In a patient presenting to the emergency department with weakness, what examination and historical features suggest transverse myelitis, and which laboratory or radiologic tests confirm the diagnosis?

Acute Transverse Myelitis: Clinical Recognition and Diagnostic Confirmation

In a patient presenting with weakness to the emergency department, suspect transverse myelitis when you find the triad of sensory changes (97.8% of cases), motor weakness (71.7%), and autonomic dysfunction (76.1%), and confirm the diagnosis with MRI of the entire spine showing T2-hyperintense intramedullary lesions, typically in the thoracic cord. 1

Key Clinical Features That Point to Transverse Myelitis

History Red Flags

• Acute to subacute onset of symptoms over hours to days
• Bilateral symptoms affecting both lower extremities predominantly
• Sensory changes are nearly universal - look for well-defined dermatomal paresthesias or a clear sensory level on the trunk 1, 2
• Recent viral illness or vaccination (in some cases)
• Back pain in thoracic or lumbar regions preceding neurological symptoms 3

Critical Examination Findings (in order of frequency)

1. Sensory disturbances (98%) - This is the most consistent finding; absence should make you reconsider the diagnosis 1
2. Autonomic dysfunction (76%) - Urinary retention, bowel incontinence, or sexual dysfunction 1, 4
3. Motor weakness (72%) - Typically bilateral lower extremity weakness with upper motor neuron signs (hyperreflexia, Babinski sign) 2, 4
4. Defined sensory level - Usually in thoracic dermatomes 1, 2

Important Clinical Pitfall

There is frequently a discrepancy between the sensory level on examination and the actual MRI lesion level 1. The sensory level may be several segments below the actual cord lesion, so don't let a "mismatched" sensory level dissuade you from the diagnosis.

Diagnostic Testing Algorithm

Step 1: Imaging (Confirmatory Test)

MRI of the entire spine with and without contrast is the gold standard and should be performed urgently 5, 6. The ACR Appropriateness Criteria designate spine MRI as "usually appropriate" for myelopathy evaluation 5.

Characteristic MRI findings:

• T2-weighted hyperintense lesions in the spinal cord (present in 90.4% of cases) 2
• Most common location: thoracic cord (57%), followed by cervical 1, 2
• Lesions may be multiple in >50% of cases 2
• Longitudinally extensive lesions (≥3 vertebral segments) suggest specific etiologies like neuromyelitis optica 7
• Cord expansion may be present 4
• Enhancement patterns vary and are not specific 2

Critical caveat: Normal MRI does NOT exclude transverse myelitis - approximately 10-40% of patients may have normal initial imaging 6, 8. If clinical suspicion is high with normal MRI, repeat imaging in 2-7 days or proceed with CSF analysis 6.

Step 2: Laboratory Testing

Cerebrospinal fluid (CSF) analysis should be performed in all suspected cases 6, 2:

• Lymphocytic pleocytosis (common finding) 2, 8
• Elevated protein (common finding) 2, 8
• Normal or mildly elevated IgG index
• Oligoclonal bands may be present (suggests MS-related myelitis) 2

Serum testing to identify underlying etiology:

• Aquaporin-4 antibodies (neuromyelitis optica spectrum disorder)
• MOG antibodies (myelin oligodendrocyte glycoprotein antibody disease) 7
• Infectious workup: Syphilis (TPHA, RPR), HIV, CMV, HSV, VZV 8
• Autoimmune panel: ANA, anti-dsDNA, SSA/SSB, ACE level (sarcoidosis) 9
• Vitamin B12, copper levels (metabolic causes)

Step 3: Additional Imaging

Brain MRI should be obtained to evaluate for MS-typical lesions, as a substantial proportion of acute myelitis cases are MS-related 2. This helps guide long-term prognosis and treatment decisions.

Common Diagnostic Pitfalls in the Emergency Department

Emergency physicians frequently misdiagnose transverse myelitis as 1:

• Herniated intervertebral disc (38.7%)
• Stroke (19.4%)
• Guillain-Barré syndrome (12.9%)
• Cauda equina syndrome (9.7%)

Key distinguishing features:

• Unlike Guillain-Barré: TM has sensory level, hyperreflexia (not areflexia), and earlier autonomic dysfunction 10
• Unlike disc herniation: TM has bilateral symptoms, sensory level, and autonomic dysfunction
• Unlike cauda equina: TM has upper motor neuron signs (hyperreflexia, Babinski) rather than lower motor neuron signs

Diagnostic Certainty Framework

Definite TM diagnosis requires 2:

• Clinical syndrome consistent with spinal cord dysfunction (sensory, motor, autonomic)
• AND MRI showing intramedullary T2 hyperintensity
• AND CSF pleocytosis or elevated protein

Suspected TM when 2:

• Clinical syndrome present with either abnormal MRI alone OR abnormal CSF alone
• Or electrophysiological evidence of cord dysfunction with clinical syndrome

The diagnosis remains idiopathic in approximately 76% of cases after complete workup 1, emphasizing the importance of excluding treatable causes through systematic laboratory evaluation.