reaches the lateral surface of the anterior genu of the petrous carotid and the anteromedial part of the cavernous sinus where the Nerve is continuous with the Greater Petrosal Nerve. The bone surrounding the upper part of 12 of 20 vidian canals protruded into the floor of the sphenoid sinus and one canal had a bony dehiscence that exposed its contents under the sinus mucosa. Nine petrous carotid arteries (45%) gave rise to a vidian artery, all of which anastomosed with the vidian branch of the maxillary artery in the vidian canal or pterygopalatine fossa. The vidian canal can be exposed by opening the floor of the sphenoid sinus, the posterior wall of the maxillary, the posterior part of the lateral wall of the nasal cavity, and the medial part of the floor of the middle fossa. CONCLUSION: The vidian canal and Nerve are important landmarks in accessing the anterior genu of the petrous carotid, anteromedial part of the cavernous sinus, and petrous apex.
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Microsurgical and endoscopic anatomy of the vidian canal.
Neurosurgery, 2009Co-Authors: Shigeyuki Osawa, Albert L. Rhoton, Askin Seker, Satoru Shimizu, Kiyotaka Fujii, Amin B. KassamAbstract:The vidian canal, the conduit through the sphenoid bone for the vidian Nerve and artery, has become an important landmark in surgical approaches to the cranial base. The objective of this study was to examine the anatomic features of the vidian canal, Nerve, and artery, as well as the clinical implications of our findings. Ten adult cadaveric specimens and 10 dried skulls provided 40 vidian canals for examination with x 3 to x 20 magnification and the endoscope. The paired vidian canals are located in the skull base along the line of fusion of the pterygoid process and body of the sphenoid bone. The canal opens anteriorly into the medial part of the pterygopalatine fossa and posteriorly at the upper part of the anterolateral edge of the foramen lacerum. The vidian Nerve, when followed posteriorly, reaches the lateral surface of the anterior genu of the petrous carotid and the anteromedial part of the cavernous sinus where the Nerve is continuous with the Greater Petrosal Nerve. The bone surrounding the upper part of 12 of 20 vidian canals protruded into the floor of the sphenoid sinus and one canal had a bony dehiscence that exposed its contents under the sinus mucosa. Nine petrous carotid arteries (45%) gave rise to a vidian artery, all of which anastomosed with the vidian branch of the maxillary artery in the vidian canal or pterygopalatine fossa. The vidian canal can be exposed by opening the floor of the sphenoid sinus, the posterior wall of the maxillary, the posterior part of the lateral wall of the nasal cavity, and the medial part of the floor of the middle fossa. The vidian canal and Nerve are important landmarks in accessing the anterior genu of the petrous carotid, anteromedial part of the cavernous sinus, and petrous apex.
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blood supply of the facial Nerve in the middle fossa the Petrosal artery
Neurosurgery, 2008Co-Authors: Hatem Elkhouly, Juan C Fernandezmiranda, Albert L. RhotonAbstract:OBJECTIVE To define the arterial supply to the facial Nerve that crosses the floor of the middle cranial fossa. METHODS Twenty-five middle fossae from adult cadaveric-injected specimens were examined under 3 to 40x magnification. RESULTS The Petrosal branch of the middle meningeal artery is the sole source of supply that crossed the floor of the middle fossa to irrigate the facial Nerve. The Petrosal artery usually arises from the first 10-mm segment of the middle meningeal artery after it passes through the foramen spinosum, but it can arise within or just below the foramen spinosum. The Petrosal artery is commonly partially or completely hidden in the bone below the middle fossa floor. It most commonly reaches the facial Nerve by passing through the bone enclosing the geniculate ganglion and tympanic segment of the Nerve and less commonly by passing through the hiatus of the Greater Petrosal Nerve. The Petrosal artery frequently gives rise to a branch to the trigeminal Nerve. The middle meningeal artery was absent in one of the 25 middle fossae, and a Petrosal artery could not be identified in four middle fossae. The Petrosal arteries were divided into three types based on their pattern of supply to the facial Nerve. CONCLUSION The Petrosal artery is at risk of being damaged during procedures in which the dura is elevated from the floor of the middle fossa, the middle fossa floor is drilled, or the middle meningeal artery is embolized or sacrificed. Several recommendations are offered to avoid damaging the facial Nerve supply while performing such interventions.
