Oesophageal Diverticula

Description

An oesophageal diverticulum is a circumscribed sacculation of the wall of the oesophagus. The diverticulum may be congenital or acquired and congenital diverticula usually occur due to a defect in the muscle layers of the oesophagus through which the mucosa can herniate. Acquired diverticula can be divided into:

• Traction diverticula involve all of the layers of the oesophageal wall and occur when peri-oesophageal inflammation and fibrosis result in the formation of adhesions between the oesopagus and surrounding tissues, distorting the normal contours of the oesophageal wall. They develop most commonly in the cranial and middle portions of the oesophagus.
• Pulsion diverticula are similar to congenital divericula in that the mucosa herniates through an acquired defect in the outer layers of the wall. They may be caused by any condition that places internal radial stress on the oesophageal wall, such as increases in intraluminal oesophageal pressure. Foreign bodies, vascular ring anomalies, strictures and severe oesophagitis can all therefore lead to the development of pulsion diverticula.

Signalment

Diverticula are rare in small animals and occur with no apparent breed or sex predilections. They should not be confused with normal variants of oesophageal anatomy, as occur particularly in Chinese Shar-peis which may have extra oesophageal loops or folds.

Diagnosis

Clinical Signs

Signs may be related to the underlying cause of the diverticulum or to the presence of impacted food or retained fluid in the sacculated area. Small diverticula may cause no clinical signs but otherwise, the following signs may occur:

• Regurgitation with hypersalivation
• Difficulty in swallowing, manifesting as odynophagia (pain on swallowing), retching and repeated efforts to swallow.
• Post-prandial dyspnoea if the sacculation impinges on the lung fields.
• Aspiraton pneumonia with tachypnoea, dyspnoea, pyrexia and coughing may occur with any cause of chronic regurgitation.
• Signs that occur if the oesophagus ruptures are described here.

Diagnostic Imaging

Plain radiographs of the chest may show an area of air or soft tissue density in assoication with the oesophagus. This finiding is not definitive as it may represent a peri-oesophageal mass, a hiatal hernia or another lesion of the lungs or mediastinum.

Administration of a radio-opaque contrast medium (such as barium) should outline the extent of the dilation.

Endoscopy (oesophagoscopy) can be used to provide a definitive diagnosis by visualising the sacculation.

Treatment

Any underlying cause of an acquired diverticulum should be removed or treated where possible. Diverticula themselves may be managed medically or surgically, depending on their size.

• Small diverticula may be managed medically by feeding soft or liquid diets and elevating the forelimbs of the animal for 10-15 minutes after each meal to encourage food boluses to pass into the stomach.
• Larger diverticular and small pulsion diverticula should be corrected surgically as they are more likely to cause clinical signs and because pulsion diverticula may enlarge over time as food becomes impacted in the sacculation. A diverticulectomy is performed after entering the chest cavity by a lateral thoracostomy or median sternotomy, depending on its exact location. The diverticulum is removed and the wall of the oesophagus is sutured longitudinally to try to prevent the formation of strictures. Since the oesophagus has no serosal layer, the repair may be augmented with muscle flaps (from the longus colli or intercostal muscles), with omentum brought into the chest cavity or with synthetic mesh. It is important that the repair not be under tension to prevent dehiscence and a headcollar and side reins may be used post-operatively to prevent this.

Prognosis

The prognosis is fair to guarded due to possible post-operative complications of oesophageal hypomotility and oesophageal stricture formation.

References

Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition) BSAVA Merck & Co (2008) The Merck Veterinary Manual Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2)