Predictors of Surgical Outcomes in Patients with Abducens Nerve Schwannoma: A Comprehensive Systematic Review and a Case Report

BACKGROUND

Abducens nerve (AN) schwannomas are extremely rare tumors. Clinical characteristics and factors that influence postoperative outcomes are not well defined.

OBJECTIVE

To characterize clinical features of AN schwannomas and predictors of surgical outcomes.

METHODS

PRISMA-guided systematic review of the literature on AN schwannomas was performed. Subsequently, univariate and multivariate regression analyses were performed to identify the predictive value of variables that influence postoperative outcomes.

RESULTS

A total of 42 studies with 55 patients were evaluated. The mean age at presentation was 43.9 ± 14.6 years. The most common presenting symptom was cranial nerve VI palsy (69.1%). Cavernous sinus (49.1%) and prepontine cistern (36.3%) were the most commonly involved locations. Complete recovery after surgery was seen in 36.3% at a median follow-up of 28.4 ± 25.8 months. Preoperative AN palsy (P < 0.001), suboccipital approach (P = 0.007), and subtotal resection of tumor (P = 0.044) were significant protective factors for postoperative complications. Prepontine location and postoperative complications were poor prognostic indicators of AN recovery (odds ratio [OR], 0.10, P = 0.030 and OR, 0.10, P = 0.028, respectively). Subtotal resection was significantly correlated with higher odds of AN recovery (OR, 6.06; P = 0.040).

CONCLUSIONS

AN schwannomas are rare but serious tumors that can cause significant morbidity, with only approximately one third of patients showing complete recovery after surgery. The suboccipital approach was a protective factor for postoperative complications, especially when combined with subtotal resection. Knowledge of these factors along with tumor characteristics helps optimize surgical planning and preoperative counseling.

Sphenoid sinus cholesterol granulomas presenting with abducens nerve palsy

We discuss two patients who presented with sphenoid sinus cholesterol granulomas and associated unilateral abducens nerve palsies. Two case reports from our institution are reported. A literature review of available articles is presented, discussing both cholesterol granulomas of the sphenoid sinus and sphenoid sinus lesions that present with unilateral abducens palsy. A total of nine cases of sphenoid sinus cholesterol granulomas have been previously reported in the literature. A wide variety of sphenoid sinus pathologies can present with unilateral abducens nerve palsies, however no sphenoid sinus cholesterol granulomas with this presentation were found in the literature. In conclusion, cholesterol granulomas should be included in the differential when a patient presents with an expansile mass of the sphenoid sinus and associated unilateral abducens nerve palsy.

Diplopia: a unique presentation of recurrence of a salivary gland carcinoma

A 79-year-old man with a history of radical excision of a left submandibular gland carcinoma ex-pleomorphic adenoma presented with a new 2 cm lump in his left submandibular region which proved to be recurrence on surgical excision. During work up for revision surgery he developed a right VI cranial nerve palsy, which was attributed to his microvascular status having had a history of three previous transient ischemic attacks (TIAs). 6 months later, his palsy had not resolved. MRI revealed new soft tissue by the cavernous segment of the internal carotid artery. The exact source of this was unclear as there was no evidence of local recurrence or nodal disease. A repeat MRI scan 16 months later revealed further growth of abnormal tissue in the cavernous sinus and the primary submandibular location, now involving multiple nerves including branches of cranial nerves IV, V, VI, VII and XII making surgical excision impossible.

Bilateral abducens nerve palsies and urinary retention caused by the rupture of a vertebral artery aneurysm: A case report and literature review

RATIONALE

Bilateral abducens nerve deficits caused by vertebral artery (VA) aneurysm have been reported, but there have been no reports regarding accompanying urinary retention.

PATIENT CONCERNS

In this report, we describe an unusual case with bilateral abducens nerve palsy and urinary retention due to rupture of a vertebral aneurysm.

DIAGNOSES

Subarachnoid hemorrhage caused by the rupture of a left VA aneurysm.

INTERVENTIONS

The VA aneurysm was successfully controlled by coil embolization.

