LAUSR

Causation is the most complex area of clinical negligence; the application of the law to the medical facts is, rightly, a matter for lawyers. Causation may be determined on the specific facts of a case with little general applicability. However, neurosurgeons are often involved in medicolegal work and a general understanding of the law can be helpful. A recent article in this journal reviewed the law in respect of causation setting out the principles of classical ‘but-for’ causation, simultaneous causation and causation as public policy (autonomy in respect of consent). Two recent cases considered continuous (consecutive, indivisible causation). Mr Williams had acute appendicitis. Abdominal CT was requested. The CT was delayed and then the report further delayed (estimated to be between two hours twenty minutes to four hours fifteen minutes delay). A laparotomy was performed, there was widespread purulent peritonitis. Mr Williams was septic with cardiac and respiratory failure. He was very unwell for several weeks, but made a full recovery. It was found that there was a negligent delay in imaging and surgery. Myocardial ischaemia was a consequence of sepsis present over a period of about six hours. Sepsis was a single continuous process; sepsis could not be divided into compartments (a nonnegligent initial compartment followed by a subsequent negligent compartment). The delay was at least two hours twenty minutes and, it was found, this materially contributed to the overall burden of sepsis and the myocardial injury, establishing causation. This is an important and relevant development for neurosurgeons where damage to the nervous system is often caused in a continuous and progressive manner. There is already a decided case involving a general practitioner, Dr John, who suffered an acute subdural haematoma (ASDH). There were delays in CT scanning and then further delays in transfer. The Judge found that the long-term harm was caused by an extended period of raised intracranial pressure occurring in part because of the primary head injury and in part because of the negligent delays in management. The negligent delays materially contributed to the injury. It was impossible to calculate, scientifically, the extent to which the negligence contributed to the overall final damage and therefore the Claimant could claim in full. Where an ASDH causes specific physical harm such as a homonymous hemianopia from occipital infarction it may be possible to say that earlier treatment, on a balance of probabilities, would/ would not have caused occipital infarction (classical but-for causation). That assessment may not be possible for example for cognitive injury where the principle of continuous causation might well apply. It takes little imagination to see the implications in many areas of neurosurgical practice. An expert witness should identify the medical facts that assist the Court in identifying the relevant issues (in this respect in relation to causation). Medical experts should not get involved in legal issues particularly where they may have an imperfect understanding of the law. Nevertheless, neurosurgeons who offer medicolegal advice should recognise that there are cases where there is continuous harm causing damage both before and after the point of negligence. Even if the case does involve continuous causation, it will often be possible to quantify a claim. For example, a patient with ASDH who should have been operated upon when they were GCS 14-15 would be expected to have a better outcome than someone who was GCS 5. In other cases, it may be impossible to quantify the effect of the non-negligent/negligent contributions, if so the expert should state that clearly. The claimant in such cases would be expected to succeed provided the effect of negligence was a material effect, but having concluded that there was a continuous, indivisible cause of harm the expert can leave the further ramifications to the lawyers.