Possibility not probability: the limits of medical knowledge

In most medical negligence cases that go to trial, the judge will determine the cause of the claimant's injuries and whether they were caused by a breach of duty.  In rare cases, the court cannot provide a claimant with the answers he seeks.

In Nicholas Collyer v Mid Essex Hospital Services NHS Trust [2019] EWHC 3577 (QB), the claimant sustained catastrophic damage to his 12th cranial nerves during surgery, leaving him unable to speak.  Despite parties presenting both negligent and non-negligent theories, the judge was unable to state that any mechanism was more likely than not to have caused the damage.  As a result, the claimant's action was dismissed.

Mr Collyer underwent a laryngectomy (removal of his voice box) on 27 February 2014 to treat recurrent laryngeal cancer.  The surgery was performed by Mr Stafford, consultant otolaryngologist and head and neck surgeon.  If surgery had been successful, the plan was to fit a valve to restore his speech. 

During the procedure, Mr Collyer sustained significant and permanent damage to both his hypoglossal (12th cranial) nerves.  This left him with almost no movement in his tongue.  He raised an action against the NHS Trust.    

Neither side's expert could find any reports of either negligent or non-negligent near total permanent nerve palsy of the hypoglossal nerves.  They agreed that it was not a reported or even recognised complication. 

Mr Collyer's expert submitted two potential negligent causes.  First, Mr Stafford may have incorporated each hypoglossal nerve in the sutures after removing the larynx.  Secondly, Mr Stafford may have made direct contact with each hypoglossal nerve when carrying out the procedure, partially transecting them.  The claimant alleged that as there were no non-negligent reports of this complication, it ought to be presumed that it was caused by Mr Stafford's negligence.      

The judge was not persuaded by either theory.  He dismissed the suggestion that Mr Stafford included the hypoglossal nerves in the sutures when closing.  This had never been seen before and was implausible.  Whilst it may have been possible to cause a partial transection of a hypoglossal nerve, in order to do so Mr Stafford would have had to move 1cm from where he ought to have been.  Mr Stafford and the two doctors assisting him would all have had to miss the muscle twitching when the nerve was damaged.  Mr Stafford would then have had to make precisely the same error on the other side.  The judge did not find that this was more likely than not.    

Mid Essex's expert presented two non-negligent theories to explain the damage: the nerves were damaged during retraction or due to intubation/neck positioning.  The judge found that neither of those was likely either.  Retraction occurred in every procedure and hypoglossal damage had never been reported previously.  Whilst it was possible that the damage was caused by intubation/neck positioning, the judge found it to be a remote possibility. 

This is a difficult case arising from tragic circumstances.  The unusual and insurmountable difficulty was the lack of medical literature to explain how Mr Collyer sustained the damage.  It was a complication that had never been reported before and, as a result, the experts had to offer theories as to how the damage may have occurred.  Whilst the judge accepted that there were theoretical explanations, none was probable.  In the absence of any other explanation, the mechanism of injury was unexplained and his action was dismissed.    

It's not enough for a claimant to show that their theory is the least unlikely: they must go further and show it is more likely than not.