What is the workup for paraparesis (partial paralysis of the lower limbs)?

Workup of Paraparesis

The workup of paraparesis must begin with urgent spinal MRI to localize the lesion and guide subsequent diagnostic testing, as the differential diagnosis and management depend critically on whether the pathology is extradural, intradural-extramedullary, intramedullary, or involves specific tracts. 1

Initial Clinical Assessment

Key Historical Features to Elicit

• Onset and tempo: Acute (<2 weeks) versus chronic progressive paraparesis fundamentally changes the differential diagnosis 2, 1
• Associated symptoms:
  • Backache (present in 75% of cases) 3
  • Paresthesias (present in 62.5% of cases) 3
  • Bladder/bowel dysfunction 2
  • Sensory level 1
• Risk factors for specific etiologies:
  • Recent thoracic aortic surgery (spinal cord ischemia occurs in 2-6% of cases) 2
  • History of cancer (spinal cord compression) 2
  • Infectious exposures, particularly tuberculosis 3
  • Family history of progressive spastic paraparesis 4

Focused Physical Examination

• Motor examination: Document degree of weakness and whether spasticity is present (found in 57.5% of paraparesis cases) 3
• Sensory examination: Identify sensory level and pattern 1
• Reflexes: Assess for upper motor neuron signs (hyperreflexia, clonus, Babinski sign) 1
• Vascular examination: Check for signs of aortic disease or peripheral arterial disease 2

Diagnostic Algorithm Based on MRI Findings

Primary Imaging: Spinal MRI

Spinal MRI is the cornerstone of the diagnostic workup and should be obtained urgently. 1 The MRI pattern determines subsequent testing:

Pattern 1: Extradural Lesions

• Most common cause: Spinal tuberculosis (30% of all paraparesis cases) 3
• Additional testing:
  • CT scan following myelography to delineate bony involvement 3
  • Tuberculin skin test, interferon-gamma release assay
  • Biopsy if diagnosis uncertain 3

Pattern 2: Intradural-Extramedullary Lesions

• Common causes: Meningiomas, nerve sheath tumors 1
• Additional testing: CT myelography for surgical planning 3

Pattern 3: Intramedullary Lesions

• Common causes: Acute transverse myelitis (20% of cases), primary spinal cord tumors (10% of cases) 3
• Additional testing:
  • CSF examination for inflammatory/infectious causes 2
  • MRI brain to assess for demyelinating plaques 3
  • Aquaporin-4 and MOG antibodies if demyelination suspected 2

Pattern 4: Intramedullary-Tract Specific

• Consider: Hereditary spastic paraparesis, metabolic disorders 4, 1
• Additional testing: Metabolic screening for inborn errors of metabolism in adults 4

Pattern 5: Spinal Cord Atrophy

• Consider: Chronic degenerative processes, hereditary conditions 1

Pattern 6: Normal Appearing Spinal Cord

• Consider: Early metabolic disorders, vascular causes, hereditary spastic paraparesis 1
• Additional testing: Metabolic workup, genetic testing 4

Laboratory Investigations

First-Line Laboratory Tests

• Complete blood count, comprehensive metabolic panel 2
• Prothrombin time, activated partial thromboplastin time (especially if vascular etiology suspected) 2
• Erythrocyte sedimentation rate, C-reactive protein (for inflammatory/infectious causes) 3

Specialized Testing Based on Clinical Suspicion

• CSF examination: Indicated when inflammatory or infectious causes suspected, particularly for Guillain-Barré syndrome variants 2
• Prothrombotic screening: If cerebral venous thrombosis suspected (can cause bilateral motor signs including paraparesis) 2
• Metabolic screening: For inborn errors of metabolism in adults presenting with isolated spastic paraparesis 4

Critical Pitfalls to Avoid

Delayed Spinal Cord Ischemia

Paraparesis can occur up to 27 days after thoracic aortic surgery, often triggered by hypotension. 5 In patients with recent aortic surgery:

• Maintain strict blood pressure control 2, 5
• Continue CSF drainage for >40 hours postoperatively 2
• Monitor for delayed neurological deficits 5

Cerebral Causes of Paraparesis

Do not assume all paraparesis is spinal in origin. Parasagittal lesions (meningiomas, cerebral venous thrombosis) can present with isolated paraparesis 2, 6. Consider brain MRI if:

• No sensory level identified
• Associated cognitive changes or seizures
• MRI spine is normal 6

Treatable Metabolic Causes

Inborn errors of metabolism can present as isolated spastic paraparesis in adults and are often treatable. 4 Include metabolic screening in the workup, particularly in younger patients or those with atypical features 4.

Urgent Interventions Based on Etiology

• Spinal cord compression from tumor: Surgical decompression combined with radiotherapy shows better outcomes than radiotherapy alone 2
• Spinal cord ischemia: Cerebrospinal fluid drainage (Class I recommendation), maintain proximal aortic pressure, consider moderate systemic hypothermia 2
• Infectious/inflammatory: Initiate appropriate antimicrobial or immunomodulatory therapy based on CSF results 2, 3

Prognostic Considerations

Two-thirds of patients with paraparesis following spinal cord ischemia will recover, and approximately half of patients with complete paraplegia will recover to the point of walking again. 2 Early intensive neurorehabilitation beginning in the acute phase improves functional outcomes 6.