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 Table of Contents    
CASE REPORT
Year : 2015  |  Volume : 8  |  Issue : 3  |  Page : 179-180  

Isolated abducens nerve palsy after closed head injury in a child


1 Department of Ophthalmology, University of Ioannina, 45500 Ioannina, Epirus, Greece
2 Department of Paediatrics, University of Ioannina, 45500 Ioannina, Epirus, Greece

Date of Web Publication20-Nov-2015

Correspondence Address:
Prof. Ioannis Asproudis
Department of Ophthalmology, University of Ioannina, Stavros Niarchos Avenue, 45500 Ioannina, Epirus
Greece
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0974-620X.169905

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   Abstract 

The authors present the rare case of a 5-year-old child with an isolated right abducens nerve palsy following a minor closed head injury. Occlusion of the left eye for 4 h daily was prescribed, and the child remained under close ophthalmological follow-up. Significant improvement was noticed in the following 6 months.

Keywords: Abducens palsy, cranial nerve palsy, head trauma


How to cite this article:
Asproudis I, Vourda E, Zafeiropoulos P, Katsanos A, Tzoufi M. Isolated abducens nerve palsy after closed head injury in a child. Oman J Ophthalmol 2015;8:179-80

How to cite this URL:
Asproudis I, Vourda E, Zafeiropoulos P, Katsanos A, Tzoufi M. Isolated abducens nerve palsy after closed head injury in a child. Oman J Ophthalmol [serial online] 2015 [cited 2020 Jan 29];8:179-80. Available from: http://www.ojoonline.org/text.asp?2015/8/3/179/169905


   Introduction Top


Large series have indicated that 34–42% of abducens nerve palsy in pediatric patients can occur as a result of open or closed skull or cervical trauma, usually along with other cranial nerve injuries or neurological signs.[1],[2] However, posttraumatic isolated abducens nerve palsy in the absence of skull fracture, hematoma or raised intracranial pressure is uncommon in children and only a handful such cases have been reported.[3],[4] When treated conservatively, pediatric patients with posttraumatic isolated abducens nerve palsy have a very good prognosis and usually recover fully within 6 months. Occlusion therapy is necessary to alleviate diplopia and prevent amblyopia in children younger than 7 years.


   Case Report Top


A 5-year-old boy with no previous ophthalmic or general medical history was referred to the University Eye Clinic of Ioannina, Greece due to acute onset of strabismus and diplopia. The patient had reportedly fallen off his bicycle 30 h ago. Clinical evaluation showed no signs of head injury, but the ophthalmic examination revealed a 30-prism diopters right esotropia, limitation of right abduction and compensatory right face turn [Figure 1]a. The boy was not particularly cooperative, and the uncorrected visual acuity was recorded as 8/10 and 5/10 in the right and left eye respectively. Pupillary reflexes were normal in both eyes. Anterior segment examination at the slit lamp and indirect fundoscopy were unremarkable in both eyes. A diagnosis of new-onset paralytic esotropia due to right abducens nerve palsy was established. Neurosurgical and pediatric consultation were unremarkable, and a computed tomography of the head was negative. Ophthalmic reviews over the next days showed that the strabismus angle was stable. In the meanwhile, brain and orbit magnetic resonance imaging of the head was performed but was unrevealing. Serological analysis for the herpes virus family was also normal. In the meanwhile, the patient progressively developed a tendency to fixate with the left eye. Thus, occlusion of the left eye for 4 h daily was prescribed, and close ophthalmic follow-up was scheduled. Over the next couple of months, the esotropia gradually decreased. At the 3 months visit, the boy's visual acuity was 10/10 in both eyes and ocular motility was normal, but intermittent esotropia for near was evident for the right eye. The stereoscopic vision was checked using the Titmus test (140 s of arc). Retinoscopy revealed a refractive error of +1,50 sph in both eyes. Six months after the accident, neither esophoria nor esotropia was noted [Figure 1]b.
Figure 1: Picture of the patient at right gaze, primary position, and left gaze, respectively, at presentation (a), and after 6 months (b)

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   Discussion Top


Sixth nerve palsy occurs more commonly in children than in adults. Leading causes are neoplasms (range: 27–39%) such as meningioma, acoustic neurinoma, nasopharyngeal carcinoma, and head injuries (range: 34–42%).[1],[2],[3],[4],[5] Less common causes are idiopathic, congenital, hydrocephalus, infections (herpes virus family, leptospirosis), otitis media, and others.[1],[2],[5]

The sixth nerve leaves the brainstem at the pontomedullary junction and follows an upward and outward path. It ascends vertically through the subarachnoid space, penetrates the dura mater, and courses vertically along the ridge of the petrous part of the temporal bone. About 3–5 mm above the petrous part of the sphenoid bone, the abducens nerve makes an angle of 120° and enters the cavernous sinus, where it runs alongside the internal carotid artery. Next, it enters the orbit through the superior orbital fissure and innervates the lateral rectus muscle.

