Relationship between the posterior cerebral artery and the cisternal segment of the oculomotor nerve

The aim of this study was to evaluate the relationship between the cisternal segment of the oculomotor nerve and the posterior cerebral artery and its branches. The oculomotor nerve and the posterior cerebral artery of 15 cadaver brains (30 hemispheres) were examined using a surgical microscope. The dorsal portion of the cisternal segment of the oculomotor nerve had a close relationship with the P(1) and P(2) segments of the posterior cerebral artery in 100% of cases, the thalamoperforating arteries in 97%, the collicular arteries in 97%, the short circumferential arteries in 33% and the posterior medial choroidal arteries in 20%. The proximal portion of the nerve had a close relationship with the P(1) segment of the posterior cerebral artery, the thalamoperforating arteries, the collicular arteries and the short circumferential arteries, whereas the distal portion had a close relationship with the P(2) segment of the posterior cerebral artery and the posterior medial choroidal arteries. The oculomotor nerve was perforated by various arteries in different portions. These arteries were the thalamoperforating arteries in 10% of the hemispheres, the collicular arteries in 16% and the short circumferential arteries in 11%. It can be concluded that the dorsal portion of the cisternal segment of the oculomotor nerve has a close relationship with the branches arising from the P(1) and P(2) segments of the posterior cerebral artery. These arteries supply the cisternal segment of the oculomotor nerve.

Ophtalmoplégie extrinsèque pure douloureuse du nerf moteur oculaire commun révélant un anévrysme de la carotide

INTRODUCTION

In third cranial nerve palsy, the lack of mydriasis evokes a noncompressive mechanism. Case report. We report a case of a slightly painful, pure extrinsic third-nerve palsy, complete except for the partial ptosis secondary to the compression by an intracavernous carotid aneurysm. Percutaneous endovascular embolization was followed by complete regression of the palsy within 4 weeks. The pupil may have been spared by the mechanism of compression after the separation of the pupillomotor and extrinsic fibers or the ischemia of the third nerve by its arterial trunk lesion.

CONCLUSION

This case report underlines that brain radiological explorations are necessary in some third-nerve pupil-sparing palsies.

Clipping vs coiling of posterior communicating artery aneurysms with third nerve palsy

The authors investigated the evolution of third nerve palsy in patients with posterior communicating artery aneurysms who underwent coiling vs clipping. There was no statistical difference of complete third nerve palsy recovery in both treatments. Both techniques were of clinical benefit. Older age, diabetes, delayed interventions, and complete third nerve palsy at presentation indicated a poor prognosis for recovery.

[An ischemic syndrome of the oculumotor nucleus: associated clinical and anatomical variations on a theme]

Nuclear syndrome of the oculomotor nerve was first described in 1981, it is characterized by the association of an ipsilateral third nerve palsy with a paresis of elevation in the contralateral eye. This syndrome can be caused by vascular or tumoral lesions in the upper midbrain. It is rarely due to ischemic unilateral mesencephalic lesions, because ischemic lesions of the midbrain are usually integrated in a diffuse involvement of the brainstem and the thalamo-sub-thalamic region. In case of nuclear syndrome of the third nerve due to isolated upper midbrain infarct in the paramedian territory, dependent on branches of the basilar artery, oculomotor symptoms are frequently isolated. On the contrary, in fascicular syndromes of the third nerve, resulting from stroke in more lateral territories upon branches of the posterior cerebral artery, many neurological symptoms are associated with the oculomotor signs. We describe 3 patients presenting with a characteristic nuclear syndrome of the third nerve, resulting from a unilateral paramedian ischemic stroke in the upper midbrain, confirmed by cerebral CT scan or MRI examination. Clinical presentation differed in each case, and marked contralateral hemiparesia, cerebellar syndrome and focal asterixis were associated in various ways with the stereotyped oculomotor disorders. In the 3 cases, the nuclear syndrome of the third nerve was associated with fascicular involvement of the nerve, in an unusual clinical picture. The theoretical distinction between nuclear and fascicular syndromes is supported by the anatomical description of the arterial segmentation in the upper midbrain, which remains debated since the first description. According to the variability of clinical presentations, it seems that the arterial territories may be more variable than initially described. Therefore, ischemic lesions of the upper midbrain may involve some vascular borderzones with a high inter-individual variability. Upper midbrain strokes may thus lead to variable clinical pictures.

