Plexopathy in Guillain-Barré Syndrome
Direct Answer
Plexopathy in GBS is managed identically to classic GBS with immediate immunotherapy (IVIg or plasma exchange) and intensive supportive care, as plexus involvement represents part of the polyradiculoneuropathy spectrum rather than a separate entity requiring distinct treatment. 1
Understanding Plexopathy in GBS Context
The facial nerve is the most frequently affected cranial nerve in GBS due to its longest intracranial course and extensive myelin coverage, making it particularly vulnerable to immune-mediated demyelination—this same vulnerability applies to nerve plexuses. 1
Plexus involvement in GBS occurs because the autoimmune attack targets nerve roots and proximal nerve segments, including brachial and lumbosacral plexuses, as part of the polyradiculoneuropathy process. 1
MRI of the plexus should be obtained if there is concern for plexus involvement to rule out alternative diagnoses and confirm nerve root enhancement/thickening consistent with GBS. 2, 1
Immediate Assessment Priorities
Respiratory and autonomic function must be assessed immediately, as approximately 20% of GBS patients develop respiratory failure requiring mechanical ventilation, which can occur rapidly without obvious dyspnea. 1, 3
Critical Monitoring Parameters:
Apply the "20/30/40 rule": Patient is at imminent risk of respiratory failure if vital capacity <20 ml/kg, maximum inspiratory pressure <30 cmH₂O, or maximum expiratory pressure <40 cmH₂O. 1
Single breath count ≤19 predicts need for mechanical ventilation—this simple bedside test should be performed serially. 1
Continuous ECG monitoring and blood pressure monitoring for arrhythmias and autonomic instability, as cardiovascular complications from autonomic dysfunction contribute to the 3-10% mortality rate. 1, 3
Grade muscle strength using Medical Research Council scale in neck, arms, and legs to track progression. 1
Diagnostic Workup for Plexopathy in GBS
Electrodiagnostic Studies:
Nerve conduction studies and EMG should be performed to support diagnosis and classify the neuropathy pattern, looking for sensorimotor polyradiculoneuropathy with reduced conduction velocities, reduced amplitudes, temporal dispersion, or conduction blocks. 1
"Sural sparing pattern" (normal sural sensory nerve action potential with abnormal median/ulnar responses) is typical for GBS, though electrodiagnostic measurements might be normal when performed early (within 1 week of symptom onset). 1
Do not dismiss GBS based on absent sural sparing in the first week—repeat testing in 2-3 weeks if clinical suspicion remains high. 1
Imaging and Laboratory:
MRI spine with and without contrast to evaluate for nerve root enhancement/thickening and rule out compressive lesions. 1
MRI of the plexus (brachial or lumbosacral) with and without contrast if concern for plexus involvement exists. 2, 1
Cerebrospinal fluid analysis for albumino-cytological dissociation (elevated protein with normal cell count), though this may be absent in the first week—do not dismiss GBS based on normal CSF protein early in disease course. 1
Screen for reversible neuropathy causes: HbA1c, vitamin B12, TSH, vitamin B6, folate, serum protein electrophoresis. 2, 1
First-Line Immunotherapy
Initiate treatment immediately in patients unable to walk unaided within 2-4 weeks of symptom onset—do not wait for antibody test results or confirmatory studies if GBS is suspected. 1, 4
Treatment Options (Equal Efficacy):
IVIg 0.4 g/kg/day for 5 consecutive days (total dose 2 g/kg) is the preferred first-line therapy due to easier administration, better tolerability, and fewer complications compared to plasma exchange. 1, 5, 4
Plasma exchange 200-250 ml/kg over 4-5 sessions is an equally effective alternative if IVIg is contraindicated or unavailable. 1, 4
Corticosteroids are NOT recommended for idiopathic GBS—they do not alter outcome and should be avoided. 1, 4, 6
Do not use PE followed immediately by IVIg, as combination therapy does not provide additional benefit. 4
Managing Treatment Response
Approximately 40% of patients do not improve in the first 4 weeks following treatment—this does not necessarily mean treatment failed, as progression might have been worse without therapy. 1
Treatment-related fluctuations (TRFs) occur in 6-10% of patients within 2 months after initial improvement, defined as disease progression following initial treatment-induced stabilization. 1, 3
For TRFs, repeating a full course of IVIg or plasma exchange is common practice, though evidence is limited. 1
Consider changing diagnosis to acute-onset CIDP if progression continues after 8 weeks from onset or if patient has three or more TRFs—this occurs in approximately 5% of patients initially diagnosed with GBS. 1, 4
Supportive Care and Complication Management
Pain Management:
Use gabapentinoids (gabapentin, pregabalin) or duloxetine for neuropathic pain—these are weakly recommended as first-line agents for pain control. 2, 1, 4
Tricyclic antidepressants or carbamazepine are alternative options for neuropathic pain. 1, 4
Gabapentin can be initiated alongside IVIg without contraindication or interaction, as they work through completely different mechanisms. 1
Encourage mobilization for muscle pain and arthralgia. 1
Autonomic Dysfunction:
Monitor for blood pressure/heart rate instability, pupillary dysfunction, and bowel/bladder dysfunction. 2, 1
Treat constipation/ileus aggressively, as gastroparesis represents autonomic nervous system dysfunction and will likely improve as underlying GBS is treated. 5
Medications to Avoid:
- Avoid medications that worsen neuromuscular transmission: β-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolides. 1, 3
Admission and Monitoring Criteria
All grades of GBS warrant workup and intervention given potential for progressive disease leading to respiratory compromise. 1
Admit to inpatient unit with capability for rapid transfer to ICU-level monitoring for Grade 3-4 disease (severe weakness limiting self-care, any dysphagia, facial weakness, respiratory muscle weakness, or rapidly progressive symptoms). 1
Even patients with moderate symptoms (Grade 2) require neurology consultation and close monitoring. 1
Frequent pulmonary function assessment with serial vital capacity and NIF measurements. 1
Daily neurologic evaluation to track progression or improvement. 1
Prognosis and Recovery
80% of patients regain independent walking ability at 6 months, though recovery can continue for more than 3 years, with improvement possible even more than 5 years after onset. 1, 5, 3
Mortality is 3-10%, primarily from cardiovascular and respiratory complications. 1, 3
Advanced age and severe disease at onset are risk factors for poor outcome. 1
Use the modified Erasmus GBS outcome score (mEGOS) to predict probability of regaining walking ability. 1, 4
Rehabilitation
Arrange a rehabilitation programme with a rehabilitation specialist, physiotherapist, and occupational therapist as a crucial step towards recovery. 1
Exercise programmes, including range-of-motion exercises, stationary cycling, walking, and strength training, can improve physical fitness, walking ability, and independence in activities of daily living. 1