The difficulty in establishing negligence when an unrecognised complication arises: Collyer v Mid Essex Hospitals NHS Trust [2019] EWHC 3577 (QB)

In this post Charley Turton of 12KBW discusses the recent decision of HHJ Coe QC (sitting as a High Court Judge) in Collyer v Mid Essex Hospitals NHS Trust [2019] EWHC 3577 (QB). The Claimant suffered permanent nerve palsy of the hypoglossal nerves during laryngectomy. In 145 years of the operation being conducted such an injury had never been reported. C argued that in these circumstances human error was the most likely cause and a “presumption of negligence” arose.


This was a liability only dispute arising from a laryngectomy procedure performed on 27 February 2014 for the treatment of recurrent laryngeal cancer. The Claimant (“C”) had previously received radiotherapy in 2013 but the cancer returned. The appropriateness of the laryngectomy was not in dispute.

Whilst the intended outcome (i.e. that C should be left cancer-free) was achieved, C sustained a permanent nerve injury with catastrophic consequences. C was left with almost no movement in his tongue, unable to speak and with difficulty swallowing.

The nerves in question were the hypoglossal (12th cranial) nerves. There was no dispute that they had suffered significant and permanent damage, described by the operating surgeon – Mr Stafford – as a complication so rare that it is unheard of. The question for the court, on which C’s claim hung, was how had this nerve injury come about?

The parties’ experts agreed that there were no reports of non-negligent bilateral, near total, permanent nerve palsy of the hypoglossal nerves following laryngectomy. C argued it is not a recognised complication of the procedure and suggested that a “presumption of negligence” therefore arises.

The possible mechanisms of injury

The parties were in agreement as to the correct procedure for performing laryngectomy. During the surgery the tongue is retracted and the hyoid bone (horseshoe-shaped bone situated between the chin and the thyroid cartilage) is drawn downwards, all of which gives rise to the risk of exerting some pressure on the hypoglossal nerves.

The court accepted that C’s operation was performed according to procedure. There was no recorded evidence of negligence in the operation note and no evidence of complication or irregularity at the time.

C argued that on balance of probability the damage arose through negligence on the part of the surgeon, who must have:

1. Either directly contacted the nerves through inappropriate manipulation or partial transection;

2. Or inadvertently incorporated the nerves into the suture line.

D argued that both scenarios were implausible and unsupported by evidence.

D offered a series of (it argued) more probable non-negligent explanations, including the fact that C had multiple comorbidities, some of which contributed to a pre-existing vulnerability of the hypoglossal nerves. C’s various pre-existing medical conditions included Type I diabetes, associated renal failure, DVT, obesity and sleep apnoea. The argument evolved into a theory that there might have been damage to the nerves caused by the previous radiotherapy and/or the C’s diabetes, but such damage was latent and resulting in vulnerability of the nerves to damage but not resulting in any loss of function. It was acknowledged that such damage would be unusual.

D eventually put forward two possible mechanisms of injury:

1. The nerves were irreparably damaged during retraction either of the base of the tongue or the hyoid bone in the context of the nerves being “vulnerable”.

2. Damage may have been caused during intubation for the anaesthesia and/or due to neck positioning, again, in the context of already vulnerable nerves.

The evidence of the experts

D’s expert – Professor Homer – stated that non-negligent damage to the nerve is possible during laryngectomy albeit the risk is very small and its occurrence has not been reported. He said that in his view every plausible mechanism/explanation that had been put forward was extremely unlikely, but the only mechanism that had some credence is pressure damage to the nerve and the tongue during retraction. He agreed that this is not a listed complication in laryngectomy, but he relied on it as being a general principle in surgery.

Crucially, the evidence of D’s expert was that had the nerves been cut, touched or damaged there would have been an inevitable observable reaction of the tongue; indeed a double reaction if both hypoglossal nerves had been damaged consecutively. No such reaction was observed during C’s surgery.

D argued that the bilateral aspect of the palsy suggested generic factors at play as opposed to the small chance that both nerves were transected.

