Background and study aims: Endoscopic therapy of achalasia by injection of botulinum toxin into the lower esophageal sphincter has very limited adverse effects and is initially successful in 70 % of patients. However, this result only lasts for 6 - 9 months on average in most patients and only half of them benefit for more than 1 year. The aim of this study was to find out which factors are predictive for a good long-term success.
Patients and methods: We retrospectively studied 25 patients with achalasia. The diagnosis had been proven by barium swallow and esophageal manometry. Therapy was carried out endoscopically between June 1996 and December 1998 by injection of 25 mouse units (MU) botulinum toxin into each of the four quadrants of the lower esophageal sphincter (LES). Lower esophageal sphincter pressure (LESP) was measured prior to and 1 week after endoscopic therapy. A standardized questionnaire was used for symptom assessment, at the initial presentation, at 1 week and at 2.5 +/- 0.8 years after treatment.
Results: The LESP was significantly reduced (pre-treatment 62.1 +/- 15.2 mmHg vs. post-treatment 43.1 +/- 12.5 mmHg; P < 0.01). Symptoms improved in 16 patients (pre-treatment symptom score 9.5 +/- 2.9 vs. post-treatment symptom score 4.7 +/- 1.8; P < 0.01). Nine patients showed no relevant improvement. From the 16 patients with a good initial response, two were lost to follow-up. In nine patients the outcome was still satisfactory after a mean of 2.5 years (1.5 - 4 years) (pre-treatment symptom score 9.5 +/- 2.9 vs. symptom score at 2.5 years after Botox 5.1 +/- 1.5; P < 0.05). These patients were on average 67.7 +/- 12.5 years old. The remaining five patients received a second or third injection of botulinum toxin, but none improved substantially for more than 6 months. One of them eventually underwent pneumatic dilation, and three laparoscopic myotomy. Thus, botulinum toxin treatment was unsuccessful in 14 patients in all. These 14 patients were, on average, significantly younger than the nine successfully treated patients (46.1 +/- 12.6 years vs. 67.7 +/- 12.5 years; P < 0.01) and had significantly higher LESP values prior to botulinum toxin therapy (72.8 +/- 8.9 mmHg vs. 47.8 +/- 9.2 mmHg; P < 0.01).
Conclusions: The long-term success of botulinum toxin injection into the LES in patients with achalasia is highest in elderly patients and in patients with an LESP not exceeding the upper normal level prior to treatment by 50 % or more. On the basis of our results, younger patients (< 55 years) with a severe increase in LESP do not seem to benefit from botulinum toxin injection and pneumatic dilation or myotomy may be more advantageous to them.