A study on the sectional anatomy of the oculomotor nerve and its related blood vessels with plastination and MRI

To obtain normal images and sectional anatomical data of the oculomotor nerve and its related arteries, the optimal angles and the length of intracisternal segment of the oculomotor nerve were measured on MPR images. Meanwhile, the relationships between the nerve and the basilar, posterior cerebral, superior cerebellar and posterior communicating arteries were observed from plastination slices, original images, MPR and MIP images. MRI revealed similar results to the plastination sections. The intracisternal segment of oculomotor nerve formed an angle with the posterior plane of the brainstem. The angle was significantly smaller in individuals under 10 and over 50 years old ( P<0.05), and there was no marked difference in the angle between the oculomotor nerve and the median sagittal plane among the different groups ( P>0.05). Shift of the basilar artery was more likely to be found in aged individuals. Most of the posterior cerebral and superior cerebellar arteries were close to the nerve, and a few of them seemed to compress it; for the posterior communicating artery, only the embryonic type was close to or seemed to compress the nerve. MRI is an accurate imaging technique for determination of the relationship of the oculomotor nerve to its related arteries.

Dissection of the intracranial internal carotid artery producing isolated oculomotor nerve palsy with sparing of pupil

Dissection of the internal carotid artery usually occurs in the cervical segment, but rarely may involve the artery in the intracranial course (1). The clinical course of intracranial dissection is often catastrophic, with rapid onset of profound neurological deficit, as a result of middle and/or anterior cerebral artery involvement. When this occurs the mortality rate is generally considered high. We describe a case of intracranial internal carotid artery dissection following trivial trauma presented with an isolated painful pupillary sparing oculomotor nerve palsy.

Hemorrhage in the oculomotor nerve as a complication of leukemia

Oculomotor paralysis of a patient with leukemia was revealed at autopsy to be caused by a hemorrhage in the oculomotor nerve. In a 63-year-old woman with pre-B-cell acute lymphatic leukemia, leukemic invasions occurred in her spinal cord and right oculomotor nerve during a hematological remission state. The oculomotor palsy was aggravated to complete paralysis during a leukemic relapse, which lasted until her death. An autopsy revealed a hemorrhage along with leukemic cells in the right oculomotor nerve at the segment in the upper orbital fissure. Although hemorrhagic oculomotor paralysis is a very rare complication, reports of its occurrence will likely increase with improved survival times of leukemia patients due to advances in chemotherapy.

Vascularization of the brain in guinea pig. IV. Angioarchitectonics of the tectum, tegmentum, and crura mescencephali

Out of three parts of the midbrain the richest vascularization is observed in the tegmentum in which are localized many nuclei. Particularly abundant blood supply shows the main nucleus of the oculomotor nerve. Less vascularized is the central oculomotor nucleus, and scanty blood vessels are found within the autonomic nucleus of the oculomotor nerve. Dense vascular net is found in the supratrochlear nucleus which lies in the central gray substance of the midbrain. Also, dense vascular net is noted within the red nucleus, trochlear nucleus, and the dorsal raphe nucleus. Within the substantia nigra less vascularized is its compact part. Very weak vascularization is observed in the periaqueductal gray and in the crura cerebri. Within the tectum more blood vessels are found in the inferior colliculus as compared with the superior colliculus. Within the crura cerebri the blood vessels do not form vascular net and they ascend into tectum and tegmentum.

Clinical studies of ocular motility disturbances: Part 2. Risk factors for ischemic ocular motor nerve palsy [corrected]

A case-control study of 46 Japanese patients who were diagnosed by exclusion as having ischemic ocular motor nerve palsy and who exhibited spontaneous recovery within 4 months was done to evaluate the risk factors involved. We also evaluated the association between the number of risk factors and the spontaneous recovery or recurrence periods. Ischemic ocular motor nerve palsy is closely related to diabetes mellitus and coronary artery disease. Patients tended to be obese; many had two or more risk factors. Aging, in combination with two or more risk factors, seems to increase the likelihood of developing this disease. Diabetes mellitus is a particularly significant risk factor for this type of palsy, especially in combination with hypertension.

Anatomy of the extraneural blood supply to the intracranial oculomotor nerve

AIMS

An anatomical study was undertaken to determine the extraneural blood supply to the intracranial oculomotor nerve.

