Abstract
Purpose: The purpose of the study was to evaluate the efficacy of botulinum toxin type A (BTX-A) injection in patients with acquired VI nerve palsy. Methods: Twenty-eight patients (16 F and 12 M), mean age 36.4 +/-- 17.8 DS; range 10 - 69 years with acquired VI nerve palsy, have been treated with BTX-A injection into the ipsilateral medial rectus, at least 6 months after onset. At 6 months follow up, a paresis and a paralysis, were respectively diagnosed if the affected eye could be actively abducted or not, across the mid-line; a simple horizontal rectus muscle procedure was performed for the paresis whilst for the paralysis, both a horizontal and vertical muscle transportation procedure were required. Results: A gradual physiological recovery of the lateral rectus muscle was observed in 9 (32%) patients (GROUP I) and surgical treatment was therefore unnecessary; the remaining 19 cases (68%), of which 5 paresis (GROUP II) and 14 paralysis (GROUP III) underwent surgery and within 1 year were all restored to orthotropia. Conclusion: Botulinum toxin type-A (BTX-A) injection is an invaluable tool in the differential diagnosis between paresis versus paralysis of the VIth nerve, allowing the correct choice of surgical procedure.
Highlights
Acquired sixth nerve palsy is usually a consequence of vascular or neurological diseases, diabetes, head trauma [1,2] or cerebral tumors [3]
In the VI nerve palsy the choice of the surgical strategy could depend on the extent of recovery induced by Botulinum toxin type-A (BTX-A) injection, which becomes an invaluable tool in surgical evaluation [8]
OJOph an important aid in the preoperative evaluation of possible postoperative diplopia on patients in which this cannot be done by means of prism or traction test; in acute paretic loss of ocular muscle function; when surgical treatment of the ocular muscles is not yet possible but the patient is obviously affected by diplopia or a forced posture of the head [2], in situations where strabismus surgery is not suitable [13], in acute Graves’ disease, and especially into VI cranial nerve paresis [2], or in association with the surgery [14]
Summary
Acquired sixth nerve palsy is usually a consequence of vascular or neurological diseases, diabetes, head trauma [1,2] or cerebral tumors [3]. Diagnosis and management of this neurogenic ocular palsy are often difficult largely due to the fact that the ophthalmologist has insufficient and/or inaccurate clinical history of the patients. It is generally necessary, prior to surgical treatment, to wait at least for 6-8 months, in order for the paralysis to be considered stable. BTX-A injection can be used either during the waiting period for the spontaneous recovery or for surgery; in cases where VI nerve palsy is resolved, BTX-A help to prevent diplopia, whereas in the case of unresolved palsy, the toxin is an invaluable tool in the differential diagnosis between paresis versus palsy, which in turn allows the correct choice of surgical procedure
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