Synergistic divergence (SD), first described by Barany et al.1 and later studied electromyographically by Wilcox et al.,2 is a rare but well-established horizontal congenital cranial dysinnervation disorder (CCDD).3–12 In addition to unusual synergism affecting horizontal muscles, there are many reports in the literature regarding anomalous vertical synergism.7,10–12 In 1996, Weinacht et al. described synergistic innervations between lateral rectus (LR) and ipsilateral vertical acting muscles under vertical Duane’s retraction syndrome.
Synergistic divergence (SD), first described by Barany et al.1 and later studied electromyographically by Wilcox et al.,2 is a rare but well-established horizontal congenital cranial dysinnervation disorder (CCDD).3–12 In addition to unusual synergism affecting horizontal muscles, there are many reports in the literature regarding anomalous vertical synergism.7,10–12 In 1996, Weinacht et al. described synergistic innervations between lateral rectus (LR) and ipsilateral vertical acting muscles under vertical Duane’s retraction syndrome.