METHODS

Human tissue blocks containing brainstem, cranial nerves II-VI, body of sphenoid, and associated cavernous sinuses were obtained, injected with contrast material, and dissected using a stereoscopic microscope.

RESULTS

Eleven oculomotor nerves were dissected, the intracranial part being divided into proximal, middle, and distal (intracavernous) parts. The proximal part of the intracranial oculomotor nerve received extraneural nutrient arterioles from thalamoperforating arteries in all specimens and in six nerves this blood supply was supplemented by branches from other brainstem vessels. Four nerves were seen to be penetrated by branches of brainstem vessels and these penetrating arteries also supplied nutrient arterioles. The middle part of the intracranial oculomotor nerve did not receive nutrient arterioles from adjacent arteries. The distal part of the intracranial oculomotor nerve received nutrient arterioles from the inferior cavernous sinus artery in all 11 nerves and in seven nerves this was supplemented by a tentorial artery arising from the meningohypophyseal trunk. The inferior hypophyseal artery arose from the meningohypophyseal trunk in all 11 cavernous sinuses dissected.

CONCLUSION

This study shows a constant pattern to the blood supply of the intracranial oculomotor nerve. It also highlights the close relation between the blood supplies to the intracavernous oculomotor nerve and the pituitary gland.

Sub total unilateral oculomotor nerve palsy in a Le Fort I osteotomy

A 35-year-old man developed a pupil sparing palsy of the oculomotor nerve after a standard Le Fort I osteotomy during which there had been more bleeding than usual. No definite cause was found but we suggest that it was caused by ischaemia of the nerve secondary to local injury by haematoma or instrumentation. The anatomical basis for this is discussed.

The neurofibrovascular bundle of the inferior oblique muscle as its ancillary origin

PURPOSE

To establish that the neurofibrovascular bundle (NFVB) of the inferior oblique muscle (IO) has ligamentous qualities that enable it to function as an ancillary origin to the muscle. Also, to show that the NFVB does function as the ancillary origin for the IO muscle, particularly when recessing and anteriorly transposing its insertion.

METHODS

Fresh (no formaldehyde preservative) cadaver and patient eyes were studied anatomically, histologically, and physiologically. Eighteen orbits were dissected to isolate the IO, the inferior rectus (IR), and the NFVB to demonstrate the linear course of the NFVB and its adjacent fibrous bands. The shape of the muscle was documented. Coronal sections of the two whole, intact orbits were analyzed histologically. Light and electron microscopic sections of an autopsy specimen and a surgical specimen were used to evaluate the capsule of the NFVB and the adjacent fibrous bands near the anterior portion of the NFVB and their attachment to the IR and IO muscle capsules. The elastic modulus was measured in six in situ and six in vitro cadaver NFVB specimens and in six in vivo surgical cases at the time of denervation of the NFVB. For additional comparison, four in vitro cadaver superior oblique tendons were similarly tested. Six eyes that developed recurrent IO overaction following an anterior transposition procedure were surgically explored to determine what structure was serving as its ancillary origin.

RESULTS

Gross anatomic and microscopic studies showed a linear orientation of the NFVB with adjacent fibrous bands anteriorly joining the IO and IR muscle capsules. The surgical specimens of the anterior portion of the NFVB show about 50% nerve and 50% fibrocollagenous capsule with the collagen fibers aligned parallel to the NFVB. The elastic modulus was highest (stiffest) in surgical specimens of the NFVB and in situ cadaver NFVB, followed by in vitro cadaver NFVB and, finally, in vitro cadaver superior oblique tendon. In patients who have undergone anterior transposition surgery, the NFVB served as the ancillary origin of the IO.

CONCLUSIONS

The name of the neurovascular bundle should be changed to the NFVB, since it has a prominent fibrocollagenous capsule and it is encased in fibrous tissue bands anteriorly. The NFVB has a linear course in the orbit from the apex to the IO muscle and is relatively stiff. The associated fibrous band extends posteriorly from the IO muscle capsule, encasing the nerve anteriorly and attaching 3 to 7 mm posteriorly into the capsule of the IR. The NFVB binds the mid posterior portion of the IO posteriorly. Its ligamentous qualities enable the NFVB to function as an ancillary origin for the IO.