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Blood supply of the facial Nerve in the middle fossa: the Petrosal artery.
Neurosurgery, 2008Co-Authors: Hatem El-khouly, Juan Fernandez-miranda, Albert L. RhotonAbstract:To define the arterial supply to the facial Nerve that crosses the floor of the middle cranial fossa. Twenty-five middle fossae from adult cadaveric-injected specimens were examined under 3 to 40x magnification. The Petrosal branch of the middle meningeal artery is the sole source of supply that crossed the floor of the middle fossa to irrigate the facial Nerve. The Petrosal artery usually arises from the first 10-mm segment of the middle meningeal artery after it passes through the foramen spinosum, but it can arise within or just below the foramen spinosum. The Petrosal artery is commonly partially or completely hidden in the bone below the middle fossa floor. It most commonly reaches the facial Nerve by passing through the bone enclosing the geniculate ganglion and tympanic segment of the Nerve and less commonly by passing through the hiatus of the Greater Petrosal Nerve. The Petrosal artery frequently gives rise to a branch to the trigeminal Nerve. The middle meningeal artery was absent in one of the 25 middle fossae, and a Petrosal artery could not be identified in four middle fossae. The Petrosal arteries were divided into three types based on their pattern of supply to the facial Nerve. The Petrosal artery is at risk of being damaged during procedures in which the dura is elevated from the floor of the middle fossa, the middle fossa floor is drilled, or the middle meningeal artery is embolized or sacrificed. Several recommendations are offered to avoid damaging the facial Nerve supply while performing such interventions.
Amin B. Kassam - One of the best experts on this subject based on the ideXlab platform.
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Microsurgical and endoscopic anatomy of the vidian canal.
Neurosurgery, 2009Co-Authors: Shigeyuki Osawa, Albert L. Rhoton, Askin Seker, Satoru Shimizu, Kiyotaka Fujii, Amin B. KassamAbstract:OBJECTIVE: The vidian canal, the conduit through the sphenoid bone for the vidian Nerve and artery, has become an important landmark in surgical approaches to the cranial base. The objective of this study was to examine the anatomic features of the vidian canal, Nerve, and artery, as well as the clinical implications of our findings. METHODS: Ten adult cadaveric specimens and 10 dried skulls provided 40 vidian canals for examination with x 3 to x 20 magnification and the endoscope. RESULTS: The paired vidian canals are located in the skull base along the line of fusion of the pterygoid process and body of the sphenoid bone. The canal opens anteriorly into the medial part of the pterygopalatine fossa and posteriorly at the upper part of the anterolateral edge of the foramen lacerum. The vidian Nerve, when followed posteriorly, reaches the lateral surface of the anterior genu of the petrous carotid and the anteromedial part of the cavernous sinus where the Nerve is continuous with the Greater Petrosal Nerve. The bone surrounding the upper part of 12 of 20 vidian canals protruded into the floor of the sphenoid sinus and one canal had a bony dehiscence that exposed its contents under the sinus mucosa. Nine petrous carotid arteries (45%) gave rise to a vidian artery, all of which anastomosed with the vidian branch of the maxillary artery in the vidian canal or pterygopalatine fossa. The vidian canal can be exposed by opening the floor of the sphenoid sinus, the posterior wall of the maxillary, the posterior part of the lateral wall of the nasal cavity, and the medial part of the floor of the middle fossa. CONCLUSION: The vidian canal and Nerve are important landmarks in accessing the anterior genu of the petrous carotid, anteromedial part of the cavernous sinus, and petrous apex.
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Microsurgical and endoscopic anatomy of the vidian canal.
