Case 34 Funny turn

One morning, the medical registrar on-call is asked by the Emergency Department to see a 46-year-old motor sports journalist, Greg Dillon, after an episode of speech disturbance (expressive dysphasia) followed by a loss of consciousness. Mr Dillon’s wife had given him jam and dextrose tablets although no blood sugar had been measured. It took over an hour for Mr Dillon’s conscious level and speech to return to normal. He has now recovered completely but has a frontal headache.

Mr Dillon is a type 2 diabetic and takes once daily insulin and twice daily gliclazide. His blood pressure is well controlled, having been switched from a beta blocker to an ACE inhibitor two weeks prior because of erectile dysfunction. He smokes around ten cigars per week. He has been busy at work over the last few weeks in the run up to the British Grand Prix.

Examination is normal, as is a 12 lead ECG.

What is your differential diagnosis?

Given the speech disturbance, the registrar takes the view that this episode was likely to have been a transient ischaemic attack and arranges appropriate investigations including a same day MRI with vascular imaging. She warns Mr Dillon that he is unlikely to be able to drive for a month following a TIA.

What do you think of the diagnosis and the advice?

When the investigations have been completed, the AMU Consultant reviews Mr Dillon without the notes (the registrar is occupied with another patient). Mr Dillon explains that he still has a headache and the consultant, taking into account a normal MR examination, suggests the diagnosis of migraine. He discharges Mr Dillon with advice to watch his diet, alcohol intake and stress levels. He says that Mr Dillon can drive, as long as he feels well.

Do you agree with the consultant?

Three days later, Mr Dillon is involved in a road traffic accident. It transpires that his blood glucose had fallen to 2.2 mmol whilst he was behind the wheel. Blood tests in the Emergency Department reveal acute renal failure (creatinine 300, baseline 90–105). Following a full recovery, Mr Dillon complains to the hospital arguing that a failure to reach the correct diagnosis had resulted in loss of his no claims motor insurance premium.

Expert opinion

The differential diagnosis for transient neurological impairment is broad and includes cerebrovascular disease, epilepsy, migraine and hypoglycaemia. The latter should always be considered in a patient taking a sulphonylurea or insulin. Loss of consciousness is very rare indeed in transient ischaemic attack (TIA) and it should not form part of an initial differential diagnosis of loss of consciousness. Both migraine and hypoglycaemia can present with focal neurological symptoms and signs but migraine would also be an unlikely cause of loss of consciousness. Hypoglycaemia may resolve relatively slowly following an oral sugar load.

A normal MRI scan does not exclude a diagnosis of TIA: approximately 50% of scans will show some diffusion-weighted change whilst the remaining 50% will not. The diagnosis of TIA therefore remains clinical.

In this case, there was inadequate consideration of the range of diagnostic possibilities. This error was compounded by the consultant taking into account only two pieces of information (transient symptoms which had provoked a TIA protocol MRI and the emergence of a headache) to reach his diagnosis.

When advising patients about driving, the DVLA medical guidance should be followed to the letter. Where a range of diagnoses remain on the differential, the most restrictive guidance should be applied until the diagnosis can be made more firmly.

Legal comment

This case highlights the importance of good communication between colleagues, especially when working in a area of high throughput such as acute medical admissions. It also raises important issues about recording advice given to patients (including in the discharge letter to the GP).

In this instance, whilst two incorrect diagnoses were entertained (TIA and migraine), the correct diagnosis (hypoglycaemia) was not considered. TIA is the only one of these three diagnoses which the DVLA says entails no driving for a period. A patient who takes medication such as insulin is not required by DVLA to stop driving after a single episode of hypoglycaemia, unless he loses consciousness (as happened in this case).

If liability to Mr Dillon were established, then he would be entitled to compensation for any personal injury sustained in the car accident as well as the direct financial losses resulting from the failure to make an earlier diagnosis. This would include a claim for loss of earning and other direct pecuniary losses. There may also be adverse reputational damage–given Mr Dillon’s occupation–due to the loss of his no claims bonus.

Stay updated, free articles. Join our Telegram channel

Join