An endoscope-assisted craniometric cadaveric study for the brain stem and the cisternal segment of the trochlear nerve.

Background and purpose: This study analyzed the relationship of trochlear nerve with neurovascular structures using craniometric measurements. The study was aimed to understand the course of trochlear nerve and minimize the risk of injury during surgical procedures. Methods: Twenty trochlear nerves of 10 fresh cadavers were studied bilaterally using endoscopic assistance through the view afforded by the lateral infratentorial-supracerebellar, and the combined presigmoid-subtemporal transtentorial approaches. Trochlear nerves were exposed bilaterally taking seven parameters into consideration: the distance between the cisternal segment of trochlear nerve and vascular structures (superior cerebellar artery/SCA; posterior cerebral artery/PCA), the origin of the trochlear nerve in the brain stem, the angle in the level of tentorial junction, length, diameter, and length of nerve in the cisternal segment. Results: We identified the brain stem and cisternal segments of the trochlear nerve. The lateral infratentorial supracerebellar approach allowed the exposure of the cisternal segments (crural and ambient cisterns), including the origin of the nerve in the brain stem. The combined presigmoid-subtemporal transtentorial approaches provided visualization of the cisternal segment of the nerve and the free edge of the tentorium. In this study, the mean length and width of the trochlear nerve in the cisternal segment were 30.3 and 0.74 mm, respectively. Length of the trochlear nerve from its origin to its dural entrance was 37.2 mm, tentorial dural entrance angle of the trochlear nerve and exit angle of the trochlear nerve from the brain stem were 127.0 degrees and 54 degrees, PCA to trochlear nerve in mid ambient cistern and SCA to trochlear nerve in mid ambient cistern were 7.3 mm and 6.8mm. Conclusion: Trochlear nerve is vulnerable to injury during the surgical procedures. Therefore, it is necessary to have a sufficient knowledge of the anatomy of cisternal segment and its relationship with adjacent neurovascular structures. The anatomical and craniometric data can be helpful in middle and posterior fossa surgery in minimizing the potential injury of the trochlear nerve.

Arterial supply of the upper cranial nerves: a comprehensive review.

The arterial supply to the upper cranial nerves is derived from a complex network of branches derived from the anterior and posterior cerebral circulations. We performed a comprehensive literature review of the arterial supply of the upper cranial nerves with an emphasis on clinical considerations. Arteries coursing in close proximity to the cranial nerves regularly give rise to small vessels that supply the nerve. Knowledge of the arteries supplying the cranial nerves is of particular importance during surgical approaches to the skull base.

[Quantitative analysis of vascular network of oculogyric nerve nuclei].

INTRODUCTION: Nuclei of oculogyric nerves (principal oculomotor nucleus, trochlear nucleus and abducens nucleus) are densely vascularized brainstem structures. The aim of this study was to determine quantitative characteristics of the vascular network of these nuclei. MATERIAL AND METHODS: The study was done on 30 adult brainstems, both male and female, without diagnosed neurological disturbances. Three-millimetre-thick stratums were taken in transversal plane and cut in 0.3 micrometer semi-serial sections stained with Mallory method. The images of studied nuclei were taken with "Leica" DM 1000 microscope and "Leica" EC3 digital camera under 400x magnification, and analyzed by ImageJ software with A 100 grid. The statistical analysis was performed by Statistical Package for the Social Sciences software with 5% level of significance. RESULTS: A statistically significant difference was found in the volume and surface density between principal oculomotor nucleus and trochlear nucleus, and between trochlear nucleus and abducens nucleus. No difference was found in the length density. DISCUSSION: The results of this research match the results of studies on characteristics of vascular network of oculogyric nerve nuclei, while the comparison of vascular networks of these nuclei, substantia nigra, vestibulocochlear nuclei and precentral gyrus illustrates differences in quantitative characteristics of blood vessels in these structures. CONCLUSION: Blood vessels of principal oculomotor nucleus and abducens nucleus have similar dimensions and approximately the same arborization pattern, while vessels of trochlear nucleus have significantly smaller dimensions and density.

[Vascular compression syndromes of the cranial nerves]. / Az agyidegek vascularis kompressziós szindrómál.

The blood vessels which are running nearby the cranial nerves and the brainstem can be elongated; curves and loops of the vessels may develop mostly due to the degenerative alterations of ageing and these vessels can compress the surrounding neural elements. The authors report a review of vascular compression syndromes based on the literature and their own experience. The typical clinical symptoms of the syndromes subserving the proper diagnosis, the pathomechanism, the significance of imaging especially the magnetic resonance angiography, the experience with the surgical technique of microvascular decompression which is the only causal treatment of the syndromes are discussed. In cases of non-responsible medical treatment the microvascular decompression should be the eligible treatment in certain syndromes (trigeminal and glossopharyngeal neuralgia, hemifacial spasm) for it is a highly effective and low risk method.

[Anatomic study of supratrochlear artery and its application in nasal reconstruction].