OUTCOMES

Urinary retention was improved after embolization and recovered by the day the patient left hospital. The bilateral abducens nerve palsy gradually recovered 6 months later.

LESSONS

This case emphasizes the importance of maintaining a broad, open mind in approaching the diagnosis and management of urinary retention associated with cranial nerve symptoms and reacting quickly to the clinical developments.

Abducent nerve palsy treated by microvascular decompression: a case report and review of the literature

Too few cases of isolated abducent nerve palsy caused by neurovascular compression syndrome have been reported. We here report on a case of abducent nerve palsy caused by neurovascular compression syndrome that was successfully treated by microvascular decompression (MVD). A 46-year-old male presented with a 6-month history of right-sided persistent abducent nerve palsy. High-resolution magnetic resonance imaging revealed a neurovascular contact of the vertebral artery with the right abducent nerve. MVD was performed via a retrosigmoid craniotomy, with remarkable improvement of the palsy. Our report suggests that MVD might be considered as an optional treatment if the symptoms progress or persist.

Abducens nerve palsy in a patient with scrub typhus: a case report

Abducens nerve palsy is a known but rare complication of a few bacterial and viral infections like Mycoplasma pneumonia, cytomegalovirus, Epstein-Barr virus, Hanta virus, herpes zoster, and measles. Abducens nerve palsy due to scrub typhus is extremely rare and so far only one case has been reported in the literature. Scrub typhus is a febrile illness caused by rickettsia, Orientia tsutsugamushi, a gram negative intracellular obligate parasite which is endemic in Asia. This disease can present with wide range of clinical manifestations with involvement of any organ system, alone or in combination. Central nervous system involvement is very common and includes meningism, altered sensorium to focal neurological deficits. We present a rare manifestation of Scrub typhus in the form of sixth cranial nerve involvement which responded to the treatment with doxycycline.

Intraorbital abducens nerve schwannoma

BACKGROUND

Schwannomas of the abducens nerve are extremely rare tumors. The tumor may be located within the cavernous sinus or more often at the prepontine region. However, literature research has identified only one case of isolated schwannoma of the orbit, arising from the terminal branches of the abducens nerve to the lateral rectus muscle. This is only the second report of an abducens nerve schwannoma located entirely intraconal.

CASE DESCRIPTION

We report a case of an intraorbital abducens nerve schwannoma in a 42-year-old man with no signs of neurofibromatosis. The lesion resulted in progressive diplopia and focal abducens palsy. The clinical, radiologic, and pathologic features are presented.

RESULTS

We point the particular aspects and discuss the possible treatments and approaches to preserve nerve function.

CONCLUSIONS

Being a benign lesion, one of the goals has always been total removal. The knowledge of the correct anatomic features made us believe that the VI nerve function could be preserved. Our case is the first example of a total removal with eye abduction preserved. Because of that, we believe that it is reasonable to aim for these goals in future cases.

Two patients with abducens nerve palsy and crossed hemiplegia (Raymond syndrome)

We report 2 patients of alternating hemiplegia with abducens nerve palsy. One patient was also complicated by contralateral supranuclear facial nerve palsy. MRI showed an infarct involving the paramedian and lateral area of the pontine basis in both patients. We considered that corticospinal tract and infraabducens nerve fibers were involved in both patients, and that the corticobulbar tract was involved in 1 patient with supranuclear facial nerve palsy. Although supranuclear facial nerve palsy was not found in the other patient, we speculated that supranucler facial nerve fibers might pass mainly through the aberrant pyramidal tract in this patient.

Recurrent orbital myositis mimicking sixth nerve palsy: diagnosis with MR imaging

We present a case with recurrent orbital myositis sequentially affecting both lateral rectus muscles separately. In the first episode, the absence of the required symptoms for the diagnosis of orbital myositis led to the erroneous diagnosis of sixth nerve palsy. Eventually, the correct diagnosis was established with cerebral MR imaging. Orbital myositis should be included in the differential diagnosis of what appears clinically to be abducens palsy, and MR imaging with a focus on the orbita is mandatory in such patients.

