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Abducens Nerve Palsy

Sixth Nerve Palsy

Abducens nerve palsy may occur due to a myriad of infectious, inflammatory, genetic, or malignant diseases. Inability to perform eye abduction, resulting in binocular horizontal diplopia, is the main symptom, whereas additional neurological deficits can be encountered depending on the site of the lesion. The initial diagnosis can be made with a proper physical examination, but imaging studies of the brain and other tests are necessary to determine the cause.


Presentation

The abducens nerve (cranial nerve VI) is known for its very long travel from the brainstem to the ipsilateral lateral rectus muscle, where it provides an important function by stimulating abduction of the eye [1] [2]. But because the nerve is quite long, it can be damaged at various points along its pathway. In fact, abducens nerve palsy is one of the most frequent nerve palsies encountered in clinical practice, with an established incidence rate of 11.3 per 100 000 individuals [3]. Certain authors have divided the pathologies that cause abducens nerve palsy according to their anatomical sites (the brain stem, subarachnoid space, the petroclival region, the cavernous sinus, and the orbit), and numerous conditions, both localized and systemic, may cause this condition [1] [2]. The principal symptom of abducens nerve palsy is the presence of binocular horizontal diplopia, as the eye is not able to perform abduction, resulting in lateral displacement [4] [5]. In addition, many symptoms accompany sixth nerve palsy depending on the location of the lesion [1] [2] [4] [5]. For example, contralateral hemiparesis, ipsilateral palsy of the facial, but also trigeminal and vestibulocochlear nerves is seen in conditions affecting the brainstem, such as Raymond’s syndrome, Millard-Gubler syndrome and Foville’s syndrome [1]. Then, papilledema, visual deficits, and symptoms suggestive of a central nervous system (CNS) infection of any etiology (bacterial, viral, fungal) may be seen if the nerve is compromised in the subarachnoid space, as various tumors, sarcoidosis, pseudotumor cerebri and meningitis have been described as potential etiologies [1]. On the other hand, epistaxis, rhinorrhea, and serous otitis media, typically encountered in nasopharyngeal carcinoma, can also be seen together in abducens nerve palsy [1]. Other notable causes of this lesion include hypertension, diabetes mellitus, trauma, and several other tumors (meningiomas, acoustic neuromas, cerebellopontine angle tumors, and metastatic deposits), implying that a broad symptomatology could present together with abducens nerve palsy [1] [4] [5] [6].

Nausea
  • Our case lacked the typical symptoms of IIH, such as headache or nausea; therefore, it is necessary to carefully determine the cause of bilateral abducens nerve palsies.[ncbi.nlm.nih.gov]
  • A 68-year-old male patient was admitted to the emergency department with complaints of severe headache, nausea, vomiting, and diplopia after head trauma due to falling.[ncbi.nlm.nih.gov]
  • In cases of abducens nerve palsy due to raised intracranial pressure, patients may experience associated symptoms of headache, pain around the eyes, nausea, or vomiting. Associated pain suggests a microvascular etiology.[eyewiki.aao.org]
  • Patients may also present with other signs of increased intracranial pressure such as headache, nausea, vomiting or papilledema.[reviewofophthalmology.com]
Eruptions
  • After intravenous antiviral and steroid treatments, the vesicular eruptions and abducens nerve palsy improved. Horner's syndrome and diplopia resolved after six months.[ncbi.nlm.nih.gov]
Diplopia
  • After dural closure, pseudomeningocele and headache resolved completely and diplopia improved partially. At 4-week follow-up, there was complete resolution of diplopia.[ncbi.nlm.nih.gov]
  • We report a 50-year-old man who suffered from 5 transient diplopia episodes in 16 months. His diplopia lasted between 2 weeks and 3 months and examination revealed isolated left abducens palsy during the attacks of diplopia.[ncbi.nlm.nih.gov]
  • Dysfunction of one or more of the ocular motor nerves or extraocular muscle injury commonly results in diplopia. Diplopia during endoscopic sinus surgery is caused by surgical trauma or local anesthetics.[ncbi.nlm.nih.gov]
  • Horner's syndrome and diplopia resolved after six months. Here we present the first report of Horner's syndrome and contralateral abducens nerve palsy associated with zoster meningitis.[ncbi.nlm.nih.gov]
  • The patient's headache resolved immediately after surgery while the diplopia and lateral rectus palsy resolved completely after 6 weeks.[ncbi.nlm.nih.gov]
Esotropia
  • RESULTS: A total of 13 patients were included, all of whom had an esotropia with profound abduction deficit (-4 or more).[ncbi.nlm.nih.gov]
  • Primary outcome measures were esotropia in primary position and abduction deficit.[ncbi.nlm.nih.gov]
  • METHODS: In a prospective, comparative, interventional case series, botulinum toxin was injected into the medial rectus muscle of 23 patients with esotropia secondary to abducens nerve palsy within 3 months of onset.[ncbi.nlm.nih.gov]
  • The augmented Hummelsheim procedure improved esotropia from 43(Δ) 5(Δ) preoperatively to 6(Δ) 7(Δ) postoperatively (P 0.0001) and reduced abduction deficits from -4 to -3 (P 0.0001).[ncbi.nlm.nih.gov]
  • Among 25 patients having unilateral surgery, the mean changes in esotropia were: 36.0(Δ) for FTT (n 9), 46.4(Δ) for FTTR (n 7), and 41.3(Δ) for FTTM (n 9).[ncbi.nlm.nih.gov]
Anisocoria
  • Two weeks later, she developed blepharoptosis and anisocoria with a smaller pupil in the right eye, which increased in the darkness.[ncbi.nlm.nih.gov]
Cranial Nerve Involvement
  • In conclusion, cranial nerve involvement in brucellosis can have good prognosis if anti-Brucella treatment is undertaken early.[ncbi.nlm.nih.gov]
  • We present a rare manifestation of Scrub typhus in the form of sixth cranial nerve involvement which responded to the treatment with doxycycline.[ncbi.nlm.nih.gov]
  • MRI is indicated for any brainstem findings to exclude pontine glioma in children (most have papilledema and nystagmus without other cranial nerve involvement) and in adults who show no improvement.[emedicine.com]
Focal Neurologic Deficit
  • Central nervous system involvement is very common and includes meningism, altered sensorium to focal neurological deficits.[ncbi.nlm.nih.gov]

