What are the non-traumatic causes of quadriplegia (four-limb paralysis) versus paraplegia (lower limb paralysis) in a young adult with no significant past medical history?

Non-Traumatic Causes of Quadriplegia vs Paraplegia

The anatomical level of spinal cord pathology determines whether a patient develops quadriplegia (cervical lesions) or paraplegia (thoracic/lumbar lesions), with the most common non-traumatic causes being spinal metastases (33%), inflammatory disorders including transverse myelitis (22%), and degenerative spinal stenosis (19-54%). 1, 2

Anatomical Localization Principle

Quadriplegia (all four limbs) results from cervical spinal cord lesions (C1-C8), while paraplegia (lower limbs only) results from thoracic or lumbar cord lesions (T1 and below). 3

• Cervical cord involvement affects both upper and lower extremities due to disruption of descending motor pathways before they reach the thoracic level 4
• Thoracic and lumbar lesions spare upper extremity function because cervical segments remain intact 3

Common Non-Traumatic Causes by Frequency

Leading Causes (Both Quadriplegia and Paraplegia)

Spinal metastases (33.3% of cases):

• Most frequent non-traumatic cause overall 1
• Can occur at any spinal level—cervical involvement causes quadriplegia, thoracic/lumbar causes paraplegia
• Often requires emergency treatment (58.6% of non-traumatic SCI cases need urgent intervention) 1

Inflammatory/demyelinating disorders (22.2%):

• Transverse myelitis is the second most common cause (20% in some series) 1, 2
• Multiple sclerosis, neuromyelitis optica, acute disseminated encephalomyelitis 3
• Level of inflammation determines distribution of paralysis
• MRI shows plaques of demyelination 2

Degenerative spinal stenosis (19.4-54%):

• Cervical stenosis with cord compression can cause quadriplegia 1, 5
• Most common cause in some series, particularly in older adults 5
• Thoracic/lumbar stenosis causes paraplegia 2

Additional Important Causes

Spinal tuberculosis (30% in endemic regions):

• Most common cause in certain geographic areas 2
• Typically affects thoracic spine, causing paraplegia
• Presents with backache (75% of cases) and paresthesias (62.5%) 2

Primary spinal cord tumors (10%):

• Includes lymphoma, ependymomas, astrocytomas 3, 2
• Level determines whether quadriplegia or paraplegia results

Vascular causes:

• Spinal cord infarction (anterior spinal artery syndrome) 6
• Spinal dural arteriovenous fistulae causing cord edema 3
• Epidural hematoma 3
• Fibrocartilaginous embolism (rare, can cause acute paraplegia or quadriplegia) 6

Infectious causes:

• Neurosyphilis, epidural abscess 3
• Can affect any spinal level

Nutritional deficiencies:

• Vitamin B12 deficiency (subacute combined degeneration) 3
• Copper deficiency 3
• Typically causes progressive myelopathy

Other inflammatory causes:

• Neurosarcoidosis 3
• Paraneoplastic syndromes 3

Critical Clinical Discriminators

Presence of a sensory level (p<0.001) and sphincter dysfunction (p=0.02) are the only significant clinical findings that distinguish true spinal cord injury from "myelopathy-mimics" such as Guillain-Barré syndrome or peripheral neuropathies. 1

Key Clinical Features to Assess:

• Sensory level: Dermatomal level below which sensation is impaired indicates spinal cord lesion location 1
• Sphincter dysfunction: Bowel/bladder involvement suggests true myelopathy 1
• Spasticity: Present in 57.5% of non-traumatic spinal cord injury cases 2
• Backache: Occurs in 75% of cases, particularly with compressive lesions 2
• Paresthesias: Present in 62.5% of cases 2

Specific Causes of Quadriplegia (Cervical Lesions)

Cervical disc herniation with stenosis can cause acute, irreversible quadriplegia even without trauma, particularly at C6-C7 level. 7

• Rare but devastating: can progress from mild symptoms to complete quadriplegia within hours 7
• Requires immediate surgical decompression to prevent permanent paralysis 7
• Developmental cervical stenosis increases risk 7

Specific Causes of Paraplegia (Thoracic/Lumbar Lesions)

Thoracic spine is the most common site for spinal tuberculosis and metastatic disease causing paraplegia. 2

• Thoracic cord lesions (T1-T12) cause paraplegia with preserved upper extremity function 3
• Conus medullaris and cauda equina lesions cause lower motor neuron pattern paraplegia 6

Critical Diagnostic Approach

MRI of the entire spine with and without contrast is mandatory for any patient presenting with bilateral sensorimotor deficits, as clinical examination alone cannot reliably distinguish spinal cord injury from mimics. 4, 1

Imaging Protocol:

• MRI spine is the modality of choice for evaluating spinal cord pathology 3
• Cervical, thoracic, and lumbar regions should be imaged based on clinical localization 3
• Contrast administration helps identify inflammatory lesions, tumors, and infections 3
• Myelography shows block in 58.5% of compressive lesions 2
• CT scan following myelography can delineate tumors and confirm tuberculosis diagnosis 2

Emergency Considerations:

58.6% of non-traumatic spinal cord injury patients require emergency treatment, making rapid diagnosis critical. 1

• Acute cord compression requires surgical decompression within hours to prevent permanent paralysis 7
• Transverse myelitis and cord infarction are medical emergencies 3
• Epidural hematoma and abscess require urgent intervention 3

Demographic Patterns

Non-traumatic spinal cord injury patients are significantly older (peak in third decade but extends to elderly), more likely female, married, and retired compared to traumatic SCI patients. 2, 5

• Incidence highest in third decade (32.5%) but affects all ages 2
• 39% of all spinal cord injury admissions are non-traumatic in etiology 5
• Non-traumatic cases more commonly present with incomplete injury and paraplegia compared to traumatic cases 5

Common Pitfalls to Avoid

Do not delay spinal MRI based on normal initial clinical findings or wait for CSF/EMG results when spinal cord pathology is suspected—one-third of patients with bilateral sensorimotor deficits have true spinal cord injury requiring emergency treatment. 1

• Clinical overlap between spinal cord injury and peripheral disorders (like Guillain-Barré syndrome) is significant 4, 1
• Cervical disc herniation can enlarge acutely without trauma, causing irreversible quadriplegia if decompression is delayed 7
• Fibrocartilaginous embolism can mimic acute myelitis but requires different management (no biopsy needed) 6
• Initial MRI may be normal in early cord infarction—sequential imaging may be necessary 6