The Royal Marsden Hospital Manual of Clinical Nursing Procedures - Lisa Dougherty [501]
As the ability to localize pain is lost, various responses may be observed when painful stimuli are applied (Carlson 2002a). It is important to note, when applying a painful stimulus, that the brain responds to central stimulation and the spine responds first to peripheral stimulation (Aucken and Crawford 1998).
Central stimulation can be applied in the following ways (Aucken and Crawford 1998, Carlson 2002a, Price 2002).
Trapezium squeeze: using the thumb and two fingers, hold 5 cm of the trapezius muscle where the neck meets the shoulder and twist the muscle.
Supraorbital pressure: running a finger along the supraorbital margin, a notch is felt. Applying pressure to the notch causes an ipsilateral (on that side) sinus headache. This method is not to be used if the facial or cranial bones are unstable, facial fractures are suspected, after facial surgery or if the assessor has sharp fingernails.
Sternal rub: using the knuckles of a clenched fist to grind on the centre of the sternum. When applied adequately, marks are left on the skin as sternal tissue is tender and bruises easily. Please note that because of the danger of bruising, this method should not be used for repeated assessment but may be indicated if a decision as to whether to rescan or alter management, for example proceed to surgery, is necessary.
Peripheral stimulation can be applied in the following way. Place the patient’s finger between the assessor’s thumb and a pencil or pen. Pressure is gradually increased over a few seconds until the slightest response is seen. Any finger can be used, although the third and fourth fingers are often most sensitive (Frawley 1990). Please note that because of the risk of bruising, pressure should not be applied to the nailbed. It must be remembered that nailbed pressure is a peripheral stimulus and should only be used to assess limbs that have not moved in response to a central stimulus (Aucken and Crawford 1998).
It cannot be overemphasized that the above methods of patient assessment should only be undertaken by appropriately qualified and trained nurses.
Pupillary activity
Careful examination of the reactions of the pupils to light is an important part of neurological assessment (Table 12.10). The size, shape, equality, reaction to light (both direct and consensual responses, that is, the response from the eye that is not directly exposed to light) and position of the eyes should be noted. Are the eyes deviated upwards or downwards? Are both eyes conjugate (moving together) or dysconjugate (not moving together)? Impaired pupillary accommodation (adjustment of the eye resulting in pupil constriction or dilation) signifies that the midbrain itself may be suffering from pressure exerted by a swelling mass in the brain. Pupillary constriction and dilation are controlled by cranial nerve III (oculomotor) and any changes may indicate pressure on this nerve or brainstem damage (Figure 12.29) (Fuller 2004).
Figure 12.29 Pressure from expanding mass and/or cerebral oedema.
Table 12.10 Examination of pupils
It should be noted that ‘normal’ visual function depends on a full and conjugate range of eye movements (involving cranial nerves III, IV, VI) in addition to normally functioning optic and oculomotor nerves and an intact visual centre in the occipital cortex (Aucken and Crawford 1998).
Motor function
Damage to any part of the motor nervous system can affect the ability to move. After assessing motor function on one side of the body, the contralateral muscle group should also be evaluated to detect asymmetry. Motor function assessment involves an evaluation of the following.
Muscle strength.
Muscle tone.
Muscle coordination.
Reflexes.
Abnormal movements.
(Aucken and Crawford 1998, Fuller 2004)
Muscle strength
This involves testing the patient’s muscle strength against the pull of gravity and then against one’s own resistance.