Early progression of ophthalmoplegia in patients with ischemic oculomotor nerve palsies

OBJECTIVE

To describe the frequency and clinical correlates of early progression of ophthalmoplegia in patients with ischemic oculomotor nerve palsies.

DESIGN

Cohort survey, case series.

SETTING

Multispecialty clinic providing primary, secondary, and tertiary care in central and northern Wisconsin.

PATIENTS

Sixteen patients evaluated within 1 week of the reported onset of ischemic oculomotor nerve palsy were identified and followed up prospectively using a standardized ophthalmoplegia grading scheme. All patients were followed up serially until their ophthalmoplegia resolved.

MAIN OUTCOME MEASURES

Descriptive analysis of the temporal course of ophthalmoplegia and frequency of progression of deficits. Comparison between the group that had progression of ophthalmoplegia with the group that did not for age, hematocrit, cholesterol level, and adiposity; presence of diabetes, hypertension, hypercholesterolemia, and coronary artery disease; history of stroke; and tobacco use.

RESULTS

Eleven (69%) of 16 patients had progression of ophthalmoplegia. The median time between reported onset and peak severity of ophthalmoplegia was 10 days. The only important difference between the progressive and nonprogressive groups was a shorter time to resolution of ophthalmoplegia for the nonprogressive group.

CONCLUSIONS

Early progression of ophthalmoplegia occurs often in patients with ischemic oculomotor nerve palsies. The power to find differences between progressive and nonprogressive groups was limited by the small number of patients available for analysis.

Paralytic strabismus

This review of the year's literature on paralytic strabismus contains some especially interesting contributions on epidemiology of ischemic ocular motor palsies, new imaging diagnostic techniques in sixth and fourth nerve palsy and in Graves' ophthalmopathy, and bilateral histological findings in one case of clinically monolateral Duane's retraction syndrome. Some reports concern the reliability of diagnostic tests routinely used for measuring cyclotorsion in superior oblique palsies.

The neurovascular relationships and the blood supply of the oculomotor nerve: the microsurgical anatomy of its cisternal segment

The 27 oculomotor nerves were examined after injection of India ink or methylmethacrylate into the vertebral and the internal carotid arteries. The ventral surface of the cisternal segment of the nerve was noted to be in close relationship with the superior cerebellar artery (96.3%) and its pontine (37.0%), mesencephalic (25.9%) and perforating branches (81.5%); the posterolateral pontine artery (70.4%) and its branches; the anterolateral pontine branches (29.6%), and the perforating branches (85.2%) of the basilar artery; the mesencephalic perforating arteries (11.1%) and their peduncular branches (62.9%); the peduncular branches of the diencephalic perforators (11.1%) and the P1 segment (18.5%); and the accessory collicular artery (3.7%). The dorsal surface of the nerve was in close relationships to the P1 and P2A segments (100%) of the posterior cerebral artery and their peduncular branches (22.2%); the posterior communicating artery (100%); the collicular (100%) and the accessory collicular artery (33.3%), and their peduncular (51.8%) or the perforating branches (22.2%); the medial posterior choroidal artery (25.9%) and its branches (11.1%); and the mesencephalic and diencephalic perforating arteries (100%). Vascular penetration was noted in 51.8% of the third nerves. The most common penetrating vessel was the collicular artery (18.5%) and its branches (22.2%). The cisternal segment of the oculomotor nerve was most often supplied by the mesencephalic perforators (88.9%). The authors discuss the possible clinical significance of the obtained anatomic data.

Risk factors for ischemic ocular motor nerve palsies

OBJECTIVE

To identify risk factors associated with neurologically isolated ischemic ocular motor nerve palsies.

DESIGN

Case-control study.

SETTING

Multispecialty clinic providing primary, secondary, and tertiary care in central and northern Wisconsin.

STUDY PARTICIPANTS

After applying strict, predetermined, inclusion and exclusion criteria to the medical records of patients with ocular motor nerve palsies, 65 case patients 50 years of age or older were identified with ischemic ophthalmoplegia. A control subject, matched for sex and exact year of age, was randomly selected for each case patient from individuals undergoing a comprehensive medical evaluation.

MAIN OUTCOME MEASURES

Prevalence of potential risk factors in case patients and controls, including diabetes, hypertension, hypercholesterolemia, coronary artery disease, left ventricular hypertrophy, adiposity, tobacco use, prior ocular motor nerve palsy, and hematocrit. Risk factors were assessed using standardized definitions.

