Left Abducens Research Articles

Diffuse Large B-Cell Lymphoma of the Nasal Cavity Presenting as Abducens Nerve Palsy

An 87-year-old man presented with a 1-week history of transient facial numbness, followed by the onset of left diplopia 1 month later. In the neurological examination, he was found to have left abducens nerve palsy. A brain MRI showed an infiltrative lesion invading the left posterior nasal cavity and pterygopalatine fossa, and extending into the left paracavernous region. The histological diagnosis was diffuse large B-cell lymphoma. We report an unusual case of diffuse large B-cell lymphoma occurring in the sinonasal tract with unilateral abducens nerve palsy presenting as an early feature.

When a bruise is not just a bruise

A 58-year-old woman developed binocular diplopia after violently retching during an episode of gastroenteritis. She experienced discomfort over the left lower eyelid and then developed diplopia, maximal on left gaze....

Paralysie des nerfs crâniens VI, VII et X dans le cadre d’une pseudotumor cerebri chez un patient de 13 ans

We describe the case of a 13-year-old boy who presented to the emergency department with an acute onset paresis of the left abducens, facial and vagus nerves. Bilateral papilledema was seen on fundoscopy. Blood tests and brain magnetic resonance imaging and angiography showed no abnormalities. A lumbar puncture revealed an elevated intracranial pressure (575mmH2O) and clear cerebrospinal fluid. The diagnosis of pseudotumor cerebri (PTC) associated with multiple cranial nerve palsies was made. Treatment with acetazolamide was initiated, resulting in progressive improvement with no sequelae and no clinical recurrence over an 8-month follow-up period. PTC in children can present with a wide spectrum of neurological signs, especially cranial nerve palsies which are most likely related to a pressure-dependent stretching mechanism. In 2007, distinctive diagnostic criteria for pediatric PTC were established, including the presence of any cranial nerve palsy in the absence of an identifiable etiology.

Spontaneous resolution of ophthalmologic symptoms following bilateral traumatic carotid cavernous fistulae

A 38-year-old woman developed bilateral carotid cavernous fistulae (CCF) following a motor vehicle collision. Her initial ophthalmologic findings included periorbital edema, palsies of the left oculomotor and abducens nerves, and residual dilated pupils. She subsequently developed significant optic disc edema and retinal vascular dilation bilaterally. Patients with similar injuries typically require neurosurgical or vascular intervention. In this case, the patient's signs resolved spontaneously by 21 months after onset, leaving no residual ocular deficits.

眼症状を呈したAnterior Condylar Confluence 硬膜動静脈瘻の1例

Object: We report a case of endovascular treatment for a dural arteriovenous fistula (DAVF) of the anterior condylar confluence (ACC) with ocular symptoms. Case presentation: A 70-year-old woman presented with left conjunctival injection, eyelid edema and abducens palsy. Angiograms revealed DAVF at the ACC. The arterial supply was the left ascending pharyngeal artery (APA) with retrograde venous drainage into the superior ophthalmic vein (SOV) through the ACC and inferior petrosal sinus (IPS). The patient was successfully treated with transvenous coil embolization. Conclusion: DAVF of the ACC is relatively rare. Although most cases of ACC DAVF start with tinnitus, this case showed ocular manifestations very similar to DAVF of the cavernous sinus fistula as the initial symptoms. Endovascular treatment is usually feasible and effective, but an understanding of the venous anatomy and pathophysiology of the disease are of utmost importance when planning the approach.

