Cervical venous hum

Cervical venous hum

Cervical venous hum is a continuous murmur heard over the internal jugular veins. It is thought to be produced by the partial compression of the internal jugular vein by the transverse process of the atlas as well by the effect of gravity. It is more common on the right side because the right internal jugular vein and brachiocephalic vein have straight access to the superior vena cava so that the flow velocity is higher on the right side.

The hum is obliterated by manual compression of the internal jugular vein, Valsalva maneuver and supine position. On the contrary, it increases on assuming the upright posture and during inspiration. The hum is louder in diastole due to the rapid atrial filling. It is a fairly common finding in children.

Conditions causing hyperkinetic circulation like anemia, pregnancy and thyrotoxicosis may make the hum more prominent. The venous hum has a plateau shape in systole and a crescendo-decrescendo shape in diastole. It is better heard in the right supraclavicular fossa, with the bell of the stethoscope and the patient looking to the left side. Intensity will decrease if the person turns his chin towards the side of auscultation. It is the most common continuous murmur.

Though most cases are not due to any significant pathology, rare cases of cervical venous hum due to intracranial A-V malformation have also been described [1,2]. In these cases, the hum was audible even in the supine position.

An interesting case of surgical treatment of cervical venous hum has also been reported [3]. This patient had pulsating tinnitus in the right ear and a venous hum heard over the right internal jugular vein. The tinnitus was abolished by maneuvers which abolished the hum. Ligation of right internal jugular vein was done resulting in permanent symptomatic relief.

References

1. Hardison JE. N Engl J Med. 1968; 278:587.
2. Cartlidge NE, Ayyar DR, Lee M. Postgrad Med J. 1970;46:726-8.
3. Brennan FJ, Salerno TA. Surgical treatment of symptomatic cervical venous hum. J Thorac Cardiovasc Surg. 1981;81:135-6