Spinal cord localization principles
It is helpful to develop an ordered approach to this problem. The following stages in the diagnostic approach should include:
1. Identifying the problem
2. Localizing the lesion
3. Assessing the severity or extent of the lesion
4. Acquiring a diagnosis
5. Determining the prognosis
Identifying the problem
History
1. Age/Breed
2. Previous history of illness; recent or previous trauma.
3. Course of the clinical signs –
Onset – very obvious or vague?
What were the initial signs? Any asymmetry?
Acute vs. progressive vs. static
Has condition stabilized, improved, worsened?
Has problem occurred before?
Clinical Examination:
It is important to do a thorough physical exam so that other diseases which may mimic neurologic conditions are not overlooked.
Especially orthopedic disorders
Localization of the lesion
Determine the locomotor status first; this will help one evaluate which limbs are involved and assess for asymmetry, strength,
and ataxia.
Assessment of proprioception
1. Knuckling response
2. Reflex stepping
3. Wheelbarrowing
Myotatic reflexes
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4. Lateral hopping
Muscle atrophy –
1. LMN – severe, within 7-10 days
2. UMN – mild, takes weeks to occur
Other reflexes that may be evaluated –
1. Cutaneous trunci reflex –
Afferent arm – segmental sensory nerves
Efferent arm – C8-T1 – lateral thoracic nerve
2. Withdrawal reflexes –
Front limb – C5-T1 cord segments
Hind limb – L6-S1 cord segments
3. Anal reflex – S1-S3 cord segments
4. Crossed extensor reflex – this is manifested as a very rapid and extreme flexion of the stimulated limb after a noxious
stimulus, with simultaneous extreme rapid extension of the opposite limb.
Bladder function
1. S1-S3 cord segments supply LMN and motor control to the bladder wall and urethral sphincters.
2. UMN vs. LMN bladder
a. UMN – 1. bladder may be full and distended
b. high resistance to manual compression
c. urine stream continues for a brief period after manual compression is stopped
d. after several days post-cord injury, the bladder will become hyperreflexic and hold less urine during the storage phase,
but still retains more urine than a normal bladder after voiding.
e. LMN – 1. bladder full and distended
f. flaccid, no tone
g. dribbling of urine
h. bladder easy to express and urine stream ceases as soon as compression is stopped.
