Unilateral Lateral Rectus Paralysis Showing Incomplete "V" Sign' on 18F-FDG PET/CT.

Extraocular muscles show physiologic radiotracer uptake on F-FDG PET/CT as is encountered in most routine scans. Certain pathologies can cause palsy of one or more of the extraocular muscles, leading to hypometabolism on F-FDG PET/CT. We present a case with a classical finding of unilateral hypometabolism of the lateral rectus muscle, disrupting the "V" sign formed due to physiologic uptake. The patient had presented with the complaint of diplopia and was being evaluated further to rule out the possibility of inflammatory/granulomatous infectious etiopathogenesis leading to compression of the abducens nerve resulting in lateral rectus palsy.

Cause of acquired onset of diplopia due to isolated third, fourth, and sixth cranial nerve palsies in patients aged 20 to 50 years in Korea: A high resolution magnetic resonance imaging study.

AIMS: This study aimed to describe the etiologies of acquired onset of diplopia due to isolated third, fourth, and sixth cranial nerve palsies in young adults in Korea. METHODS: This retrospective study included 127 patients aged 20 to 50 years with acquired onset isolated third, fourth, and sixth cranial nerve palsies who received care at the Strabismus and Neuro-ophthalmology Department of Samsung Medical Center from 2013 to 2017. The etiologies of the palsies determined by clinical assessment, high-resolution magnetic resonance imaging (MRI) with three-dimensional constructive interference in steady state, and laboratory testing were analyzed. RESULTS: Fifty-nine patients manifested sixth cranial nerve palsy. Forty-six patients had fourth cranial nerve palsy and 22 patients had third cranial nerve palsy. The most common etiologies of the ocular motor nerve palsies were presumed inflammatory lesions (21.3%), followed by presumed microvascular causes (17.3%), and neoplasms involving the central nervous system (15.7%). Neoplasms were the most common cause of sixth cranial nerve palsy (25.4%). The most common cause of fourth cranial nerve palsy was presumed microvascular ischemia (28.3%), and presumed inflammatory lesions was the most common cause of third cranial nerve palsy (36.4%). Other non-traumatic causes included vascular lesions, ischemic brainstem stroke, intracranial hemorrhage, non-aneurysmal neuro-vascular contact, multiple sclerosis, and infection. CONCLUSION: A substantial proportion of young adult patients with ocular motor nerve palsies manifested pathologies other than presumed microvascular ischemia or idiopathic causes. Neuroimaging and laboratory tests have important roles in the evaluation of patients aged 20-50 years with acquired ocular motor nerve palsies.

Nasopharyngeal carcinoma presenting as a sixth nerve palsy and Horner's syndrome.

The combination of a sixth nerve palsy and ipsilateral Horner's syndrome localises the disease process to the posterior cavernous sinus and can be a result of various pathologies in this region. A 74-year-old Chinese woman presented with a 9-month history of binocular horizontal diplopia worse when looking left. She was found to have a left sixth nerve palsy and Horner's syndrome and MRI revealed an enhancing soft tissue mass in the nasopharynx with involvement of the bones of the skull base and invasion of the left cavernous sinus. Endoscopic biopsy of the mass confirmed the diagnosis of non-keratinising squamous cell carcinoma, which was Epstein-Barr virus positive. She was treated with radiation therapy. Patients with a sixth nerve palsy and ipsilateral Horner's syndrome should have urgent neuroimaging with careful attention to the cavernous sinus since sympathetic fibres join the sixth nerve for a short distance in this location.

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.

Abducens Nerve Schwannoma: A Case Report and Literature Review.

BACKGROUND: Abducens nerve function seldom shows complete recovery after removal of abducens nerve schwannoma. No cases with unclear course of the abducens nerve during surgery have been reported to achieve complete recovery of nerve function. CASE DESCRIPTION: We report the case of a 44-year-old woman who presented with occasional dysgeusia without abducens nerve paresis. Magnetic resonance imaging showed a solid tumor about 2 cm in diameter at the left cerebellopontine cistern. Cranial nerves except the abducens nerve appeared intact. The tumor was removed via suboccipital craniotomy. The abducens nerve was totally invisible on the surface of the tumor throughout the procedure. Only short segments of abducens nerve were identifiable at around Dorello's canal and the root exit zone. The tumor was resected by subcapsular dissection, and part of the tumor capsule was preserved as a scaffold for nerve generation, although whether any abducens nerve was included remained uncertain. Histopathologic examination confirmed World Health Organization grade I schwannoma. Postoperatively, the patient presented with complete left abducens nerve paresis and diplopia, but abducens nerve function began to improve 3 months later and had completely recovered within 16 months after surgery. CONCLUSIONS: This represents the first description of abducens nerve schwannoma in which the course of the abducens nerve was intraoperatively unclear but complete recovery was achieved. In such cases, intentional subcapsular dissection may potentiate functional recovery.

