Wednesday, 29 July 2009

Just in time, here's an edited version of SimonSingh's Guardian article on chiropractic:

Beware the spinal trap

Some practitioners claim it is a cure-all, but the research suggests chiropractic therapy has mixed results – and can even be lethal, says Simon Singh.

You might be surprised to know that the founder of chiropractic therapy, Daniel David Palmer, wrote that “99% of all diseases are caused by displaced vertebrae”. In the 1860s, Palmer began to develop his theory that the spine was involved in almost every illness because the spinal cord connects the brain to the rest of the body. Therefore any misalignment could cause a problem in distant parts of the body.

In fact, Palmer’s first chiropractic intervention supposedly cured a man who had been profoundly deaf for 17 years. His second treatment was equally strange, because he claimed that he treated a patient with heart trouble by correcting a displaced vertebra.

You might think that modern chiropractors restrict themselves to treating back problems, but in fact some still possess quite wacky ideas. The fundamentalists argue that they can cure anything, including helping treat children with colic, sleeping and feeding problems, frequent ear infections, asthma and prolonged crying – even though there is not a jot of evidence.

I can confidently label these assertions as utter nonsense because I have co-authored a book about alternative medicine with the world’s first professor of complementary medicine, Edzard Ernst. He learned chiropractic techniques himself and used them as a doctor. This is when he began to see the need for some critical evaluation. Among other projects, he examined the evidence from 70 trials exploring the benefits of chiropractic therapy in conditions unrelated to the back. He found no evidence to suggest that chiropractors could treat any such conditions.

But what about chiropractic in the context of treating back problems? Manipulating the spine can cure some problems, but results are mixed. To be fair, conventional approaches, such as physiotherapy, also struggle to treat back problems with any consistency. Nevertheless, conventional therapy is still preferable because of the serious dangers associated with chiropractic.

In 2001, a systematic review of five studies revealed that roughly half of all chiropractic patients experience temporary adverse effects, such as pain, numbness, stiffness, dizziness and headaches. These are relatively minor effects, but the frequency is very high, and this has to be weighed against the limited benefit offered by chiropractors.

More worryingly, the hallmark technique of the chiropractor, known as high-velocity, low-amplitude thrust, carries much more significant risks. This involves pushing joints beyond their natural range of motion by applying a short, sharp force. Although this is a safe procedure for most patients, others can suffer dislocations and fractures.

Worse still, manipulation of the neck can damage the vertebral arteries, which supply blood to the brain. So-called vertebral dissection can ultimately cut off the blood supply, which in turn can lead to a stroke and even death. Because there is usually a delay between the vertebral dissection and the blockage of blood to the brain, the link between chiropractic and strokes went unnoticed for many years. Recently, however, it has been possible to identify cases where spinal manipulation has certainly been the cause of vertebral dissection.

Laurie Mathiason was a 20-year-old Canadian waitress who visited a chiropractor 21 times between 1997 and 1998 to relieve her low-back pain. On her penultimate visit she complained of stiffness in her neck. That evening she began dropping plates at the restaurant, so she returned to the chiropractor. As the chiropractor manipulated her neck, Mathiason began to cry, her eyes started to roll, she foamed at the mouth and her body began to convulse. She was rushed to hospital, slipped into a coma and died three days later. At the inquest, the coroner declared: “Laurie died of a ruptured vertebral artery, which occurred in association with a chiropractic manipulation of the neck.”

This case is not unique. In Canada alone there have been several other women who have died after receiving chiropractic therapy, and Edzard Ernst has identified about 700 cases of serious complications among the medical literature. This should be a major concern for health officials, particularly as under-reporting will mean that the actual number of cases is much higher.

If spinal manipulation were a drug with such serious adverse effects and so little demonstrable benefit, then it would almost certainly have been taken off the market.

Simon Singh is a science writer in London and the co-author, with Edzard Ernst, of Trick or Treatment? Alternative Medicine on Trial. This is an edited version of an article published in The Guardian for which Singh is being personally sued for libel by the British Chiropractic Association.

Sunday, 1 March 2009

Just because I can

Just to try out the technology, here are some embedded sound recordings from my Sound Lantern acount.

The story of why they were recorded can be found here.

Friday, 6 February 2009

Musical Acoustics Network meeting

In January I traveled to the Open University for a meeting of the Musical Acoustics Network, which has run out of money but is still meeting. In between sessions Jim Woodhouse pointed out that I was wrong to say (as I did in a previous post here, and repeated in a discussion session, a video of which you can see by following the above link) that delay line digital waveguide models can't reproduce dispersion and hence inharmonicity. And he should know, he helped to invent the technique in the 70s. What you do is let the wave packet propagate along the waveguide without dispersion and then pass it through an all-pass filter whose phase response is designed to delay each frequency by the amount it would have done as it travelled the length of the true string, or segment of the string if you're simulating bowing and you need to know the waveform at the bowing point as well as at the bridge. This led on to a discussion with Jim and Murray Campbell about the audibility of dispersion and nonlinearity in plucked string instruments, which we continued by email, and in the course of which it cropped up that nonlinearity is definitely audible in the Kantele (a Finnish folk instrument). The biggest surprise for me was that my Voice Recognition software recognised the word 'kantele' repeatedly and without difficulty, although 'Nyckelharpa' came out as 'New Car Park'.

I'm back

What a long lay-off, largely due to the problems I've been having writing. I've been trying to get to grips with the aforementioned half keyboard, and with Dragon Naturally Speaking voice recognition software, but neither is anything like as fast as I used to type two-handed on a regular keyboard, so just keeping up with the day job has become quite a challenge, let alone extra-curricular typing like this. But I've been spurred into action by being linked to from the ISVR outreach page. I intend to complete the diary of my parliament week from the notes I made at the time, but they may be interspersed with other things.