Prognosis of symptomatic and asymptomatic middle cerebral artery disease - a long-term follow-up
Objective: In contrast to extracranial carotid artery stenosis, there are only limited data on the course and prognosis of symptomatic and asymptomatic intracranial arterial disease. Therefore, patients with vascular pathology of the middle cerebral artery (MCA) were followed prospectively using transcranial Doppler sonography (TCD). Patients and Methods: We consecutively followed 102 patients with significant MCA stenosis or occlusion detected by TCD. Among a total of 120 MCA stenoses and 11 occlusions, 47 were classified as symptomatic (SMCA) and 84 as asymptomatic (AMCA) at study entry. Neurologic and sonographic investigations were performed at regular intervals of six to 12 months with a mean follow-up time of 29 months. Patients were treated with platelet inhibitors (73%) or low-dose anticoagulation (27%) according to the individual physician’s decision. Results: Thirteen of a total of 19 cerebral ischemic events (11 strokes, 8 TIA) occurred in the territory of the qualifying MCA (8 SMCA, 5 AMCA), resulting in an annual incidence of 4.8% (SMCA 6.6%, AMCA 3.3%). 14.6% of the patients treated with platelet inhibitors, but only 7.4% of those treated with anticoagulants suffered new events. Kaplan-Meier analysis showed a significant reduction of events during anticoagulation therapy (p=0.04). According to TCD classification of stenosis, MCA disease was progressive in 11.5%, unchanged in 72.5% and regressive in 16.0%; recurrent symptoms were associated with disease progression in 23%. Conclusions: In comparison with the natural history of extracranial arterial disease the annual risk of ischemic events in AMCA disease is significantly higher, whereas in SMCA disease a similar incidence of recurrent events was observed. Regression rate of stenosis grade and the prophylactic effect of anticoagulation therapy in MCA disease is higher than in extracranial stenosis, suggesting different pathomechanisms of obstruction.