ANSWER 61
This man has had an episode characterized by sudden onset loss of consciousness associ-
ated with the development of generalized convulsions. The principal differential diagnosis
is between an epileptic fit and a syncopal (fainting) attack. Syncope is a sudden loss of con-
sciousness due to temporary failure of the cerebral circulation. Syncope is distinguished
from a seizure principally by the circumstances in which the event occurs. For example,
syncope usually occurs while standing, under situations of severe stress or in association
with an arrhythmia. Sometimes a convulsion and urinary incontinence occur. Thus, neither
of these is specific for an epileptic attack. The key is to establish the presence or absence of
prodromal symptoms. Syncopal episodes are usually preceded by symptoms of dizziness and
light-headedness. Other important neurological syndromes to exclude are transient ischaemic
attacks, migraine, narcolepsy and hysterical convulsions. Transient ischaemic attacks are
characterized by focal neurological signs and no loss of consciousness unless the verte-
brobasilar territory is affected. The onset of migraine is gradual, and consciousness is rarely
lost. In narcolepsy, episodes of uncontrollable sleep may occur but convulsive movements
are absent and the patient can be wakened.
In this man’s case the episode was witnessed by his wife who gave a clear history of a grand
mal (tonic–clonic seizure). There may be warning symptoms such as fear, or an abnormal
feeling referred to some part of the body – often the epigastrium – before consciousness is
lost. The muscles become tonically contracted and the person will fall to the ground. The
tongue may be bitten and there is usually urinary incontinence. Due to spasm of the respi-
ratory muscles, breathing ceases and the subject becomes cyanosed. After this tonic phase,
which can last up to a minute, the seizure passes into the clonic or convulsive phase. After
the contractions end, the patient is stupurose which lightens through a stage of confusion to
normal consciousness. There is usually a post-seizure headache and generalized muscular
aches.
In adults, idiopathic epilepsy rarely begins after the age of 25 years. Blood tests should be
performed to exclude metabolic causes such as uraemia, hyponatraemia, hypoglycaemia
and hypocalcaemia. Blood alcohol levels and gamma-glutamyltransferase levels should
also be measured as markers of alcohol abuse. A computed tomography (CT) scan of the
brain is needed to exclude a structural cause such as a brain tumour or cerebrovascular
event. This man should be referred to a neurologist for further investigation including an
electroencephalogram (EEG). This is necessary as he will probably not be able to continue
in his occupation as a taxi driver. Treatment with anticonvulsants for a single fit is also
controversial.
- It is vital to get an eye-witness account of a transient neurological episode to make a
diagnosis. - New-onset epilepsy is rare in adults and should therefore be fully investigated to
exclude an underlying cause.