BOTOX injection to treat strabismus after infant botulism ty
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A 9-week-old previously healthy, full-term white female presented with a two-week history of increased irritability, constipation, decreased feeding, intermittent vomiting, and lethargy. The parents reported that her cry became weak and shrill. Neurologic examination revealed bilateral reactive but sluggish pupils constricting from 5 to 3 mm, full extraocular movements, and ptosis obscuring the corneal reflex. She was diagnosed with infant botulism, admitted to the intensive care unit, and received human botulism immune globulin. A stool specimen tested positive for Clostridium botulinum toxin type B. An ophthalmologic examination was performed at age 13 weeks, three weeks after discharge, during which the patient demonstrated central, steady, and maintained fixation with either eye.

At 4 months of age, the child's pediatrician noticed a “left lazy eye.” Repeat ophthalmologic examination showed a greater than 40 prism diopter intermittent alternating exotropia for both distance and near. Her cycloplegic refraction showed right eye: 2.00 + 2.00 at 105° and left eye: 2.00 + 2.00 at 75°. Her left eye showed poorer fixation and more frequent deviation than the right eye. She was treated with patching of the right eye 1–2 hours daily. At 6 months of age, both eyes fixated and followed well; however, an intermittent exotropia with poor control persisted. The alignment failed to improve after an additional two months of patching. After discussing treatment options, the family elected to proceed with botulinum toxin A injection (BTX-A). At 7 months of age, she received transconjunctival, intramuscular injections of onabotulinumtoxinA without electromyographic guidance, with 2.5 units to the right lateral rectus muscle and 5 units to the left lateral rectus muscle while under general anesthesia.

One week following the procedure, she displayed a flick exotropia in the primary position. Three months after the initial injection, alignment was adequate under binocular viewing however, with cross cover testing she demonstrated a poorly-controlled exophoria of 30 prism diopters. The decision was made to again proceed with intramuscular injections of onabotulinumtoxinA. At 1 year of age, the patient underwent transconjunctival, intramuscular injections of 10 units onobotulinumtoxinA to the left lateral rectus muscle without electromyographic guidance. Her exotropia decreased to 20 prism diopters in the first month following injection, and subsequently returned to 40 prism diopters three months later. At 16 months of age, she underwent bilateral lateral rectus muscle recession of 10 mm. Seven weeks postoperatively, she displayed a 15 prism diopter intermittent exotropia by cross cover testing.