Petroclival Meningioma Presenting With an Ipsilateral Sixth Nerve Palsy and a Contralateral Homonymous Quadrantanopia: A Unique and Topographically Localizing Syndrome.

An 84-year-old woman reported onset of headaches, diplopia, and blurred vision. On examination, she was found to have a left sixth nerve palsy and an incongruous right homonymous hemianopia. Brain MRI demonstrated a left petroclival meningioma, causing this unusual combination of clinical findings. The patient was treated with radiation therapy and has remained stable over 4 years of follow-up.

Parasellar Schwannomas: Extradural vs Extra-Intradural Surgical Approach.

BACKGROUND: Schwannomas of the parasellar region may arise from the trigeminal, oculomotor, trochlear, and abducens nerves. OBJECTIVE: To define the tumor origin, location, and dural relationship (extradural vs extra-intradural vs cisternal) on preoperative magnetic resonance imaging (MRI), in order to plan the best surgical approach (purely extradural vs extra-intradural). METHODS: Twenty-four patients with parasellar schwannomas who underwent surgery were retrospectively analyzed. Twenty arose from the trigeminal nerve (7 intracavernous and 13 within the Meckel's cave), 3 from the oculomotor nerve, and 1 from the abducens nerve. The preoperative identification of the tumor location (extradural vs extra-intradural vs cisternal) and the nerve of origin was defined on MR sequences. All patients were operated on through a pterional approach (extradural or extra-intradural route). RESULTS: The tumor location was correctly defined on MRI in 22 out of 24 cases (92%) and the nerve of origin in 22 (92%). An extradural approach without intradural exploration was performed in all 5 intracavernous trigeminal schwannomas, in 11 out of 13 of the Meckel's cave, and in 2 schwannomas of the oculomotor nerve. Two schwannomas of the Meckel's cave with transgression of the medial dural wall, 1 of the oculomotor nerve, and the abducens nerve schwannoma required an extra-intradural approach. Complete tumor resection was obtained in 19 out of 24 cases (80%). CONCLUSION: The pterional extradural approach is sufficient for Dolenc type I and II trigeminal schwannomas, excepting for those transgressing the inner dural layer. Schwannomas of the oculomotor and abducens nerves with cisternal location require an extradural-intradural approach.

Abducens nerve palsy due to inferior petrosal sinus thrombosis.

Isolated unilateral abducens nerve palsy is usually due to ischemia, trauma or neoplasm. Dorello's canal is the space between the petrous apex and superolateral portion of the clivus, bound superiorly by Gruber's ligament. The abducens nerve travels with inferior petrosal sinus (IPS) though the Dorello's canal before entering the cavernous sinus. A 31-year-old man presented with neck pain, and binocular horizontal diplopia, worse looking towards left and at distance. He had a history of intravenous drug abuse but no history of hypertension or diabetes. On examination, he had complete left 6th nerve palsy with normal fundi, pupils, and other cranial nerves. Methicillin-resistant Staphylococcus aureus bacteremia was detected with naïve tricuspid valve endocarditis and multiple septic emboli to lungs with infarcts. His cerebrospinal fluid was normal. MRI of the brain was normal. MRV of head and neck showed thrombosis of the left internal jugular vein, left sigmoid sinus and left inferior petrosal sinus with normal cavernous sinus and no evidence of mastoiditis. He was treated with broad spectrum antibiotics. He was not anticoagulated for fear of pulmonary hemorrhage from pulmonary infarcts. Although cerebral venous sinus thrombosis commonly presents with elevated intracranial pressure, isolated ipsilateral 6th nerve palsy from its compression in Dorello's canal due to thrombosis of the ipsilateral inferior petrosal sinus is extremely rare. To our knowledge, only two patients have been reported with isolated abducens palsy due to IPS thrombosis; one caused by septic emboli and the other developed it during IPS cortisol level sampling.

