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Fig. 7.1 Anatomy of the central nervous system. A Lateral surface of the brain. B Spinal cord, nerve roots and meninges. C Cross-section of the

spinal cord. D Spinal motor neurone. The terminals of presynaptic neurones form synapses with the cell body and dendrites of the motor neurones.

122 • The nervous system

Seizure

An epileptic seizure is caused by paroxysmal electrical discharges

from either the whole brain (generalised seizure) or part of the

brain (focal seizure). A tonic–clonic seizure (convulsion) is the

most common form of generalised seizure, and typically follows a

stereotyped pattern with early loss of consciousness associated

with body stiffening (tonic phase) succeeded by rhythmical jerking

crescendoing and subsiding over 30–120 seconds (clonic phase);

this is followed by a period of unresponsiveness (often with

heavy breathing, the patient appearing to be deeply asleep) and

finally confusion as the patient reorientates (postictal phase).

The history from the patient and witnesses can help distinguish

syncope from epilepsy (Box 7.2). Focal seizures may or may not

involve loss of awareness (complete loss of consciousness is less

typical) and are characterised by whichever part of the brain is

involved: for example, a focal motor seizure arising from the motor

cortex, or temporal lobe seizures characterised by autonomic

and/or psychic symptoms, often associated with automatisms

such as lip smacking or swallowing. Functional dissociative

attacks (also known as non-epileptic or psychogenic attacks, or

pseudoseizures) are common, and may be difficult to distinguish

from epileptic seizures. These attacks are often more frequent

than epilepsy, sometimes occurring multiple times in a day, and

may last considerably longer, with symptoms waxing and waning.

Other features may include asynchronous movements, pelvic

thrusts, side-to-side rather than flexion/extension movements

and absence of postictal confusion. The widespread availability

of videophones allows witnesses to capture such events and

may prove invaluable.

• If intermittent, how long do they last, and how long does

the patient remain symptom-free in between episodes?

• Was the onset sudden or gradual/evolving?

Precipitating, exacerbating or

relieving factors

• What was the patient doing when the symptoms

occurred?

• Does anything make the symptoms better or worse,

such as time of day, menstrual cycle, posture or

medication?

Associated symptoms

Associated symptoms can aid diagnosis. For example, headache

may be associated with nausea, vomiting, photophobia (aversion

to light) and/or phonophobia (aversion to sound) in migraine;

headache with neck stiffness, fever and rash may be associated

with meningitis (Box 7.1).

Common presenting symptoms

Headache

Headache is the most common neurological symptom and

may be either primary or secondary to other pathology. Primary

(idiopathic) causes include:

• migraine

• tension-type headache

• trigeminal autonomic cephalalgias (including cluster

headache)

• primary stabbing, cough, exertional or sex headache

• primary thunderclap headache

• new daily persistent headache.

Secondary (or symptomatic) headaches are less common,

but include potentially life-threatening or disabling causes such

as subarachnoid haemorrhage or temporal arteritis. One of the

key history aspects is rapidity of onset; isolated headache with

a truly abrupt onset may represent a potentially serious cause

such as subarachnoid haemorrhage or cerebral vein thrombosis,

whereas recurrent headache is much more likely to be migraine,

particularly if associated with other migrainous features like aura,

nausea and/or vomiting, photophobia and phonophobia (Box

7.1). Asking patents what they do when they have a headache

can be instructive. For example, abandoning normal tasks and

seeking a bed in a dark, quiet room suggest migraine, whereas

pacing around the room in an agitated state, or even head

banging, suggests cluster headache.

Transient loss of consciousness

Syncope is loss of consciousness due to inadequate cerebral

perfusion and is the most common cause of transient loss of

consciousness (TLOC). Vasovagal (or reflex) syncope (fainting)

is the most common type and precipitated by stimulation of the

parasympathetic nervous system, as with pain or intercurrent

illness. Exercise-related syncope, or syncope with no warning or

trigger, suggests a possible cardiac cause. TLOC on standing

is suggestive of orthostatic (postural) hypotension and may be

caused by drugs (antihypertensives or levodopa) or associated

with autonomic neuropathies, which may complicate conditions

such as diabetes.

7.2 Features that help discriminate vasovagal syncope

from epileptic seizure

Feature Vasovagal syncope Seizure

Triggers Typically pain, illness,

emotion

Often none (sleep

deprivation, alcohol,

drugs)

Prodrome Feeling faint/

lightheaded, nausea,

tinnitus, vision

dimming

Focal onset (not always

present)

Duration of

unconsciousness

<60 s 1–2 mins

Convulsion May occur but usually

brief myoclonic jerks

Usual, tonic–clonic

1–2 mins

Colour Pale/grey Flushed/cyanosed, may

be pale

Injuries Uncommon,

sometimes biting of

tip of tongue

Lateral tongue biting,

headache, generalised

myalgia, back pain

(sometimes vertebral

compression fractures),

shoulder fracture/

dislocation (rare)

Recovery Rapid, no confusion Gradual, over 30 mins;

patient is often confused,

sometimes agitated/

aggressive, amnesic

The history • 123

7

than ischaemia include use of anticoagulation, headache, vomiting,

seizures and early reduced consciousness. Haemorrhagic stroke

is much more frequent in Asian populations. Spinal strokes are

very rare; patients typically present with abrupt bilateral paralysis,

depending on the level of spinal cord affected. The anterior

spinal artery syndrome is most common and causes loss of

motor function and pain/temperature sensation, with relative

sparing of joint position and vibration sensation below the level

of the lesion.