Abducens nerve schwannoma mimicking intrinsic brainstem tumor

Schwannomas of the abducens nerve are extremely rare tumors affecting cavernous, cisternal or both segments of sixth cranial nerve. Clinical features and neuroradiological imagery are frequently insufficient to reach an accurate pre-operative diagnosis. We report a patient with a cystic tumor with ring-like contrast enhancement at the right anterior pontomesencephalic junction. Radical excision was performed via anterior transpetrosal approach and showed an extrinsic tumor originating from the sixth nerve. A postoperative sixth nerve palsy had disappeared completely 9 months after the surgery. The correct diagnosis of an abducens nerve schwannoma is established by the intraoperative finding of a tumor attachment to the sixth nerve and by histopathological analysis. The various differential diagnoses, the clinical and radiological features of this diagnosis and management are issues discussed in this illustrated review.

Isolated intraorbital schwannoma arising from the abducens nerve

CASE REPORT

A case of isolated schwannoma of the orbit, arising from the terminal branches of the abducens nerve to the lateral rectus muscle, is reported. The patient presented with a painless proptosis of the left eye.

DISCUSSION

Preoperative diagnosis of benign intraorbital neoplasm was made by means of CT and MR scans; the mass was radically excised through a microsurgical lateral orbitotomy and the pathological examination revealed a schwannoma. Features of orbital schwannoma are described, together with some details concerning the surgical strategy and the history of the evolution of the lateral orbitotomy.

Review of a series with abducens nerve palsy

OBJECTIVE

In this report, we aimed to investigate the patients that presented at our clinic complaint with diplopia due to the abducens nerve palsy and neurosurgical disease.

METHODS

The study design was a retrospective review of ten cases with the abducens nerve palsy. The causes of the abducens nerve paralysis of our patients were as follows: two cases with head trauma, three cases with pituitary tumors, one case with sphenoid sinus mucocele, one case with greater superficial petrosal nerve cellular schwannoma at the petrous apex, one case with hypertensive intraventricular hemmorhage, one case with hydrocephalus, and one case with parotid tumor and skull base/brain stem invasion.

RESULTS

Depending on the location of the lesion, the symptoms due to nuclear damage showed no improvement as in our case with adenocarcinoma of the parotid gland. The lesions sited at the subarachnoid portion of the abducens nerve or in the cavernous sinus, the abducens nerve palsy improved or botilinum injection was performed during recovery period.

CONCLUSION

We presented abducens nerve palsy cases due to neruosurgical disorders. A botilinum injection was performed in three patients with the abducens palsy. Botilinum injection can help patients with sixth nerve palsy during the recovery period.

Periodic abducens nerve palsy in adults caused by neurovascular compression

Unilateral abducens nerve palsy with periodic recurrences is a well-recognised finding in children, but is rare in adults. The underlying pathophysiological mechanism is unknown. Vascular compression of the nerve is suspected but never demonstrated. We describe an adult patient with, altogether, 11 periods of unilateral right-sided abducens palsy and arterial contact at the root exit zone of the symptomatic side.

Isolated nontraumatic abducens nerve palsy

INTRODUCTION

Abducens nerve palsy (ANP) is the most common isolated palsy. The injury of the abducens nerve can occur anywhere along its long course, so differential diagnosis of ANP occasionally demands thorough investigation to find the proper cause.

PATIENTS

Ten patients with isolated ANP are presented. The causes included nasopharyngeal carcinoma, diabetes, cholesteatoma of the inner ear, carotid-cavernous fistula, subarachnoid bleeding, hydrocephalus, toxic ANP, multiple sclerosis, clinically isolated syndrome suggestive of multiple sclerosis, and Tolosa-Hunt syndrome.

DISCUSSION

Based on the cases presented and review of the literature, we argue that every patient with isolated nontraumatic ANP requires brain MRI as an initial diagnostic tool. If this finding remains inconclusive, additional tests including angiography and CSF examination should be performed.

