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Cutaneous sensory testing - Coggle Diagram
Cutaneous sensory testing
What does it tell us
A dermatome is an area of skin that corresponds to a specific nerve root and spinal cord segment
decreased or absent cutaneous pain perception aids in identifying the specific peripheral nerves, nerve roots and spinal cord segments involved in a disease process
pinch skin with haemostat...
conscious perception of stimulus (behavioural response e.g. turning head, vocalising)
indicates function of...
cutaneous nerve being tested
afferent nociceptive pathways within spinal cord and brain
appropriate portions of cerebral cortex
Withdrawal reflex
indicates function of...
cutaneous nerve tested
spinal cord segments
efferent motor neurone of the withdrawal reflex
Absent/diminished
demarcate the boundaries to see whether it has a segmental or peripheral nerve distribution and whether it is absent below a certain level of the trunk
Cutaneous trunci (panniculus) reflex
pinch skin of dorsal trunk between T2 and L4-L5 + observe contraction of the cutaneous trunci muscles bilaterally, which produces a twitch overlying the skin
present in the thoracolumbar region and absent in the neck and sacral region
1) Dermatome tested
2) Skin sensory nerve enters spinal cord at level of segments corresponding to that dermatome
(approx. 2 vertebrae cranial to the level tested)
3) afferent sensory info ascends spinal cord
4) synapses bilaterally at
C8-T1
spinal cord segments, with the motor neurone of the
lateral thoracic nerve
5) which courses through the
brachial plexus
and innervates the
cutaneous trunk muscle
Can be decreased or lost caudal to a lesion anywhere in the pathway
indicates presence of a transverse myelopathy
can be lost ipsilaterally with a disease affecting the brachial plexus (+ hence the motor lateral thoracic nerve)
Testing begins at the
ilial wings
(L4)
if reflex present at this level the entire pathway is intact and further testing is not necessary
note:
in the absence of other neurological deficits, the lack of cutaneous trunk reflex means very little
Nocioception testing
For pain to be perceived consciously these
must
be intact...
the sensory component of the peripheral nerves and associated spinal cord segments
spinal cord
brainstem and related thalamocortical system
Nociceptive fibres are located deep in the spinal cord white matter
project to both sides of the spinal cord
form a multi synaptic bilateral network
Thus: only a
severe bilateral spinal cord lesion
impairs nocioception
useful prognostic indicator in cases of spinal disease
assess in all 4 limbs, tail and perineal region
Palpation and mainupation to detect painful areas or restricted movement
best performed last in the neurological exam
Head
asymmetry
focus of pain
gentle manipulate neck in dorsal, lateral and ventral flexion
spine
apply gentle downward pressure on the spinous process and then along the transverse process
degree of pressure should be increased progressively
presence of spinal hyperaesthesia or deformity noted
standing or recumbent
Back pain may be elicited by palpating the paravertebral muscles; pain may result in muscle spasms, crying, or growling.
limbs
Focal muscle atrophy
indicates disease in spinal cord segment, nerve root or peripheral nerve that innervates that muscle
could be related to disuse atrophy associated with an orthopaedic condition