Dissecting Aneurysm of Vertebral Artery Manifestating as Contralateral Abducens Nerve Palsy

Isolated abducens nerve paresis related to ruptured vertebral artery (VA) aneurysm is rare. It usually occurs bilaterally or ipsilaterally to the pathologic lesions. We report the case of a contralateral sixth nerve palsy following ruptured dissecting VA aneurysm. A 38-year-old man was admitted for the evaluation of a 6-day history of headache. Abnormalities were not seen on initial computed tomography (CT). On admission, the patient was alert and no signs reflecting neurologic deficits were noted. Time of flight magnetic resonance angiography revealed a fusiform dilatation of the right VA involving origin of the posterior inferior cerebellar artery. The patient suddenly suffered from severe headache with diplopia the day before the scheduled cerebral angiography. Neurologic examination disclosed nuchal rigidity and isolated left abducens nerve palsy. Emergent CT scan showed high density in the basal and prepontine cistern compatible with ruptured aneurismal hemorrhage. Right vertebral angiography illustrated a right VA dissecting aneurysm with prominent displaced vertebrobasilar artery to inferiorly on left side. Double-stent placement was conducted for the treatment of ruptured dissecting VA aneurysm. No diffusion restriction signals were observed in follow-up magnetic resonance imaging of the brain stem. Eleven weeks later, full recovery of left sixth nerve palsy was documented photographically. In conclusion, isolated contralateral abducens nerve palsy associated with ruptured VA aneurysm may develop due to direct nerve compression by displaced verterobasilar artery triggered by primary thick clot in the prepontine cistern.

Abducens nerve palsy during pegvisomant therapy in an acromegalic patient

Pegvisomant is a recent treatment modality of acromegaly, which is most effective in regulating IGF-1 levels. Tumor growth has been reported in 5% of the acromegaly cases treated with pegvisomant. Herein we report a case of acromegaly resistant to surgical treatment, radiotherapy and medical therapy with a somatostatin analogue and cabergolin. Due to presence of pituitary tumor with cavernous sinus invasion and unremitting disease activity pegvisomant therapy was initiated. She developed left abducens nerve palsy after pegvisomant treatment. The objective of this report is to emphasize the value of close follow-up of the acromely cases under pegvisomant therapy, especially if they have cavernous sinus infiltrating tumor. A 44-year-old woman with acromegaly presented with visual defect and diplopia on left lateral gaze. Her complaint developed 3 years after initiation of pegvisomant therapy. Her neurologic examination was consistent with mild abducens nerve palsy on left side. Other causes for abducens nerve palsy were excluded. Pegvisomant was discontinued upon patient request. Although sella MRI did not reveal a tumor growth, even minimal growth within cavernous sinus can cause cranial nerve involvement. Therefore close and careful follow-up of cavernous sinus infiltrating tumors after pegvisomant therapy is crucial to early recognition of complications.

Intracranial melanocytic meningeal tumours and melanosis oculi: case report and literature review

BackgroundMelanocytic meningeal tumours are rare extra-axial neoplasms of the nervous system, with only three reported cases in the cavernous sinus. Herein we describe for the first time the association of ocular melanosis and multiple intracranial melanocytic meningeal tumours, with the presenting lesion being in the cavernous sinus. The importance of this association is discussed together with the diagnostic and therapeutic challenges of the case.Case presentationA 20-year-old man presented with a left sixth cranial nerve deficit; general examination documented only congenital melanosis of the homolateral eye. MRI examination showed a space occupying lesion in the left cavernous sinus, which was followed conservatively for 2 years, until a new space occupying lesion was evident at the level of the right frontal convexity: both lesions presented with neuroradiological characteristics suggestive of melanin content.The frontal convexity lesion was removed: intraoperatively the dura was markedly and diffusely melanotic. Histological examination documented a melanocytic meningeal tumour, with a proliferative index of 3 %. The patient underwent 3D-Conformal Radiation Therapy on the lesion of the cavernous sinus (total dose 5040 cGy), with initial tumour reduction. Three years later, due to a symptomatic growth, he underwent partial removal of the lesion in the cavernous sinus. Histological examination was unchanged. He then received adjuvant Temozolomide with Low Dose Fractionated Radiation Therapy (LD-FRT). Due to further disease progression cisplatin plus fotemustine were administered, concomitant with LD-FRT: after two cycles MRI documented significant disease regression. After a period of apparent disease control, the patient presented with persistent cough and evidence of multiple thoracic metastases, which lead to his death, seven years after presentation.ConclusionsIntracranial melanocytic meningeal tumours are challenging lesions, both from a diagnostic and therapeutic point of view; though rare, the possible association with ocular melanosis should be recognized and might facilitate an early diagnosis. Surgery remains the best possible option when feasible. In the event of partial resection, this “benign” disease might be clinically aggressive.