[Pathological study on abducent paralysis of the vocal cord in a patient having multiple system atrophy with nasogastric intubation]

A 74-year-old man developed instability of gait from age 64, difficulty in writing from age 66 and dysarthria-hypohidrosis from around age 67. These symptoms progressed slowly accompanied with orthostatic hypotension and dysarthria, which decline his ADL. At age 71, he was admitted to our hospital and underwent nasogastric intubation. After admission, he also showed the decrease in his voluntary activities, accidental ingestion and loud snoring during sleep. He died of accidental aspiration pneumonia at age 74. Postmortem examination revealed severe pathological changes as multiple system atrophy (MSA) in the central nervous system. There was a small ulcer in the hypopharyngeal region, and acute inflammation of the ulcer came down to the posterior cricoarytenoid muscle. Combined with severe neurogenic atropy due to MSA, local inflammation of the ulcer associated with nasogastric intubation appeared to have resulted in severe damage of the posterior cricoarytenoid muscle.

Superior sagittal sinus thrombosis and bilateral sixth-nerve palsy in a child with nephrotic syndrome

We report on a patient with nephrotic syndrome who developed superior sagittal sinus thrombosis. He presented with double vision due to bilateral sixth-nerve palsy and papilledema. The thrombosis resolved with intravenous heparin and oral corticosteroids. A month later there were no signs of ocular movement paresis, and both optic nerves were normal.

Microanatomical architecture of Dorello's canal and its clinical implications

OBJECTIVE

We investigated the membranous architecture of the abducens nerve at the petroclival region and describe the characteristics of this area in cadaveric specimen and two children with hydrocephalus and sixth nerve palsy using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Five adult cadaver heads were used to investigate the petroclival part of the abducens nerve. The heads were injected with colored latex for microsurgical dissection, and the length of the dural sleeve of the abducens nerve and its width at the apex were measured. In one cadaver head, the area between the petroclival entrance porus of the abducens nerve and the cavernous sinus was histologically studied under light microscopy. In two patients with hydrocephalus and abducens nerve palsy, the petroclival area was screened by using the MRI fat suppression technique.

RESULTS

In the cadavers, the arachnoid membrane on the clivus extended within the dural sleeve as far as the petrous apex, as an extension of the subarachnoid space. The average length of the dural sleeve was 9.5 mm and the average width was 1.5 mm at the apex, where the nerve entered the cavernous sinus. MRI scans showed that the cerebrospinal fluid distance of the petroclival region was 5 mm in the first patient and 7 mm in the second.

CONCLUSION

The subarachnoid space inside the dural sleeve of the abducens nerve can be defined by using thin-slice MRI scans. Enlargement of the dural sleeve at the petroclival region may coexist with the abducens nerve palsy. It has been documented in this study that the arachnoid membrane forms a membraneous barrier between the subarachnoid and subdural spaces within Dorello's canal.

Pontine tuberculoma presenting with horizontal gaze palsy

A 38-year-old immunocompetent man presented with a horizontal supranuclear gaze palsy as the only neurologic manifestation of a pontine tuberculoma. Although a biopsy of the brain lesion was not performed, it was attributed to tuberculosis because of chest x-ray evidence. The patient was given empirical anti-tuberculous therapy. After one month, the gaze palsy had fully recovered and repeat MRI showed a decrease in the size of the lesion. This is the first reported case of supranuclear gaze palsy without diplopia as a manifestation of a tuberculous brain stem lesion.

Alveolar rhabdomyosarcoma of the clivus with intrasellar expansion: Case report

Rhabdomyosarcomas are common tumors of the head and neck region in children. However, a primarily intracranial localization of this tumor entity is rare. We report on a 3-year-old boy presenting with double vision due to left VI (th) nerve palsy. No other neurological deficits were recognized by clinical inspection. MRI scans visualized an enhancing mass lesion in the upper clivus compressing the cavernous sinus and the pituitary gland. Transsphenoidal biopsy was performed and histopathological examination as well as molecular diagnostics confirmed the diagnosis of an alveolar rhabdomyosarcoma (ARMS). Staging identified a metastatic lesion in the fourth thoracic vertebra resulting in the diagnosis of stage IV disease. Treatment modality included stereotactic radio- and chemotherapy.