Neurosurgery, 2009Co-Authors: Shigeyuki Osawa, Albert L. Rhoton, Askin Seker, Satoru Shimizu, Kiyotaka Fujii, Amin B. KassamAbstract:The vidian canal, the conduit through the sphenoid bone for the vidian Nerve and artery, has become an important landmark in surgical approaches to the cranial base. The objective of this study was to examine the anatomic features of the vidian canal, Nerve, and artery, as well as the clinical implications of our findings. Ten adult cadaveric specimens and 10 dried skulls provided 40 vidian canals for examination with x 3 to x 20 magnification and the endoscope. The paired vidian canals are located in the skull base along the line of fusion of the pterygoid process and body of the sphenoid bone. The canal opens anteriorly into the medial part of the pterygopalatine fossa and posteriorly at the upper part of the anterolateral edge of the foramen lacerum. The vidian Nerve, when followed posteriorly, reaches the lateral surface of the anterior genu of the petrous carotid and the anteromedial part of the cavernous sinus where the Nerve is continuous with the Greater Petrosal Nerve. The bone surrounding the upper part of 12 of 20 vidian canals protruded into the floor of the sphenoid sinus and one canal had a bony dehiscence that exposed its contents under the sinus mucosa. Nine petrous carotid arteries (45%) gave rise to a vidian artery, all of which anastomosed with the vidian branch of the maxillary artery in the vidian canal or pterygopalatine fossa. The vidian canal can be exposed by opening the floor of the sphenoid sinus, the posterior wall of the maxillary, the posterior part of the lateral wall of the nasal cavity, and the medial part of the floor of the middle fossa. The vidian canal and Nerve are important landmarks in accessing the anterior genu of the petrous carotid, anteromedial part of the cavernous sinus, and petrous apex.
Takeshi Kawase - One of the best experts on this subject based on the ideXlab platform.
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Greater Petrosal Nerve schwannomas—analysis of four cases and review of the literature
Neurosurgical Review, 2010Co-Authors: Shinya Ichimura, Kazunari Yoshida, Agung Budi Sutiono, Takashi Horiguchi, Hikaru Sasaki, Takeshi KawaseAbstract:Schwannomas arising from the Greater Petrosal Nerve (GPN) are exceedingly rare: only 10 such cases have been reported in the English literature. We report on four cases of GPN schwannomas and discuss the surgical approach for their removal. Four patients with GPN schwannomas underwent surgery at Keio University Hospital. We present the pre- and postoperative clinical findings and describe the structures around the GPN schwannomas as observed during the surgery. Histological sections were performed around the GPN using Masson’s trichrome stain to elucidate the membrane structures. Three patients presented with xerophthalmia, and one with facial palsy, hearing disturbance, and generalized convulsions. Contrast-enhanced magnetic resonance images revealed tumors in the temporal lobe. Bone-window computed tomography showed erosion of the anterior petrous apex. During the operation, the temporal lobe was retracted epidurally. The tumors were visible inside the interdural space and covered with the epineurium. In three cases, the tumors were completely removed, and in one case, the tumor was subtotally removed with intraoperative facial monitoring. In the histological sections, we confirmed that the GPN ran within the interdural space. Approaching epi- and interdurally is suitable for the removal of GPN schwannomas because the GPN is located within the interdural space. The advantage of this approach is that the landmark points can be identified. Moreover, the possibility of injuring the temporal lobe is low because the temporal lobe is not exposed in this approach.
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Greater Petrosal Nerve schwannomas analysis of four cases and review of the literature
Neurosurgical Review, 2010Co-Authors: Shinya Ichimura, Kazunari Yoshida, Agung Budi Sutiono, Takashi Horiguchi, Hikaru Sasaki, Takeshi KawaseAbstract:Schwannomas arising from the Greater Petrosal Nerve (GPN) are exceedingly rare: only 10 such cases have been reported in the English literature. We report on four cases of GPN schwannomas and discuss the surgical approach for their removal. Four patients with GPN schwannomas underwent surgery at Keio University Hospital. We present the pre- and postoperative clinical findings and describe the structures around the GPN schwannomas as observed during the surgery. Histological sections were performed around the GPN using Masson’s trichrome stain to elucidate the membrane structures. Three patients presented with xerophthalmia, and one with facial palsy, hearing disturbance, and generalized convulsions. Contrast-enhanced magnetic resonance images revealed tumors in the temporal lobe. Bone-window computed tomography showed erosion of the anterior petrous apex. During the operation, the temporal lobe was retracted epidurally. The tumors were visible inside the interdural space and covered with the epineurium. In three cases, the tumors were completely removed, and in one case, the tumor was subtotally removed with intraoperative facial monitoring. In the histological sections, we confirmed that the GPN ran within the interdural space. Approaching epi- and interdurally is suitable for the removal of GPN schwannomas because the GPN is located within the interdural space. The advantage of this approach is that the landmark points can be identified. Moreover, the possibility of injuring the temporal lobe is low because the temporal lobe is not exposed in this approach.
