What are the clinical features and diagnostic work‑up for a child with transverse myelitis superimposed on Guillain‑Barré syndrome?

Concurrent Guillain-Barré Syndrome and Transverse Myelitis in Children

Clinical Presentation

When a child presents with acute flaccid weakness, consider concurrent GBS and transverse myelitis if you observe a sharply defined sensory level, severe bladder dysfunction, or autonomic instability—features that distinguish this rare overlap syndrome from isolated GBS. 1

Key Distinguishing Features from Isolated GBS

• A sharply defined sensory level is the most important clinical clue; this finding is atypical for pure GBS and should immediately raise suspicion for concurrent spinal cord involvement 1
• Severe bladder dysfunction at onset (urinary retention or incontinence) strongly suggests myelitis, as bladder symptoms are uncommon in isolated GBS 1
• Autonomic dysfunction (blood pressure/heart rate instability, pupillary abnormalities) occurs in both conditions but is more prominent when both are present 1
• Age over 8 years appears to be a risk factor for this concurrent presentation in pediatric patients 1

Clinical Features Shared by Both Conditions

• Bilateral ascending weakness starting in the legs and progressing to arms, with diminished or absent deep tendon reflexes (present in 82-100% of pediatric GBS cases) 2
• Distal paresthesias or sensory loss preceding or accompanying weakness 3, 2
• Pain (muscular, radicular, or neuropathic) as an early symptom, affecting approximately two-thirds of patients 3, 2
• Preceding infection within 6 weeks of symptom onset, reported in about two-thirds of cases; Mycoplasma pneumoniae has been specifically associated with this concurrent presentation 4, 5

Atypical Presentations in Young Children

• Children under 6 years may present with nonspecific features including poorly localized pain, refusal to bear weight, irritability, meningism, or unsteady gait—failure to recognize these as early GBS/myelitis can delay diagnosis 6

Diagnostic Work-Up

Initial Assessment Priority

Immediately assess respiratory function and autonomic stability, as approximately 20% of patients develop respiratory failure requiring mechanical ventilation, which can occur rapidly even without obvious dyspnea. 7

• Measure vital capacity, negative inspiratory force (NIF), and maximum inspiratory/expiratory pressures at presentation and serially 7
• Apply the "20/30/40 rule": patient is at risk if vital capacity <20 ml/kg, maximum inspiratory pressure <30 cmH₂O, or maximum expiratory pressure <40 cmH₂O 7
• Perform continuous ECG and blood pressure monitoring for arrhythmias and autonomic instability 7

Neurological Examination Specifics

• Grade muscle strength using the Medical Research Council scale in neck, arms, and legs 7
• Document the presence and level of any sensory level—a sharply defined sensory level is the key distinguishing feature of concurrent myelitis 1
• Test for bladder dysfunction through history and examination; severe bladder involvement at onset strongly suggests myelitis 1
• Assess cranial nerve function, particularly for bilateral facial palsy (the most commonly affected cranial nerve in GBS) 7
• Check reflexes systematically; while typically absent in GBS, some patients with pure motor variants may have normal or even exaggerated reflexes 6

Laboratory Studies

• Complete blood count, glucose, electrolytes, kidney function, liver enzymes to exclude metabolic causes of weakness 7
• Serum creatine kinase (CK): elevation suggests muscle involvement and may indicate the AMAN variant of GBS or concurrent myositis 7, 4
• Mycoplasma pneumoniae serology (IgM and IgG) given its association with concurrent GBS and myelitis; repeat serology to document rising titers 4, 5

Cerebrospinal Fluid Analysis

• Perform lumbar puncture to assess for albumino-cytological dissociation (elevated protein with normal cell count), the classic CSF finding in GBS 3, 7
• Do not exclude GBS based on normal CSF protein in the first week—protein elevation may not appear until later in the disease course 7
• Marked CSF pleocytosis (significant white cell elevation) should prompt reconsideration of the diagnosis and raise concern for infectious or other inflammatory causes 7
• Analyze CSF for cell count, differential, cytology, glucose, and viral/bacterial cultures 7

Electrodiagnostic Studies

Nerve conduction studies and electromyography are essential to confirm peripheral nerve involvement and distinguish this from pure myelitis. 3, 7

