Pericollicular surgical approaches to the rhomboid fossa. Part I. Anatomical basis

1997 ◽  
Vol 87 (6) ◽  
pp. 893-899 ◽  
Author(s):  
Christian Strauss ◽  
Elke Lütjen-Drecoll ◽  
Rudolf Fahlbusch
Keyword(s):  
Surgical Approaches ◽  
Detailed Knowledge ◽  
Lower Cranial Nerve ◽  
Content Type ◽  
Anatomical Basis ◽  
Nervus Facialis ◽  
Rectangular Area ◽  
Rhomboid Fossa ◽  
Oculomotor Nuclei ◽  
Functional Morbidity

✓ A safe paramedian approach to the rhomboid fossa for surgical treatment of intrinsic brainstem lesions is based on detailed knowledge of the morphometric anatomy of superficially located motor structures. The morphometry of the rhomboid fossa is described in this report on the basis of histological studies conducted in six human brainstem specimens, with special emphasis on the colliculus facialis and the trigona nervi hypoglossi and vagi. Morphometric data include analysis of shrinkage factors in each specimen. The colliculus is a landmark for the nervus facialis, oculomotor nuclei, and the paramedian pontine reticular formation. In the surgeon's view from the posterior approach, the colliculus covers an area of 5.7 mm in the mediolateral and 6.8 mm in the craniocaudal direction and is located 0.6 mm lateral to the median sulcus. The fibers of the nervus facialis come as close as 0.2 mm to the surface of the fourth ventricle. The colliculus is located 15.7 mm above the obex. The trigona nervi hypoglossi and vagi cover a rectangular area measuring 3.1 by 6.5 mm and serve as a landmark for lower cranial nerve nuclei. These nuclei are located 0.3 mm lateral to the midline. An area with a maximum extension of 0.9 cm between the colliculus and trigona can be used for an infracollicular paramedian approach. The same applies to a supracollicular approach cranial to the colliculus and caudal to the fibers of the nervus trochlearis within the medullary velum, with a craniocaudal extension of 4 mm. Superficial motor nuclei and fibers can be identified by neurophysiological mapping, which helps to define safe surgical corridors into the rhomboid fossa, thus reducing functional morbidity caused by the operative approach in intrinsic pontine and pontomedullary lesions.

Pericollicular approaches to the rhomboid fossa. Part II. Neurophysiological basis

1999 ◽  
Vol 91 (5) ◽  
pp. 768-775 ◽  
Author(s):  
Christian Strauss ◽  
Johann Romstöck ◽  
Rudolf Fahlbusch
Keyword(s):  
Electrical Stimulation ◽  
Nerve Fibers ◽  
Surgical Approaches ◽  
Motor Nucleus ◽  
Anatomical Structures ◽  
Content Type ◽  
Stimulation Parameters ◽  
Motor Nerves ◽  
Rhomboid Fossa ◽  
Fine Print

Object. The authors describe their technique of electrophysiological mapping to assist pericollicular approaches into the rhomboid fossa.Methods. Surgical approaches to the rhomboid fossa can be optimized by direct electrical stimulation of superficially located nuclei and fibers. Electrophysiological mapping allows identification of facial nerve fibers, nuclei of the abducent and hypoglossal nerves, motor nucleus of the trigeminal nerve, and the ambiguous nucleus. Stimulation at the surface of the rhomboid fossa performed using the threshold technique allows localization above the area that is located closest to the surface. Simultaneous bilateral electromyographic (EMG) recordings from cranial motor nerves obtained during stimulation document the selectivity of evoked EMG responses. With respect to stimulation parameters and based on morphometric measurements, the site of stimulation can be assumed to be the postsynaptic fibers at the axonal cone. Strict limitation to 10 Hz with a maximum stimulation intensity not exceeding 2 mA can be considered safe. Direct side effects of electrical stimulation were not observed.Conclusions. Electrical stimulation based on morphometric data obtained on superficial brainstem anatomy defines two safe paramedian supra- and infracollicular approaches to the rhomboid fossa and is particulary helpful in treating intrinsic brainstem lesions that displace normal anatomical structures.

