Rajabally Criteria for GBS
The Rajabally criteria are electrodiagnostic criteria designed to classify Guillain-Barré syndrome subtypes (demyelinating vs. axonal) with improved diagnostic accuracy compared to older criteria sets, showing the highest sensitivity and specificity in pediatric populations when validated against reference standards 1, 2.
What Are the Rajabally Criteria?
The Rajabally criteria (published in 2015) represent an optimized electrodiagnostic classification system for GBS subtypes. These criteria were developed to improve upon earlier systems (Hadden, Ho, Dutch criteria) by:
- Better identifying demyelinating features with sensitivity of 100% for demyelination 1
- Accurately detecting axonal patterns with sensitivity of 97-100% for axonal subtypes 1
- Reducing equivocal classifications with excellent agreement (0.93) when compared to Hadden criteria 1
Key Distinguishing Features
The Rajabally criteria incorporate several electrophysiological parameters to differentiate GBS subtypes:
- Motor nerve conduction velocities and amplitude measurements
- Temporal dispersion patterns in motor responses
- Conduction block characteristics
- Sensory nerve action potential abnormalities
- Recognition of reversible conduction failure (RCF) as a feature that can occur in axonal GBS 2
Important Clinical Context
The Rajabally criteria showed superior diagnostic accuracy (misclassification error rate of 45%) compared to Hadden criteria (48%) when applied at first electrodiagnostic study 2. However, sparse linear discriminant analysis performed even better (15.3% error rate), suggesting room for further optimization 2.
Practical Application
When performing electrodiagnostic studies in suspected GBS:
- Evaluate at least 4 motor nerves and 2 sensory nerves in both upper and lower limbs 1
- Timing matters: Median duration from symptom onset to testing in validated studies was 7 days 1
- Consider repeat studies: A second study 2-3 weeks later improves accuracy, particularly when initial findings show low amplitude responses or unclear demyelinating features 3
Critical Pitfall
Nearly half (46.6%) of axonal GBS patients show reversible conduction failure in motor nerves at second study 2. This means a single electrodiagnostic study may misclassify axonal cases as demyelinating, though this distinction does not currently alter treatment decisions 3, 4.
Limitations and Current Perspective
While the Rajabally criteria improve electrodiagnostic accuracy:
- The demyelinating vs. axonal dichotomy is increasingly challenged and not endorsed by recent EAN/PNS guidelines 4
- Treatment remains the same (IVIG or plasma exchange) regardless of electrophysiological subtype 4, 5
- Electrodiagnostic studies are supportive but not required for GBS diagnosis, which remains primarily clinical 6
The Rajabally criteria are most useful for research purposes, prognostication, and understanding underlying pathophysiology rather than guiding acute treatment decisions 3.