What are the causes and management of paraparesis?

Aetiologies and Management of Paraparesis

Paraparesis (partial weakness of both lower limbs) has multiple causes ranging from vascular, infectious, inflammatory to structural lesions, with thoracic aortic disease repair complications and spinal cord ischemia being significant causes requiring prompt management to prevent progression to complete paralysis. 1

Common Aetiologies of Paraparesis

Vascular Causes

• Spinal cord ischemia following thoracic aortic surgery (2-6% incidence) - most feared complication of descending thoracic aortic repairs 1
• Risk factors include emergency surgery, dissection, extensive disease, prolonged aortic cross-clamp time (>60 minutes increases risk to 20%), aortic rupture, level of aortic cross-clamp, patient age, prior abdominal aortic surgery, hypogastric artery exclusion, and renal dysfunction 1
• Cerebral venous thrombosis involving the sagittal sinus can cause bilateral motor signs including paraparesis 1

Inflammatory/Autoimmune Causes

• Guillain-Barré syndrome variants - particularly the paraparetic variant with weakness limited to lower limbs 1
• Acute transverse myelitis (20% of non-traumatic paraparesis cases) 2
• Multiple sclerosis with spinal cord involvement 2, 3

Infectious Causes

• Spinal tuberculosis (30% of non-traumatic paraparesis in some regions) - most common cause in developing countries 2
• HTLV-1 associated tropical spastic paraparesis/myelopathy 3
• Other tropical infections: brucellosis, neuroborreliosis, schistosomiasis, neurocysticercosis 3

Structural Causes

• Primary spinal cord tumors (10% of non-traumatic paraparesis) 2
• Spinal cord compression from metastatic disease 1
• Cervical spondylotic myelopathy 4
• Arteriovenous malformations of the spinal cord 4

Metabolic/Nutritional Causes

• Hereditary spastic paraparesis associated with inborn errors of metabolism 5
• Vitamin B deficiencies and folate deficiencies 3
• Toxic causes: lathyrism, fluorosis, konzo (from cyanide-containing bitter cassava) 3

Diagnostic Approach

Initial Imaging

• MRI of the spine is the cornerstone of diagnosis, with findings classifiable into six patterns 6:
  • Extradural lesions
  • Intradural/extramedullary lesions
  • Intramedullary lesions
  • Intramedullary-tract specific lesions
  • Spinal cord atrophy
  • Normal appearing spinal cord 6

Laboratory Investigations

• Complete blood count, chemistry panel, prothrombin time, and activated partial thromboplastin time for suspected vascular causes 1
• Screening for prothrombotic conditions in suspected cerebral venous thrombosis 1
• D-dimer testing may help exclude cerebral venous thrombosis 1
• CSF examination when inflammatory or infectious causes are suspected 1

Management Strategies

For Vascular Causes (Post-Thoracic Aortic Surgery)

• Cerebrospinal fluid drainage is recommended as a primary spinal cord protective strategy in patients at high risk of spinal cord ischemic injury during thoracic aortic repair (Class I recommendation) 1
• Spinal cord perfusion pressure optimization using proximal aortic pressure maintenance and distal aortic perfusion (Class IIa recommendation) 1
• Moderate systemic hypothermia for protection during open repairs (Class IIa recommendation) 1
• Prevention of postoperative hypotension and continued CSF drainage for >40 hours to reduce paraparesis incidence 1
• Neurophysiological monitoring (somatosensory or motor evoked potentials) to detect spinal cord ischemia and guide treatment (Class IIb recommendation) 1

For Inflammatory/Autoimmune Causes

• Treatment depends on specific etiology
• For Guillain-Barré variants: intravenous immunoglobulin or plasma exchange 1
• For multiple sclerosis: disease-modifying therapies and symptomatic management 3

For Infectious Causes

• Spinal tuberculosis: anti-tubercular therapy with or without surgical decompression 2
• HTLV-1 associated myelopathy: supportive care and symptomatic management 3

For Structural Causes

• Surgical decompression for spinal cord compression from tumors or other mass lesions 1
• Combined surgery and radiotherapy for malignant spinal cord compression has shown better outcomes than radiotherapy alone 1
• For patients with malignant spinal cord compression who were paraparetic before treatment, 43.4% regained ambulation with radiotherapy alone, while 58% regained ambulation with surgery followed by radiotherapy 1

For Metabolic/Nutritional Causes

• Specific treatments for identified inborn errors of metabolism 5
• Vitamin supplementation for deficiency states 3

Prognosis

• Two-thirds of patients with paraparesis following thoracic aortic surgery will recover 1
• About half of patients with complete paraplegia will recover to the point of walking again 1
• Prognosis varies widely depending on underlying etiology, with potentially better outcomes for reversible causes (infectious, inflammatory) compared to degenerative or hereditary causes 2, 4

Prevention of Complications

• Avoid postoperative hypotension in patients with spinal cord ischemia 1
• Early mobilization and rehabilitation to prevent deconditioning 1
• Management of neurogenic bladder and bowel dysfunction to prevent secondary complications 1
• Pain management, as pain is frequently reported in patients with paraparesis 1