Vertical integration in the real estate sector: three Swedish case studies

2017 ◽  
Vol 10 (2) ◽  
pp. 195-210 ◽  
Author(s):  
Hans Lind
Keyword(s):  
Real Estate ◽  
Vertical Integration ◽  
Bargaining Power ◽  
Detailed Knowledge ◽  
Extensive Literature ◽  
Production Chain ◽  
Content Type ◽  
The Real ◽  
The Real Estate ◽  
Real Estate Sector

Purpose The purpose of this paper is to explain why some real estate companies choose to have a vertically integrated structure, instead of specializing in only stage of the production chain. Design/methodology/approach The first stage of the research was an extensive literature review to generate hypotheses. A case study method was then chosen, as more detailed knowledge about the companies were judged to be needed to evaluate the different hypothesis. Documents about the companies were studied and interviews carried out. Findings In the studies cases, there is no support for theories related to vertical integration as a way to monopolize a market and only marginal support for theories that focus on contracting problems related to the so called hold up problem. The most important factors for the companies were that vertical integration gives information and more options that are important in small number bargaining situations. The companies bargaining power increases when they are better informed about, e.g. costs and profits in nearby activities, and when they can use in-house units, if there are problems to find reasonable conditions on the outside market. Research limitations/implications The main limitation is that only three cases were studied. Practical/implications The study can be helpful both to companies that choose to integrate vertically and those that chose not to. There are similar problems related to information and bargaining power that needs to be handled. Originality/value This is the first study that test theories about vertical integration in the real estate sector.

scholarly journals Influence of new cinematographic and television operators on the attractivity of tourist destinations

2020 ◽  
Vol 6 (3) ◽  
pp. 219-222 ◽  
Author(s):  
Cyril Blanchet ◽  
Nathalie Fabry
Keyword(s):  
Consumer Behavior ◽  
Design Methodology ◽  
Detailed Knowledge ◽  
Recommendation Algorithm ◽  
Content Type ◽  
Tourist Destinations ◽  
User Data ◽  
The Impact

Purpose This paper aims to anticipate the influence of new cinematographic and television operators on the attractiveness of tourist destinations. Design/methodology/approach The methodology developed is two-fold: first, long-haul observation of the sector, and second, a state of the literature on the topic. Findings These platforms reshape the distribution of audiovisual content and influence consumer behavior. Through the detailed knowledge of users (user data, recommendation algorithm), the platforms have important information at their disposal to build future tourism trends. Originality/value In the continuity of research in film tourism, the authors question the impact of platforms that are now emerging as significant operators in the distribution and creation of audiovisual content.

scholarly journals The relationship between the deep fibular nerve and the dorsalis pedis artery and its surgical importance

2009 ◽  
Vol 42 (01) ◽  
pp. 018-021
Author(s):  
R. Chitra
Keyword(s):  
Vascular Supply ◽  
Lower Limbs ◽  
Surgical Approaches ◽  
Tarsal Tunnel ◽  
Detailed Knowledge ◽  
Dorsalis Pedis Artery ◽  
Extensor Hallucis Longus ◽  
Relationship Of ◽  
The Relationship ◽  
Fibular Nerve

ABSTRACTThe aim of this study was to demonstrate the relationship between the deep fibular nerve and the dorsalis pedis artery to provide useful anatomical knowledge for safe surgical approaches in plastic surgery. The dissection of 30 cadaver lower limbs was undertaken to describe the relationship of the deep fibular nerve to the dorsalis pedis artery in the anterior tarsal tunnel and on the dorsum of the foot. The anterior tarsal tunnel is a flattened space between the inferior extensor retinaculum and the fascia overlying the talus and navicular. The deep fibular nerve and its branches pass longitudinally through this fibro-osseous tunnel, deep to the tendons of the extensor hallucis longus and extensor digitorum longus. Four distinct relationships of the deep fibular nerve to the dorsalis pedis artery were determined. The dorsalis pedis neurovascular island flap contains both the dorsalis pedis artery and the deep fibular nerve. Because the design of a neurovascular free flap requires detailed knowledge of the nerve and vascular supply, the data presented here are intended to help surgeons during surgical approaches to the foot and ankle.