Delayed Onset of Papilledema in Cerebral Venous Sinus Thrombosis (CVST) (P07.257)

Objective: To present 2 cases of delayed onset papilledema and visual disturbance in CVST patients presenting initially with only headaches. Background The clinical presentations of CVST are variable, but the most common are headache (70-97%) and isolated intracranial hypertension (18-40%). Although 28-41% of patients have papilledema at presentation, it9s unusual to have delayed intracranial hypertension with papilledema after there9s sinus recanalization. Design/Methods: We report 2 CVST cases of worsening intracranial hypertension with visual symptoms and signs, despite improvement of thromboses on imaging. Results: 33-year-old male body builder with 2 months of worsening headaches had normal neurological exam. Contrast MR venogram showed superior sagittal sinus thrombosis. Investigations revealed myeloproliferative disorder with JAK-2 mutation, and antiphospholipid syndrome. Treated with heparin bridging to warfarin (INR2-3). Two months later, CT venogram showed no thrombus, but he developed visual obscurations, tinnitus, and new onset papilledema, peripheral field defects with normal visual acuity. Ten weeks later, he had worsening constrictive field deficits, with recurrence of thromboses in multiple sinuses. Visual field loss progressed on acetazolamide, so he had ventriculoperitoneal shunting, then aspirin and warfarin (INR3-3.5). Papilledema resolved and visual fields improved at 4months. 14-year-old girl had sudden onset headache, photophobia and vomiting after sneezing, and normal neurological exam. Contrast MR venogram showed right transverse sinus thrombosis. On contraceptive pill (estrogen & progestin), with MTHFR heterozygosity and elevated factor VIII. Received heparin then warfarin. Three weeks later, partial sinus recanalization, but she developed tinnitus, blurred vision and diplopia, with new onset severe papilledema, constrictive field deficits, partial left abducens nerve palsy, but normal visual acuity. Acetazolamide has stabilized papilledema and visual field defects at 10weeks. Conclusions: Clinicians need to remain vigilant in assessing for delayed onset papilledema and visual loss in CVST, even after anticoagulation and sinus recanalization. Follow up with serial quantitative perimetry rather than visual acuity is necessary. Disclosure: Dr. Wang has nothing to disclose. Dr. Matar has nothing to disclose. Dr. Allport has nothing to disclose.

Neurosarcoidosis Revealed by Isolated Abducens Nerve Palsy (P07.154)

Objective: To report a rare case of neurosarcoidosis revealed by isolated abducens nerve palsy. Background Isolated abducens nerve palsy has been rarely reported in neurosacroidosis. Design/Methods: Case report. Results: A 23 year old man with no past medical history developed left painless left eye proptosis and double vision. Three month later, he was hospitalized because of new onset of seizure. His neurological examination demonstrated left abducens palsy. His blood work up was normal including normal ACE level. His CSF examination showed normal protein level, 9 white cells without any malignant cells. EEG was normal. Head MRI with and without contrast demonstrated revealed diffuse thickening and enhancement of the dura involving left cavernous sinus, mild mass-effect upon left temporal lobe, soft tissue enhancement extending anteriorly through foramen rotundum into the left orbital apex. His dural biopsy revealed extensive chronic inflammation containing non-necrotizing granulomas, consistent with sarcoidosis. The patient was started on high dose of methylprednisolone for 5 days. (1g each day), followed by a tapering prednisone for 2 months. The patient progressively improved. He became asymptomatic after one week of treatment and did not have any recurrence of seizure after 8 months of follow up. Conclusions: Although rare, neurosarcoidosis should be considered in the differential diagnosis of cavernous sinus syndromes with isolated sixth nerve palsy. Disclosure: Dr. Rajasingham has nothing to disclose. Dr. Souayah has received personal compensation for activities with Walgreens as a consultant. Dr. Souayah has received research support from Talecris.

