The Use of Roentgen Therapy in the Carotid Sinus Syndrome

IT is the purpose of this paper to present five cases in which roentgen therapy has been used for the treatment of the carotid sinus syndrome. Radiologists have irradiated the autonomic nervous system for various pathologic conditions, but as a whole the results have been discouraging, and many look upon roentgen therapy in this field with considerable skepticism. For many years physiologists have been interested in the slowing of the heart rate which can be induced by pressure over the vagus nerve. All authors now give credit to Hering for demonstrating the true nature of this reflex. He showed that this reflex arose as a result of pressure over the carotid sinus with its rich supply of autonomic nerve fibers. The carotid sinus is a bulbous dilatation of the internal carotid artery at its point of origin from the external carotid artery. Some variation in its location has been described but it is always in close relationship to the area where the internal and external carotids arise from the common carotid artery. One point of practical interest to the radiologist is that this bifurcation may be located at various levels in the neck from just above the angle of the jaw down to the thyroid gland. Most commonly, however, it is located just below the angle of the jaw. The wall of the sinus is thinner than the adjacent parts of the artery owing to a decrease in the size of the media. The adventitia is richly supplied with sensory receptors. This network of nervous tissue leaves the carotid sinus as the sinus nerve. The most direct connection is with the glosso-pharyngeal nerve. The vagus and superior cervical ganglia are also connected with the sinus nerve. Some investigators claim there is a connection with the hypoglossal nerve. It has been conclusively demonstrated that the nerve impulse arising from the carotid sinus can be due to stretching or distention of the sinus from within or by pressure on the outside of this area. The impulses travel centrally to the medulla, and from the medulla the efferent pathways may be along the vagus and vasomotor depressor nerves to the periphery or to the cortex by the way of the thalamic region. The carotid sinus syndrome may be bizarre or consist simply of syncope of varying duration. It is usually possible to explain the symptoms on the basis of the efferent pathways, either to the periphery or to the cerebral cortex. Usually three reflex areas may account for the clinical picture: a vagal reflex resulting in cardiac slowing or standstill; a vasomotor reflex resulting in a fall of blood pressure; or a cerebral reflex which may cause syncope without significant changes in pulse rate or blood pressure. Etiology.—Sigler found that arteriosclerosis and hypertensive heart disease were common in a large group of patients who had cardiac slowing on pressure over the carotid sinus.