Definitions
Neurological observations are those investigations and examination that relate to the assessment of the nervous system. These commonly focus upon six key areas:
- Level of consciousness
- Pupillary activity
- Motor function
- Sensory function
- FAST (stroke recognition)
- Vital signs.
One observation that is commonly part of a neurological assessment (although primarily an endocrine function) is blood sugar analysis. This will also be discussed as a part of this chapter.
Indications
There are a variety of indications for neurological assessment and observations that relate to any condition or presentation that could or does exhibit altered neurological status. Neurological observations should be aimed at:
- Detecting abnormality
- Detecting deterioration
- Detecting improvement.
A systematic approach to neurological assessment can assist in the detection of changes over time.
Level of consciousness assessment
Consciousness encompasses a conscious perception of sensations, voluntary initiation and control of movement, and capabilities associated with higher mental function (such as memory, logic or judgement).2 Clinically, consciousness is graded upon a four-point scale relating to response to stimuli running on a continuum from the highest level of awareness to the most depressed, as seen below:
From Marieb E, Hoehn K. (2007) Human Anatomy and Physiology.2
There are two common methods used in the assessment of levels of consciousness by healthcare professionals, the AVPU score and Glasgow Coma Scale.
AVPU score
The AVPU score is a brief examination of responsiveness that is initiated in the primary survey.3 The scale was introduced as a method for rapid neurological assessment in the trauma patient4 with the use of scoring based upon a grading of initial response upon the following stimuli:
| A | Alert (no stimulus required). |
| V | Verbal stimulus required to elicit a response. |
| P | Painful stimulus required to elicit response. |
| U | Unresponsive to all stimuli. |
The method for eliciting pain response will be discussed later (see GCS section). Anecdotal evidence suggests that AVPU is simpler and quicker to use than the Glasgow coma score,5 however studies have suggested that the AVPU score may not provide the sensitivity to detect subtle changes in neurological status that result from non traumatic causes of neurological derangement.5,6
The Glasgow Coma Scale
This scale was introduced in 1974 by Teasdale and Jennett7 as a standardised tool to aid physicians in the assessment and comparison of patients with altered levels of consciousness. This scale, following modifications, has been in use by healthcare professionals ever since.8 Whilst this method is commonly accepted as the technique of choice within health services, studies have suggested that the scale may not always be reliably used in comparison to other methods such as AVPU.9,10
The Glasgow Coma Score (GCS) evaluates three key categories of behaviour that closely reflect activity in the higher centres of the brain; eye opening, verbal response and motor response.11 Within each category a score is given for the level of response, with the lower the score the greater the deterioration of neurological function. The lowest score a patient can receive is 3 and the highest value is 15 (indicating a fully alert state). The GCS chart for adults can be seen in Box 7.1.
The GCS table is applicable for adolescents and has been adapted for paediatrics as seen in Box 7.2; however the use in children under the age of 3 is questionable due to developmental issues.13
Best eye response
Eye opening is closely linked with being awake and alert and as such is easily identified. Eye opening mechanisms are controlled by a collection of neurones located in the brain stem, hypothalamus and thalamus known as the reticular activating system that is stimulated by sensory input.2 The patient is considered to have spontaneous eye opening when the eyes are opened without any stimulation. If either a verbal or painful stimulus is required then this must be recorded, a guide to undertaking eye response testing is seen in Table 7.1.
Best verbal response
The best verbal response assesses two aspects of cerebral function:
- Comprehension or understanding of what has been said.
- Ability to express thoughts into words or expression.
This can be achieved by speaking to the patient in a normal voice. It is best practice not to ask yes or no questions as they can lead to missed information. The best verbal response also assesses the patient’s awareness of themselves in relation to time and space. An element of consideration is required when assessing a best verbal response, many authors suggest that the patient must be able to state the day and date to be considered orientated.7 However thought must be given to the patient’s status, as many patients who have been hospitalised for a long time for example will have little need to know the date. A guide to undertaking a best verbal response can be seen in Table 7.2.
