Pathology: Blood or qi deficiency. This is seen in cases of deficiencies and failure of Qi and blood. It can also be seen in disharmonies of the even emotions, weakness in Yang Qi, internal damage to jing, and penetration of dampness.
Testing for venous blood clots. Venous blood clots may be detected in a variety of ways, though ultrasound is most commonly used. Occasionally, the patient's size and shape limit the ability for ultrasound to provide a definitive answer. Venography is an alternative test to look for a clot.
A variety of tests may be performed to rule out other conditions. Such tests include magnetic resonance imaging (MRI), which shows the damage to the pons, and magnetic resonance angiography, which can show the blood clot in the arteries of the brainstem. These tests can also rule out damage elsewhere in the brain.