RESULTS

After adjustment for potential confounding factors, significant risk factors and their associated odds ratios (ORs) and 95% confidence intervals (CIs) were as follows: previously diagnosed diabetes, OR = 5.75 (CI = 1.68 to 19.7); left ventricular hypertrophy, OR = 5.20 (CI = 1.30 to 20.82); and, hematocrit (per percentage increase), OR = 1.35 (CI = 1.13 to 1.61).

CONCLUSION

In addition to the generally accepted risk factor of diabetes, left ventricular hypertrophy and elevated hematocrit appeared to be important determinants of ischemic ocular motor nerve palsy. Additional studies should be undertaken to confirm these findings.

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.

Isolated atraumatic third nerve palsy: clinical features and imaging techniques

We have reviewed 34 consecutive patients imaged for an isolated third nerve palsy over a 2-year period. With pupil sparing the third nerve palsy was most often due to ischaemic microvascular disease. The commonest cause of a third nerve palsy with pupillary involvement was a posterior communicating artery aneurysm. Clinical features such as speed of onset, pain and completeness of palsy were not reliable in the diagnosis of either the nature or the location of the cause. Pupillary involvement was however often associated with a compressive lesion. Imaging along the whole course of the nerve is recommended for adequate evaluation.

Anterior transposition of the inferior oblique. Anatomic assessment of the neurovascular bundle

Anterior transposition of the inferior oblique insertion has been described as an effective procedure for weakening the inferior oblique and for decreasing dissociated vertical deviation. It has been postulated that this occurs by converting the inferior oblique muscle from an elevator to a depressor. We found histologic, radiologic, and clinical evidence that anterior transposition of the inferior oblique muscle converts it to a depressor by means of the firm posterior attachment of the inferior oblique muscle at the site of its neurovascular bundle. This new functional insertion at the neurovascular bundle created by the anterior transposition allows for the depressor effect seen after this procedure.

[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.

Ischaemic oculomotor nerve palsy. Clinical features and vascular risk factors in 23 patients

Of 61 patients with isolated third nerve palsy, 23 (38%) had the characteristic clinical features of an ischaemic oculomotor nerve palsy. The essential sign of this usually painful disorder of acute onset was a marked discrepancy between complete or severe paresis of the extraocular muscles innervated by the third nerve, and sparing of the pupillary sphincter. All patients had completely recovered within 3 months. Fourteen had a history or on follow-up had other cranial mononeuropathies. Except for two patients, all were above the age of 60 years. Of the 23 cases, 11 had diabetes mellitus and 8 an abnormal glucose tolerance test, while in 4 the latter was normal. Almost all had hypertension and were overweight, and half were smokers. In 18 patients, four or five vascular risk factors were present.

[Paralysis of the 3d cranial nerves in diabetes and common oculomotor vascularization]

The purpose of this paper is to present explanations for various patterns of IIIrd cranial nerve involvement in diabetes mellitsus, based on its vascularisation. Three clinical cases of diabetes with numerous attacks of IIIrd nerve paralysis are reported. The following patterns were observed: (1) isolated; (2) associated with Vth nerve involvement and; (3) associated with invovlement of the Vth, IVth, VIth, and occasionally IInd and VIIth nerves. An anatomical study of IIIrd nerve vascularisation demonstrates three territories which could correspond to the 3 patterns of clinical expression. The arterial branches to the IIIrd nerve give off no collaterals in the posterior region of the circle of Willis. In the supra-cavernous region, vascularisation of the IIIrd nerve may be associated with that of the IVth. Eventually, vascularisation of the IIIrd nerve in the intracavernous region is associated with that of the Vth, IVth, VIth, and occasionally IInd and VIIth cranial nerves. Thus, a painless paralysis of the IIIrd nerve (isolated or associated only with an involvement of the IVth) would predictably be related to a vascular disturbance limited to the first or second portion of this nerve, whereas a painful paralysis of the IIIrd nerve, without or with associated involvement of other cranial nerves, would relate to a vascular distrubance in the intra-cavernous region. The anatomo-clinical relationships that have been presented: (1) support the vascular basis of IIIrd nerve paralysis in diabetes; (2) explain the various clinical patterns of IIIrd nerve involvement in that disorder and; (3) act as a model which can be applied to the study of ischemic pathology in other cranial nerves and other etiologies.