The long intracranial course of the abducens nerve makes it vulnerable to injuries, but it seems that several anatomic factors may contribute to this. Nerve injury occurs most often at the site of dural entry point and at the petrous apex. Although traumatic palsy of the sixth nerve is usually seen in combination with intracranial hemorrhage, skull fracture, facial fracture or elevated intracranial pressure, it may occur in the absence of such lesions. In such cases, it has been suggested that the most likely mechanism of injury is stretching of the nerve by acceleration in the mid-sagittal plane. The apex of the petrous part of the temporal bone acts as the fulcrum, so the nerve is compressed, contused, and stretched at this point.

The appropriate management of posttraumatic isolated abducens nerve palsy remains a matter of debate. It has been suggested that botulinum toxin should be used early to induce iatrogenic paralysis of the ipsilateral medial rectus, thus counterbalancing the original muscle paralysis and preventing or overcoming the contracture of the ipsilateral medial rectus.[6],[7] On the other hand, a prospective multicenter study with patients with acute traumatic palsy has shown that the probability of spontaneous recovery is similar to that of recovery with botulinum toxin injection.[8] Spontaneous recovery from sixth nerve palsy usually occurs within 6 months, with improvement noted in most cases at 3 months.[3],[4],[9] Bilateral involvement and complete lateral rectus palsy may signify a worst prognosis.[9],[10] In our case, given the fact that the patient could attend frequent ophthalmic follow-up visits, we opted for conservative management. In any event, to alleviate diplopia and prevent amblyopia in children younger than 7 years old, intermittent occlusion of the contralateral eye is important if the strabismus is not alternating. Prisms can also be used to maintain binocularity when the angle of deviation is <15-prism diopters.

Surgery may be considered if there is no recovery within 6 months to 1 year.[6] The type of surgery depends on the angle of deviation and the ability to abduct past the midline. In cases of total abducens palsy, a muscle transposition procedure is indicated. In cases with partial palsy, a resection/recession procedure should initially be tried. Nonetheless, success is variable and more than one operation, or the combination of botulinum toxin injections with surgery, may be needed.

 
   References Top

1.
Kodsi SR, Younge BR. Acquired oculomotor, trochlear, and abducent cranial nerve palsies in pediatric patients. Am J Ophthalmol 1992;114:568-74.  Back to cited text no. 1
    
2.
Harley RD. Paralytic strabismus in children. Etiologic incidence and management of the third, fourth, and sixth nerve palsies. Ophthalmology 1980;87:24-43.  Back to cited text no. 2
    
3.
Hollis GJ. Sixth cranial nerve palsy following closed head injury in a child. J Accid Emerg Med 1997;14:172-5.  Back to cited text no. 3
    
4.
Janssen K, Wojciechowski M, Poot S, De Keyser K, Ceulemans B. Isolated abducens nerve palsy after closed head trauma: A pediatric case report. Pediatr Emerg Care 2008;24:621-3.  Back to cited text no. 4
    
5.
Lee MS, Galetta SL, Volpe NJ, Liu GT. Sixth nerve palsies in children. Pediatr Neurol 1999;20:49-52.  Back to cited text no. 5
    
6.
Merino P, Gómez de Liaño P, Villalobo JM, Franco G, Gómez de Liaño R. Etiology and treatment of pediatric sixth nerve palsy. J AAPOS 2010;14:502-5.  Back to cited text no. 6
    
7.
Mittal V, Sachdeva V, Kekunnaya R, Gupta A, Venkateshwar Rao B. Etiology and treatment of pediatric sixth nerve palsy. J AAPOS 2011;15:507-8.  Back to cited text no. 7
    
8.
Holmes JM, Beck RW, Kip KE, Droste PJ, Leske DA. Botulinum toxin treatment versus conservative management in acute traumatic sixth nerve palsy or paresis. J AAPOS 2000;4:145-9.  Back to cited text no. 8
    
9.
Holmes JM, Droste PJ, Beck RW. The natural history of acute traumatic sixth nerve palsy or paresis. J AAPOS 1998;2:265-8.  Back to cited text no. 9
    
10.
Holmes JM, Beck RW, Kip KE, Droste PJ, Leske DA, Pediatric Eye Disease Investigator Group. Predictors of nonrecovery in acute traumatic sixth nerve palsy and paresis. Ophthalmology 2001;108:1457-60.  Back to cited text no. 10
    


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