Meningiomas arising from the falcotentorial junction

1995 ◽  
Vol 82 (5) ◽  
pp. 726-738 ◽  
Author(s):  
Shoji Asari ◽  
Tomohide Maeshiro ◽  
Susumu Tomita ◽  
Masamitsu Kawauchi ◽  
Nobuyoshi Yabuno ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Mr Imaging ◽  
Superior Sagittal Sinus ◽  
Posterior Part ◽  
Detailed Knowledge ◽  
Content Type ◽  
Sagittal Sinus ◽  
Adjacent Structures ◽  
Upward Gaze Palsy ◽  
Fine Print

✓ Meningiomas arising from the falcotentorial junction are extremely rare. The authors describe the clinical features, neuroimaging studies, and results of surgical treatment of meningiomas of the falcotentorial junction and clarify the characteristics of this lesion based on a review of the literature and seven patients treated at their institution. The most common symptoms resulted from intracranial hypertension. Upward-gaze palsy appeared in only one patient. Computerized tomography (CT) showed no specific findings, but there was no evidence of edema around the tumor. Magnetic resonance (MR) imaging revealed a round, smooth-bordered mass with a peritumoral rim, without edema, and showing marked contrast enhancement. The multiplanar capability of MR imaging delineated the relationship between the tumor and adjacent structures better than did CT. Detailed knowledge of the vascular structures, especially evidence of occlusion of the galenic venous system and the development of collateral venous channels, is critical for successful surgery; stereoscopic cerebral angiography is necessary to achieve this aim. The seven patients described developed five types of collateral venous channels: through the basal vein of Rosenthal to the petrosal vein, through the veins on the medial surface of the parietal and occipital lobes to the superior sagittal sinus, through superficial anastomotic veins, through veins of the posterior fossa to the transverse or straight sinus, and through the falcian veins to the superior sagittal sinus. The first three types mainly developed after occlusion of the galenic system. The tumors were removed through the occipital transtentorial approach with a large window at the posterior part of the falx. A favorable prognosis for patients undergoing surgical treatment of falcotentorial junction meningiomas can be expected if detailed neuroimaging studies and microsurgical techniques are used.

Intra-axial tumors of the cervicomedullary junction

1987 ◽  
Vol 67 (4) ◽  
pp. 483-487 ◽  
Author(s):  
Fred Epstein ◽  
Jeffrey Wisoff
Keyword(s):  
Operative Management ◽  
Neurological Recovery ◽  
Radical Excision ◽  
Term Survival ◽  
Lower Cranial Nerve ◽  
Content Type ◽  
Cervicomedullary Junction ◽  
Cranial Nerve Dysfunction ◽  
Aggressive Surgical Approach ◽  
Spinal Cord Dysfunction

The authors present their experience with the operative management of 20 intra-axial tumors of the cervicomedullary junction. There were two distinct modes of clinical presentation: lower cranial nerve dysfunction and spinal cord dysfunction. Both groups of patients had indolent courses: in 75% of the patients the symptoms had been present for 6 months to 2 years. Radical excision was carried out in all patients. There was no surgical mortality. Postoperative neurological recovery was directly related to the preoperative status; one patient had a significant new deficit. The authors conclude that intrinsic gliomas of the cervicomedullary junction are amenable to radical excision and that an aggressive surgical approach offers the potential for both neurological recovery and long-term survival. The neuroradiological evaluation and operative technique are discussed.

