Carotid Sinus Syndrome
In this condition dizziness, pre-syncope or syncope may be precipitated by any manoeuvre which causes mechanical stimulation of the carotid sinus – such as turning the head, looking up, or wearing tight collars.
The carotid sinus is a dilated portion of one of the major arteries supplying blood to the head. The sinus has nerve endings and acts as a pressure detector feeding back information to the vasomotor centre – an area in the brain stem that controls blood pressure and heart rate.
Carotid sinus hypersensitivity is diagnosed when carotid sinus massage causes a three second, or longer, pause in the heart beat (cardio inhibition) – see ECG traces – or lowering of the blood pressure by 50 mm Hg. or more (vasodepression). 56% of cases of unexplained syncope are found to have Carotid sinus hypersensitivity.
Carotid Sinus Syndrome is diagnosed when typical pre-syncopal or syncopal symptoms accompany carotid sinus massage. 26% of cases of unexplained syncope are found to have Carotid Sinus Syndrome.
Carotid Sinus Syndrome is rare under 50 years age.
Cardioinhibitory carotid sinus syndrome is more common, and easier to treat, than the vasodepressor type.
Interestingly, 80% of fallers found to have carotid sinus syndrome are amnesic for witnessed associated loss of consciousness. The individual will simply report a fall – an important point in history taking.
Prodromal symptoms are more common with vasodepressor carotid sinus syndrome, making it easier to take appropriate action.