Shinya Ichimura - One of the best experts on this subject based on the ideXlab platform.
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Epidural anterior petrosectomy with subdural visualization of sphenobasal vein via the anterior transPetrosal approach—technical case report
Neurosurgical Review, 2012Co-Authors: Shinya Ichimura, Kazunari Yoshida, Hiroshi Kagami, Makoto Inaba, Maaya Orii, Yohei Kitamura, Isako Saga, Masahiro TodaAbstract:The drainage of the superficial middle cerebral vein (SMCV) is classified into four subtypes. The sphenobasal vein (SBV) drains from the SMCV to the pterygoid venous plexus at the temporal skull base. Epidural procedures in the standard anterior transPetrosal approach (ATPA) may damage the route of the SBV. We report a case in which modified surgical procedures via the ATPA were used to preserve the SBV. A 45-year-old man complained of right facial pain. Magnetic resonance images revealed a right cerebellopontine tumor suggestive of an epidermoid cyst. Right carotid angiography revealed that the SMCV drained into the pterygoid venous plexus via the SBV. The convexity dura mater of the temporal lobe was cut and the anterior part of the temporal lobe was retracted subdurally. The SBV was visualized from the subdural side. The basal dura mater of the temporal lobe posterior to the SBV was cut and the posterior part of the temporal lobe was retracted epidurally. After dissecting the dura mater medial to the Greater Petrosal Nerve and to the edge of the petrous apex, the petrous apex was exposed and drilled out without injuring the SBV. The superior petrous sinus and the tentorium were cut. The tumor compressed the root exit zone of the trigeminal Nerve. The tumor was grossly totally removed. The modified ATPA (epidural anterior petrosectomy with subdural visualization of the SBV) is effective in preserving the SBV.
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Greater Petrosal Nerve schwannomas—analysis of four cases and review of the literature
Neurosurgical Review, 2010Co-Authors: Shinya Ichimura, Kazunari Yoshida, Agung Budi Sutiono, Takashi Horiguchi, Hikaru Sasaki, Takeshi KawaseAbstract:Schwannomas arising from the Greater Petrosal Nerve (GPN) are exceedingly rare: only 10 such cases have been reported in the English literature. We report on four cases of GPN schwannomas and discuss the surgical approach for their removal. Four patients with GPN schwannomas underwent surgery at Keio University Hospital. We present the pre- and postoperative clinical findings and describe the structures around the GPN schwannomas as observed during the surgery. Histological sections were performed around the GPN using Masson’s trichrome stain to elucidate the membrane structures. Three patients presented with xerophthalmia, and one with facial palsy, hearing disturbance, and generalized convulsions. Contrast-enhanced magnetic resonance images revealed tumors in the temporal lobe. Bone-window computed tomography showed erosion of the anterior petrous apex. During the operation, the temporal lobe was retracted epidurally. The tumors were visible inside the interdural space and covered with the epineurium. In three cases, the tumors were completely removed, and in one case, the tumor was subtotally removed with intraoperative facial monitoring. In the histological sections, we confirmed that the GPN ran within the interdural space. Approaching epi- and interdurally is suitable for the removal of GPN schwannomas because the GPN is located within the interdural space. The advantage of this approach is that the landmark points can be identified. Moreover, the possibility of injuring the temporal lobe is low because the temporal lobe is not exposed in this approach.