Intraoperative anatomical studies in patients with aneurysms of the anterior communicating artery complex

1992 ◽  
Vol 76 (4) ◽  
pp. 629-634 ◽  
Author(s):  
Edgar Nathal ◽  
Nobuyuki Yasui ◽  
Takeshi Sampei ◽  
Akifumi Suzuki
Keyword(s):  
Surgical Approach ◽  
Radical Surgery ◽  
Anatomical Variations ◽  
Surgical Approaches ◽  
Anterior Communicating Artery ◽  
Anatomical Studies ◽  
Content Type ◽  
Number Of Patients ◽  
Vascular Elements ◽  
Fine Print

✓ The intraoperative anatomical findings of the anterior communicating artery (ACoA) complex in 46 patients with anatomical variations were compared to those in an equal number of patients without variations in order to determine the visualization of the elements of the vascular complex. All patients underwent radical surgery for an ACoA aneurysm by one of three different surgical approaches: transsylvian, anterior interhemispheric, or basal interhemispheric. Visualization of the vascular elements was similar in patients with or without anatomical variations. The differences observed were dependent on the surgical approach selected and on the projection of the aneurysm. It was found that, even when the intraoperative anatomical field and the number of vascular elements visualized are different from those obtained in autopsy studies, the vascular microanatomical characteristics can be confirmed with each surgical approach to the extent necessary to ensure safe clipping of aneurysms in patients both with and without anatomical variations.

scholarly journals Management of anterior inferior cerebellar artery aneurysms: an illustrative case and review of literature

2009 ◽  
Vol 26 (5) ◽  
pp. E6 ◽  
Author(s):  
Nicholas C. Bambakidis ◽  
Sunil Manjila ◽  
Shervin Dashti ◽  
Robert Tarr ◽  
Cliff A. Megerian
Keyword(s):  
Surgical Techniques ◽  
Surgical Approaches ◽  
Anterior Inferior Cerebellar Artery ◽  
Parent Artery ◽  
Illustrative Case ◽  
Detailed Knowledge ◽  
Clinical Effects ◽  
Advantages And Disadvantages ◽  
Parent Artery Occlusion ◽  
Cerebellar Artery

Aneurysms of the anterior inferior cerebellar artery (AICA) are relatively rare among intracranial aneurysms. They can occur in 1 of 3 regions of the AICA: 1) craniocaudal (high or low riding), 2) mediolateral-premeatal (proximal), and 3) meatal-postmeatal (distal). The management strategies for treatment differ according to the location and configuration of the aneurysm. The existing body of neurosurgical literature contains articles published on aneurysms arising from the AICA near the basilar artery (BA), intracanalicular/meatal aneurysms, and distal AICA. Several therapeutic options exist, encompassing microsurgical and endovascular techniques. The authors describe a case of treatment involving a large BA-AICA aneurysm approached via exposure of the presigmoid dura using a retromastoid suboccipital craniectomy and partial petrosectomy. Treatment of these lesions requires detailed knowledge of the anatomy, and an anatomical overview of the AICA with its arterial loops and significant branches is presented, including a discussion of the internal auditory (labyrinthine) artery, recurrent perforating arteries, subarcuate artery, and cerebellosubarcuate artery. The authors discuss the various surgical approaches (retromastoid, far lateral, subtemporal, and transclival) with appropriate illustrations, citing the advantages and disadvantages in accessing these AICA lesions in relation to these approaches. The complications of these different surgical techniques and possible clinical effects of parent artery occlusion during AICA surgery are highlighted.

