There are two essential questions in any neurological diagnosis:
1 What is/are the site(s) of the lesion(s)?
2 What is the likely pathology?
Most of the diagnoses in neurology are made on a detailed history alone. The method of recording the details is beyond the scope of this chapter, but an important point is that the history should read chronologically and portray the story of the disease. A summary should conclude the history.
Headache at some time is an almost universal experience. It varies from an infrequent and trivial nuisance to a symptom of serious disease.
Mechanism of headache
Pain receptors are found in the vessels at the base of the brain (both arterial and venous) and in the meninges . These receptors are also present in extracranial vessels, the muscles of the scalp, neck and face, the paranasal sinuses, the eyes and the teeth. The brain substance itself is almost devoid of pain receptors.
The pain of headache is mediated by mechanical and chemical (e.g. 5-hydroxytryptamine, histamine) stimulation of receptors: nerve impulses are carried centrally via the fifth and ninth cranial nerves and via the upper cervical sensory roots.
Intracranial mass lesions displace the meninges and the basal vessels. When these structures are physically moved by changes in cerebrospinal fluid (CSF) pressure (e.g. coughing), pain is exacerbated. Cerebral oedema, which accumulates around mass lesions, causes further shift. Headache is typically worse after lying down for some hours (as cerebral oedema increases). Any headache, however mild, that is present on waking and which is made worse by coughing, straining or sneezing may well be due to displacement or dilatation of the intracranial vessels and may be due to a mass lesion. These are often called ‘the headaches of raised intracranial pressure’. Vomiting often accompanies them.
Headache of subacute onset
The onset and progression of a headache over days or weeks with or without the features of ‘pressure headaches’ should always raise the suspicion of an intracranial mass lesion or serious intracranial disease. Encephalitis and viral meningitis should be considered. Giant-cell arteritis causes headache, with scalp tenderness, particularly over the age of 60 years.
The single episode of severe headache
This common emergency is caused principally by:
• Subarachnoid haemorrhage
• Migraine and, occasionally,
Particular attention should be paid to the suddenness of onset (suggestive of a subarachnoid haemorrhage), neck stiffness and vomiting (meningeal irritation) and rashes and fever (meningitis).
Migraine and tension headache are the commonest causes of recurrent pain. Sinusitis, glaucoma and migrainous neuralgia should also be considered. Hangover headache is usually obvious! Malignant hypertension occasionally causes a patient to seek medical advice because of headache. Headaches are not caused by essential hypertension.
Intermittent hydrocephalus due to an intraventricular tumour is a rare cause of recurrent prostrating headache with weakness of the lower limbs. ‘Eyestrain’ from refractive error is an unusual cause of headache. Headache following head injury Subdural haematoma should be considered, whether or not the headaches are suggestive of a mass lesion. The vast majority of post-traumatic headaches , which last days, weeks or months are not, however, associated with any serious intracranial cause.
Almost all recurring headaches with a history going back for several years or more are due to muscle tension and/or migraine. Depression usually accompanies them.
DIZZINESS, VERTIGO AND BLACKOUTS
‘Dizziness’ is a word patients use for a wide variety ofcomplaints ranging from a vague feeling of unsteadiness to severe, acute vertigo. It is also frequently used to describe the light-headedness that is felt in anxiety and ‘panic attacks’, during palpitations, and in syncope or chronic ill-health. Therefore, the site of this symptom must be determined, i.e. whether it is perceived in the limbs, the chest or the head.
Vertigo (an illusion of movement) is a more definite symptom. It is usually a sensation of rotation in which the patient feels that their surroundings are spinning or moving. Vertigo indicates disease of the labyrinth, vestibular pathways or their central connections.
Like dizziness, ‘blackouts’ is a vague, descriptive term implying either altered consciousness, visual disturbance or falling. Epilepsy, syncope, hypoglycaemia and other conditions must be considered (see p.916). However, commonly no sinister cause is found. A careful history, particularly from an eye-witness, is essential.
Sensory loss (ioint position)
Apraxia of gait
This is a common presenting complaint in neurological disease; the main causes are given. Arthritis and muscle pain also alter the gait, making it stiff and slow. The recognition of an abnormal gait is important in diagnosis.
Spasticity with or without pyramidal weakness causes stiffness and jerkiness of gait, which is maintained on a narrow base. The toes catch level ground, causing wearing down and scuffing of the toes of the shoes. The pace shortens. Clonus may be noticed as involuntary extensor jerking of the legs. When the problem is predominantly unilateral and weakness is marked (in a hemiparesis), the weaker leg drags stiffly and is circumducted.
Here there is muscular rigidity in both the extensors and the flexors of the limbs. Power remains normal. The gait slows; the pace shortens to a shuffle. The base remains narrow. Falls occur. A stoop is apparent and swinging of the arms is diminished. The gait is ‘festinant’, i.e. hurried, as small rapid steps are taken. There is particular difficulty in initiating movement and in turning quickly. Sometimes when the patient stops or is halted, a few rapid, small and unsteady backward steps are taken; this is known as retropulsion.
In disease of the lateral lobes of the cerebellum the stance becomes broad-based, unstable and tremulous. The gait tends to veer towards the side of the more affected cerebellar lobe.
In disease of the cerebellar vermis (a midline structure), the trunk becomes unsteady and there is a tendency to fall backwards (truncal ataxia).
The ataxia of peripheral sensory lesions (e.g. polyneuropathy, is due to diminution of the sense of proprioception (joint position). The patient cannot perceive accurately the position of the legs. The gait becomes broad-based and high-stepping or ‘stamping’. The ataxia is made worse by removal of additional sensory input, e.g. in the dark or when the eyes are closed. This is the basis of a positive Romberg’s test, which was first described in the sensory ataxia of tabes dorsalis.
Weakness of the lower limbs
With distal weakness the affected leg is lifted overobstacles. When the dorsiflexors of the foot are weak, such as in a common peroneal nerve palsy, the foot, having been lifted, returns to the ground with a visible and audible ‘slap’. Weakness of proximal lower limb muscles (e.g. polymyositis, muscular dystrophy) leads to difficulty in rising from the sitting position. Once upright, the patient walks with a waddling gait, the pelvis being ill-supported by each lower limb as it carries the full weight of the body.
Apraxia of gait
In frontal-lobe disease (e.g. tumours, hydrocephalus, infarction) the central organization of walking is disturbed. The patient is able to move the legs normally while sitting or lying but cannot walk in an organized way. This is known as ‘apraxia of gait’ -a failure of the skilled movement of walking. Urinary incontinence and a degree of dementia are often present.