OBJECTIVE: To study the anatomy of the cutaneous branch (CB) of supratrochlear artery and its relevance to the design of frontal flap in nasal reconstruction. METHODS: 10 fresh cadavers were dissected to study the position and course of the CB of supratrochlear artery (supraorbital rim and facial midline as landmark). The communication between the CB and supraorbital artery was also studied. 5 cases of ultra-thin frontal flaps and 11 cases of bi-flap( cutaneous flap and muscular flap) were designed on anatomic basis. The survival rate of flap, the stability and aesthetic appearance of the reconstructed nose were followed up. RESULTS: The supratrochlear artery gave off constant CB (1.18 +/- 0.36) cm from upper orbital rim and (1.35 +/- 0.34) cm from the midline of face. The CB passed in a subcutaneous plane and communicated with the bilateral muscular branch, CB of the opposite side and bilateral supraorbital artery. The supratrochlear artery only had CB with no muscular branch in 3 cases. All the flaps survived completely except one with blister on the nose tip which healed spontaneously. The postoperative aesthetic appearance was very satisfactory. CONCLUSIONS: The supratrochlear artery has constant CB. The frontal ultra-thin flap pedicled with the CB can improve the therapeutic effect of nasal reconstruction.

MR anatomy of the proximal cisternal segment of the trochlear nerve: neurovascular relationships and landmarks.

PURPOSE: To assess the anatomic features and vascular relationships of the proximal portion of the cisternal segment of the trochlear nerve. MATERIALS AND METHODS: In 30 subjects (60 nerves) and in one patient with right superior oblique myokymia (SOM), the anatomy of the trochlear nerve was depicted with three-dimensional (3D) Fourier transformation constructive interference in steady state (CISS) magnetic resonance (MR) imaging, whereas the adjacent vessels were detected with 3D time-of-flight (TOF) MR imaging before and after gadopentetate dimeglumine administration. The images were evaluated with respect to the identification of the trochlear nerve, the distance between the point of exit (PE) and the midline, the visualized length, the vascular relationships, and the distance between the PE and the point of neurovascular contact. RESULTS: 3D CISS MR imaging depicted the proximal cisternal segment of the trochlear nerve in the transverse, sagittal, and coronal planes in 57 (95%), 51 (85%), and 48 (80%) of 60 nerves, respectively. The distance from the midline to the PE was 3-9 mm, and the maximum visualized length of the trochlear nerve was 1-14 mm. An arterial-trochlear neurovascular contact was seen at the root exit zone (REZ) in eight (14%) nerves and at a mean distance of 3.4 mm distal to the PE in 29 nerves (51%). The patient with SOM had arterial-trochlear neurovascular contact at the REZ. CONCLUSION: Use of 3D CISS sequences and 3D TOF sequences with or without gadopentetate dimeglumine enables accurate identification of the proximal cisternal segment of the trochlear nerve and its neurovascular relationships.

Remission of superior oblique myokymia after microvascular decompression.

Superior oblique myokymia (SOM) is an ocular motility disorder characterized by oscillopsia, vertical or torsional diplopia, sometimes combined with pressure sensation. Although the pathophysiological basis is unclear, isolated case reports have documented its association with intracranial pathological processes. We present a case of SOM associated with a vascular compression of the fourth nerve at the root exit zone. Following microneurosurgical decompression, SOM completely resolved and paralysis of the fourth nerve occurred. This was less disturbing.

Relationships of the cisternal segment of the trochlear nerve.

OBJECT: The cisternal portion of the trochlear nerve (fourth cranial nerve) can easily be injured during intracranial surgical operations. To help minimize the chance of such injury by promoting a thorough understanding of the anatomy of this nerve and its relationships to surrounding structures, the authors present this anatomical study. METHODS: In this study, in which 12 cadaveric heads (24 sides) were used, the authors describe exact distances between the trochlear nerve and various surrounding structures. Also described are relatively safe areas in which to manipulate or enter the tentorium, and these are referenced to external landmarks. CONCLUSIONS: This information will prove useful in planning and executing surgical procedures in and around the free edge of the tentorium cerebelli.

The neurovascular relationships and the blood supply of the trochlear nerve: surgical anatomy of its cisternal segment.

We examined in detail the cisternal segments of 15 trochlear nerves in brain stems injected with India ink and fixed in formalin. The nerves were found to emerge as singular trunks (33.3%), singular trunks with accessory rootlets (13.3%), or two or three roots with (26.7%) or without accessory rootlets (26.7%). The nerves were in close relationship or in contact with the superior cerebellar artery, that is, with the main trunk of the superior cerebellar artery, its medial and lateral terminal stems, the accessory superior cerebellar artery, and the vermian, paravermian, collicular, and lateral hemispheric arteries as well as their small branches. Some of these vessels were connected by anastomoses in 86.7% of the cases. The anastomotic channels varied from 40 to 530 microns in diameter. The cisternal segment of each trochlear nerve was usually supplied by a single long artery, which most often arose from the vermian artery (26.7%) or the collicular artery (26.7%). The feeding vessel ranged from 30 to 80 microns in caliber. We discuss the possible clinical significance of the anatomic data observed in the present study.