Case 1: Why does my eye keep turning in?

A five-year-old boy accompanied by his mother presented to the paediatrician’s office with a three-day history of his left eye turning in. He had no emesis, headache or other complaints, except for double vision. The symptoms were preceded by a mild upper respiratory tract infection. His medical history was remarkable for two similar episodes six and 12 months before, both involving his left eye and both following a sinus infection. At that time, a computed tomography scan of his head was performed and was found to be normal except for an incidental finding of an unrelated arachnoid cyst. Subsequent magnetic resonance imaging (MRI), after the second episode, confirmed an otherwise normal brain. He was also evaluated by an ophthalmologist and found to have 20/20 vision. In both previous episodes, the esotropia resolved after two to four weeks. On examination, the boy was alert and interactive. He had normal vital signs, including a blood pressure of 99/62 mmHg. His head circumference was 52 cm (50th percentile for his age). He had no neurocutanoeus lesions. Examination of the head, eyes, ears, nose and throat was only remarkable for left esotropia and an inability to abduct the left eye; otherwise he had full extraocular movements. He had equal and reactive pupils, and a normal fundoscopic examination with no evidence of papilledema. His neurological examination was unremarkable with intact cranial nerves (except for the left sixth cranial nerve), 5 of 5 motor strength, intact proprioception, a negative Romberg’s test, normal reflexes and a normal gait.

Abducens Nerve Palsy Associated With Pseudomeningocele After Lumbar Disc Surgery

Clinical case report and review of the literature. To highlight the importance of including cerebrospinal fluid leak and pseudomeningocele in the differential diagnosis in a patient presenting with diplopia due to abducens palsy after spine surgery and to highlight the possibility of cure after successful surgical repair of the dural defect. Abducens nerve palsy after spine surgery is extremely rare, with only 3 reported cases in the literature. We report the first case of abducens nerve palsy associated with a clinically evident pseudomeningocele, which was completely cured by successful repair of the dural defect. A 53-year-old male patient with diabetes presented 6 weeks after lumbar disc surgery with persistent headache, a fluctuant swelling at the operated site, and diplopia secondary to left abducens nerve palsy. Clinical examination revealed a left abducens nerve palsy and magnetic resonance imaging showed a pseudomeningocele due to dural tear at L4-L5. He underwent exploration, and the dural defect was repaired using 6-0 Vicryl and reinforced with a fibrin sealant. After dural closure, pseudomeningocele and headache resolved completely and diplopia improved partially. At 4-week follow-up, there was complete resolution of diplopia. Clinical examination showed full recovery of the lateral rectus function, indicating resolution of the abducens palsy. Magnetic resonance imaging showed complete resolution of pseudomeningocele. Although uncommon, abducens nerve palsy after cerebrospinal fluid leak should be considered in the differential diagnosis of diplopia developing in a patient who has undergone spine surgery. After confirmation of pseudomeningocele radiologically, early surgical intervention with repair of the dural defect can result in complete recovery of the abducens nerve palsy.

Multiple cranial neuropathies after a rash in two patients

A previously healthy 31-year-old male presented with acute eft facial weakness and horizontal binocular diplopia on looking o the left. Three weeks prior to that, he had fever, myalgia and a eneralized papulovesicular rash 10 days following exposure to his -month-old son who had similar skin lesions. His constitutional ymptoms and rash resolved completely over 2 weeks. Neuroogical examination revealed complete left facial paralysis with ncomplete eye closure and abduction failure of the left eye with onsequent horizontal diplopia. The reminder of the cranial nerve xamination was normal. There were no skin rashes, meningism r long tract signs. These findings were consistent with acute left ower motor neuron facial and left abducens neuropathies. Craial magnetic resonance imaging (MRI) did not detect abnormal arenchymal, leptomeningeal or ependymal lesions or enhanceent. Cerebrospinal fluid (CSF) examination revealed a white cell ount of 8/mm3 (99% lymphocytes, 1% monocytes) and protein of .56 g/L.