The pathophysiology of oral pharyngeal apraxia and mutism following posterior fossa tumor resection in children

1995 ◽  
Vol 83 (3) ◽  
pp. 467-475 ◽  
Author(s):  
Andrew T. Dailey ◽  
Guy M. McKhann ◽  
Mitchel S. Berger
Keyword(s):  
Posterior Fossa ◽  
Pediatric Patients ◽  
Tumor Resection ◽  
Posterior Fossa Tumor ◽  
Posterior Fossa Tumors ◽  
Lower Cranial Nerve ◽  
Content Type ◽  
Cranial Nerve Function ◽  
Pharyngeal Musculature ◽  
Fine Print

✓ Mutism following posterior fossa tumor resection in pediatric patients has been previously recognized, although its pathophysiology remains unclear. A review of the available literature reveals 33 individuals with this condition, with only a few adults documented in the population. All of these patients had large midline posterior fossa tumors. To better understand the incidence and anatomical substrate of this syndrome, the authors reviewed a 7-year series of 110 children who underwent a posterior fossa tumor resection. During that time, nine (8.2%) of the 110 children exhibited mutism postoperatively. They ranged from 2.5 to 20 years of age (mean 8.1 years) and became mute within 12 to 48 hours of surgery. The period of mutism lasted from 1.5 to 12 weeks after onset: all children had difficulty coordinating their oral pharyngeal musculature as manifested by postoperative drooling and inability to swallow. Further analysis of these cases revealed that all children had splitting of the entire inferior vermis at surgery, as confirmed on postoperative magnetic resonance studies. Lower cranial nerve function was intact in all nine patients. Current concepts of cerebellar physiology emphasize the importance of the cerebellum in learning and language. The syndrome described resembles a loss of learned activities, or an apraxia, of the oral and pharyngeal musculature. To avoid the apraxia, therefore, the inferior vermis must be preserved. For large midline tumors that extend to the aqueduct, a combined approach through the fourth ventricle and a midvermis split may be used to avoid injuring the inferior vermis.

Continuous electromyography monitoring of motor cranial nerves during cerebellopontine angle surgery

2000 ◽  
Vol 93 (4) ◽  
pp. 586-593 ◽  
Author(s):  
Johann Romstöck ◽  
Christian Strauss ◽  
Rudolf Fahlbusch
Keyword(s):  
Detailed Analysis ◽  
Cranial Nerve ◽  
Cerebellopontine Angle ◽  
Operative Procedure ◽  
Cranial Nerves ◽  
Postoperative Outcome ◽  
Lower Cranial Nerve ◽  
Content Type ◽  
Lower Cranial Nerves ◽  
Fine Print

Object. Electromyography (EMG) monitoring is expected to reduce the incidence of motor cranial nerve deficits in cerebellopontine angle surgery. The aim of this study was to provide a detailed analysis of intraoperative EMG phenomena with respect to their surgical significance.Methods. Using a system that continuously records facial and lower cranial nerve EMG signals during the entire operative procedure, the authors examined 30 patients undergoing surgery on acoustic neuroma (24 patients) or meningioma (six patients). Free-running EMG signals were recorded from muscles targeted by the facial, trigeminal, and lower cranial nerves, and were analyzed off-line with respect to waveform characteristics, frequencies, and amplitudes. Intraoperative measurements were correlated with typical surgical maneuvers and postoperative outcomes.Characteristic EMG discharges were obtained: spikes and bursts were recorded immediately following the direct manipulation of a dissecting instrument near the cranial nerve, but also during periods when the nerve had not yet been exposed. Bursts could be precisely attributed to contact activity. Three distinct types of trains were identified: A, B, and C trains. Whereas B and C trains are irrelevant with respect to postoperative outcome, the A train—a sinusoidal, symmetrical sequence of high-frequency and low-amplitude signals—was observed in 19 patients and could be well correlated with additional postoperative facial nerve paresis (in 18 patients).Conclusions. It could be demonstrated that the occurrence of A trains is a highly reliable predictor for postoperative facial palsy. Although some degree of functional worsening is to be expected postoperatively, there is a good chance of avoiding major deficits by warning the surgeon early. Continuous EMG monitoring is superior to electrical nerve stimulation or acoustic loudspeaker monitoring alone. The detailed analysis of EMG-waveform characteristics is able to provide more accurate warning criteria during surgery.

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