Discrepancies can occur in the assessment of verbal response; therefore it is imperative that the practitioner uses language that the patient can understand to reduce the likelihood of misunderstanding.
Table 7.1 Best eye response18
| Observation | Score | Method |
| Eye response: If the patient is unable to open their eyes as a result of trauma or surgery the letter ‘c’ indicating closed should be recorded. This will ensure that false recordings are reduced. | ||
| This score indicates the level of arousal/consciousness | 4 – Spontaneously | The patient’s eyes should open as you approach. If the patient is asleep wake them first as the assessment is based upon best response. |
| 3 – To speech | The patient will respond to your voice. The simplest way is to use their name. If there is no response consider using a raised voice as the patient may be hearing impaired. | |
| 2 – To pain | The patient should open their eyes to painful stimulus (discussed below) | |
| 1 – No response | The patient’s eyes remain closed despite painful stimuli. | |
Table 7.2 Best verbal response19
| Observation | Score | Method |
| Verbal response: The patient may have difficulty in speaking (dysphasia). If this is the case ‘D’ should be indicated in the chart, if the patient is intubated then the letter ‘T’ should be used. | ||
| This score indicates the level of orientation to time, place and self. | 5–Orientated | The patient must be able to state their name, who they are, where they are and what the month is (or time of day – morning, evening, night). |
| 4 – Confused | If the patient is able to hold a conversation but unable to answer the previous questions correctly they should be considered confused. Correct any wrongly answered questions and re-ask them later in the assessment using a different order to avoid copying. | |
| 3 – Inappropriate words | The patient will use random words that make little sense or are out of context. This typically consists of swearing and shouting. A painful stimuli may be required to gain a response. | |
| 2 – Incomprehensible sounds | The patient will only respond with moaning and groaning. Painful stimuli may be required to gain a response. | |
| 1 – No response | There is no verbal response despite painful stimuli. | |
Best Motor Response
The best motor response is used to test how well the brain is functioning as a whole by testing the identification of sensory input and the subsequent motor response. The best possible motor response is the ability to understand simple commands and respond.11 A guide to undertaking an assessment of best motor response can be seen below in Table 7.3.
It is not recommended to use the command of ‘squeeze my fingers’ as an obeyed command as this is a primitive reflex and may occur involuntarily.16 It is recommended that a central response is used to test a response to pain as a peripheral stimulus may provoke a spinal reflex and therefore not assess cerebral functioning.11 Spinal reflexes may cause limbs to flex briskly and can even be elicited in patients who have been certified as brainstem dead.15 It can also be very difficult to differentiate flexion from pain and withdrawal from pain if using a peripheral pain stimuli.
Painful stimuli
A response to painful stimulus is a very contentious issue and should only be applied if the patient does not respond to other stimuli.8 There are numerous legal and ethical issues that should be considered on each occasion, therefore it is recommended that explanation is given to any onlookers to save confusion and later complications.11 There are two overarching approaches to painful response, both having inherent flaws and benefits that must be considered; these approaches are central and peripheral stimuli.16
Table 7.3 Best motor response11,19
| Observation | Score | Method |
| Motor response: If the patient is receiving paralytic drugs as Glasgow coma scale cannot be assessed. | ||
| This indicates brain function. | 6 – Obeys commands | Ask the patient to perform a series of different movements such as sticking out their tongue or raising their arms. |
| 5 – Localises to pain | Apply a central painful stimulus (as described later in Table 7.4). The patient should purposefully move the arm towards the site of pain to remove the cause. | |