Ocular neuromyotonia with spastic lid closure

Ocular neuromyotonia is characterized by tonic spasms of extraocular muscles evoked by eccentric gaze that induces transient strabismus and diplopia. We report the case of a 70-year-old woman who initially presented with unilateral deficits in fifth and sixth cranial nerve functions attributed to a fifth cranial nerve schwannoma. After radiation treatment, she developed neuromyotonia and synkinesis of the ipsilateral third cranial nerve. During the attacks of neuromyotonia, the left eyelids were often spastically closed, a phenomenon not previously reported. The ocular neuromyotonia regressed spontaneously within 3 years, but components of the synkinesis persisted. Ephaptic transmission in a damaged third cranial nerve may be responsible for the neuromyotonia and synkinesis. Synkinesis is a more enduring manifestation.

Optic neuropathy and sixth cranial nerve palsy caused by compression from a dolichoectatic basilar artery

A 53-year-old man with progressive visual loss in the right eye and diplopia manifested dysfunction of the right optic nerve and the right sixth cranial nerve. MRI revealed a markedly enlarged and tortuous basilar artery, its proximal portion compressing the right sixth cranial nerve at the exit from the pons and its distal portion elevating and compressing the right optic nerve. This is the first report of optic neuropathy and sixth cranial nerve palsy caused by a dolichoectatic basilar artery.

A Case of Bilateral Simultaneous Sixth Cranial Nerve Palsies Secondary to Diabetes Mellitus

Ocular motor cranial nerve palsy secondary to diabetes mellitus usually affects one cranial nerve at a time. We report a patient with simultaneous bilateral sixth nerve palsies attributed to diabetes. Although an extremely rare cause of this phenomenon, diabetes may be the explanation after other causes have been excluded.

Posttraumatic acute bilateral abducens nerve palsy in a child

INTRODUCTION

Acute bilateral abducens nerve palsy after traumatic clivus epidural haematoma is a rare condition in trauma patients.

CASE REPORT

In this report, we present a case with this rare neurological complication of head trauma and discuss the possible mechanisms for abducens nerve palsy and clival epidural haematoma.

[Case of herpes zoster ophthalmicus with abducent palsy: the cause and magnetic resonance imaging findings]

PURPOSE

To report the cause and magnetic resonance imaging (MRI) findings in a case of abducent palsy following herpes zoster ophthalmicus.

CASE

A 76-year-old man presented with acute onset of pain, a vesicular cutaneous eruption and herpes zoster ophthalmicus on the right side. He developed complete abducent palsy on the right side two weeks after onset. MRI with gadolinium enhancement showed Meckel's sinus, which contains the trigeminal ganglion, and the abducent nerve on the right side. The patient was treated with intravenous acyclovir and methylprednisolone. The abnormal enhancement shown on MRI vanished immediately and the ophthalmoplegia resolved significantly.

CONCLUSION

This is the first reported case where an affected cranial nerve was detected next to the inflammatory cavernous sinus in ophthalmoplegia following herpes zoster ophthalmicus. These MRI findings showed that this ophthlamoplegia was induced by direct viral invasion or extension of inflammation to the ipsilateral cranial nerve. Further studies need to be performed to clarify the role of specific antiviral therapy or anti-inflammatory agents in treating this complication of herpes zoster.

Paralysies oculomotrices douloureuses : une approche diagnostique

We review the question of diagnosis of painful and relatively isolated ophthalmoplegia due to diseases affecting the ocular motor nerves. For each clinical setting, we provide an overview of the main causes and a practical way to approach the diagnosis. As vascular malformations should always be kept in mind in patients with painful ophthalmoplegia, emergency neuroradiological investigations may be needed. However, the etiological scope is wide and the rationale for choosing the more appropriate examination and its optimal timing depends exclusively on the clinical evaluation. Despite advances in investigation techniques, diagnosis may remain difficult or even unresolved in a certain number of patients. We discuss successively paralysis of the third, sixth and fourth nerve, paralysis of several ocular motor nerves, recurrent ophthalmoplegia and ischaemic ocular motor palsies, which are the most frequent cause.

