What are the key examination findings that differentiate Guillain-Barré Syndrome (GBS) from transverse myelitis in a patient presenting with rapidly progressive weakness?

Key Examination Findings Differentiating GBS from Transverse Myelitis

The critical examination distinction is that GBS presents with areflexia/hyporeflexia in a symmetric ascending pattern, while transverse myelitis presents with hyperreflexia below the spinal cord lesion level, a sensory level, and early bladder/bowel dysfunction. 1

Reflex Examination: The Most Discriminating Feature

Guillain-Barré Syndrome

• Diminished or absent deep tendon reflexes throughout, typically beginning in lower limbs and progressing upward 2, 3
• Areflexia is present in most patients at presentation and almost all at nadir 3
• Reflexes remain absent or reduced even as weakness ascends 4

Transverse Myelitis

• Hyperreflexia below the level of the spinal cord lesion 1
• Positive Babinski sign (upgoing plantar response) indicating upper motor neuron involvement 1
• Initial hyporeflexia may occur in acute phase (spinal shock) but evolves to hyperreflexia within days to weeks 5

Sensory Examination Patterns

Guillain-Barré Syndrome

• Distal paresthesias in a stocking-glove distribution 2, 3
• Mild sensory loss that is symmetric and length-dependent 4
• No clear sensory level on the trunk 1
• Sensory findings are often less prominent than motor findings 3

Transverse Myelitis

• Distinct sensory level on the trunk corresponding to the spinal cord lesion 1
• All sensory modalities affected below the lesion level 5
• Sharp demarcation between normal and abnormal sensation 1

Motor Examination Characteristics

Guillain-Barré Syndrome

• Bilateral ascending weakness starting distally in legs, progressing to arms and cranial muscles 2, 3, 6
• Symmetric involvement (though timing may vary slightly between sides) 6
• Proximal and distal muscles affected as disease progresses 4
• Facial weakness common (most frequently affected cranial nerve) 2
• Pattern is lower motor neuron (flaccid paralysis) 4

Transverse Myelitis

• Weakness below the spinal cord lesion level with relatively preserved strength above 1
• Pattern is upper motor neuron (spastic paralysis after acute phase) 5
• Bilateral but may be asymmetric initially 5
• No cranial nerve involvement unless brainstem is affected 1

Autonomic Dysfunction Patterns

Guillain-Barré Syndrome

• Cardiovascular instability: blood pressure fluctuations, arrhythmias 2, 3
• Pupillary dysfunction 3
• Bowel/bladder dysfunction occurs but is not an early or prominent feature 3
• Marked persistent bladder dysfunction at onset should prompt reconsideration of GBS diagnosis 2

Transverse Myelitis

• Early and prominent bladder/bowel dysfunction (urinary retention, fecal incontinence) 1, 7, 8
• This is a hallmark feature distinguishing it from GBS 1

Cranial Nerve Examination

Guillain-Barré Syndrome

• Bilateral facial palsy is the most common cranial nerve finding 2
• Ophthalmoplegia, ataxia, and areflexia suggest Miller Fisher variant 2, 3
• Dysphagia and diminished cough reflex may develop 2
• Assess corneal reflex in patients with facial palsy 2

Transverse Myelitis

• Cranial nerves typically spared unless there is concurrent brainstem involvement 1
• Presence of cranial nerve findings should raise suspicion for alternative diagnosis or concurrent pathology 7

Respiratory Examination

Guillain-Barré Syndrome

• Progressive respiratory muscle weakness in ~20% of patients 3, 6
• Assess vital capacity, negative inspiratory force, single breath count 2
• "20/30/40 rule": risk if VC <20 ml/kg, MIP <30 cmH₂O, MEP <40 cmH₂O 2
• Single breath count ≤19 predicts need for mechanical ventilation 2

Transverse Myelitis

• Respiratory compromise only if cervical cord involvement (C3-C5 level affecting phrenic nerve) 1
• Less common than in GBS unless high cervical lesion 5

Common Diagnostic Pitfalls

Critical caveat: Marked persistent asymmetry, bladder dysfunction at onset, or the presence of a sensory level should immediately redirect your thinking away from GBS toward transverse myelitis or other CNS pathology 2. Conversely, areflexia with ascending weakness and no sensory level strongly favors GBS over transverse myelitis 1.

The rare overlap syndrome (concurrent GBS and transverse myelitis) should be considered if recovery takes longer than anticipated or if examination findings are mixed, requiring both MRI spine and electrodiagnostic studies for definitive diagnosis 7, 8.