Inadequate blood flow through this system results in a fairly specific set of symptoms. It is important to diagnose this problem because VBI carries a high risk of stroke. In fact, there is a 25 to 30 percent risk of fatal stroke within 5 years of diagnosis. Subclavian steal refers to a situation where there is stenosis of the main artery to the arm and during use of the arm, blood flow actually goes from the vertebral artery to the arm instead of to the brain. This may be weakness, loss of sensation or both.
Double vision is a common finding.
Trouble with swallowing or speaking due to difficulty controlling the tongue may occur. Partial loss of vision involving both eyes may also be seen. Dizziness associated with one or more of the above problems may often be seen. As always, a careful history and physical examination are the first steps in diagnosis. Depending on the severity of symptoms, a CT scan or preferably an MRI scan of the brain will usually be obtained.