Prognostic Significance of Serial Nerve Conduction in GB Syndrome

Background and aims: We evaluated dynamic changes in neurophysiology of Guillain-Barré syndrome (GBS) at different time points and the role of demyelination and axonal burden in predicting outcome.

Methods: Nerve conduction study (NCS) was done in 44 GBS patients at admission and at 1 and 3 months, and were categorized into acute inflammatory demyelinating polyradiculoneuropathy (AIDP), acute motor axonal neuropathy (AMAN), acute motor sensory axonal neuropathy (AMSAN), equivocal and in-excitable motor nerve (IMN). The demyelinating and axonal burden on motor NCS at admission, 1 and 3 months were computed and correlated with disability at 3 and 6 months. Disability was assessed using Clinical Grading Scale.

Results: Twenty-four (54.3%) had AIDP, 5 (11.4%) AMAN, 12 (27.3%) equivocal and 3 (6.8%) had IMN at admission. Maximum instability was noted in equivocal group; majority of whom became AIDP at three months. Neurophysiological subtypes at different time points did not correlate with 6 months disability, but demyelination burden at admission (r = -0.42; P = 0.005) and axonal burden at one month (r = 0.43; P = 0.04) correlated with six months disability.

Conclusion: Inverse correlation of axonal burden at one and three months with disability suggests role of secondary axonal damage in predicting outcome. Repeat NCS at one month helps in categorizing GBS and also in prognostication.