My neighbours are having a late night party...... again!
My neighbours were having a party late at night: Boom, boom, boom, went the bass. At least, I thought they were having a party, and the next night, and then next nighttoo. There was a pattern. It was alway the same bass beat: quite slow, about once per second. Eventually I realised that I was listening to my own pulse. My left carotid artery has a ‘kink’ in it. My blood pressure was up a bit and the blood flow through the artery was becoming turbulent, creating the vibration that I could hear. Turbulent flow that can be heard is called a ‘bruit’. Some clinicians pronounce it to rhyme with ‘fruit’, more pretentious practitioners (like me) pronounce it ‘brooee’.
Turbulence can happen secondary to tortuosity of a vessel, as in my case, or due to narrowing of a vessel, due to, for instance, atherosclerosis. It is estimated that approximately 15% of ischaemic strokes are due to carotid artery stenosis (1).
Although it seems to make sense to listen to carotid arteries in an attempt to identify patients with vascular stenosis, it has been demonstrated that the positive predictive value of a carotid bruit is quite low (2), and many patients with carotid bruits have no significant carotid stenosis.
A lack of bruit has a negative predictive value of stenosis of 97% (3),. Most authors feel that the positive predictive value of a bruit on auscultation is low, but one study (4) suggests that it could be as high as 85%. An older study, in 1973, suggested that 65% of carotids with bruits had carotid stenosis (5). This was backed up in another study (6) but this study suggested that over 30% of patients with high-grade stenosis had no bruit. Another study (7) appeared to have similar findings, with a poor positive predictive value of a bruit, but a better negative predictive value. It seems that the negative predictive value of carotid auscultation is similar to that of reflex testing (8), something that is quite normal practice in the field of manual medicine.
An article in the BMJ (9), made the statement that ‘low diagnostic accuracy led to auscultation for bruits being replaced with carotid ultrasound’. This is fine for a practitioner with the requisite skill-set and equipment at the point-of-care, but is not hugely helpful to most manual therapists in clinical practice. Furthermore, for the practitioner in the clinical setting, having some confidence, albeit measured, that there is no significant carotid stenosis, may aid the decision making process about whether or not to proceed with manual therapy
For a chiropractor with a patient experiencing neck and shoulder pain, the issue is: ‘is this patient at significant risk of having a stroke in the short-term’, and ‘am I OK to treat this patient's neck right now’?
Although there is no research that identifies ‘at risk’ groups with certainty, the patients that I would be most concerned about would be young women with hypermobility tendencies, particularly if they are on the pill and if they smoke. The other group that would concern me significantly would be older, male, smokers or ex-smokers, particularly anyone with a history of painless loss of vision in one eye (amaurosis fugax). This latter group may well have almost complete carotid occlusion, making a bruit unlikely. Personally, I would not proceed with any manipulative treatment of the spine with this latter group.
Given that ultrasound scanning is not immediately available to most practitioners seeing patients with neck pain and headache, it seems to me that it makes sense to use an investigative procedure that helps to rule out carotid stenosis. I accept that many will not agree with me, but to me, it makes sense to at least have a listen to a patient's carotid arteries, before proceeding with any manipulative treatment to the neck.
How do you listen to the carotid arteries? Use the bell side of the stethoscope, and listen to the carotid arteries, lateral to the ‘Adams apple’ in the region of the SCM. Compare the two sides. Can you hear a bruit (sounds like a ‘woosh’) on either side, or does it sound just like the heartbeat, which is normal. There is a really helpful guide here (10), and quite a good example to listen to here (courtesy of James Heilman MD, via Wikipedia):
I use an electronic stethoscope (Littman CORE Digital) to make listening to bruits easier.
How often have I found carotid bruits in daily chiropractic practice? Rarely, is the answer, probably about one per year. Almost never in new patients. More commonly in existing patients on their annual review, often patients who I have been seeing for many years without hearing one! There have been a good number of patients where I have heard a bruit from a carotid artery, but then have heard it on the contralateral carotid, and then have also heard it when listening to the heart. These patients have heart issues, often a failing heart valve. The noise of the turbulant flow in the heart is being heard up the carotid arteries in these cases.
What do I do when I hear a carotid bruit? I refer the patient back to the GP and ask them to have a listen and ask their opinion about whether a carotid ultrasound might be helpful……. Is the GP grateful for my opinion? Err…. probably not. Is the patient grateful? Definitely!
Anyway, my neighbours stopped having nightly house parties, thank you for asking! It seemed to coincide with me starting on medication for my blood pressure……
This blogpost is intended only for clinicians who have been taught vascular assessment as part of their undergraduate training. It is my opinion only. This should not be interpreted as advice about whether to or how to carry out a vascular assessment of a patient. I repeat: this is simply my own clinical experience and is offered up for your reflection.
References:
