Hi, Thanks for writing in. Moments of dizziness can happen due to decreased blood flow from heart to brain. When it happens, the blood flowing through the vessels from heart to brain might have a reduced flow. These are by the carotid and vertebral arteries on either sides. This is more significant when you are standing upright and doing any moderate to heavy physical activity. Since he has got scans for inner ear and brain done, it is confirmed that there is no abnormality in the vestibular system in the ear or any serious conditions in the brain. Since his CT scan or MRI scan brain is normal, it can help if he gets Electronystagmography (ENG) or videonystagmography (VNG) done to record abnormal eye movements while the head is placed in different positions or your balance organs are stimulated with water or air. For this he might consult the ENT specialist. The best way to analyze if the reduced blood flow to the brain is causing your dizziness is by doing a carotid and vertebral arteries Doppler ultrasound. It will show the flow of blood from the heart to the brain and if it is adequate. Dizziness can also occur due to stress related anxiety or overflow of emotions.