A 56-year-old woman with adult-onset ophthalmoplegic migraine presenting with recurrent bilateral abducens nerve palsy

A 56-year-old woman had been experiencing episodic left eye pain followed within 3 days by double vision and adduction of the left eye since the age of 30. The episodes occurred once per month, and her symptoms spontaneously resolved within 3 days. The patient was diagnosed with ophthalmoplegic migraine (OM) with left abducens nerve palsy at the age of 53 years. In May 2011, she developed bilateral retro-orbital pain followed by double vision and limitation of abduction of the right eye. She recalled having a cold and high fever 10 days before the onset of the headache. MRI showed no thickening or enhancement of the right abducens nerve. Constructive interference in steady-state (CISS) MRI showed neurovascular contact between the right abducens nerve and anterior inferior cerebellar artery. Right abducens nerve palsy accompanied by OM was diagnosed after other diseases that can cause ophthalmoplegia were excluded. The patient's eye symptoms gradually improved following steroid treatment. There have been a few similar case reports of adult patients with OM showing left and right abducens nerve palsy at different time points. In this case report, we discuss the possible mechanisms related to OM.

Intracranial Germinoma Manifesting as Cavernous Sinus Syndrome

An 11-year-old girl presented with a rare case of neurohypophyseal germinoma manifesting as cavernous sinus syndrome with left abducens nerve palsy. Magnetic resonance (MR) imaging showed a mass located in the left cavernous sinus. Biopsy revealed an inflammatory reaction with lymphocytic infiltration. Postoperative MR imaging showed regression of the mass. Her eye movements were also restored. However, after 5 months, she developed right oculomotor and abducens nerve palsy, and MR imaging showed a large suprasellar mass invading the bilateral cavernous sinuses. The transcranial biopsy sample showed positive staining for placental alkaline phosphatase and c-kit, and the diagnosis of germinoma was confirmed. Chemotherapy and radiotherapy were administered, and the patient has been in complete remission for over 4 years.

A Case of ALK+ Anaplastic Large T Cell Lymphoma (ALCL) with Lymphomatous Meningitis

Abstract 5226 Background:Anaplastic large T cell lymphoma may present with indolent cutaneous T cell infiltration, progressing to more aggressive skin disease and systemic involvement. In adults lymphomatous meningitis is very rare complication. Case Report:A 62 year old Jamaican woman had been diagnosed with biopsy proven psoriasis when 42 years of age. Ustekinumab had been initiated without effect two months prior to her presentation to us. A new cutaneous nodule on her left neck was then found, shave biopsy of which revealed psoriasiform dermatitis with epidermotropism, suspicious for early patch stage mycosis fungoides. The lesion was CD30+, suggestive of ALCL and was positive for ALK. Positron emission tomography revealed an SUV of 6.0 in the neck mass, but lymph nodes in all regions had an SUV of <2.3. Axillary lymph node biopsy, bone marrow biopsy and flow cytometry were negative. Local electron beam radiation was administered to the left supraclavicular space with complete resolution of the cutaneous nodule. About 2 months following completion of radiation therapy she noted anorexia, 30 lb weight loss, night sweats and left hip pain. Physical examination revealed a sick woman, with whole body scaling red-brown macules and plaques. CBC was normal except for Hb of 10 g/dl, platelets 453,000/dl. Hepatic and renal function studies were normal. ESR was 84 mm/hr, lactic dehydrogenase 670 IU (reference range 300–600 IU) and calcium 15.1 mg/dl. HTLV1, HIV, hepatitis panel and anti-nuclear antibody serologies were negative. Computer automated tomography of the pelvis demonstrated 6×2×8 cm soft tissue mass on the sacrum invading left sacro-iliac joint and ilium. Biopsy revealed ALCL, positive for CD43, CD2dim, CD7dim, CD30, and nuclear and cytoplasmic ALK1, while negative for CD43, 3, 4, 5, 8, 19,20, 34, 138, PAX5, AE1/AE3, Cam5, S100 and TdT. The mass was irradiated with alleviation of pain, but cutaneous nodules progressively appeared and continuous fever developed with negative blood cultures. There was increasing confusion, blurred vision and bilateral abducens paralysis. Magnetic resonance imaging of the head and spine revealed dural enhancement and multiple extra- and intercranial interosseous masses, one of which involved the posterior sella turcica. Cyclophosphamide, doxorubicin, vincristine and prednisone were initiated; lumbar puncture was refused. Within 2 days after treatment initiation the cutaneous nodules disappeared, fever subsided, the left abducens palsy resolved completely while the right improved. Conclusion:Our patient's long standing indolent skin disease abruptly progressed to cutaneous and systemic ALCL, with evidence of lymphomatous meningitis. The response of her abducens palsies and other CNS findings to systemic chemotherapy alone suggests that her meningeal involvement may have arisen from that of adjacent bones. Involvement of CNS in ALK positive systemic anaplastic large cell lymphoma is rare and reported in mainly pediatric cases. Disclosures:No relevant conflicts of interest to declare.

