Vertebrobasilar Insufficiency: Getting Your Neck ‘Cracked’

It is not uncommon to find people in Singapore that enjoy a good crack of the neck once a while. It was particularly special way to end a hair-cut in the good old days at now-almost-extinct indian barber shops. There are also those who pop in to some massage or “chinese-sensei” shops that do these ‘bone-cracking’ service.

Some do it because they enjoy the loose-ness of the neck area. Others do it because they were informed that it is good maintenance to do so to keep the neck loose.

But often they are not aware of the serious risk that they face. The risk of vertebrobasilar insufficiency (VBI), or vertebral basilar ischemia to be exact. VBI is temporary reduction in the blood flow to the back of the brain.

In other words a stroke.

Mechanical Causes

Blood clots can cause VBI, as well as other forms of stroke. It is the narrowing of the vessel from cholesterol or any other reasons for a reduce blood flow through the artery. A less common cause is mechanical forces, particularly in the neck region, that apply pressure on the verterbral arteries or in the worse case scenario, severe it, particularly when the neck is cracked at its end of range. The danger lies if the technique is poor and not precise, i.e. many cracks rather than just the one intended. This puts a lot of sheer or traction force on the artery, possibly leading to tears or occlusion of the blood vessels. See diagram for more details on the anatomy.

Also to note, that the ‘cracking’ or manipulation in this article refers to the manipulation of the neck. It is generally consider safe to manipulate the thoracic or lumbar spine, that’s the mid and lower back. Before manipulating the cervical spine, the practitioner should first perform a test for VBI symptoms.

How Often Does Vertebrobasilar Insufficiency Result From Manipulation?

It has been difficult to accurately determine the incident rate of Vertebrobasilar Accidents (VBA) due to under reporting. One study reviewing published literature found an incident rate that ranged from 1 per 20,000 patients to 1 per 1-million cervical manipulations¹.  To get a sense of these numbers, in 2009 for air travel in the US, there was 0.0036 accidents per 1 million miles flown and 2.55 accidents per 1 million flight departures².

Regardless of the actual incident rate, one should be clear about the risk and that cervical manipulation should be applied selectively. Cervical manipulation has a place in the specific treatment of neck related condition³. But often it is useful to bear in mind that there are alternative approaches to treatment that may be more effective over the long term but not as easing in the immediate short-term.

Anecdotally, there appears to be an increasing trend amongst senior experienced therapist to minimise the use of cervical manipulation in favour of other treatment approaches, in spite of the risks of vertebrobasilar insufficiency (VBI).

Reference

1. Assendelft WJ, Bouter LM, Knipschild PG. Complications of spinal manipulation: a comprehensive review of the literature. J Fam Pract. 1996; 42: 475–480.[Medline]
2. Table 6. Accidents, Fatalities, and Rates, 1990 through 2009, for U.S. Air Carriers Operating Under 14 CFR 121, Scheduled Service (Airlines) NSTB Aviataion Accident Statistics
3. Use of high and low velocity cervical manipulative therapy procedures by Australian manipulative physiotherapists, G. Jull, Australian Journal of Physiotherapy 2002 Vol. 48: 189-193
4. Ernst E (January 2002). “Spinal manipulation: its safety is uncertain”. CMAJ 166 (1): 40–1