Effectiveness of Prism Therapy Versus Botulinum Toxin Injection in the Management of Sixth Cranial Nerve Palsy: A Systematic Review and Meta-analysis
Erum Habib1, Omar Abdullah Gill2, Maria Qadri3, Ariba Asif2, Sana Iftikhar4, Sahla Waqas2, Muhammad Usman Iqbal2, Syeda Vilay Zehra3, Muhammad Moiz Javed5, Areej Riaz2
1Dow University of Health Sciences, 2King Edward Medical University, 3Jinnah Sindh Medical University, 4Sheikh khalifa bin zayad Al Nahyan Medical and dental college Lahore, 5Geisinger College of Health Sciences
Objective:
To compare the effectiveness of prism therapy versus botulinum toxin injections in improving ocular alignment and reducing diplopia in sixth cranial nerve palsy.
Background:
Sixth cranial nerve palsy causes horizontal double vision due to impaired lateral eye movement. Prism therapy and botulinum toxin injections are common treatments, but their comparative effectiveness remains unclear.
Design/Methods:
A literature search of PubMed, Embase, Scopus, and Cochrane databases was performed from their inception until September 31, 2025. Pooled estimates were calculated using random-effects models, reporting risk ratio RR with 95% confidence intervals (CI). Heterogeneity was evaluated using I² and X² statistics. All statistical analysis were performed in R Studio (v4.4.3) using "meta" package. A p-value of <0.05 was considered statistically significant.
Results:
This meta-analysis included four studies with 194 patients (Prism therapy=102; Botulinum toxin injection=107) with sixth cranial nerve palsy. Prism therapy was not significantly different from botulinum toxin injection in improving overall success rates in sixth nerve palsy (RR 0.89, 95% CI 0.68–1.15, p = 0.375, I² = 27.5%). No significant differences were observed in the angle of deviation among recovered patients (RR 1.23, 95% CI 0.70–2.17, p = 0.468, I² = 0%) or non-recovered patients (RR 1.11, 95% CI 0.53–2.34, p = 0.785, I² = 0%). Severity of the palsy showed that in grade –4 abduction deficit, botulinum toxin was associated with a higher recovery rate (RR 0.60, 95% CI 0.32–1.16, p = 0.128, I² = 10.4%) though the difference was not statistically significant, whereas in grade –5 palsy, no significant difference was found between interventions (RR 0.87, 95% CI 0.51–1.49, p = 0.613, I² = 46.4%).
Conclusions:
Botulinum toxin and prism therapy show similar effectiveness in sixth nerve palsy. Botulinum toxin may offer better recovery in moderate cases, but no clear advantage is seen in severe palsy. Further studies are needed to confirm these findings.
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