Transcortical Venous Approach for Direct Embolization of a Cavernous Sinus Dural Arteriovenous Fistula

Dural arteriovenous fistulas (dAVFs) represent 10% to 15% of all intracranial arteriovenous malformations. Most often, embolization is accomplished with transfemoral catheter techniques. We present a case in which embolization of a cavernous sinus dAVF was made possible through transcranial cannulation of a cortical draining vein. An 82-year-old woman presented with diplopia, left sixth cranial nerve palsy, intraocular hypertension, and bilateral chemosis. Angiography revealed a complex cavernous dAVF with cortical venous reflux, supplied by both external carotid arteries and the left meningohypophyseal trunk. Percutaneous transvenous access failed, and only partial occlusion was achieved by transarterial embolization. A frontotemporal craniotomy was performed to access the superficial middle cerebral vein in the left sylvian fissure. Under fluoroscopic guidance, a microcatheter was advanced through this vein to the floor of the middle cranial fossa and into the dAVF, permitting coil occlusion. This transcranial vein technique may be a useful adjunct in dAVF therapy when percutaneous transarterial or transvenous approaches fail or are not possible.

Hemifacial spasm associated with intraparenchymal brain stem tumor

parenchymal brain stem lesions remains unclear. A 58-year-old woman, who had been experiencing slowly progressive left facial weakness, diplopia, and dysphagia for 7 years, developed intermittent facial twitches around her left orbicularis oculi, lower face, and platysma. On examination, she had severe left facial weakness, left abducens palsy, moderate dysarthria, tongue atrophy, and mild right hemiparesis. Intermittent contractions were visible in left frontalis, orbicularis oculi, and zygomaticus muscles. These occurred as single twitches and as brief series of contractions (Video). Magnetic resonance imaging revealed a nonenhancing lesion (maximum diameter, 22 mm) in the left lower pons and the central and left upper medulla, with increased signal on T2-weighted and proton density images, consistent with a lowgrade pontomedullary glioma or hamartoma. Notably, the lesion involved the facial nucleus and spared the root exit zones of both facial nerves (Fig. 1). Nerve conduction studies showed significantly reduced amplitudes in the left facial nerve, especially in the orbicularis oris and mentalis branches; however, responses were evident in all facial muscles tested. In blink reflex studies, left supraorbital nerve (SON) stimulation produced normal-latency ipsilateral R1 and significantly prolonged ipsilateral and normal contralateral R2 latencies (55.3 and 39.9 ms, respectively). Right SON stimulation produced normal ipsilateral R1 and R2 latencies, but absent contralateral R2 response. These findings suggest interruption of normal inputs to the left facial nucleus. They are also evidence of cross-communication that could originate from the intramedullary portion of the facial nerve or from the facial nucleus. Electromyography revealed evidence of chronic but not acute neurogenic changes in affected facial muscles. Discharges consistent with HFS were recorded from the left orbicularis oris during an episode of repeated spasm-like contractions, typical of HFS, of the left cheek and perioral muscles. The left orbicularis oris had 1þ fasciculations, as well as intermittent single discharges associated with clonic spasms, typical of HFS. No myokymic discharges were observed. Although involuntary facial muscle contractions have been reported in association with intraparenchymal lesions, 4,5 these conditions may have represented ‘‘spastic paretic hemifacial contracture’’ (SPHC), which is characterized by sustained facial muscle contractions and continuous muscle activity. 6,7 In 1 case 4 electromyography showed high-frequency bursts, but clonic spasms were not mentioned. In the other case 5 contractions were sustained, and electrophysiology showed tonic, nearly continuous activity of the facial nerve and high-frequency discharges in its innervated muscles. Both cases may thus have represented SPHC rather than HFS. To our knowledge, therefore, the present report is the first description of facial twitching with the clinical and electrophysiologic hallmarks of idiopathic HFS, associated with an intraparenchymal brain lesion affecting the facial nucleus but not the facial nerve’s root. Legend to Video. Hemifacial spasm and signs of brain stem dysfunction in the patient described in the present report. The video shows intermittent involuntary muscle contractions mainly involving the zygomaticus and to a lesser degree the frontalis and orbicularis oculi on the left side of the face. These occur at variable intervals, at times as single twitches and other times as brief trains of contractions.