Bilateral abducent and facial nerve palsies following fourth ventricle shunting: two case reports

CASE REPORTS

Treatment of isolated fourth ventricle syndrome is difficult and there is no widely agreed method. Fourth ventriculo-peritoneal shunting is the most commonly utilized procedure for the management of this syndrome. Complications from shunting are common and are usually related to malfunction, infection, dislocation and overdrainage. We present two unusual cases in which both patients developed bilateral abducens and facial nerve palsies following shunting of an isolated fourth ventricle. Magnetic resonance imaging (MRI) in both cases revealed collapse of the fourth ventricles with downward displacement of the brain stem. In the first case the trans-tentorial pressure difference was equilibrated with the aid of a "Y" connector between the supratentorial and infratentorial shunts, with full recovery of the neurological deficits; in the second case this approach failed and following a complicated neurosurgical course successful endoscopic aqueductal stenting was performed.

DISCUSSION

Pathogenesis of cranial nerve palsies following fourth ventricle shunting and the rationale of treatment are discussed and the literature is reviewed.

Intracranial peripheral primitive neuroectodermal tumor manifesting as abducens nerve palsy

INTRODUCTION

Peripheral primitive neuroectodermal tumor (PNET) occurring as an extra-axial lesion within the intracranial space and extending to the subarachnoid space is extremely rare.

CASE REPORT

An 18-month-old girl presented with an intracranial peripheral PNET manifesting as abducens nerve palsy. Magnetic resonance imaging on admission revealed a lesion affecting the trigeminal and abducens nerves. The tumor was partially removed via the subtemporal approach. Histological examination showed a high-grade, undifferentiated neoplasm of small cell type with positive immunostaining for MIC2. The histological diagnosis was peripheral PNET.

OUTCOME

Craniospinal radiotherapy reduced the tumor size, but adjuvant chemotherapy designed for Ewing's sarcomas and PNETs was not effective. She died 1 month after the last chemotherapy, despite whole craniospinal irradiation (total dose 53.2 Gy) and chemotherapy.

Usefulness of MR imaging in children without characteristic clinical findings of Duane's retraction syndrome

BACKGROUND AND PURPOSE

Duane's retraction syndrome (DRS) consists of a congenital abduction deficit of the eyeball accompanied by retraction of the globe on attempted adduction and by upshoots or downshoots of the affected eye on adduction. These characteristic diagnostic signs of DRS, however, might not be manifested in early childhood. We evaluated the usefulness of MR imaging as a diagnostic tool in such cases.

METHODS

Thin-section gradient-echo imaging at the brain stem level was performed in two pediatric patients with only abduction deficit and 10 control children. Imaging findings were analyzed focused on the presence or absence of the abducens nerve.

RESULTS

The abducens nerve on the affected side was absent in three of three affected eyes in two patients. The right and left abducens nerves were well identified in all 10 control subjects.

CONCLUSION

MR imaging is useful for the differential diagnosis of abduction deficit of the eyeball in pediatric patients. The absence of the abducens nerve suggests DRS strongly in children with abduction deficit.

Aspergillus granuloma of the cavernous sinus: magnetic resonance imaging with pathologic correlation

This case illustrates the correlation between Magnetic Resonance Imaging (MRI) and the pathological findings in a case of cavernous sinus (CS) aspergilloma.

Primary Cerebral Angiitis Containing Marked Xanthoma Cells With Massive Intraparenchymal Involvement-Case Report-

A 27-year-old woman was referred to our hospital with mild disorientation, bilateral abducens nerve palsy, and mild left hemiparesis. Magnetic resonance (MR) imaging revealed diffuse mass lesions resembling malignant glioma in the right frontal intraparenchymal region, with enhancement of multiple meningeal and intraparenchymal nodules. Partial resection of the frontal lesion was performed. Histological examination revealed that the specimens consisted of brain tissue, with marked perivascular infiltration of histiocytes and sheets of xanthomatous cells. The diagnosis was primary cerebral angiitis containing marked xanthoma cells. Steroid therapy was administered over 1 week. MR imaging showed that the remaining lesions resolved gradually, and had disappeared 2 years after surgery. No neurological symptoms or recurrence of the tumor has been observed during the 6-year period since the operation.

