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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 29  |  Issue : 1  |  Page : 26-29

Botulinum toxin in the management of acquired abducens nerve palsy: Prospective Interventional controlled trial


Department of Ophthalmology, Little Flower Hospital, Ernakulam, Kerala, India

Date of Web Publication19-Jun-2017

Correspondence Address:
Joseph John
Department of Ophthalmology, Little Flower Hospital, Angamaly, Ernakulam - 683 572, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/kjo.kjo_46_17

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  Abstract 


Aim: The aim of this study is to assess the effectiveness of botulinum toxin in patients presenting with isolated lateral rectus palsy.
Materials and Methods: This prospective interventional controlled trial from March 2012 to March 2015. Inclusion criteria were acquired lateral rectus palsy, no other neurological defects, normal magnetic resonance imaging scan, and age >30 years. The cases were treated with 15–25 units of botulinum toxin depending on the angle of squint. The surgical field is prepared, the medial rectus insertion grasped firmly with forceps, and the eye rotated to the primary position. Botulinum toxin is injected 5 mm from the medial rectus insertion, inside the bulk of muscle through a 27-gauge needle (without electromyographic guide) under topical anesthesia. No peritomy is done. Controls were treated with intravenous steroids for 3 days changed to oral steroids on tapering doses. Cases and controls were followed up 10, 30, 60, 120, and 180 days after initiating treatment. Wilcoxon signed-rank test is used for paired samples; Mann–Whitney U-test is for independent samples; P< 0.05 was considered statistically significant.
Results: Ten cases (six female) were enrolled into the study. Ten age-matched controls (six female) were also enrolled. The baseline characteristics of cases and controls were comparable in terms of duration of symptoms, head posture, primary deviation in the primary position, and limitation of abduction. After 10 days of injection, 100% of cases attained primary deviation <10 prism diopters and subsidence of diplopia in the primary position. Nearly 80% of cases showed partial recovery of abduction after 30 days. Controls attained primary deviation <10 prism diopters and subsidence of diplopia in the primary position after 150 days (range: 120–180 days).
Conclusion: Botulinum toxin is effective in achieving early subsidence of diplopia in the primary position and early recovery of abduction in patients presenting with isolated lateral rectus palsy.

Keywords: Botulinum toxin, Mann–Whitney U, Wilcoxon


How to cite this article:
John J, Joseph K E. Botulinum toxin in the management of acquired abducens nerve palsy: Prospective Interventional controlled trial. Kerala J Ophthalmol 2017;29:26-9

How to cite this URL:
John J, Joseph K E. Botulinum toxin in the management of acquired abducens nerve palsy: Prospective Interventional controlled trial. Kerala J Ophthalmol [serial online] 2017 [cited 2023 Feb 8];29:26-9. Available from: http://www.kjophthal.com/text.asp?2017/29/1/26/208485


  Introduction Top


Botulinum toxin Type A is one of the seven serotypes produced by the anaerobic bacteria clostridium botulinum.[1],[2] The toxin interferes with acetylcholine release from nerve endings by antagonization of serotonin-mediated calcium ion release. Botulinum toxin, injected into the ipsilateral medial rectus muscle, has been advocated in the management of acute sixth nerve palsy or paresis.

In conservatively managed cases, contracture of the medial rectus muscle may prevent complete resolution of diplopia despite complete recovery of lateral rectus muscle function. Botulinum toxin reduces contracture of the medial rectus muscle and allows for more complete restoration of ductions.[3]

Aim

To assess the effectiveness of botulinum toxin in patients presenting with isolated lateral rectus palsy.


  Materials and Methods Top


This study was approved by the Institutional Review Board, Clinical Research Ethics Committee before performing this study. After explaining the purpose of the study and the possible outcomes to the patients, informed consent was obtained from all patients. The procedures conformed to the tenets of the Declaration of Helsinki.

This is a prospective, interventional, controlled trial done at a tertiary eye care center in Kerala from March 2012 to March 2015.

The inclusion criteria were acquired lateral rectus palsy, no other neurological defects, normal magnetic resonance imaging scan, and age >30 years. After explaining to the patients about the two modes of intervention, they were allowed to choose the same. The cases were treated with 15–25 units of botulinum toxin depending on the angle of squint. The controls were treated with intravenous betamethasone for 3 days changed to oral steroids on tapering doses. Both cases and controls were advised part-time occlusion of the fellow eye. Cases and controls were followed up 10, 30, 60, 120, and 180 days after initiating treatment.

Head posture, primary deviation in primary position, limitation of abduction, and the presence of diplopia in primary position were noted at baseline and at each follow-up visit. Head posture was measured with the help of protractor while the patient is fixing at a distance of 6 metres. The angle of deviation is measured in prism diopters by the simultaneous prism and cover test in the primary position at a distance of 6 metres.

Abduction deficit was recorded on the scale described by Scott and Kraft:[4] zero (normal), −1 (to 75% full rotation), −2 (to 50% full rotation), −3 (to 25% full rotation), −4 (to midline), and −5 (inability to abduct to the midline). Diplopia chart was made using red–green Goggles and yellow streak and the presence of diplopia in the primary position was recorded.