| 4 – Withdraws from pain | The patient will flex their arms in response to a painful stimulus but will not move towards the source of the pain. | |
| 3 – Flexion to pain | Also referred to as decorticate positioning. It occurs when there is a block in the motor pathway between the cerebral cortex and brain stem. It is a slower response to a painful stimulus. It is recognised by a flexion of the upper arm and rotation of the wrist. It may also result in the thumb flexing across the fingers. | |
| 2 – Extension to pain | Also known as decerebrate positioning. This is the result of a blocked or damaged motor pathway within the brainstem. This is characterised by straightening of the elbow and internal rotation of the shoulder. The legs may also straighten with the toes pointing downwards. | |
| 1 – | There is no physical response despite painful stimuli. | |
Table 7.4 Eliciting painful stimuli18,19
| Stimulus | Procedure | Rationale |
| Trapezium squeeze | 1. This is achieved by using the thumb and two fingers as ‘pincers’. Feel for the large muscle mass of the trapezius (located at the angle where the neck and shoulders meet) and twist or squeeze. | A gentle pinch of approximately half an inch hurts but does not cause real pain. |
| Supraorbital pressure | 2. Pain is achieved by applying pressure over a branch of the facial nerve. This can be found upon the inner aspect of the eyebrow in a small notch. Place the hand upon the patients head and the flat of the thumb or knuckle is placed over the notch. Pressure should gradually be applied for a maximum of thirty seconds. | Pressure applied here causes pain in the form of a headache. This method should not be used in facial trauma or glaucoma as it may further injury.34 Caution is also required as orbital pressure may also cause bradycardia. |
| Jaw pressure | 3. Apply pressure to the angle of the jaw just in front of the ear lobe using the thumb. | This method should not be used in cases of facial trauma. |
| Sternal rub | 4. This involves grinding the knuckles or palm upon the centre of the sternum. | This method can cause bruising over time and is considered to be an outdated and should only be used with extreme caution.16 |
Central stimuli
There are four commonly used distinct methods of providing a central painful stimulus: trapezium squeeze, supraorbital pressure, jaw pressure and sternal rub as described in Table 7.4.
The use of the centralised pain response to elicit eye opening response can be difficult as it may cause grimacing or eye closure as a natural response therefore making it counter-productive when assessing for eye opening.8 However central stimuli are perceived to be more reliable as they can produce an overall body response thus making a centralised stimulus more reliable when assessing motor function.17 Whilst there are little data to suggest a recommended method of centralised painful stimuli, anecdotal evidence suggests that the sternal rub technique should be discontinued due to concerns over potential patient injury including bruising and skin breakdown.11 In addition the use of supra-orbital pressure should only be undertaken by those who are competent in its’ use due to concerns of potential injury or adverse reaction.
Peripheral stimuli
A peripheral stimulus is interpreted by the peripheral nervous system and communicated to the central nervous system via the spinal cord to the brain. However a peripheral response may also elicit a spinal reflex making the use of peripheral stimuli limited in terms of motor assessment. Due to reasons stated earlier a peripheral stimulus is more suited to best eye opening response.2,8 Table 7.5 describes the common techniques in applying a peripheral pain stimulus.
Table 7.5 Peripheral pain stimulation
| Stimulus | Procedure | Rationale |
| Lateral finger or toe pressure | Using a pen or similar object (consider infection control) apply pressure to the lateral aspect of a finger or toe, avoid the nail bed. Rotate the object around the finger/toes away from the nail. This should be performed for no longer than 10 seconds. | It is advisable to avoid the nail bed as beneath the bed are a number of structures such as tendons, nerves and blood vessels.2 These can be damaged by the use of extreme pressure upon the nail. |
By avoiding pressure over the nail short term pain can be applied with a reduced likelihood of longer term damage to underlying structures.