The blood supply of the intracavernous cranial nerves: an anatomic study.

Cranial nerve deficits are the most common complications of cavernous sinus surgery. Often the deficit occurs despite anatomic preservation of the nerve, and ischemic injury is thought to be the cause. A better understanding of the blood supply of these nerves may help to prevent such complications. The authors performed a cadaveric microsurgical study of the intracavernous cranial nerves and their blood supply in 20 cavernous sinuses. The oculomotor nerve received branches from the inferolateral trunk or its equivalent in all specimens (100%). The proximal trochlear nerve received branches from the inferolateral trunk in 80% of the specimens and from the tentorial artery of the meningohypophyseal trunk in 20%. The distal half was supplied by the branches from the inferolateral trunk only. In the region of Dorello's canal, the proximal third of the abducens nerve received branches from the dorsal clival artery of the meningohypophyseal trunk. The middle and distal thirds received branches from the inferolateral trunk. The ophthalmic and proximal maxillary segments of the trigeminal nerve received branches from the inferolateral trunk. The distal maxillary segment was supplied by the artery of the foramen rotundum. In the majority of cases, the medial third of the Gasserian ganglion received branches from both the inferolateral trunk and the tentorial artery. The middle third of the ganglion received branches from either the inferolateral trunk or the middle meningeal artery. Our findings indicate the important role the intracavernous branches of the internal carotid artery play in the blood supply of the intracavernous cranial nerves, and stress the need to preserve these branches to prevent or minimize postoperative deficits.

AIDS presenting as focal segmental membranous glomerulopathy.

The case of a young, heterosexual man who was investigated for proteinuria is reported. A renal biopsy specimen showed a focal and segmental membranous glomerulopathy. He was later found to be HIV positive and died from cerebral infarction associated with HIV vasculitis 16 months after his initial presentation. Unusual forms of immune complex mediated glomerulopathies should alert the pathologist to the possibility of HIV associated disease.

Cryptic angioma in the trochlear nerve. Excision of the invaded portion and successful repair with an autologous graft: case report.

Cryptic angiomas, which are intrinsic to cranial nerves, are uncommon. Such lesions involving the trochlear nerve have not been previously described. The authors have therefore found it interesting to report a case fortuitously discovered in a patient with trigeminal neuralgia who underwent a fifth nerve microvascular decompression through the supracerebellar space. The angioma was not responsible for the neuralgia, but because of its potential risk of bleeding, the lesion was treated by resection of the trochlear nerve in its invaded portion. Then, the nerve was successfully repaired with an autograft harvested from the distal part of the sural nerve.

[Diabetic ophthalmoplegia--a clinico-pathological study of the first case in Japan].

Many reports of diabetic ophthalmoplegia have been published from the clinical points of view. However, there have been only three autopsied cases in which the ocular nerves were investigated histopathologically. A 72-year-old housewife was diagnosed to have glycosuria at the age of 67, but no medical treatment was done. She admitted to the hospital, because of acute onset of right eyelid drooping and diplopia for previous four days. She showed complete eyelid ptosis, moderate dilatation of right pupil, loss of light reaction, and extraocular muscle palsy except abduction on the right. Blood pressure was normal. A glucose tolerance test was diabetic and HbA1c was moderately increased. Her diabetes was fairly well-controlled with a diet therapy and injection of lente insulin. Two and a half months after admission, the course of illness became regressive. Seven months later, external ophthalmoplegia was disappeared and only slight anisocoria was seen. She readmitted to the hospital one year and eleven months later, because of anorexia and emaciation. She died of adenocarcinoma of the stomach without chemotherapy. The duration from onset of ocular symptoms to death was two years and one month. At postmortem examination, stomach cancer infiltrated extensively to the abdominal and pelvic viscera, but no metastasis to the nervous system or intraorbital tissues was found. There were mild to moderate atherosclerotic changes in the small-and middle-sized arteries of the kidneys, pancreas and adrenal glands corresponding to her age. Moderate atherosclerosis was found in all of the major arteries including Willis ring, siphon of the right internal carotid artery and Vertebro-basilar one.(ABSTRACT TRUNCATED AT 250 WORDS)

Oculomotor, trochlear, and abducens nerves penetrated by cerebral vessels. Microanatomy and possible clinical significance.

Twenty formaldehyde-fixed brains were examined under the stereoscopic microscope. In 12 brains (60%), the oculomotor nerves were penetrated by the circumflex mesencephalic artery or by a branch of the perforating vessels of the posterior cerebral artery, either on one side (40%) or on both (20%). In one brain (5%), a particular relationship was noticed between the trochlear nerve and the superior cerebellar artery. The abducens nerves were penetrated by the corresponding pontine veins in three brains (15%). These anatomical findings might have important clinical implications.