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Epidural catheter... another location to die in..

After passing the epidural catheter through the Ligamentum Flavum we expect the catheter to end up in the epidural space (best)..somtimes intrathecal( sure less good)..and rarely in the subdural(even more less good)...but now there is another place that epidural catheter may end up....

According to a study publised in Anaesthesia intensive care 2011 Nov;39(6):1038-42 .The authors (Collier, Reina et al) suggest the existence of a fourth space.

Failed epidurals


In some of these patients, radiological studies showed restricted spread of contrast injected into the failed epidurals.

 This striking compartmentalisation that you see in the above photo  , didn’t look at all like any spread you would expect from epidural or subdural injections.

The fourth space
The authors realized this could represent ‘a fourth space’, more precisely located within the dura.



Next, the authors obtained samples of the epidural sac from cadavers and analyzed them.

After preparing the samples the authors could, in some of them, clearly identify anomalous separations of the laminae that make up the dura.

The separations could expand into compartments, the intradural spaces.

They also documented how an epidural catheter can fit into one of these intradural spaces.

 The above photo shows an 20G epidural catheter passing through one of these intradural space.

This could be the answer to some epidural fails that we anaesthetists otherwise struggle to explain.

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