Comparative neuromuscular histopathology of cricopharyngeal achalasia patients with and without previous botulinum toxin treatment.

Objectives: Botulinum toxin injection (BTX) and cricopharyngeal (CP) myotomy are performed in the treatment of CP achalasia (CA). The objective of this study was to examine the effects of BTX on neuromuscular histopathologic findings and to make direct comparisons between specimens of muscle from CA patients who had received BTX to the upper esophageal sphincter and from CA patients who had no previous exposure to BTX.

Methods: We performed a retrospective review (2001 to 2005) of CP muscle specimens from all patients who underwent myotomy for CA. Cases of Zenker's diverticulum were excluded. Patient demographics, clinical course, and neuromuscular pathology findings were noted from the chart.

Results: Nineteen patients with CA were identified: 10 male and 9 female, with a mean age of 57 years. Eleven had no prior BTX (6 male and 5 female; mean age, 62 years); 8 had previous treatment with BTX (4 male and 4 female; mean age, 51 years). Eight of the 11 BTX-naive patients revealed predominantly myopathic changes on histology. Those with previous BTX tended to be younger; 6 of the 8 had a clinical benefit from their BTX and ultimately went on to myotomy. The CP muscle specimens featured both mixed and neurogenic pathologic changes in 5 of the 8 patients with BTX. Although these findings suggest some impact of BTX on the CP muscle, the difference between the groups was not statistically significant (p < .20, chi2 test).

Conclusions: Treatment with BTX may have some clinical and histopathologic impact on the upper esophageal sphincter of patients with CA. Although neuropathic changes were noted in the CP muscle of previously injected patients at the time of their CP myotomy, the neuromuscular pathologic findings overall were not significantly different from those of BTX-naive patients.