Pupillary assessment
Careful examination of the pupils is an important part of a neurological assessment and is often the only way to assess the neurological status of a sedated patient. Pupils should be assessed for size, shape, and response to a light stimulus. Any change of pupil response may be an indication of raised intracranial pressure or lesion.19
Pupil size and shape
Pupil size will vary for a variety of reasons such as light, anxiety, drug use and pain, as a result of sympathetic and parasympathetic responses to stimuli,2 suggested causes of pupil size abnormality can be found in Table 7.6. Pupil size is measured in millimetres (diameter) with a normal pupil size ranging from 2–6 mm.19 Each pupil should be assessed individually and documented, this should be undertaken prior to any light being shone in them – it is important to note that levels of ambient light may affect pupil size. Many forms of documentation and some pen torches have a guideline scale for the measurement of pupils, these should be used to ensure objectivity of measurement. In the average patient the pupils will be of equal size, however it is estimated that up to 20% of patients will have unexplained unequal pupils (anisocoria).20 A difference of up to 1 mm is acceptable and may be physiological, especially if this is maintained in both light and dark conditions.21
Table 7.6 Abnormal pupil sizes – Common causes. Adapted from Cox and Roper (2006).21
| Pupil size | Common causes |
| Pin point pupils | Opiate overdose, brainstem CVA (pontine), miotic eye drops, Horner’s syndrome. |
| Dilated pupils | Fear, anxiety, anti-cholinergic drug overdose, brainstem CVA (mid brain), pain, mydriatic eye drops. |
| Unequal dilated pupils (unreactive) | IIIrd nerve palsy, mydriatic eye drops. |
| Unequal constricted pupils (unreactive) | Miotic eye drops, Horner’s syndrome. |
There are numerous causes of abnormal pupil size, these are just some of the common causes that may be found.
Pupils are generally round in shape and equal. However certain conditions such as glaucoma (oval pupil) and ocular trauma (grossly irregular pupil) can alter the shape of both or an individual pupil. It is therefore important in the presence of an abnormal pupil size or shape to ask the patient or relative whether this is new to the patient.
Pupil response
In the presence of a bright light the pupils should constrict to reduce the amount of light that enters the eye.2 However in the presence of an insult the sensory (afferent) or motor (efferent) pathways may be damaged and reduce or eliminate pupil response. With a light stimulus to one eye there should be experienced a direct response (constriction of the pupil) and consensual light reflex (constriction of the other pupil).2 For this to take place an intact sensory and motor pathway is required. This response should occur in both light and dark conditions, although the response may be more difficult to spot in very light conditions. Pupil response to a light source should be relatively swift, therefore sluggish or slow responses should be noted, as should exceptionally brisk response as they can suggest neurological injury.21
A guide for the examination of direct and consensual light reflex can be seen below.
Assessing light response21
| Procedure | Rationale |
| 1. Gain informed consent from the patient to undertake the procedure. | This will help to reduce anxiety and make the patient easier to examine. It is also a basic requirement for professional practice. |
| 2. Reduce the light from ambient sources wherever possible. | This enables a better view of the pupil and makes any response easier to view. |
| 3. Wash the hands thoroughly. | As manual opening of the eye may be required this can reduce cross infection. |
| 4. With the eyes open review the size and shape of the pupil. | See section upon pupil size and shape. |
| 5. Using a bright pen torch move a light source from the outer aspect of the eye toward the pupil. This should cause pupil constriction (direct light reflex). The light only needs to be shone into the pupil for a very brief period to elicit a response. Assess the level of constriction and the speed of response. | This will assess the sensory and motor pathways. |
| 6. Repeat the process, this time watch the other eye to assess consensual light reflex. | This will assess the motor pathway for the opposing eye. |
| 7. Repeat the previous two steps shining the light into the opposing eye. | This will assess the sensory and motor pathways of the opposing eye. |
Assessing motor function
Damage to the nervous system may result in changes in the patient’s ability to move. To assess patient motor function an evaluation of the following areas should be undertaken:
- Inspection and palpation of muscle mass
- Assessment of tone
- Assessment of reflexes
- Assessment of movement and power
- Assessment of co-ordination
- Assessment of abnormal movements.
Inspection and palpation of muscle mass
Long standing motor neurone lesions/damage may result in the loss of muscle bulk due to atrophy and lack of muscle use. Diseases such as motor neurone or stroke are common causes of such signs.22
Assessment of tone
This involves the assessment of the resistance to passive movement of the limbs. Increased resistance suggests increased tone whereas decreased resistance suggests decreased tone. These tests are not routinely undertaken in prehospital care.
Assessment of reflexes
There are a variety of reflexes that can be tested. Typically these require great skill and experience to undertake and are not commonly used in prehospital care, examples include the deep tendon reflexes such as the knee jerk. However there are some reflexes that may be assessed within the community environment. These include the blink, gag, swallow, oculocephalic and plantar reflexes.
