The Eustachian Tube as a Landmark for Early Identification of the Abducens Nerve During Endonasal Transclival Approaches

2018 ◽  
Vol 16 (6) ◽  
pp. 743-749 ◽  
Author(s):  
Juan M Revuelta Barbero ◽  
Somasundaram Subramaniam ◽  
Raywat Noiphithak ◽  
Juan C Yanez-Siller ◽  
Bradley A Otto ◽  
...  
Keyword(s):  
Eustachian Tube ◽  
Abducens Nerve ◽  
Horizontal Projection ◽  
Entry Zone ◽  
Root Entry Zone ◽  
Vertical Distance ◽  
Fresh Frozen ◽  
The Mean ◽  
Projection Point

Abstract BACKGROUND Expanded endonasal approaches have the potential to injure the abducens nerve (cranial nerve [CN] VI). The nerve's root entry zone (REZ) and cisternal segment (CS) are particularly prone to injury during the clivus resection and dural incision of transclival approaches. OBJECTIVE To investigate the role of the eustachian tube (ET) as a surgical landmark for the REZ and CS of CN VI. METHODS Transclival expanded endonasal approaches were performed bilaterally in 6 fresh-frozen cadaveric specimens (12 sides). Anatomic relationships between ET and CN VI were documented with neuronavigation. RESULTS The mean vertical distance from the inferior brainstem point to the horizontal projection of CN VI REZ, CS midpoint, and interdural segment (ID) were 26.38 mm (95% confidence interval [CI] 17.36-35.4), 38.61 mm (95% CI 25.61-51.61), and 42.68 mm (95% CI 30.14-55.22), respectively. The relative vertical distance from the ET to the horizontal projections of the REZ, CS midpoint, and its ID were 6.43 mm (95% CI 3.25-9.61), 18.66 mm (95% CI 11.52-25.8), and 22.72 mm (95% CI 16.02-29.42), respectively. In the axial plane the angles between the ET and (1) the REZ and its midline horizontal projection point, (2) the midpoint and its midline horizontal projection point, and (3) ID and its midline horizontal projection point were 9.81 ± SD 5.20°, 18.50 ± SD 4.87°, and 24.71 ± SD 6.21°, respectively. CONCLUSION The ET may serve as a constant landmark to reliably predict the position of the REZ and CS of CN VI.

scholarly journals The Petroclinoid Ligament: Its Morphometrics, Relationships, Variations, and Suggestion for New Terminology

2019 ◽  
Vol 81 (06) ◽  
pp. 603-609
Author(s):  
Joe Iwanaga ◽  
Juan J. Altafulla ◽  
Santiago Gutierrez ◽  
Graham Dupont ◽  
Koichi Watanabe ◽  
...  
Keyword(s):  
Abducens Nerve ◽  
Age At Death ◽  
Surgical Microscope ◽  
Fresh Frozen ◽  
Posterior Clinoid Process ◽  
The Mean ◽  
Definition Of ◽  
Two Sides

AbstractThe anatomy and definition of the petroclinoid ligament (PCL) and its relationship with the abducens nerve are variably described. The goal of this study was to clarify the anatomy of the PCL and better elucidate its relationship with the abducens nerve. Thirty-six sides from 18 fresh-frozen adult cadaveric heads were used in this study. Specimens were all Caucasian and derived from 10 males and 8 females. The mean age at death was 79 years. Dissection of the PCL and abducens nerve was performed using a surgical microscope. The anterior and posterior attachments of the PCL, and position of the abducens nerve were noted. Subsequently, the width, thickness, and length of the ligament, and diameter of the abducens nerve were measured. Thirty-one sides (86.1%) were found to have a PCL, on two sides (5.6%), the PCL was ossified, and on three sides (8.3%), the PCL was absent. The width, thickness, and length of the PCL ranged from 0.54 to 3.39, 0.07 to 0.49, and 3.27 to 17.85 mm, respectively. No PCL had an anterior attachment onto the posterior clinoid process but rather, the clivus. Therefore, based on our findings, the PCL would be better described as the petroclival ligament.

Role of Postoperative Magnetic Resonance Imaging after Microvascular Decompression of the Facial Nerve for the Treatment of Hemifacial Spasm

Neurosurgery ◽  
2002 ◽  
Vol 50 (4) ◽  
pp. 720-726 ◽  
Author(s):  
Jin Woo Chang ◽  
Jong Hee Chang ◽  
Jae Young Choi ◽  
Dong Ik Kim ◽  
Yong Gou Park ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Angiography ◽  
Facial Nerve ◽  
Hemifacial Spasm ◽  
Short Range ◽  
Three Dimensional ◽  
Resonance Imaging ◽  
Entry Zone ◽  
Root Entry Zone

