Introduction

• See brachial plexus root avulsion Brachial plexus: root avulsion.
• Clinical signs more severe than partial avulsions.
• Cause: result of trauma, usually road traffic accidents (RTA).
• Signs: neurological deficits apparent immediately following injury.
• Neurogenic muscle atrophy takes 7-10 days to develop.
• Prognosis: for recovery poor.

Pathogenesis

Etiology

• Traumatic traction of spinal nerve roots at their origin inside the dura mater.

Predisposing factors

• Lack of leash laws and/or irresponsible pet ownership.
• Intact dog.
• Bitch in heat.

• Dog lives on busy road or in city.

• Dog allowed to exercise unsupervised.
• Old or faulty extending lead.
• Dog exercised off the lead.

Pathophysiology

• Traumatic.

• Limb forcibly abducted or rotated at its attachment to the body → traumatic traction on the spinal nerve roots at their origin inside the dura mater → disruption of the neural elements → interruption of spinal reflexes. Ventral roots are especially susceptible.
• Skin desensitization → decrease in muscle tone → onset of neurogenic muscle atrophy.
• Some shrinkage of the areas of skin desensitization as nerves grow in from neighboring innervated areas.

Timecourse

• Neurological deficits apparent immediately after injury.
• Neurogenic muscle atrophy from 7-10 days after injury.

Diagnosis

Treatment

Prevention

Outcomes