• Look for sensorimotor polyradiculoneuropathy with reduced conduction velocities, reduced amplitudes, temporal dispersion, or conduction blocks 7
• The "sural sparing pattern" (normal sural sensory nerve action potential with abnormal median/ulnar responses) is typical for GBS and highly specific 7
• Findings consistent with acute motor polyneuropathy affecting both motor and sensory fibers support concurrent GBS 8
• Repeat electrodiagnostic studies in 2-3 weeks if initial studies are normal but clinical suspicion remains high, as early studies may be falsely negative 7

Neuroimaging

MRI of the spine with and without gadolinium contrast is mandatory when concurrent myelitis is suspected and should not be delayed. 3, 8

• Spinal MRI protocol should include T1-weighted sequences with and without gadolinium, T2-weighted sequences in sagittal and axial planes, fat-suppressed T2-weighted sequences (STIR), and high-resolution heavily T2-weighted 3D sequences 3
• Look for enhancing hyperintense lesions in the spinal cord on T2-weighted images, which confirm transverse myelitis 8, 4
• Nerve root enhancement on gadolinium-enhanced imaging supports GBS diagnosis (sensitivity 83-95%) and is particularly valuable in young children where clinical assessment is challenging 3
• Brain MRI may reveal additional demyelinating lesions suggesting acute disseminated encephalomyelitis (ADEM), which can also occur concurrently with GBS 9

Antibody Testing

• Anti-ganglioside antibodies (including anti-GQ1b for Miller Fisher variant) may be present in a subgroup of GBS patients 3
• Do not delay treatment while awaiting antibody results if GBS is clinically suspected 7

Diagnostic Algorithm

1. Recognize the clinical pattern: acute ascending weakness + sharply defined sensory level + severe bladder dysfunction = suspect concurrent GBS and myelitis 1
2. Secure the airway and monitor respiratory function immediately 7
3. Obtain urgent neurology consultation for every suspected case 7
4. Perform electrodiagnostic studies to confirm peripheral nerve involvement (distinguishes from pure myelitis) 8
5. Obtain spinal MRI with contrast to identify cord lesions (distinguishes from pure GBS) 8
6. Do not wait for complete diagnostic work-up to initiate treatment if the patient is deteriorating 7

Common Pitfalls and How to Avoid Them

• Pitfall: Assuming isolated GBS when reflexes are absent and delaying spinal imaging

  • Solution: Always check for a sensory level and bladder dysfunction; if present, obtain urgent spinal MRI even with typical GBS features 1

• Pitfall: Dismissing GBS because CSF protein is normal in the first week

  • Solution: Do not exclude GBS based on normal CSF protein early in the disease course; repeat if needed 7

• Pitfall: Stopping diagnostic work-up after diagnosing one condition (either GBS or myelitis)

  • Solution: If recovery takes longer than anticipated or clinical features don't fit perfectly, reconsider the possibility of concurrent pathology 8

• Pitfall: Missing the diagnosis in young children due to nonspecific presentations

  • Solution: Maintain high suspicion for GBS/myelitis in any child with acute weakness, refusal to walk, or irritability following infection 6

• Pitfall: Attributing elevated CK solely to muscle disease and missing the neurological diagnosis

  • Solution: Elevated CK can occur in AMAN variant of GBS or concurrent myositis; always perform electrodiagnostic studies and neuroimaging 4

Treatment Implications

• Intravenous immunoglobulin (IVIg) 0.4 g/kg/day for 5 days is first-line therapy for GBS 7, 8
• High-dose intravenous methylprednisolone should be added when transverse myelitis is confirmed on MRI 8
• Both treatments can be administered concurrently when both conditions are present 8, 9
• Treatment should be initiated based on clinical suspicion without waiting for complete diagnostic confirmation if the patient is deteriorating 7

Prognosis

• Concurrent GBS and myelitis carries a worse prognosis than isolated GBS, with most patients demonstrating residual paresis and some showing significant long-term motor deficits 1
• Early recognition is crucial for determining prognosis and guiding initial treatment 1
• While isolated GBS has an 80% rate of independent walking at 6 months, concurrent myelitis significantly reduces this favorable outcome 7, 1