Primary Causes of Paraplegia
Paraplegia results from spinal cord injury or disease, with traumatic causes (motor vehicle accidents, falls, violence) being most common, followed by non-traumatic etiologies including vascular compromise, degenerative disease, tumors, and infections.
Traumatic Causes
Traffic accidents, falls, and violence are the leading causes of traumatic spinal cord injury worldwide, with an incidence of 4-9 new cases per 100,000 people annually 1. The proportion of patients with paraplegia versus tetraplegia is now approximately equal 1.
Specific Traumatic Mechanisms:
- Motor vehicle accidents - most frequent cause in both adults and children 1, 2
- Falls from heights - including falls from trees, ladders, horse-carts, and suicidal jumps 3
- Violence - including penetrating injuries 1
- Pediatric injuries - notably, nearly half of traumatic paraplegia cases in children occur without contiguous spinal fracture or dislocation, resulting from transient vertebral subluxation, disc herniation, cord traction/stretching, or vascular compromise with infarction 2
Non-Traumatic Causes
Vascular Etiologies:
- Aortic dissection - acute paraplegia from spinal cord malperfusion occurs in 1-3% of thoracic aortic dissection patients 4
- Thoracoabdominal aortic aneurysm - chronic contained rupture can cause vertebral erosion and spinal cord compression, with 12.5% of patients presenting with neurologic impairment including paraplegia 4
- Spinal cord ischemia - from atheromatous disease, aortic surgery complications, systemic hypotension, or sickle cell disease 5
- Spinal dural arteriovenous fistulae - cause cord edema and progressive myelopathy 4
Degenerative Disease:
Spondylotic myelopathy is the most common cause of extrinsic spinal cord compression in chronic/progressive paraplegia, particularly affecting the cervical spine 4, 5. Contributing factors include:
- Spinal degenerative changes and disc herniations 5
- Spinal malalignment 5
- Congenitally short pedicles that accentuate compression 5
- Cervical disc herniation can rarely cause acute non-traumatic paraplegia, requiring emergency surgical decompression 6
Neoplastic Causes:
- Primary or metastatic tumors in extradural and intradural extramedullary spaces compressing the spinal cord 4, 5
- Intramedullary spinal cord tumors 4
Infectious/Inflammatory Causes:
- Schistosomiasis - particularly S. mansoni and S. haematobium in Africa, causing myelitis and gradual onset paraplegia 4
- Tuberculosis (Pott disease) 4
- Neurosyphilis 4
- Human T-cell lymphotropic virus myelitis 4
- Transverse myelitis 4
Demyelinating Diseases:
- Multiple sclerosis - spinal cord involvement in 80-90% of patients 4
- Neuromyelitis optica 4
- Acute disseminated encephalomyelitis 4
Metabolic/Nutritional:
Post-Surgical Complications:
- Seromas, pseudomeningoceles, hematomas, epidural abscesses causing extrinsic cord compression 4, 5
- Adjacent level degenerative disease after spinal surgery 4
Special Considerations
Hepatic Myelopathy:
Hepatic myelopathy presents as paraplegia with progressive spasticity and weakness of lower limbs, characterized by severe motor abnormalities exceeding mental dysfunction, related to marked porto-caval shunting 4. This condition does not respond to standard ammonia-lowering therapy but may reverse with liver transplantation 4.
Coarctation of the Aorta:
Paraplegia secondary to spinal cord ischemia is a rare but recognized complication of aortic coarctation repair, more common with poor collateral circulation 4.
Critical Diagnostic Pitfall
In children with traumatic paraplegia, absence of radiographic fracture or dislocation does not exclude significant spinal cord injury - thoracic level injuries can occur from transient subluxation or vascular mechanisms without bony abnormalities 2. MRI is crucial for detecting spinal cord lesions that may not be apparent on plain radiographs 6.
Prognostic Factors
- Three-quarters of patients with initially complete spinal cord injury remain complete, while most with initially preserved motor function show substantial recovery 1
- Intramedullary cord signal changes on MRI represent important prognostic factors for neurosurgical outcomes in spondylotic myelopathy 5
- Treatment duration averages 17.4 weeks for women with spinal cord injury 3