The sensitivity of electrodiagnostic criteria in subtype identi cation at the presentation in patients of Guillain-Barre syndrome

The sensitivity of electrodiagnostic criteria in subtype identi cation at the presentation in patients of Guillain-Barre syndrome L. Mathukumalli N.1, Yaranagula S.2, A. Kanikannan M.3*, Chepuru R.4, Yareeda S.5, Sarva S.6, Borgohain R.7 DOI: https://doi.org/10.17511/ijmrr.2020.i02.01 1 Neeharika L. Mathukumalli, Assistant Professor, Department of Neurology, Nizam’s Institute of Medical Sciences, Hyderabad, Telangana, India. 2 Sai Deepak Yaranagula, Senior Resident, Department of Neurology, Nizam’s Institute of Medical Sciences, Hyderabad, Telangana, India. 3* Meena A. Kanikannan, Professor, Department of Neurology, Nizam’s Institute of Medical Sciences, Hyderabad, Telangana, India. 4 Ramesh Chepuru, Senior Resident, Department of Neurology, Nizam’s Institute of Medical Sciences, Hyderabad, Telangana, India. 5 Sireesha Yareeda, Assistant Professor, Department of Neurology, Nizam’s Institute of Medical Sciences, Hyderabad, Telangana, India. 6 Sailaja Sarva, Senior Lab Technologist, Department of Neurology, Nizam’s Institute of Medical Sciences, Hyderabad, Telangana, India. 7 Rupam Borgohain, Professor and Head of Department, DM Neurology, Department of Neurology, Nizam’s Institute of Medical Sciences, Hyderabad, Telangana, India.


Introduction
Guillain-Barré Syndrome (GBS) is an acute inflammatory polyradiculoneuropathy. According to WHO, the overall incidence of GBS is 0.4 to 4.0 people per 1,00,000 per year [1]. Typically, the disease manifests as ascending symmetrical weakness with diminished reflexes with or without sensory involvement.Individuals of all ages can be affected, but it's more common among adults and particularly in the male.  Electrophysiology plays an important role in identifying pathology. Over the decades, a number of electrophysiological criteria have been evolved for the sub typing of GBS [10][11][12][13][14][15][16][17][18]. Studies comparing the various criteria have been few [19][20][21].
This study was done with the aim of describing the clinical and electrophysiological findings in a cohort of patients with GBS and to evaluate the sensitivity of 5 electrophysiological criteria in patients with GBS at the time of presentation.

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Electrophysiological subtypes with the week of NCS All criteria had progressively increased sensitivity to diagnosing axonal subtype with increasing week of NCS. All criteria showed the highest sensitivity to AIDP in 2nd week of illness followed by 1st week.
Sensitivity to diagnosing AIDP was lowest in 3rd week and beyond. The highest proportion of patients was categorized into "Others" in the 1st week of illness irrespective of the criterion applied

Discussion
This study retrospectively analyzed the electrophysiological data in 288 patients of GBS patients at presentation. Majority of the patients in the present study were in their third decade of life, a finding similar to previous studies from India [20,21] [20,21]. Fever is most common followed by GE and respiratory infections were similar to Kalita et al [20]. While the previous study by Alexander et al had a higher proportion of AIDP [21] this study showed an axonal variant being more common than AIDP presentation irrespective of the criteria used.
The sensitivity of 5 diagnostic criteria for electrophysiological classification was looked into.
The concurrence of criteria was higher for axonal variants in all weeks of presentation than AIDP. In the diagnosis of AIDP, Ho and Hadden's criteria were most sensitive. Italian criteria were least sensitive for AIDP but most sensitive for axonal type.  [19,20,21].
Although the current study tested the Italian, Dutch (Van der Meche) and Ho criteria similar to the above studies, the remaining 2 criteria (Hadden and Rajabally) (Table 3). This is probably due to the differences in the characteristics of the cohorts. All criteria had lower sensitivity for AIDP, in the less severe subgroup (Hughes grade 3 or less) of our cohort.
This suggests that the criteria under-report AIDP in less severely affected patients of GBS. The less severe nature of our cohort as a whole compared to previous studies may be the reason for the lower sensitivity of the criteria for AIDP.
The timing from onset to NCS was also lower in our cohort and may have contributed to the lesser sensitivity to AIDP than the other studies (

Conclusion
This study demonstrates that the timing of NCS and severity of the disease, both influence the grouping Of the patient into demyelinating or axonal variants, irrespective of the criteria used. Therefore, the clinical picture must be taken into account, and the electrodiagnostic classification by the various criteria must be interpreted with caution.
And as the electrophysiological changes evolve over time in a given case of GBS, repeat conduction at various time points especially in the first few weeks of illness may be required to subtype and thus prognosticate.
What does the study add to the existing knowledge The present study finding showed that the criteria under-report AIDP in less severely affected patients of GBS.

Author's contribution
All the authors participated actively during the whole study. All the authors reached out to each other in many ways like study design, data collection, and manuscript preparation.