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Most doctors with any practical experience of achalasia would be willing to admit that the disorder often provides considerable professional satisfaction. Firstly, it can be very satisfying to make the diagnosis. Far too often, patients will have suffered from gradually worsening dysphagia for many years and the diagnosis will have been missed at earlier consultations. The second moment of satisfaction can be enjoyed when the symptoms are relieved immediately after a relatively simple procedure such as pneumatic dilatation.
Malfunction of the lower oesophageal sphincter (LOS) plays a key role in the genesis of dysphagia in achalasia, in which it usually maintains an abnormally high resting tone. More importantly, however, the LOS does not relax sufficiently on swallowing, causing a persistent barrier to food boluses. In addition, the oesophageal body lacks normal propagation of contractions.
Presently there are four therapeutic options in achalasia, all of which are directed at lowering the tone of the LOS.
In what is considered to be the first report on treatment of achalasia, Sir Thomas Willis in 1672 described the successful dilatation of the sphincter using a whale bone.1 Since then several types of dilating instruments have been used, but today endoscopically guided pneumodilatation with a low-compliant polyethylene balloon is preferred by most gastroenterologists. The occurrence of gastro-oesophageal reflux disease (GORD) after pneumodilatation is rare. Pneumodilatation with modern balloons is associated with a perforation rate of 0–4%, the perforations rarely requiring surgical intervention.2
The surgical approach, consisting of longitudinal myotomy of the LOS, is named after Heller. Either a thoracic or an abdominal approach can be used, the latter being associated with a higher incidence of GORD. For this reason, Heller’s myotomy through an abdominal route is often combined with fundoplication.3 More recently thoracoscopic and laparoscopic techniques for LOS myotomy have been described. Surgical myotomy carries a mortality risk approaching zero. Studies comparing dilatation and surgical myotomy have shown that the efficacy of these procedures is comparable.4
The third therapeutic option in achalasia consists of adminstration of a calcium channel blocker such as nifedipine. This treatment is generally considered to be less effective than surgery and dilatation,2 and is therefore used mainly for short periods—for example, while the patient is on a waiting list for a more definitive procedure.
Since 1994, a fourth option has emerged, namely intrasphincteric injection of botulinum toxin type A, a toxin produced byClostridium botulinum that inhibits acetycholine release from nerve endings.5 This approach was shown to lead to short term symptom relief in up to 90% of patients.6 By six months, 20 (65%) of the 31 patients treated were still in remission. The endoscopic injection procedure is simple and no major complications have been reported as yet. A question that remained unanswered in the early studies with botulinum toxin concerns the duration of its effect in comparison with surgery and pneumodilatation.
In this issue (see page 231) Vaezi et aldescribe a randomised study in which they compared the immediate and long term efficacy of botulinum toxin with pneumatic dilatation. Their study is the first that formally compares these two treatment modalities in a prospective way. The most important result of the study, from a clinical point of view, is that botulinum toxin injection resulted in a significantly lower remission rate at 12 months than did pneumatic dilatation (32% compared with 70% of patients in complete remission). As an explanation for the apparent difference between the outcome of their study and those of some previous reports, the authors rightly highlight the fact that in previous studies of botulinum toxin in achalasia, repeat injections were given to patients who relapsed shortly after the initial injection. In an earlier study that compared botulinum toxin injection with pneumatic dilatation, only patients who did not respond to botulinum toxin treament were pneumodilated, rendering the comparison unfair.7
Vaezi and colleagues also examined the response of a number of objective parameters to treatment with botulinum toxin and pneumodilatation. Changes in diameter and length of the barium column at radiographical examination of the oesophagus paralleled changes in symptom scores. Somewhat surprisingly, however, botulinum toxin, in contrast to pneumatic dilatation, did not have a statistically significant effect on LOS pressure. Even at one month after botulinum injection no reduction in LOS pressure was found. This finding is in contrast with observations made in earlier studies. The possibility that measurement of mid-expiratory rather than of end-expiratory LOS pressure might have obscured an effect of botulinum toxin is discarded in the discussion section of the paper, although the authors do not provide us with the measurements.
The results of the study by Vaezi and colleagues raise more doubts on the clinical value of botulinum toxin treatment in achalasia than hitherto expressed. It is important to those actively involved in the treatment of patients with achalasia to consider the results of Vaeziet al’s study carefully. As the aim of treatment in achalasia, a life-long disease, is to reduce symptoms with a minimum number of interventions during the patient’s lifetime, a new treatment that has to be repeated frequently is likely to be less satisfactory, both to the patient and to the doctor, than the existing range of potential treatments.
As has been the case with many other new therapeutic options for various other diseases, the initial enthusiasm for botulinum toxin treatment in achalasia may have been too great. It seems that the pendulum is swinging back again. It is highly unlikely, though, that it will swing back to the whale bone approach!
See article on page 231
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