Workup

The diagnosis of abducens nerve palsy is rather easy to make by conducting a proper physical examination that will include a complete assessment of eye muscles. It is necessary, however, to perform a thorough neurological examination, which might reveal other symptoms that could aid in determining the site of the lesion [2] [4]. After the examination, and a detailed patient history that will assess the course and progression of symptoms, imaging studies should be employed. Computed tomography (CT) is often performed as an initial method, but magnetic resonance imaging (MRI) of the endocranium is recommended for evaluation of the underlying cause of abducens nerve palsy, as it provides a more detailed view of the cranial structures [2] [5] [7]. Isolated reports have questioned its cost-effectiveness, however, since many patients in whom vascular diseases are responsible for the lesion improve spontaneously within a short period of time [5] [7]. Nevertheless, MRI is an effective method, while laboratory studies, including a complete blood count (CBC), a full lipid profile, glucose levels, erythrocyte sedimentation rate (ESR), antinuclear antibodies (ANA), and rheumatoid factor, are important in raising clinical suspicion toward vasculitis, diabetes mellitus and atherosclerosis [5]. Because infections and increased intracranial pressure (ICP) are also potential causes of abducens nerve palsy, a lumbar puncture with subsequent examination of the cerebrospinal fluid is recommended as well [1] [6].

Treatment

  • Immune globulin intravenous (human) (IGIV) is effective in the treatment of various autoimmune and inflammatory disorders.[ncbi.nlm.nih.gov]
  • After the exclusion of other organic lesions, especially idiopathic intracranial hypertension, and an assessment of the risk-benefit ratio, discontinuation of treatment must be considered in such cases.[ncbi.nlm.nih.gov]
  • PURPOSE: To compare the effects and complications of botulinum toxin injection into the medial rectus muscle with and without electromyographic (EMG) assistance for treatment of abducens nerve palsy.[ncbi.nlm.nih.gov]
  • Types of treatment Treatment of sixth nerve palsy depends on its cause.[fairview.org]
  • However, despite a relatively long history of botulinum toxin treatment in ocular muscle paralysis ( 4 , 6 ), its use and investigations of treatment with it in diabetic mononeuropathy have been less than scarce.[care.diabetesjournals.org]

Prognosis

  • In conclusion, cranial nerve involvement in brucellosis can have good prognosis if anti-Brucella treatment is undertaken early.[ncbi.nlm.nih.gov]
  • CS is one of the subtypes of ordinary schwannomas and exhibits malignant features on microscopic examination, although it has a good clinical prognosis. No adjuvant treatment was applied because of the tumor's benign character.[ncbi.nlm.nih.gov]
  • Abducens nerve palsy is reported to have a good prognosis after the symptoms have been alleviated.[ncbi.nlm.nih.gov]
  • Palsies related to trauma or brain masses have a guarded prognosis and recovery, if any, may take up to one year.[encyclopedia.com]
  • Prognosis - Sixth nerve palsy Not supplied. Treatment - Sixth nerve palsy Not supplied. Resources - Sixth nerve palsy Not supplied.[checkorphan.org]