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Greater Petrosal Nerve schwannomas analysis of four cases and review of the literature
Neurosurgical Review, 2010Co-Authors: Shinya Ichimura, Kazunari Yoshida, Agung Budi Sutiono, Takashi Horiguchi, Hikaru Sasaki, Takeshi KawaseAbstract:Schwannomas arising from the Greater Petrosal Nerve (GPN) are exceedingly rare: only 10 such cases have been reported in the English literature. We report on four cases of GPN schwannomas and discuss the surgical approach for their removal. Four patients with GPN schwannomas underwent surgery at Keio University Hospital. We present the pre- and postoperative clinical findings and describe the structures around the GPN schwannomas as observed during the surgery. Histological sections were performed around the GPN using Masson’s trichrome stain to elucidate the membrane structures. Three patients presented with xerophthalmia, and one with facial palsy, hearing disturbance, and generalized convulsions. Contrast-enhanced magnetic resonance images revealed tumors in the temporal lobe. Bone-window computed tomography showed erosion of the anterior petrous apex. During the operation, the temporal lobe was retracted epidurally. The tumors were visible inside the interdural space and covered with the epineurium. In three cases, the tumors were completely removed, and in one case, the tumor was subtotally removed with intraoperative facial monitoring. In the histological sections, we confirmed that the GPN ran within the interdural space. Approaching epi- and interdurally is suitable for the removal of GPN schwannomas because the GPN is located within the interdural space. The advantage of this approach is that the landmark points can be identified. Moreover, the possibility of injuring the temporal lobe is low because the temporal lobe is not exposed in this approach.
Tomio Okamura - One of the best experts on this subject based on the ideXlab platform.
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Neurogenic and endothelial nitric oxide regulates blood circulation in lingual and other oral tissues.
Journal of cardiovascular pharmacology, 2012Co-Authors: Noboru Toda, Kazuhide Ayajiki, Tomio OkamuraAbstract:Blood flow in oral tissues, including the tongue, salivary glands, gingiva, dental pulp, and lip, plays an important role in modulating the complex oral functions involved in food intake. Oral tissue circulation is regulated by nitric oxide (NO) synthesized by neuronal NO synthase mainly present in parasympathetic vasodilator neurons and also by endothelial NO sythase. Electrical stimulation of parasympathetic Nerves causes vasodilatation and blood flow increase in the tongue, submandibular gland, and lip in various mammals in vitro and in vivo. Lingual arteries isolated from Japanese monkeys respond to perivascular Nerve stimulation by electrical pulses and nicotine with relaxations that are mediated via neurogenic NO. There is evidence supporting the hypothesis that the superior salivatory nucleus delivers central information through the geniculate ganglion and Greater Petrosal Nerve to the pterygopalatine ganglion, which sends off impulses through nitrergic Nerves to oral tissues. Endothelial NO also plays an important role in improving oral blood circulation not only in resting conditions but also under conditions activated by chemical and physical stimuli in the tongue, submandibular and parotid glands, dental pulp/gingiva, and cheek pouch. Maintenance of health in oral circulation by minimizing factors responsible for impairment of endothelial and neurogenic NO bioavailability would be important for the prophylaxis of life-style related diseases.
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Nitrergic Nerves derived from the pterygopalatine ganglion innervate arteries irrigating the cerebrum but not the cerebellum and brain stem in monkeys
Hypertension Research, 2012Co-Authors: Kazuhide Ayajiki, Shuhei Kobuchi, Masashi Tawa, Tomio OkamuraAbstract:The functional roles of the nitrergic Nerves innervating the monkey cerebral artery were evaluated in a tension-response study examining isolated arteries in vitro and cerebral angiography in vivo . Nicotine produced relaxation of arteries by stimulation of Nerve terminals innervating isolated monkey arteries irrigating the cerebrum, cerebellum and brain stem. Relaxation of arteries induced by nicotine was abolished by treatment with N ^G-nitro- L -arginine, a nitric oxide synthase inhibitor, and was restored by addition of L -arginine. Cerebral angiography showed that electrical stimulation of the unilateral Greater Petrosal Nerve, which connects to the pterygopalatine ganglion via the parasympathetic ganglion synapse, produced vasodilatation of the anterior, middle and posterior cerebral arteries in the stimulated side. However, stimulation failed to produce vasodilatation of the superior and anterior–inferior cerebellar arteries and the basilar artery in anesthetized monkeys. Therefore, nitrergic Nerves derived from the pterygopalatine ganglion appear to regulate cerebral vasomotor function. In contrast, circulation in the cerebellum and brain stem might be regulated by nitrergic Nerves originating not from the pterygopalatine ganglion, but rather from an unknown ganglion (or ganglia).