- Blink reflex: This is a protective reflex that can be affected by damage to the trigeminal and facial cranial nerves. These may be noted by a lack of blinking to stimulation of the cornea.
- Gag and swallow reflex: These are not routinely tested however history and clinical examination may suggest a loss of gag or swallow function. For example aspiration of foodstuffs. Altered responses suggest damage to the glossopharyngeal or vagus cranial nerves.
- Oculocephalic: This reflex is an eye movement that occurs in patients with severely decreased level of consciousness. When the reflex is present if the head is moved to one side the eyes will move in the opposite direction. However in patients with absent brain stem reflexes the eyes will appear to remain stationary in the centre.
- Plantar reflexes: An abnormal plantar reflex is evident upon the stimulation upon the lateral border of the underside of the foot. A normal response is the flexion of the great toe and adduction of the other toes. An abnormal response is noted when the great toe extends (or dorsiflexes) and the other toes abduct. This is a sign of upper motor neurone damage, however may be normal in babies under the age of one year.23
Assessment of movement and power
This involves the assessment of the patients muscle power and movement against resistance. If the patient is unable to generate any power against resistance then gravity should be used. These tests are not commonly used in prehospital care.
Assessment of co-ordination
Any disease or injury that affects the cerebellum or basal ganglia can affect co-ordination. The ability to perform complex movement smoothly and efficiently requires intact sensory and motor pathways. This can be simply tested with tasks such as asking the patient to run their heel up and down the shin of the opposite leg or by asking the patient repeatedly and rapidly pat the palm of one hand with the palm of the other hand and then with the back of the hand. This should be performed as quickly and regularly as possible.
Assessment of abnormal movements
When carrying out a neurological examination the patient should be observed for any abnormal movements such as jerks, tremor, tics, seizures or fasciculation (ripples or twitches underlying the skin in muscles at rest). These are all suggestive of neurological deficiency.
Sensory function assessment
Sensory functions and input allows the individual to respond to input from the external environment. When injury or illness damages the sensory pathways the ability to respond is decreased. This occurs in conditions such as spinal injury and stroke.22 Assessment of sensory function should include:
- Central and peripheral vision: this can be achieved briefly by asking the patient about their vision or the use of standardised visual acuity charts.
- Hearing and ability to understand verbal communication: This can be briefly achieved by asking the patient about their hearing or asking them respond to simple commands such as tested in the Glasgow Coma Scale.
- Superficial sensations: This can be tested by applying a light stimulus to the skin (light touch or pain). Areas that can be tested are linked to sensory areas known as dermatomes that relate to specific nerve routes as seen below.
- Deep sensations: This relates to sensations of muscle and joint pain and the ability to recognise joint position. This can be briefly assessed by asking the patient to identify the position a joint is placed in when the patient has their eyes shut.
FAST
The FAST test is the acronym for the face, arm, speech test. This procedure is the current recommended technique for pre-hospital care staff in the recognition of stroke to allow for prompt management and referral.24 Limited studies have been undertaken upon this technique; however initial findings suggest that there is a high level of diagnostic accuracy in the use by pre-hospital care personnel.24
The FAST approach is a simplified approach to a rapid assessment of a suspected stroke patient. Through the assessment of three specific areas of neurological functioning a level of suspicion of stroke can be gained. The FAST approach is shown in Table 7.7.
Table 7.7 The FAST approach to stroke recognition.24
| Test | Findings |
| Face – Does the patient have a symmetrical face or are there any signs of a facial droop? | The presence of a facial droop can be indicative of stroke or facial nerve palsy. |
| Arm – Does the patient have equal power in their arms? Place the patients arms straight out in front of them, does one arm drift downwards? | The presence of an arm drift suggests a weakness to that limb and potential for hemiparesis. |
| Speech – Is there evidence of slurred speech? Are they able to speak normally? | Slurring of speech may indicate stroke due to weakness of facial muscles. |
Figure 7.1 The dermatomes – sensory areas related to spinal nerves. Reproduced from Faiz, O. and Moffat, D., Anatomy at a Glance, copyright 2006, with permission of Blackwell Publishing.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
