27

The Unconscious or Confused Patient

BACKGROUND

Level of consciousness: assessment of the unconscious and confused patient

The reticular activating system in the brainstem maintains normal consciousness. Processes that disturb its function will lead to altered consciousness.

This can happen as a result of (Fig. 27.1):

• diffuse encephalopathy: generalised disturbance of brain function affecting the whole brain, including the reticular activating system

• supratentorial lesions: either massive lesions or those associated with distortion of the brainstem—‘coning’ (see below)

• infratentorial lesions: producing direct damage to the brainstem.

Assessment of patients with altered consciousness will be divided into:

• resuscitation (including some examination to allow you to know how to resuscitate)

• examination.

Examination of unconscious patients must:

• describe in a repeatable way the level of consciousness, so that it can be compared with other observers' results

• distinguish the three syndromes listed above

• attempt to define a cause—frequently requires further investiga- tions.

The terms used to describe levels of unconsciousness—drowsiness, confusion, stuporous, comatose—are part of everyday language and are used in different senses by different observers. It is therefore better to describe the level of consciousness individually in the terms described below. Some issues relating to confusion and delirium are discussed towards the end of the chapter.

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Figure 27.1 Sites of lesions that produce unconsciousness:
A. Key; B. Diffuse encephalopathy; C. Supratentorial lesions; D. Infratentorial lesions

Changes in level of consciousness and associated physical signs are very important and need to be monitored. Always record findings.

The Glasgow Coma Scale is a quick, simple, reliable method for monitoring level of consciousness. It includes three measures: eye opening, best motor response and best verbal response.

History can be obtained in patients with altered consciousness, from either friends, relatives, bystanders, or nursing or ambulance staff. The clothing (incontinent?), jewellery (alert bracelets/necklaces), wallet and belongings are silent witnesses that may help (Fig. 27.2).

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Figure 27.2 Clues to diagnosis in the unconscious patient

Herniation or coning

Coning is what occurs when part of the brain is forced through a rigid hole, either:

1. the uncus and the temporal lobe through the cerebellar tentorium (which separates the cerebrum from the cerebellum): uncal herniation; or

2. the cerebrum is pushed centrally through the tentorium: central herniation.

There is a characteristic progression of signs in both types of herniation.

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The signs of herniation are superimposed on signs due to the supratentorial mass causing the coning, and are progressive.

WHAT TO DO

EXAMINATION

This is aimed at:

• finding or excluding focal neurological abnormalities

• looking for evidence of meningism

• determining the level of consciousness and neurological function.

WHAT YOU FIND AND WHAT IT MEANS

Patients with coma can be classified into one of the following groups:

1. Patients without focal signs

a. without signs of meningism

b. with meningism.

2. Patients with focal signs indicative of either central herniation or uncal herniation (supratentorial lesions).

3. Patients with brainstem signs not indicative of coning (infra-tentorial lesions).

In most patients, accurate diagnosis depends on appropriate further investigations. These investigations are given in parentheses for the Common Causes of Coma.

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Locked-in syndrome: very rarely, patients with a midbrain lesion (usually a stroke) can become ‘locked in’. They are awake and aware but the only movement under voluntary control is moving their eyes upwards—limiting communication. However, they will look up if you ask them to (but only if you do—so think about the diagnosis).

COMMON CAUSES OF COMA

The most common are marked with an asterisk.

THE CONFUSED PATIENT—DELIRIUM

Some additional comments on patients with confusion or delirium.

Background

The cardinal features of delirium (or acute confusional state) are:

• recent onset

• impaired attention

• disordered thinking.

Patients may be apathetic or agitated and have delusions or hallucinations (often visual).

Delirium occurs with a diffuse encephalopathy (see Fig. 27.1B)—a process that leads to unconsciousness—coma—if more severe. This can arise from a wide range of causes (see later).

Delirium occurs more often in patients with a pre-existing cognitive deficit—and in those patients can arise with less severe provocation.

Patients with confusion are often difficult to assess; an approach is outlined here.

History will be limited. Obtain what information you can from witnesses, family members or members of staff—particularly about usual level of function and of anything to suggest a pre-existing cognitive deficit.

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Think ‘one hit or two?’

A patient with prior brain disorder (hit 1) requires a less significant insult (hit 2) to become confused. Indeed, patients with significant pre-existing brain disorders (such as mild dementia) can become very confused with a systemic upset that does not primarily involve the brain—such as a chest or urinary infection.

Someone with a previously healthy brain requires a more significant insult to the brain (hit 1) to cause confusion.

What to do

A complete general and neurological examination may be impossible if the patient will not co-operate—in which case, it is worth focusing on the most important elements.

Check pulse, blood pressure, respiratory rate and glucose.

Look for signs of infection on general examination.

Check for neck stiffness.

Observe behaviour (see Chapter 3).

Assess orientation in time, place and person (see Chapter 3).

Check attention and concentration—using digit span and serial sevens.

Use simple tests for memory.

If possible, check visual fields, eye movement, fundoscopy, facial symmetry, power in all four limbs, reflexes and plantar response. Sensory testing is likely to be limited.