Abstract OBJECTIVE: This study was performed to investigate the role of postoperative three-dimensional short-range magnetic resonance angiography in the prediction of clinical outcomes after microvascular decompression (MVD) for the treatment of hemifacial spasm. METHODS: We examined pre- and postoperative magnetic resonance imaging scans obtained between March 1999 and May 2000 for 122 patients with hemifacial spasm, to evaluate the degree of detachment of the vascular contact and changes in the positions of offending vessels. The degree of vascular decompression of the facial nerve root was classified into three groups, i.e., contact, partial decompression, or complete decompression. Contact was defined as unresolved compression, as indicated by postoperative three-dimensional short-range magnetic resonance angiography. Partial decompression was defined as incompletely resolved compression; vascular indentation of the facial nerve was improved, but contact with the facial nerve remained. Complete decompression was defined as completely resolved compression. These findings were compared with the surgical findings and clinical outcomes. RESULTS: Of 122 patients with MVD, complete decompression of offending vessels at the root entry zone of the facial nerve was observed for 106 patients (86.9%), partial decompression was observed for 10 patients (8.2%), and contact with offending vessels was observed for 6 patients (4.9%) by using postoperative three-dimensional short-range magnetic resonance angiography. Our study demonstrated that the types of offending vessels affected neither the degree of decompression of the root entry zone of the facial nerve nor surgical outcomes (P > 0.05). Also, there was no significant relationship between the degree of decompression and improvement of symptoms (P > 0.05). Furthermore, there was no significant relationship between the degree of decompression and the timing of symptomatic improvement (P > 0.05). CONCLUSION: Our data suggest that MVD of the facial nerve alone may not be sufficient to resolve symptoms for all patients with hemifacial spasm. Therefore, unknown factors in addition to vascular compression may cause symptoms in certain cases, and it may be necessary to remove those factors, simultaneously with MVD, to obtain symptom resolution.

Distal-Ulna Stump Stability: The Role of Distal Interosseous Membrane: Myth or Reality? Anatomical Research

Hand ◽  
2021 ◽  
pp. 155894472199972
Author(s):  
Luciano A. Poitevin ◽  
Daniel Postan ◽  
Sergio Valente
Keyword(s):  
Distal Radioulnar Joint ◽  
Interosseous Membrane ◽  
Distal Ulna ◽  
Lateral Border ◽  
Fresh Frozen ◽  
Additional Stability ◽  
Triangular Fibrocartilage ◽  
The Mean ◽  
Anatomical Research

Background Distal-ulna stump (DUS) instability often occurs when performing a distal radioulnar joint (DRUJ) arthroplasty. Recent studies suggest that the distal interosseous membrane (DIOM) reinforces the triangular fibrocartilage complex, providing additional stability to the DRUJ. The aim of this study was to determine whether the DIOM stabilizes the ulnar stump. Methods Twenty fresh-frozen random forearms were dissected. The presence of a distal oblique bundle (DOB) was recorded and measured. The radius was fixed to a vise and the ulna kept free. The DRUJ was fixed with a lag screw. A bone slice was removed by transverse ulna osteotomies 10 and 15 mm proximal to the DRUJ. A 10-N force was applied to the ulna in dorsal and volar directions. Displacements were measured. The DIOM was then transected, and maneuvers and measurements were repeated and compared. Results A distinct distal membrane was present in 70% and a cord-like DOB in 30%. The mean length was 29 mm. Its origin was proximal to the sigmoid notch; its insertion was on the distal third of the ulna, at its lateral border. This attachment is comprised between 39 and 48 mm proximal to the ulnocarpal joint. Initial displacements averaged 22 mm dorsally and 13 mm volarly. After DIOM transection, ulnar translocation increased to 31 mm dorsally and 19 mm volarly. Conclusion In DRUJ arthroplasties, the DIOM does not appear to be a stabilizer of the DUS beneath a useful threshold. Its retaining effect occurs only after an initial 22-mm dorsal displacement, which we consider not clinically admissible. Therefore, in DRUJ arthroplasties, some augmentation might be advisable.

Tonic neck reflex of the decerebrate cat: a role for propriospinal neurons

1985 ◽  
Vol 54 (4) ◽  
pp. 978-987 ◽  
Author(s):  
E. E. Brink ◽  
I. Suzuki ◽  
S. J. Timerick ◽  
V. J. Wilson
Keyword(s):  
Decerebrate Cat ◽  
Entry Zone ◽  
Root Entry Zone ◽  
Upper Cervical ◽  
Dorsal Columns ◽  
Qualitative Effect ◽  
Neck Rotation ◽  
Propriospinal Neurons ◽  
Tonic Neck Reflex

In decerebrate, acutely labyrinthectomized cats we used neck rotation to study the role of direct upper cervical afferents to the cervical enlargement and of cervical and lumbar propriospinal neurons in the tonic neck reflex. Interruption of the dorsal columns between C4 and C5 had no qualitative effect on the dynamics of the reflex although gain usually increased. Direct upper cervical afferents to the cervical enlargement therefore have no unique role in producing the reflex. Many medially located propriospinal neurons in C4 were modulated by neck rotation. About 40% had axons, mostly crossed, that terminated in the cervical enlargement. The others projected more caudally, some as far as L3-L4 or even the lumbar enlargement. For a population of C4 neurons, including propriospinal neurons, we measured the response vector with combinations of roll and pitch stimuli. These vectors ranged from pitch to roll. Many propriospinal neurons in L3-L4, projecting to the lumbosacral enlargement, were also modulated by neck rotation with a variety of response vectors. Some of these neurons had an ascending projection. As in previous experiments, C4 neurons were modulated by neck rotation after spinal transection rostral to the C1 dorsal root entry zone; a wide variety of response vectors was observed. In contrast, almost no modulated L3-L4 neurons were found in the same experiments. The results suggest a role for propriospinal neurons in the tonic neck reflex. They also demonstrate that responses of lumbar neurons to neck rotation are much more dependent on supraspinal pathways than are those of cervical neurons.

