What are the acute, subacute, and chronic causes of paraplegia?

Causes of Paraplegia by Temporal Onset

Acute Paraplegia (Hours to Days)

Acute paraplegia requires immediate imaging with MRI of the entire spine to identify life-threatening compressive lesions, cord ischemia, or hemorrhage. 1

Vascular Causes

• Spinal cord ischemia from aortic dissection, thoracoabdominal aortic surgery complications, systemic hypotension, or atheromatous disease causes acute paraplegia in 1-3% of thoracic aortic dissection patients 2
• Anterior spinal artery syndrome presents with sudden onset motor paralysis and loss of pain/temperature sensation while preserving proprioception 1
• Cerebrospinal fluid drainage should continue up to 72 hours post-operatively after thoracoabdominal aortic repair to prevent delayed onset paraplegia 1, 3

Compressive Causes

• Epidural hematoma from trauma, anticoagulation, or vascular malformations requires emergent surgical decompression 1
• Acute disc herniation with canal stenosis can cause nontraumatic acute complete paraplegia, particularly at C6-C7, requiring immediate decompressive surgery 4
• Malignant spinal cord compression demands high-dose dexamethasone (96 mg IV daily) immediately upon clinical suspicion, which improves ambulation rates (81% vs 63% at 3 months) 3

Inflammatory/Infectious Causes

• Acute transverse myelitis from acute disseminated encephalomyelitis (ADEM) or neuromyelitis optica (NMO) presents with rapid onset bilateral weakness 1
• Acute cerebellitis can present with truncal ataxia and altered consciousness, though this typically causes ataxia rather than pure paraplegia 1

Traumatic Causes

• Spinal cord contusion or laceration from vertebral fracture-dislocation is the most common traumatic cause 1
• Cerebral contusions in bilateral precentral gyri can rarely cause pure motor paraplegia and may be misdiagnosed as spinal concussion, particularly as FLAIR MRI lesions disappear in the subacute phase 5

Subacute Paraplegia (Days to Weeks)

Subacute presentations require MRI with and without IV contrast to identify demyelinating disease, infections, or neoplastic processes. 1

Demyelinating Diseases

• Multiple sclerosis affects the spinal cord in 80-90% of patients, most commonly the cervical cord, and presents with lesions disseminated in space and time 1
• Neuromyelitis optica causes longitudinally extensive transverse myelitis (≥3 vertebral segments) with characteristic aquaporin-4 antibodies 1

Infectious Causes

• Schistosomiasis (S. mansoni and S. haematobium) causes gradual onset paraplegia in patients with travel to endemic areas in Africa and should always be considered in this population 3, 2
• Treatment consists of praziquantel 40 mg/kg twice daily for 5 days plus dexamethasone 4 mg four times daily, reducing over 2-6 weeks 3
• Negative serology should not exclude schistosomiasis in endemic area travelers with compatible clinical picture; consider empiric treatment trial 3
• Tuberculosis (Pott disease) causes vertebral destruction with epidural abscess formation 2
• Human T cell lymphotropic virus myelitis and HIV vacuolar myelopathy present with progressive spastic paraparesis 1

Neoplastic Causes

• Metastatic spinal cord compression requires surgical decompression followed by radiation therapy, which is superior to radiation alone for patients with single level compression, neurologic deficits present <48 hours, age <65 years, or predicted survival ≥3 months 3
• Dexamethasone administration should not be delayed while awaiting imaging in suspected malignant cord compression 3
• Primary intramedullary tumors (astrocytoma, ependymoma) are best evaluated with contrast-enhanced MRI 1

Metabolic Causes

• Subacute combined degeneration from vitamin B12 (cobalamin) deficiency or copper deficiency causes characteristic posterior and lateral column involvement 1
• Nitrous oxide inhalation can cause similar metabolic myelopathy 1

Autoimmune Causes

• Paraneoplastic myelopathy presents with subacute or acute onset and requires MRI without and with IV contrast for evaluation 1

Chronic Paraplegia (Weeks to Months)

Chronic progressive myelopathy requires MRI to distinguish between compressive and non-compressive etiologies, with contrast enhancement recommended for initial diagnostic evaluation. 1

Degenerative Causes

• Spondylotic myelopathy is the most common cause of extrinsic spinal cord compression in chronic/progressive paraplegia, particularly affecting the cervical spine 1, 2
• Intramedullary cord signal changes on MRI represent important prognostic factors for neurosurgical outcomes 1, 2
• IV contrast is typically not required for diagnosis, but characteristic patterns of enhancement can be seen immediately at and below a level of stenosis 1
• Rare conditions such as Hirayama disease (cervical flexion myelopathy), dorsal arachnoid webs, and ventral cord herniation can result in progressive myelopathy 1

Vascular Causes

• Spinal dural arteriovenous malformations/fistulas present with chronic and slowly progressive myelopathy from venous hypertension 1
• MRI without and with IV contrast demonstrates spinal cord edema and enlarged veins along the dorsal surface of the spinal cord 1
• Thoracoabdominal aortic aneurysm can cause chronic contained rupture leading to vertebral erosion and spinal cord compression, with 12.5% of patients presenting with neurologic impairment including paraplegia 2

Chronic Infectious Causes

• Chronic tuberculosis, schistosomiasis, and tertiary syphilis can present with progressive myelopathy 1

Metabolic/Toxic Causes

• Radiation-induced myelopathy is a rare dose-dependent complication that anatomically localizes to a prior radiation port 1
• 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 2

Hereditary Causes

• Hereditary spastic paraplegia is a rare neurodegenerative disorder with predominant spasticity in lower extremities, with prevalence ranging from 0.1 to 9.6 per 100,000 6
• Frequent degeneration occurs in the axon of cervical and thoracic spinal cord's lateral region, comprising the corticospinal routes 6

Progressive Demyelinating Disease

• Primary progressive multiple sclerosis tends to have more spinal cord involvement than relapsing-remitting MS 1

Critical Diagnostic Pitfalls to Avoid

• Do not delay dexamethasone administration while awaiting imaging in suspected malignant cord compression 3
• Do not rely on negative serology to exclude schistosomiasis in endemic area travelers with compatible clinical picture 3
• Do not mistake cerebral contusions in bilateral precentral gyri for spinal cord pathology, as FLAIR MRI lesions disappear in the subacute phase 5
• Do not perform only SSEP monitoring during aortic procedures—motor evoked potentials (MEPs) are significantly more sensitive (29% vs 7%) for detecting anterior spinal cord ischemia 3
• Do not assume acute disc herniation requires trauma—nontraumatic enlargement of cervical disc herniation with canal stenosis can cause acute irreversible paraplegia 4