Method of reconstitution of botulinum toxin, Botox (Allergan, Irvine, CA)

Each vial of Botox contains 50 units of botulinum toxin which is reconstituted with 2 ml normal saline so that 0.1 ml contains 2.5 units. It is used within 1 hour.[2]

Method of administration of Botox

The surgical field is prepared, the medial rectus insertion grasped firmly with forceps, and the eye rotated to the primary position. Botox is injected 5 mm from the medial rectus insertion, inside the bulk of muscle through a 27-gauge needle with tuberculin syringe (without electromyography guide) under topical anesthesia. No peritomy is done.

Statistical analysis

Wilcoxon signed-rank test is used for paired samples; Mann–Whitney U-test is used for independent samples; P< 0.05 was taken as statistically significant.


  Results Top


Ten cases (six female) were enrolled into the study. Ten age-matched controls (six female) were also enrolled. All except one case had diabetes mellitus. The baseline characteristics of cases and controls [Table 1] were comparable in terms of duration of symptoms (P = 0.56), head posture (P = 1), primary deviation in primary position (P = 0.79), and limitation of abduction (P = 0.84). One case required repeat injection 10 units of Botox after 10 days. After 10 days of injection, 100% of cases attained primary deviation <10 prism diopters and subsidence of diplopia in primary position, and 50% of cases showed partial recovery of abduction [Table 2].
Table 1: Baseline characteristics of patients

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Table 2: Improvement in botulinum toxin group

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Head posture improved from 44° ± 11° at baseline to 21° ± 7° after 10 days (P = 0.002) and to 18° ± 6° (P = 0.002) after 30 days. Primary deviation at primary position improved from 37 ± 12 prism diopters at baseline to 6 ± 2 prism diopters after 10 days (P = 0.002). The limitation of abduction decreased from −3.2 ± 0.9 at baseline to −2.4 ± 1.8 after 10 days (P = 0.05) and to −0.7 ± 1.2 (P = 0.002) after 30 days.

After 30 days, 80% of cases showed partial recovery of abduction. Controls attained primary deviation <10 prism diopters and subsidence of diplopia in primary position after 150 days (range: 120–180 days). [Table 3] and [Table 4] summarize the changes during follow-up in cases and controls. [Figure 1],[Figure 2],[Figure 3] compare changes in various parameters among cases and controls.
Table 3: Changes during follow-up in cases

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Table 4: Changes during follow-up in controls

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Figure 1: Improvement in head posture in cases and controls

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Figure 2: Variation in primary deviation in cases and controls

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Figure 3: Improvement in abduction in cases and controls

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Other than mild subconjunctival hemorrhage, there were no adverse events recorded in the study.


  Discussion Top


In a study conducted by Holmes et al. and the Pediatric Eye Disease Investigator Group on botulinum toxin treatment versus conservative management in acute traumatic sixth nerve palsy or paresis, the recovery rate was high and similar in patients who received botulinum toxin within 3 months of injury (73%) and in those who were treated conservatively (71%).[5]

In another study on etiology and treatment of pediatric sixth nerve palsy, Merino et al. found that botulinum toxin was successful in 70% of cases.[6]

In this study, the cases attained 100% subsidence of diplopia and primary deviation <10 prism diopters in primary position within 10 days, whereas the controls took 120–180 days for the same.

In a study on the necessity of electromyographic assistance in botulinum toxin injection, Sanjari et al. concluded that the effectiveness of botulinum toxin injection is the same with or without electromyographic assistance in the treatment of abducens nerve palsy.[7] This is in accordance with this study.

This study has some limitations. The recruitment of patients into cases and controls was not randomized.


  Conclusion Top


Botulinum toxin is effective in achieving early subsidence of diplopia in the primary position and early recovery of abduction in patients presenting with isolated lateral rectus palsy.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

1.
Dutton JJ, Fowler AM. Botulinum toxin in ophthalmology. Surv Ophthalmol 2007;52:13-31.  Back to cited text no. 1
    
2.
Diamond GR. Forms of nonsurgical strabismus management. In: Yanoff M, Duker JS, editors. Yanoff and Duker: Ophthalmology. 3rd ed. Ch. 11.13. Philadelphia: Mosby Publishing; 2009.  Back to cited text no. 2
    
3.
Rubin SE. Paralytic strabismus. In: Yanoff M, Duker JS, editors. Yanoff and Duker: Ophthalmology. 3rd ed. Ch. 11.10. Philadelphia: Mosby Publishing; 2009.  Back to cited text no. 3
    
4.
Scott AB, Kraft SP. Botulinum toxin injection in the management of lateral rectus paresis. Ophthalmology 1985;92:676-83.  Back to cited text no. 4
    
5.
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. 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.
Sanjari MS, Falavarjani KG, Kashkouli MB, Aghai GH, Nojomi M, Rostami H. Botulinum toxin injection with and without electromyographic assistance for treatment of abducens nerve palsy: A pilot study. J AAPOS 2008;12:259-62.  Back to cited text no. 7
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]



 

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