Kernig’s sign

• Flex one of the patient’s legs to 90 degrees at both the

hip and the knee, with your left hand placed over the

medial hamstrings (Fig. 7.3).

• Extend the knee while the hip is maintained in flexion.

Look at the other leg for any reflex flexion. Kernig’s sign is

positive when extension is resisted by spasm in the

hamstrings. Kernig’s sign is absent with local causes of

neck stiffness, such as cervical spine disease or raised

intracranial pressure.

Drug history

Always enquire about drugs, including prescribed, over-thecounter, complementary and recreational/illegal ones, as they

can give rise to many neurological symptoms (for example,

phenytoin toxicity causing ataxia; excessive intake of simple

analgesia causing medication overuse headache; use of cocaine

provoking convulsions).

Family history

Obtain a family history for at least first-degree relatives:

parents, siblings and children. In some communities, parental

consanguinity is common, increasing the risk of autosomal

recessive conditions, so you may need to enquire sensitively about

this. Many neurological disorders are caused by single-gene

defects, such as myotonic dystrophy or Huntington’s disease.

Others have important polygenic influences, as in multiple

sclerosis or migraine. Some conditions have a variety of

inheritance patterns; for example, Charcot–Marie–Tooth disease

may be autosomal dominant, autosomal recessive or X-linked.

Mitochondria uniquely have their own DNA, and abnormalities in

this DNA can cause a range of disorders that manifest in many

different systems (such as diabetes, short stature and deafness),

and may cause common neurological syndromes such as migraine

or epilepsy. Some diseases, such as Parkinson’s or motor

neurone disease, may be either due to single-gene disorders

or sporadic.

Social history

Social circumstances are relevant. How are patients coping with

their symptoms? Are they able to work and drive? What are their

support circumstances, and are these adequate?

Alcohol is the most common neurological toxin and damages

both the CNS (ataxia, seizures, dementia) and the PNS

(neuropathy). Poor diet with vitamin deficiency may compound

these problems and is relevant in areas affected by famine and

alcoholism or dietary exclusion. Vegetarians may be susceptible

to vitamin B12 deficiency. Recreational drugs may affect the

nervous system; for example, nitrous oxide inhalation causes

subacute combined degeneration of the cord due to dysfunction

of the vitamin B12 pathway, and smoking contributes to vascular

and malignant disease. Always consider sexually transmitted

or blood-borne infection, such as human immunodeficiency

virus (HIV) or syphilis, as both can cause a wide range of

neurological symptoms and are treatable. A travel history may

give clues to the underlying diagnosis, such as Lyme disease

(facial palsy), neurocysticercosis (brain lesions and epilepsy) or

malaria (coma).

Occupational history

Occupational factors are relevant to several neurological disorders.

For example, toxic peripheral neuropathy, due to exposure to

heavy or organic metals like lead, causes a motor neuropathy;

manganese causes Parkinsonism. Some neurological diagnoses

may adversely affect occupation, such as epilepsy in anyone who

needs to drive or operate dangerous machinery. For patients with

cognitive disorders, particularly dementias, it may be necessary

to advise on whether to stop working.

The physical examination • 125

7

Dysphonia usually results from either vocal cord pathology,

as in laryngitis, or damage to the vagal (X) nerve supply to

the vocal cords (recurrent laryngeal nerve). Inability to abduct

one of the vocal cords leads to a ‘bovine’ (and ineffective)

cough.

Dysphasias

Dysphasia is a disturbance of language resulting in abnormalities

of speech production and/or understanding. It may involve other

language symptoms, such as writing and/or reading problems,

unlike dysarthria and dysphonia.

Anatomy

The language areas are located in the dominant cerebral

hemisphere, which is the left in almost all right-handed people

and most left-handed people.

Broca’s area (inferior frontal region) is concerned with word

production and language expression.

Wernicke’s area (superior posterior temporal lobe) is the

principal area for comprehension of spoken language. Adjacent

regions of the parietal lobe are involved in understanding written

language and numbers.

The arcuate fasciculus connects Broca’s and Wernicke’s areas.

Examination sequence

• During spontaneous speech, listen to the fluency and

appropriateness of the content, particularly paraphasias

(incorrect words) and neologisms (nonsense or

meaningless new words).

• Show the patient a common object, such as a coin or

pen, and ask them to name it.

• Give a simple three-stage command, such as ‘Pick up this

piece of paper, fold it in half and place it under the book.’

• Ask the patient to repeat a simple sentence, such as

‘Today is Tuesday.’

• Ask the patient to read a passage from a newspaper.

• Ask the patient to write a sentence; examine the

handwriting.

Expressive (motor) dysphasia results from damage to Broca’s

area. It is characterised by reduced verbal output with non-fluent

speech and errors of grammar and syntax. Comprehension is

intact.

Receptive (sensory) dysphasia occurs due to dysfunction in

Wernicke’s area. There is poor comprehension, and although

speech is fluent, it may be meaningless and contain paraphasias

and neologisms.

Global dysphasia is a combination of expressive and receptive

difficulties caused by involvement of both areas.

Dysphasia (a focal sign) is frequently misdiagnosed as

confusion (non-focal). Always consider dysphasia before assuming

confusion, as this fundamentally alters the differential diagnosis

and management.

Dominant parietal lobe lesions affecting the supramarginal gyrus

may cause dyslexia (difficulty comprehending written language),

dyscalculia (problems with simple addition and subtraction) and

dysgraphia (impairment of writing). Gerstmann’s syndrome is the

combination of dysgraphia, dyscalculia, finger agnosia (inability

to recognise the fingers) and inability to distinguish left from

right. It localises to the left parietal lobe in the region of the

angular gyrus.