20 Pelvic limb paresis and paralysis
Causes of Acute Nonambulatory Paraparesis/Paraplegia
Paraparesis and paraplegia most commonly occur as a result of a spinal cord lesion caudal to the C6–T2 segment (cervicothoracic intumescence). Spinal cord disorders that commonly cause paraparesis or paraplegia are listed in Box 20.1. In some cases spinal cord injury is due to a cause with an acute onset (e.g. traumatic disc injury, fibrocartilaginous embolism) while in others it occurs due to acute deterioration of a more chronic disease (e.g. neoplasia).
Approach to Acute Nonambulatory Paraparesis/Paraplegia
Major body system examination
Clinical Tip
• The pelvic limbs are intuitively the focus of the physical examination in animals with paraparesis or paraplegia. However, it is important to remember that paraparesis and paraplegia in themselves are not life-threatening conditions and assessment of cardiovascular status, respiratory status, mentation and pain should be prioritized. Life-threatening abnormalities, typically the result of trauma in these cases, should be addressed first.
• Assessment of deep pain perception: this is a useful prognostic indicator in spinal cord disease. Deep pain perception is confirmed as a conscious response (e.g. head turning, trying to bite, growling) to a painful stimulus and must be differentiated from limb withdrawal which only requires an intact local flexor reflex. The withdrawal reflex assesses the integrity of the L4–S2 spinal cord segments and their associated nerve roots, as well as the femoral and sciatic nerves.
• Spinal reflexes, typically patellar reflex: may be normal, hyperreflexive (upper motor neuron) or hyporeflexive (lower motor neuron).