Botox Injection into the Lower Esophageal Sphincter Induces Hiatal Paralysis and Gastroesophageal Reflux.

BACKGROUND: Endoscopic intrasphincteric injection of botox (ISIB) is used routinely for the treatment of achalasia esophagus and other spastic motor disorders. Studies show that botox reduces the smooth muscle lower esophageal sphincter (LES) pressure. The esophageal hiatus, formed by the right crus of diaphragm surrounds the cranial half of the LES, it works like an external LES.

AIM: We studied the effects of ISIB on the LES and hiatal contraction and reflux (GER).

METHODS: 14 patients treated with ISIB were studied. Esophageal manometry-impedance recordings were performed before and after the ISIB. Hiatal contraction was assessed during tidal inspiration, forced inspiration, Muller maneuver and straight leg raise. In 6 subjects, the manometry were repeated 6-12 months after the ISIB. The esophagogastric junction (EGJ) pressure was measured at end-expiration (LES pressure) and at the peak of maneuvers (hiatal contraction). Trans-diaphragmatic pressure (pdi, force of diaphragmatic contraction) was measured at the peak of forced inspiration. GER was measured from impedance recordings.

RESULTS: The EGJ pressure at end-expiration (LES pressure) decreased significantly after botox injection. The peak EGJ pressure at tidal inspiration, forced inspiration, Muller maneuver and straight leg raise was also dramatically reduced by the ISIB. There was no effect of botox on the pdi during forced inspiration. Seven of the 10 subjects demonstrated GER during maneuvers following the ISIB. Six to 12 months after ISIB, hiatal contraction returned to the pre ISIB levels.

CONCLUSION: ISIB, in addition to decreasing LES pressure, paralyzes the esophageal hiatus (crural diaphragm) and induces GER.