Parapareis (weakness in the rear limbs) and paraplegia (paralysis of the rear limbs)
unaccompanied by signs of additional CNS disturbance suggests that the disease is located caudal
If the rear limb reflexes are intact, the lesion is between T2 and L3. If the rear leg reflexes
are diminished to absent, the lesion is between L4 and S2.
This can be refined further in that lesions
between L4 and L5 result in loss of femoral nerve function, manifested as a decrease in the patellar
tendon reflex and inability to support weight in the rear legs.
Lesions between L6 and S2 result in
sciatic nerve dysfunction, reducing rear leg withdrawal, cranial tibialis muscle, gastrocnemius
muscle and sciatic nerve reflexes.
The differential diagnosis of paraparesis and paraplegia include a number of congenital
diseases, including vertebral malformations, various spinal cord malformations, multiple
cartilaginous exostoses, lysosomal storage diseases, and breed-specific disorders. Other disorders
are similar to those which affect the cervical spinal cord including meningomyelitis (from various
causes), degenerative disc disease, spinal cord trauma, fibrocartilaginous infarction, and neoplasia.
In some breeds, the differential also includes degenerative myelopathy.
The neurologic assessment of patients with rear leg problems helps to confirm that the
disease is neurologic in nature and its location. Weakness can indicate neurologic disease, muscle
disease or systemic illness. On the other hand, reproducible deficits in proprioception usually is
indicative of neurologic disease, whether knuckling, stumbling or falling or conscious
proprioceptive deficits or dysmetria of unconscious proprioceptive dysfunction. When deciding
whether a rear leg lameness is secondary to orthopedic or neurologic disease, examination of
proprioceptive function can help make the differentiation.
Unlike cervical disease, there are several neurologic tests which can assist in lesion
localization with TL disease. If the lesion is between T2 and L3, Schiff-Sherrington syndrome may
be seen. Also, between T2 and L4 is the panniculus response, where superficial stimulation of the
skin over the back results in stimulation of intraspinal pain pathways with the resultant contraction
of the latisimus dorsi muscle. Due to the overlap of sensory dermatomes, the panniculus response
will be absent 1-2 segments caudal to the lesion. Hyperpathia on deep palpation will be present at
the cranial edge of the lesion and hyperesthesia will be evident on pin prick of the skin at the cranial
and caudal edges of the lesion. By locating hyperpathia and hyperesthesia and demonstrating the
loss of the panniculus response 1-2 segments caudally, the lesion is found.
The ancillary diagnostic tests for TL spinal disease are identical to those for cervical disease
with the exception that lumbar CSF should be obtained in most instances. Since the flow of CSF
is from cranial to caudal, lumbar CSF more accurately represents changes within the TL spinal
column. This is usually obtained by carefully passing a needle into the subarachnoid space between
L5-L6 or L4-L5.