Bilateral intracavernous carotid artery aneurysms presenting as abducens nerve palsy: case report.

Bilateral intracavernous carotid artery aneurysms are very rare and can be usually observed in patients with multiple intracranial aneurysms. Here we present the case of a 73 year-old woman who experienced worsening diplopia due to progressive bilateral paresis of the lateral rectus muscles. Computed tomography (CT) and magnetic resonance imaging (MRI) examinations showed bilateral roundish parasellar and intracavernous masses, with homogeneous contrast-enhancement and absence of subarachnoid haemorrhage (SAH). Cerebral angiography revealed bilateral aneurysms of the intracavernous carotid artery. Once considered the age of the patient, the anatomical features of the aneurysms and the risks of traditional or endovascular surgery, we decided not to proceed to any treatment other than the orthoptic correction of the diplopia and the careful correction of arterial hypertension. We provide a brief review of the literature on bilateral intracavernous aneurysms and a discussion about their treatment.

Abducens nerve schwannoma: a case report and review of the literature.

BACKGROUND: Schwannomas of the abducens nerve are extremely rare tumors; only 10 cases have been reported so far. The tumor may be located within the cavernous sinus (CS) or more commonly at the prepontine region. Patients usually present with VIth cranial nerve paresis. CASE DESCRIPTION: We report a case of a 42-year-old male patient who presented with headache, vertigo, and hearing deficit, but no symptoms or signs related to a VIth cranial nerve impairment. Computed tomography and magnetic resonance imaging showed a large mass with a ring-like contrast enhancement in the prepontine area. Surgical treatment, via a simple retrosigmoid suboccipital approach, revealed a schwannoma originating from the VIth cranial nerve at its prepontine portion. Postoperative histological examination confirmed the diagnosis of schwannoma, and the patient had only a VIth cranial nerve palsy, which resolved during long-term follow-up. CONCLUSIONS: Abducens schwannomas are rare tumors, representing less than 1% of all intracranial schwannomas in our clinic and about 13% of oculomotor nerve schwannomas reported in the literature. These lesions can be mainly divided into tumors originating from the intracavernous portion of the VIth cranial nerve or more commonly from the cisternal part of the nerve, leading to a lesion in the prepontine region. In such cases, with no invasion of the cavernous sinus, radical tumor resection with preservation of the abducens nerve can be performed via a simple suboccipital retrosigmoid approach.

CT stereotaxy guided lateral trans-cerebellar programmable fourth ventriculo-peritoneal shunting for symptomatic trapped fourth ventricle.

A trapped fourth ventricle is a rare clinico-radiological entity producing symptoms suggestive of a progressive posterior fossa mass lesion. It is mainly reported in children as a late complication of lateral ventricular shunting to relieve infantile post-meningitic or post-hemorrhagic hydrocephalus. Optional treatment of the trapped fourth ventricle remains controversial. Placement of fourth ventricular shunting via a conventional midline approach can be fraught with complications in about 40% of the patients. Authors report a successful CT Stereotaxy guided high pressure (80 mm H(2)O) programmable fourth ventriculo-peritoneal shunting via a lateral trans-cerebellar approach in a 14-year-old girl with a trapped fourth ventricle, which occurred as a late complication of ventriculo-peritoneal shunting in her infancy. Her preoperative symptoms of raised intracranial pressure, bobble-head doll syndrome and bilateral abducens palsies completely improved following the surgery. Lateral trans-cerebellar stereotactic placement of the fourth ventricular catheter and the use of high-pressure (low flow) programmable shunt (to avoid complications associated with over drainage) are beneficial in some patients with trapped fourth ventricle.

Intracavernous schwannoma of the abducens nerve: a review of the clinical features, radiology and pathology of an unusual case.

We report a case of an intracavernous abducens nerve schwannoma presenting in a 19 year old male of Mediterranean origin. This is only the second report of an abducens nerve schwannoma located entirely within the cavernous sinus. The lesion resulted in a progressive diplopia and focal abducens palsy. The clinical, radiological and pathological features are presented. A literature search has identified only four other abducens nerve schwannomas arising completely or partly within the cavernous sinus. We review these cases and aspects of other ocular cranial nerve schwannomas.