Etiology

  • In many instances, the origin is obvious and management straightforward; however, the list of possible etiologies and mimics is vast and diverse and diagnostic decisions can be challenging and even controversial.[ncbi.nlm.nih.gov]
  • ., In this report, we describe four patients with isolated abducens nerve palsy who presented with an acute onset diplopia whose detailed history and examination were suggestive of an ischemic etiology.[ncbi.nlm.nih.gov]
  • Together with a lack of the preceding headache or febrile illness, we propose that neurovascular compression is a possible etiology of recurrent, isolated abducens nerve palsy.[ncbi.nlm.nih.gov]
  • The association is based on the temporal relationship and the exclusion of other possible etiologic factors following extensive laboratory and imaging diagnostics.[ncbi.nlm.nih.gov]
  • Abducens weakness in the above-50 age group is most commonly caused by a vascular etiology. The authors discuss the pathogenesis of this rare clinical entity and present pertinent literature review.[ncbi.nlm.nih.gov]

Epidemiology

  • Keywords: 590 strabismus: etiology • 354 clinical (human) or epidemiologic studies: prevalence/incidence • 400 esotropia and exotropia 2002, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved.[iovs.arvojournals.org]
  • Epidemiology of type 2 diabetes: Indian scenario. Indian J Med Res 2007;125:217-30. [ PUBMED ] 12. Wild S, Roglic G, Green A, Sicree R, King H. Global prevalence of diabetes: Estimates for the year 2000 and projections for 2030.[ijo.in]
Sex distribution
Age distribution

Pathophysiology

  • The underlying pathophysiological mechanism is unknown. Vascular compression of the nerve is suspected but never demonstrated.[ncbi.nlm.nih.gov]
  • A previously unreported potential pathophysiologic injury mechanism is theorized based upon anatomical structure and mode of injury.[ncbi.nlm.nih.gov]
  • No study provides a pathophysiologic explanation for these transient palsies.[ncbi.nlm.nih.gov]
  • The possibility of multifactorial pathophysiology therefore seems likely.[doi.org]
  • Sixth nerve palsy causes the eyes to deviate inward (see: Pathophysiology of strabismus).[en.wikipedia.org]

Prevention

  • Acute management can be medical, with surgical therapy reserved for refractory cases or to prevent future episodes.[ncbi.nlm.nih.gov]
  • The surgical techniques to prevent this complication are discussed. Copyright 2015 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.[ncbi.nlm.nih.gov]
  • Prompt diagnosis and management before intracranial extension can prevent devastating complications.[ncbi.nlm.nih.gov]
  • The disorder prevents some of the muscles that control eye movement from working properly. Affected people cannot turn the eye outwards toward the ear. Other signs and symptoms may include double vision, headaches, and pain around the eye.[rarediseases.info.nih.gov]
  • Occlusion therapy is necessary to alleviate diplopia and prevent amblyopia in children younger than 7 years.[ojoonline.org]

References

Article

  1. Azarmina M, Azarmina H. The Six Syndromes of the Sixth Cranial Nerve. Journal of Ophthalmic & Vision Research. 2013;8(2):160-171.
  2. Ayberk G, Ozveren MF, Yildirim T, Ercan K, Cay EK, Koçak A. Review of a series with abducens nerve palsy. Turk Neurosurg. 2008;18(4):366-373.
  3. Patel SV, Mutyala S, Leske DA, Hodge DO, Holmes JM. Incidence, associations, and evaluation of sixth nerve palsy using a population-based method. Ophthalmology. 2004;111(2):369-375.
  4. Reyes KB, Lee HY, Ng I, Goh KY. Abducens (sixth) nerve palsy presenting as a rare case of isolated brainstem metastasis from a primary breast carcinoma. Singapore Med J. 2011;52(11):e220-222.
  5. Porter RS, Kaplan JL. Merck Manual of Diagnosis and Therapy. 19th Edition. Merck Sharp & Dohme Corp. Whitehouse Station, N.J; 2011.
  6. Nair AG, Ambika S, Noronha VO, Gandhi RA. The diagnostic yield of neuroimaging in sixth nerve palsy - Sankara Nethralaya Abducens Palsy Study (SNAPS): Report 1. Indian J Ophthalmol. 2014;62(10):1008-1012.
  7. Reid JE, Reem RE, Aylward SC, Rogers DL. Sixth Nerve Palsy in Paediatric Intracranial Hypertension. Neuro-Ophthalmology. 2016;40(1):23-27.

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Last updated: 2019-07-11 21:11