Validación funcional

There were three factors that might predispose to syncope. Firstly, the patient had a cold. Secondly, he had consumed a small amount of alcohol.

Thirdly, he was in a warm environment. A change in posture interacted with three predisposing factors to produce syncope. The initial history placed the onset of the event on the couch. In reality, the onset was after the patient had got up and walked a few steps, and it was necessary to go back a few minutes in time to elicit the history of postural change.

He turned round, and went back and sat on the couch. There was then a gap in his awareness until he came round. He was asked in what way he had felt unwell just after he got up from the couch. He said that he felt dizzy, and that his vision had become blurred. He identified this feeling as being

similar to the one he had on standing up too quickly, a feeling of dizziness accompanied by

blurring and darkening of the vision.

The patient fainted in the sitting position, preventing an immediate fall, and preventing restoration of perfusion to the brain.

Unconsciousness and recovery were longer than usual, and the patient had stiffness and jerks.

C^ASE1

A 35-year-old male had an episode of loss of consciousness. The general practitioner obtained

an account of the event from the man's wife. She said that he had been sitting on the couch the

previous evening, had lost consciousness,

slumping to one side. He went stiff, and had had a few jerks, and gradually came round, feeling groggy for a few minutes.

At this point, the diagnosis is one of epileptic seizure. However, it is important to be clear on the circumstances of any attack, so further

questioning is indicated.

The general practitioner had not unreasonably diagnosed epileptic seizure. At the clinic, however

,

the patient was asked how he had been feeling that night. He said that he had a cold. He had been sitting on the couch in front of a warm fire,

drinking a glass of whisky. He had got up to refill his glass, and approximately half way to the living room had felt unwell.

She was admitted for video EEG recording, and several attacks were recorded in the first 3 days. All corresponded to the husband’

description, and all were PNES. Enquirys discovered a background of childhood sexual abuse. No interictal EEG abnormalities were detected.

The diagnosis of PNES is established, but the possibility of a background epilepsy remains. Onset of PNES aged 6 years is not usual, and the events were infrequent for many years, suggesting another cause.

Her medication was gradually withdrawn after her discharge from hospital. On review at 1 month, her husband said that the attacks had greatly reduced, but said that he now realized

there had been two types of attack, the more recent, frequent attacks being different from

the original ones. A detailed description of the more recent attacks was obtained. The

patient would fall abruptly to the ground, initially floppy, then stiff. She would then go blue. After 30 seconds or so, she would

recover her colour, then relax and gradually recover consciousness, with a short phase of

confusion.

When different attacks are occurring eyewitnesses may find it difficult to distinguish between them. In this case, it was only when the frequent type of event ceased that the husband could give a clear description of the less frequent type. In this case it was not possible to establish the diagnosis definitively, but the eyewitness description of the recent attacks is highly suggestive of cardiac arrest. The fact that the patient had a history of sexual abuse illustrates the diagnostic limitations of background factors.

An ECG was performed urgently, and showed a prolonged QT interval.

There is a good argument for performing routine ECG in all patients presenting with attacks of loss of consciousness.

C^ASE2

A 27-year-old female presented with a history of episodes of loss of consciousness. These had started when she was 6 years old and had

originally been infrequent, at one or two per year .

Over the preceding year, the frequency had increased to the point where she was having three or four per week.

At this point the disorder appears like worsening intractable epilepsy

, but a change in the behaviour of epilepsy should prompt a

reassessment.

She herself had no warning of the attacks.

Following them, she felt drained, but had no specific postictal symptoms. Her husband gave a description.

She would become agitated, with a progressively severe tremulous movement involving both arms.

This would increase over several minutes, and spread to the point where she had violent alternating movements of all four limbs, with side-to-side

movements of the head. This would go on for several minutes, occasionally for longer

. There was no cyanosis, tongue biting, or incontinence.

This description is not compatible with tonic–clonic seizures, and suggests PNES, possibly

of recent onset on the background of a longstanding seizure disorder

.

REVISION QUESTIONS

1 Vasovagal syncope:

a Presents with lateralized visual aura.

b Causes biting of the tip of the tongue.

c Is usually infrequent.

d May cause myoclonic jerks.

e May be provoked by exercise.

2 True petit mal seizures:

a Are associated with a generalized spike-wave discharge.

b Usually last 30–60 seconds.

c Usually originate in the temporal lobe.

d May occur many times per day.

e May occur in juvenile myoclonic epilepsy.

Answers 1 a False. Lateralized visual aura suggests

epileptic seizure.

b True. In tonic–clonic seizures, tongue biting is usually lateral, or the inside of the cheek is

bitten.

c True.

d True.

e False. Provocation by exercise should suggest

cardiogenic syncope.

2 a True.

b False. Seizures last several seconds at most.

c False. They are generalized seizures.

d True.

e True.

3 a True.

b True, though in a minority of patients.

c False.

d False. Movements are normally alternating or

tremulous. Asynchronous jerks may

occasionally occur .

e True. A history of minor head injury is elicited in approximately 50% of patients.

C^ASE3

A 55-year-old female presented to the neurology clinic complaining of memory difficulties over the previous few months. On taking a detailed history, it became clear that her problem was intermittent. She was actually complaining of short gaps in her memory, at intervals of every few hours or so, though sometimes with gaps of a few days. The gaps in memory were brief, lasting 2 or 3 minutes at most.

According to her own account, she behaved completely normally during these gaps, and appeared to carry on normal activity. She felt completely normal before the attacks and after.

While the initial complaint was of poor memory suggesting a cognitive problem, a paroxysmal disturbance of memory over a time of seconds or minutes should always arouse suspicion of seizures.

The eyewitness account was obtained. It transpired that most of the gaps in memory passed without an eyewitness being aware of anything amiss. However, on one occasion she had a gap in her memory while driving. The eyewitness reported that she had become disoriented, and seemed unaware of where she was. She continued to drive, but could not carry on a sensible conversation for 30 seconds or so.

This illustrates the tendency for focal epileptic seizures to vary in severity (reflecting a variation in the extent of the propagation of the discharge). In this case, it was only when a more severe seizure occurred that it became evident that the functional disturbance extended beyond memory.

A standard EEG was normal. Ambulatory EEG monitoring was carried out. This showed frequent spike discharges over the left temporal region, which correlated with periods of loss of memory.

3 Psychogenic nonepileptic seizures:

a Are usually frequent.

b May cause injury.

c Are not stereotyped.

d Are associated with synchronous clonic movements.

e Are associated with head injury.