ANSWER 83
This woman gives a history of transient neurological symptoms with no residual signs. She is
at increased risk of cerebrovascular disease because of her smoking, hypertension and dia-
betes. She is describing recurrent transient ischaemic attacks(TIAs) which by definition
resolve completely in less than 24 h, and, in practice, often much quicker. Two months before
her admission she had an episode of amaurosis fugax (transient uniocular blindness) which
is often described as like a shutter coming down over the visual field of one eye. The TIAs are
affecting the left cerebral hemisphere in the area of brain supplied by the left carotid artery
causing right-sided weakness and dysarthria. TIAs may be caused by thromboembolism from
ulcerated plaques in the carotid arteries or aortic arch, from cardiac sources such as a dilated
left atrium, and more rarely due to haematological causes such as polycythaemia rubra vera,
sickle cell disease or hyperviscosity due to myeloma. The symptoms may be the same each
time or vary. Her ECG shows atrial fibrillation and she has the signs of mitral regurgitation
with a pansystolic murmur and displaced apex beat. There are three obvious potential sources
for emboli:
- a left carotid artery stenosis (in a correct location to account for the distribution of
these TIAs and more likely in the presence of a carotid bruit) - the left atrium in atrial fibrillation with clinically evident mitral regurgitation
- a previous myocardial infarction with mural thrombosis.
- Migraine: the aura of migraine is a spreading and slowly intensifying phenomenon
and the symptoms are usually positive, e.g. scotomata. The aura is usually followed
by a severe headache. However, migraines can be associated with focal neurological
deficits, e.g hemiplegia. - Focal epilepsy: this also normally causes positive symptoms such as twitching and
sensory symptoms which may march up one limb and from one limb to another on
the same side. - Syncope: unlike most TIAs there is loss of consciousness but there are usually no
focal signs. Dizziness often precedes the attack. - Space-occupying lesion: a cerebral tumour or abscess can produce fluctuating
symptoms and signs. The symptoms are usually more gradual in onset and are
often associated with headaches or personality changes. - Miscellaneous: hysteria, cervical spondylosis, hypoglycaemia and cataplexy.
- Migraine: the aura of migraine is a spreading and slowly intensifying phenomenon
! Major causes of transient neurological syndromes
This patient should be investigated with a computed tomography (CT) of the head to exclude
a structural space-occupying lesion, echocardiography to assess left-atrial size, the mitral
valve (to exclude infective valvular vegetations) and to rule out thrombus in the left ven-
tricle related to the previous infarct, and a Doppler ultrasound of the carotid arteries. If a
critical carotid stenosis (#70 per cent) is present, carotid endarterectomy should be consid-
ered. The patient should be anticoagulated with warfarin because of her atrial fibrillation
and carotid stenosis. Her blood pressure and diabetes should be carefully controlled and her
lipids measured and treated if appropriate.
- Most transient ischaemic attacks persist for only a few minutes.
- Approximately 40 per cent of patients with cerebral infarction have a prior history of
transient ischaemic attacks. - Multiple risk factors need to be taken in to account in the investigation and management
of vascular disease.