Does orbital proprioception contribute to gaze stability during translation?

Translational motion induces retinal image slip which varies with object distance. The brain must know binocular eye position in real time in order to scale eye movements so as to minimize retinal slip. Two potential sources of eye position information are orbital proprioception and an internal representation of eye position derived from central ocular motor signals. To examine the role of orbital proprioceptive information, the position of the left eye was perturbed by microstimulation of the left abducens nerve during translational motion to the right or left along the interaural axis in two rhesus macaques. Microstimulation rotated the eye laterally, activating eye muscle proprioceptors, while keeping central motor commands undisturbed. We found that microstimulation-induced eye position changes did not affect the translational VOR in the abductive (lateral rectus) direction, but it did influence the responses in the adductive (medial rectus) direction. Our findings demonstrate that proprioceptive inputs appear to be involved in the TVOR responses at least during ipsilateral head movements and proprioceptive influences on the TVOR may involve vergence-related signals to the oculomotor nucleus. However, internal representation of eye position, derived from central ocular motor signals, likely plays the dominant role in providing eye position information for scaling eye movements during translational motion, particularly in the abducent direction.

Abducens Nerve (VI) Injury Caused by Halo-Femoral Traction: A Case Report

Stretch and traction on cranial nerves during surgery may cause localized ischemia or change of position of the cranial nerve leading to subsequent dysfunction. Cranial nerve palsies (VI, IX, X and XII) are the commonly affected nerves. Here we report a cranial nerve VI palsy from a halo-femoral suspension following a posterior spinal fusion. We present an 11-year-old girl with idiopathic scoliosis who was admitted for surgical correction. She had no neurological problems preoperatively. The initial video-assisted thoracoscopic anterior release and cranial bifemoral traction were uneventful. Postoperatively, ten-pound weights were added at the head and another ten were added for counter-traction. Weights were added daily in 5-pound increments. Postoperative day 2, the patient complained of “double vision” which resolved upon decreasing the traction weight only by 5 pounds. She underwent an uneventful posterior spinal fusion one week later with a total intravenous anesthesia technique; motor evoked potentials were adequate throughout the procedure. One day later, she again developed left sixth cranial nerve palsy with inability to gaze laterally. There were no other neurological deficits, headaches or even double vision. Neurology and ophthalmology consultations excluded hypoxia/hypoperfusion as possible etiologies. The femoral pins and occipital frame were removed on day 3 in order to obtain imaging and also to remove a potential source of infection. The left lateral rectus palsy was noted to improve that same day. Radiological imaging results were ultimately normal. There is a need for frequent neurological examinations in patients in halo-tractions and prompt removal of the instrument at the first sign of eye problems. doi:10.4021/jnr39e