The Phreno-oesophageal ligament

The phreno-oesophageal ligament (POL) is a fascinating structure that plays a very important role in the integrity of the OGJ - yet it is much overlooked. For an excellent article reviewing the anatomy and pathophysiology click here.

Essentially the ligament anchors the lower oesophagus to the diaphragm - the upper leaf of the ligament is very rich in elastic fibres and collagen, making it strong and able to recoil. This is important as the oesophagus can shorten by up to 6-7cm when its longitudinal muscle contracts, as happens in belching, vomiting and a number of pathological situations.

The POL inserts over an average distance of 1cm into the lower oesophageal wall but it is the precise point where it inserts that is vital. Normally it inserts 1 to 8cm (mean 3.35cm) above the lower oesophageal sphincter (LOS) but in cases of oesophagitis it is lower (0 - 3cm, mean 1.13cm). This holds true for cases of hiatus hernia (HH) as well (without oesophagitis - mean distance above sphincter = 3.6cm; with oesophagitis mean = 0.5cm).

The lower the insertion the nearer it is to the LOS and thus the more of a lateral force it exerts on the sphincter when it is 'trying' to exert a longitudinal force on the oesophagus to pull it back against longitudinal muscle contraction.

Rupture of the POL when stretched too far (as can be the case in very large HHs) would mean this force is no longer exerted and explains the paradox that very large HHs tend to be symptom-free, at least as far as reflux is concerned.

Unfortunately, the treatment of reflux is unlikely to be as simple as dividing or reattaching the ligament more proximally to negate or redistribute its exerted forces. Detaching and reattaching the POL either below, on or above the original point of insertion has been tried with dogs in an experimental setting (Bremner CG et al. Surgery 1970; 67(5): 735-40). Although the numbers involved were small this experiment showed that when the POL was attached proximally the LOS pressure increased afterwards but some reflux was detectable, whereas when it was attached distally no significant pressure changes were observed. This suggests that there is more than one factor involved in the maintainance of LOS integrity and altering one does not necessarily affect the whole environment.  Why the POL varies so considerably in its insertion point is a matter for conjecture and one could postulate a genetic component to the pathophysiology of reflux disease.

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