C’s expert – Mr Gooder – was of the opinion that, in the case of a laryngectomy, damage to the hypoglossal nerves could only occur negligently, although he agreed that he had never heard of even one hypoglossal nerve having been enclosed in sutures. The theory was his own. In respect of the transection theory, he gave an unconvincing explanation as to why no observable reaction was noted at the time of the surgery.


The arguments

C argued human error is always more likely than an event that has never been reported before, particularly in an operation that has been performed for over 145 years.

D argued (i) medicine is not a precise science; there must be room for wholly unexpected results notwithstanding appropriate surgical technique and (ii) the negligent mechanisms put forward by C were too outlandish to be plausible and therefore the burden of proof could not be met.

There was a significant dispute of fact as to whether C had movement in his tongue immediately following the surgery, which would indicate whether the mechanism of injury occurred during surgery or not. The notes suggested that some movement was observed; whereas C and his family were adamant in their contrary position.


The law

• Where there are multiple possible causes of damage, C must prove that the negligent cause is not only the most likely but is more likely than not to be the cause (Rhesa Shipping Co S.A. v Edmunds and Fenton Insurance Co Ltd [1985] 1 WLR 948, “the Popi M”).

• D may suggest and seek to prove some other non-negligent cause but there is no obligation to do so, or to so prove on the balance of probability.

• Common sense must prevail. If the judge concludes even on a whole series of cogent grounds that the occurrence of an event is extremely improbable, a finding by him that it is nevertheless more likely to have occurred than not does not accord with common sense.

• If the court is able, for good reason, to dismiss causes A, B and C, it may be able to reach the conclusion that D was the effective cause, but the mere elimination of A, B and C is not of itself sufficient. The court must step back and, looking at all the evidence, consider whether on the balance of probabilities D is proved to be the cause.” (O’Connor v The Pennine Acute Hospitals NHS trust [2015] EWCA Civ 1244).

• “If an untoward outcome is extremely rare or is impossible to explain in the light of the current state of medical knowledge, the judge will be bound to exercise great care in evaluating evidence before making such a finding, but if he does so, the prima facie inference of negligence is rebutted and the plaintiffs claim will fail.” (Ratcliffe v Plymouth and Torbay Health Authority; Exeter and North Devon Health Authority [1998] PIQR 170)

• Where it can be proved that the injury suffered does not ordinarily happen if reasonable skill and care is deployed, that raises a case that there was negligence. But that is not to say that res ipsa loquitur necessarily applies. It does not. Res ipsa loquitur has a very limited application in cases where each side calls evidence.


The result

HHJ Coe QC found that the mechanism of injury occurred during surgery, on the basis of C’s “compelling” evidence that he could not move his tongue immediately afterwards. Despite this, the mystery of precisely how the injury occurred remained unsolved and the judge was unable to find that the negligent mechanisms suggested by C were more likely than not to have been the cause of the damage. In fact, he could not find that any of the mechanisms suggested by either party met this test. Accordingly, the court could not identify the cause of C’s injury. Despite the hypothesising of the experts, it remains unexplained.


This case is notable because it operates at the fringes of medical knowledge. The parties’ experts, and indeed the medical profession as a whole, had almost no experience of the outcome C suffered. As such they were forced to identify a possible cause rather than a likely one. It is perhaps not surprising therefore that mistakes were made by both experts.

C’s expert made suggestions which the court found to be implausible. In cases which are unique in medical experience, the difficulty for legal practitioners will be identifying at an early stage whether their expert’s opinion crosses into the realm of implausibility. This may well necessitate a second opinion.

Such cases will necessarily be few and far between. When they do arise, the outcome will turn on the smallest of margins, but the legal test remains simple and clear. Claimants must prove negligence on the balance of probabilities.

The tipping of that balance will come down to the extent of medical knowledge, the conviction of the experts and their relative levels of expertise, and whether there is any objective evidence which points to one conclusion over another. The danger of frequenting blind alleys in the evidence is bound to loom large, especially in the early stages of litigation.

This case makes clear that claimants will face an uphill battle in discharging the burden of proof where experts are driven to theorising.

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