Introduction: Direct EC-IC bypass has become the standard of care for Moyamoya disease. We describe a rare phenomenon of acute contralateral ICA occlusion after direct bypass in a small cohort of patients.
Methods: The Stanford Moyamoya database which spans 25 years and includes 822 patients was queried to find cases. All patients had undergone a standardized procedure – direct ST-MCA bypass under mild hypothermia. An age and sex matched control group (who did not develop contralateral ICA occlusion) was also generated.
Results: The incidence of symptomatic contralateral ICA occlusion was 1.09% (n=9). This occlusion occurred within 24 hours post-surgery in all patients. The female:male ratio 8:1 in contrast with the overall cohort of patients where the female:male ratio was 2.5:1 [OR=2.836, CI 0.51-72.86]. Similarly, 8 out of 9 patients who developed this complication were non-Asian in ethnicity vis a vis 6 Asians and 3 non-Asians in the control group (OR=13.25, CI 1.3-411.7, p=0.026). Interestingly, in 7 out of 9 patients who developed ICA occlusion contralateral to the side of surgery, the contralateral ICA was either normal or had non-critical stenosis prior to surgery. In the control group, only 2 patients had a normal or non-critically stenosed contralateral ICA whereas 7 had either critical stenosis or occlusion of the contralateral ICA (p=0.028). None of the other variables analyzed were significantly different between groups.
Conclusions: Contralateral ICA occlusion seems to occur more frequently in women, non-Asians and in those with patent contralateral ICA vessels. A reduced demand on the contralateral ICA could be responsible for this occlusion.
Patient Care: We describe a rare but worrying phenomenon associated with direct ST-MCA bypass for patients with moyamoya disease. Further studies are required to identify patients at risk and to elucidate the hemodynamic mechanism underlying this complication.
Learning Objectives: Contralateral acute vessel occlusion is a rare phenomenon but should be watched for and managed aggressively.