scholarly journals Neuropeptides and the Nodes of Ranvier in Cranial Headaches

2022 ◽  
Vol 12 ◽  
Author(s):  
Jacob C. A. Edvinsson ◽  
Kristian A. Haanes ◽  
Lars Edvinsson
Keyword(s):  
Trigeminovascular System ◽  
Satellite Glial Cells ◽  
Entry Zone ◽  
Root Entry Zone ◽  
C Fibers ◽  
Calcitonin Gene ◽  
The Central Nervous System ◽  
Sensory Fibers ◽  
Different Parts

The trigeminovascular system (TGV) comprise of the trigeminal ganglion with neurons and satellite glial cells, with sensory unmyelinated C-fibers and myelinated Aδ-fibers picking up information from different parts of the head and sending signals to the brainstem and the central nervous system. In this review we discuss aspects of signaling at the distal parts of the sensory fibers, the extrasynaptic signaling between C-fibers and Aδ-fibers, and the contact between the trigeminal fibers at the nerve root entry zone where they transit into the CNS. We also address the possible role of the neuropeptides calcitonin gene-related peptide (CGRP), the neurokinin family and pituitary adenylyl cyclase-activating polypeptide 38 (PACAP-38), all found in the TGV system together with their respective receptors. Elucidation of the expression and localization of neuropeptides and their receptors in the TGV system may provide novel ways to understand their roles in migraine pathophysiology and suggest novel ways for treatment of migraine patients.

Predictive Variables for the Successful Treatment of Trigeminal Neuralgia With Gamma Knife Radiosurgery

Neurosurgery ◽  
2011 ◽  
Vol 70 (3) ◽  
pp. 566-573 ◽  
Author(s):  
Kopriva Marshall ◽  
Michael D. Chan ◽  
Thomas P. McCoy ◽  
Adam C. Aubuchon ◽  
J. Daniel Bourland ◽  
...  
Keyword(s):  
Trigeminal Neuralgia ◽  
Dorsal Root ◽  
Gamma Knife Radiosurgery ◽  
Dominant Factor ◽  
Entry Zone ◽  
Dorsal Root Entry Zone ◽  
Root Entry Zone ◽  
Facial Numbness ◽  
The Mean

Abstract Background: Gamma Knife radiosurgery (GKRS) has been reported to be an effective modality to treat trigeminal neuralgia. Objective: To determine predictive factors for the successful treatment of trigeminal neuralgia with GKRS. Methods: Between 1999 and 2008, 777 GKRS procedures for patients with trigeminal neuralgia were performed at our institution. Evaluable follow-up data were obtained for 448 patients. Median follow-up time was 20.9 months (range, 3–86 months). The mean maximum prescribed dose was 88 Gy (range, 80–97 Gy). Dosimetric variables recorded included dorsal root entry zone dose, pons maximum dose, dose to the petrous dural ridge, and cisternal nerve length. Results: By 3 months after GKRS, 86% of patients achieved Barrow Neurologic Institute I to III pain scores, with 43% of patients achieving a Barrow Neurologic Institute I pain score. Twenty-six percent of patients reported posttreatment facial numbness; 28% of patients reported a post-GKRS procedure for relapsed pain, and median time to next procedure was 4.4 years. Multivariate analysis revealed that the development of postsurgical numbness (odds ratio [OR], 2.76; P = .006) was the dominant factor predictive of efficacy. Longer cisternal nerve length (OR, 0.85; P = .005), prior radiofrequency ablation (OR, 0.35; P = .028), and diabetes mellitus (OR, 0.38; P = .013) predicted decreased efficacy. The mean dose delivered to the dorsal root entry zone dose in patients who developed facial numbness (57.6 Gy) was more than the mean dose (47.3 Gy) given to patients who did not develop numbness (P = .02). Conclusion: The development of post-GKRS facial numbness is a dominant factor that predicts for efficacy of GKRS. History of diabetes mellitus or previous radio-frequency ablation may portend worsened outcome.

Extended Transpterygoid Endonasal Far Lateral Approach: The Role of the Eustachian Tube Revised

Skull Base ◽  
2009 ◽  
Vol 19 (01) ◽  
Author(s):  
Paolo Battaglia ◽  
Guglielmo Romano ◽  
Iacopo Dallan ◽  
Maurizio Bignami ◽  
Luca Muscatello ◽  
...  
Keyword(s):  
Eustachian Tube ◽  
Lateral Approach ◽  
Far Lateral Approach ◽  
Far Lateral

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

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