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434 P R I N C I P L E S A N D P R A C T I C E O F C R I T I C A L C A R E

is seen with severe metabolic disturbances or upper have been assessed because this noxious stimulation may
brainstem lesions. It is characterised by extension and cause alteration in pupillary reactivity (hence one reason
pronation of the arm(s) and extension of the legs. Patients for the lack of preference for its use).
may have an asymmetrical response and may posture
spontaneously or to stimuli. Corneal reflexes
Motor tone is first assessed by flexing the limbs and noting The corneal reflex is assessed by holding the patient’s eye
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increased or absent tone. If no tone is present, the open and lightly stimulating the cornea. The stimuli
hand is lifted approximately 30 cm above the bed and should result in a reflexive blink, best seen in the lower
carefully dropped while protecting the limb from injury. eyelid. The traditional assessment technique involves
The test is repeated with all extremities. Typically, the using a wisp of cotton, lightly brushed along the lower
lower the level of consciousness, the closer to flaccid the aspect of the cornea. An alternative, and less potentially
limb(s) will be. An asymmetrical examination may traumatic, method is to gently instil isotonic eye drops
indicate a lesion in the contralateral hemisphere or or saline irrigation ampoules onto the cornea. This reflex
brainstem. is dependent upon CN V for its sensation and CN VII for
its motor response. Loss of this reflex is indicative of
The next assessment, peripheral reflex response, is response lower brainstem damage, but may be absent due to
to tactile stimuli peripherally and usually elicits a reflex trauma, surgery, or long-term contact lens usage.
response rather than a central or brain response. It is
important to apply stimuli in a progressive manner, using
the least noxious stimuli necessary to elicit a response. If Oropharyngeal reflexes
there is no response to light or firm pressure, the clinician The oropharyngeal reflexes are controlled by CN IX and
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must use noxious stimuli. Each extremity is assessed indi- CN X. The gag reflex is elicited by lightly stimulating the
vidually. The typical technique for peripheral noxious soft palate with a suction catheter or tongue blade. Clini-
stimuli involves pressure on the nail beds for asserting a cians should always avoid stimulating a gag reflex by wig-
peripheral stimulus. The triple-flexion response is a with- gling the endotracheal tube because doing so may result
drawal of the limb in a straight line with flexion of in an inadvertent extubation. A gag reflex is a forceful,
the wrist–elbow–shoulder or the ankle–knee–hip. This symmetrical lowering of the soft palate. The cough reflex
response is considered a spinal reflex and is not an indica- is usually assessed only in patients with an endotracheal
tion of brain involvement in the movement. The triple- tube. This reflex is elicited by gently passing a suction
flexion response is common in patients with severe catheter through the tube and stimulating a cough. Loss
neurological impairment. It is not uncommon in patients of these reflexes is indicative of lower brainstem damage. 37
who have become brain dead, and great care must be
taken to avoid confusion between brain and spinal- Post Traumatic Amnesia Scale
mediated responses. If the patient has any other motor Posttraumatic amnesia (PTA) is a disorder after brain injury
activity to peripheral extremity noxious stimuli, it is an that is classified as a traumatic delirium and may even
indication of higher brain function. 38
be found in patients who rate a GCS of 15. The inci-
If a noxious stimuli is applied centrally through a sternal dence of delirium after a brain injury event is high espe-
rub, trapezius pinch or supraorbital nerve pressure and cially with severe injuries and loss of consciousness.
the patient moves an extremity, it is an indication of brain Delirium is discussed in detail in Chapter 7, however,
involvement in the movement and not a spinal reflex. traumatic delirium historically has been referred to in
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The movement should be noted as normal, decorticate the literature as posttraumatic amnesia. Posttraumatic
(flexor: either withdrawal or spastic) or decerebrate amnesia is defined as the ‘time elapsed from injury until
(extensor) and documented accordingly. It should be recovery of full consciousness and the return of ongoing
noted that careful consideration should be given to the memory’. 39,p.841 It is the initial stage of recovery from brain
choice of noxious stimuli with trapezius pinch the pre- injury and is characterised by anterograde (formation of
ferred choice as both sternal rub and supraorbital nerve new memory) and retrograde (memory before injury)
pressure can be traumatic when applied. In ventilated amnesia, disorientation and rapid forgetting. Brief periods
patients, endotracheal suction can also be a substitute for of PTA can occur after minor concussion and may be the
a central noxious stimulus, but the choice of stimulus only clinical sign of any brain injury. This is where PTA
needs to be consistent. is useful for defining severity of injury and alert the clini-
cian in regard to greater surveillance and investigation as
Facial symmetry described in Table 16.6. Patients often progress directly
Facial symmetry is often difficult to appreciate in, for from coma into delirium without a clearly-defined stupor
stage, so using a tool to measure PTA can be useful to
example, severely ill patients due to oedema, endotra- gauge the actual condition of the patient in the delirium
cheal tube tape and nasogastric tubes. An asymmetric state. Duration of PTA is extremely variable, ranging from
response is indicative of a lesion of CN VII. Complete minutes to months. Although the early stages of PTA are
hemi-facial involvement is typically seen in peripheral easily recognised, identifying the end point is difficult
dysfunction (Bell’s palsy), whereas superior division and complex. 40
(forehead) sparing weakness indicates a pontine/
medullary (central) involvement. It is important to refrain The duration of PTA is the best indicator of the extent of
from supraorbital pressure until after pupillary responses cognitive and functional deficits after TBI. In Australia,