Acute ocular motor mononeuropathies: prospective study of the roles of neuroimaging and clinical assessment

The role for immediate neuroimaging in patients 50 years of age or older with acute isolated third, fourth, and sixth nerve palsies is controversial. We prospectively evaluated 66 patients, aged 50 years and older (median 67 years, range 50-85), with acute isolated ocular motor mononeuropathies. Our purpose was to evaluate both the role of neuroimaging and the role of clinical assessment in determining etiology. We found that clinical features, including time to maximal diplopic symptoms, were not predictive of etiology (median 2 days to maximal diplopic symptoms for both peripheral microvascular and other etiologies). The presence of any common vascular risk factor, including diabetes mellitus, hypertension, hypercholesterolemia, or coronary artery disease, was significantly associated with peripheral microvascular etiology in this cohort (p=0.0004, Fisher's exact test). Despite the high prevalence of peripheral microvascular ischemia as an etiology in this age group, other causes were identified by magnetic resonance imaging (MRI) or computed tomography (CT) scanning in 14% of patients. Diagnoses included brainstem and skull base neoplasms, brainstem infarcts, aneurysms, demyelinating disease, and pituitary apoplexy. Neuroimaging procedures may have a role in the initial evaluation of patients 50 years of age or older with acute ocular motor mononeuropathies.

Schwannoma of the abducens nerve in the cavernous sinus

Six cases of cavernous abducens nerve schwannoma have been reported. A new case of a 39 year old female with abducens nerve paresis, exophtalmos, chemosis and headache due to a 1,36 x 2,58 cm cystic right cavernous abducens nerve schwannoma is presented and discussed. The cavernous sinus was opened between the trochlear and ophthalmic nerves. A portion of the tumor capsule adherent to the internal carotid artery was not resected. No deficits were added by surgery. After 30 months of follow up there is no evidence of relapse and only abducens nerve paresis persists.

The mechanism of injury of the abducens nerve in severe head trauma: a postmortem study

The aim of this study is to investigate the mechanism of injury of abducens nerve at petroclival region in severe head trauma. Twenty specimens provided from 10 autopsied cases due to severe head trauma were investigated macroscopically and histopathogically. The slices of the abducens nerve taken consecutively along its course at petroclival region were stained with Hematoxylline-Eosin and evaluated under light microscope. In addition, coexisting cervical injuries in these cases were assessed macroscopically. Edema and perineural hemorrhagia of abducens nerve were identified in all cases. Nerve injury was found more exaggerated at the sites of dural entry point and petrous apex than any other parts of the abducens nerve. Furthermore, microscopically, also remarkable perineural hemorrhage of the abducens nerve was observed at the site of its anastomoses with the sympathetic plexus on the lateral wall of the internal carotid artery (ICA). Abducens nerve is injured at the sites of dural entry point, petrous apex and lateral wall of the ICA, directly proportional with the severity of the trauma. This finding is also significant in verification of the severe head trauma.

Sixth nerve schwannoma: a case report with literature review

A 40-year-old woman presented with diplopia and left VI nerve palsy. After investigations, diagnosis of a meningioma in the parasellar-prepontine region was considered. Following angiography and embolization, near-total excision of the tumour attached to abducens nerve was performed. Histological examination was consistent with the diagnosis of schwannoma. This is the thirteenth case report of a schwannoma of cranial nerve VI and the first such case where embolization of feeding tumour vessels was performed.

Horizontal monocular saccadic failure: an unusual clinically isolated syndrome progressing to multiple sclerosis

This paper describes an unusual clinically isolated syndrome of inflammatory demyelination that was characterized by a right VI nerve palsy and right internuclear ophthalmoparesis (INO), along with an unusual form of dissociated nystagmus. Magnetic resonance imaging (MRI) revealed an isolated lesion within the right dorsomediolateral pontine tegmentum. Four years later, the subject developed a partial sensory transverse myelitis, confirming clinically definite multiple sclerosis (MS). This paper extends the range of isolated syndromes associated with MS.