What is the most likely diagnosis for a patient presenting with lower limb weakness, difficulty walking, a T10 sensory level, and urinary retention without back pain?

Transverse Myelitis: Most Likely Diagnosis

In a patient presenting with acute bilateral lower limb weakness, a T10 sensory level, urinary retention, and notably the absence of back pain, transverse myelitis is the most likely diagnosis. 1, 2, 3, 4

Clinical Reasoning for Diagnosis

The absence of back pain is the critical distinguishing feature in this presentation:

• Spinal cord compression typically presents with significant back pain as a prominent early symptom, which this patient lacks 5, 6
• Transverse myelitis characteristically presents with acute bilateral lower limb weakness, sensory level, and urinary retention, often without significant back pain 1, 2, 3, 4

Key Diagnostic Features Supporting Transverse Myelitis

Characteristic Clinical Triad

• Bilateral motor weakness affecting lower limbs with acute onset over days 1, 2, 3, 4
• Sensory level (T10 in this case) with numbness below the level of involvement 1, 2, 3
• Autonomic dysfunction manifesting as urinary retention, which developed a few days prior to presentation 1, 2, 3, 4

Timeline Considerations

• The 3-day progression is consistent with transverse myelitis, which typically develops acutely to subacutely 1, 2, 3, 4
• Guillain-Barré syndrome would show ascending weakness starting distally, absent reflexes throughout, and typically lacks a clear sensory level 5

Why Other Diagnoses Are Less Likely

Spinal Cord Compression (Option A)

• Back pain is typically present and often severe in compressive myelopathy 5, 6
• The absence of pain makes this diagnosis significantly less likely in this clinical context 5

Guillain-Barré Syndrome (Option B)

• GBS presents with ascending weakness starting in the legs and progressing upward, not a defined sensory level 5
• Areflexia is universal in GBS, whereas this patient has a clear T10 sensory level suggesting spinal cord pathology 5
• Urinary retention is uncommon in early GBS and represents dysautonomia rather than a sensory level 5

Cauda Equina Syndrome (Option D)

• Cauda equina syndrome affects nerve roots below the conus medullaris (typically L1-L2 level) 5, 6, 7
• A T10 sensory level indicates spinal cord involvement, not cauda equina nerve roots 5, 6
• Cauda equina presents with lower motor neuron signs (flaccid weakness, absent reflexes in legs), saddle anesthesia, and often severe back pain 5, 6, 7

Immediate Diagnostic Workup Required

Urgent MRI Spine

• MRI thoracic spine with contrast is the diagnostic test of choice to confirm transverse myelitis and exclude compressive lesions 1, 2, 3, 4
• Expected findings include cord swelling and increased T2 signal at the level of involvement 1, 2, 3

Cerebrospinal Fluid Analysis

• CSF typically shows pleocytosis and elevated protein in transverse myelitis 1, 2, 3, 4
• Essential for identifying infectious or inflammatory etiologies 1, 2, 3, 4, 8

Etiologic Investigation

• Infectious workup including viral serologies, particularly in endemic areas (Schistosoma, Lyme disease, recent viral infections) 5, 2, 3, 8
• Autoimmune screening for conditions like neuromyelitis optica, multiple sclerosis, and systemic autoimmune diseases 4
• Recent infection history (COVID-19, mumps, other viral illnesses) 1, 4

Treatment Implications

High-dose intravenous methylprednisolone (typically 1g daily for 3-5 days) should be initiated promptly once diagnosis is confirmed, as outcomes are time-dependent 1, 2, 3, 4

Critical Pitfall to Avoid

Do not delay MRI imaging or treatment while waiting for extensive etiologic workup—empiric corticosteroid therapy should begin once compressive lesions are excluded by imaging, as early treatment improves neurological outcomes 1, 2, 3, 4