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Nitrergic Control of Cerebral Vascular Tone and Blood Flow, and a Possible Blood–Brain Barrier Function
Tzu Chi Medical Journal, 2009Co-Authors: Kazuhide Ayajiki, Takumi Tamayama, Kazuya Shinozaki, Tomio OkamuraAbstract:Neural control of vascular tone is important for the maintenance of circulatory homeostasis. Neurogenic vascular relaxation is obtained not only by the inhibition of constrictor Nerves, but also by the stimulation of dilator Nerves. We have reported that the vasodilator Nerve innervating the cerebral artery is nitrergic in nature. In anesthetized animals, electrical stimulation (ES) of a pterygopalatine ganglion (PPG) or a Greater Petrosal Nerve (GPN) only dilated cerebral arteries on the stimulated side. Nitric oxide (NO) synthase inhibitors abolished this dilation. Surgical denervation at the PPG instantly produced cerebroarterial constriction. In rats, ES of the Nerve bundles from the PPG significantly increased cerebral blood flow, which was inhibited by NO synthase inhibitors. After systemic infusion of FITC (fluorescence)-dextran (10 kD) in anesthetized dogs, ES was applied to one side of the PPG. The fluorescent intensity in certain areas of the brain was higher on the stimulated side. Similar findings were obtained histochemically. T1-weighted MRI enhanced by gadolinium-DTPA during the GPN-stimulation in monkeys showed higher signal intensities in certain brain regions on the stimulated side. These findings suggest that nitrergic Nerves tonically dilate the cerebral artery to maintain the cerebral circulation and may play a role in the regulation of blood-brain barrier permeability.
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Cerebral vasodilatation induced by stimulation of the pterygopalatine ganglion and Greater Petrosal Nerve in anesthetized monkeys.
Neuroscience, 2000Co-Authors: Noboru Toda, Toshiki Tanaka, Kazuhide Ayajiki, Tomio OkamuraAbstract:Abstract Although brain cell viability depends largely on cerebral circulation, mechanisms of blood flow control, such as autoregulation, or of the pathogenesis of functionally impaired blood supply to brain regions, such as in cerebral vasospasm after subarachnoid hemorrhage, have not been clearly defined. Our recent studies support the hypothesis that nitric oxide, released from nitrergic Nerves, plays a crucial role as a neurotransmitter in vasodilating cerebral arteries from primate and subprimate mammals. In the present study, we demonstrated, by using arterial angiography, that electrical stimulation of the pterygopalatine ganglion produced vasodilatation of ipsilateral cerebral arteries of anesthetized Japanese monkeys. The response was abolished by intravenous injections of N G -nitro- l -arginine, a nitric oxide synthase inhibitor. Denervation of the ganglion elicited cerebral vasoconstriction, indicating that vasodilator Nerves from the vasomotor center were tonically active. Stimulation of the Greater Petrosal Nerve, upstream of the pterygopalatine ganglion, also elicited cerebral vasodilatation, which was abolished by treatment with the nitric oxide synthase inhibitor and with hexamethonium, indicating that the Nerve is in connection via synapses with the nitrergic Nerve innervating cerebral arteries. Endogenous nitric oxide released from the Nerve may contribute to the maintenance of blood flow in major cerebral arteries necessary to supply blood to the different brain regions. Without this influence, cerebral arteries might be constricted to the extent that blood flow is impeded. This is the first direct evidence indicating an important role of nitric oxide liberated by pre- and postganglionic Nerve stimulation in the control of cerebral arterial tone in primates.
