title: Early discrimination of sensorimotor Guillain-Barré syndrome into demyelinating or axonal subtype by automated nerve excitability testing.
abstract: In the early stage of disease, differentiating acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor sensory axonal neuropathy (AMSAN) using only a conventional nerve conduction studies (NCS) may be difficult. We evaluated the differences in the motor axonal excitability properties of 16 cases of sensorimotor Guillain-Barré syndrome by nerve excitability testing (NET). The antiganglioside antibody assay and follow-up NCS resulted in 12 patients diagnosed as AIDP and 4 patients as AMSAN. Clinical and excitability parameters in each group were compared with those in 30 normal controls. Automated NET with threshold tracking techniques was used to calculate the strength-duration time constant (SDTC), threshold electrotonus (TE), current-threshold relationship (CTR), and recovery cycle (RC) of excitability. Except for subtle changes in excitability parameters, AIDP showed no definitive difference relative to normal controls. Comparison between AMSAN and normal controls also revealed no significant differences in the SDTC, TE, and CTR parameters. However, there were clear differences in some of the RC parameters: the relative refractory period was significantly longer in the AMSAN group than in the AIDP group (4.40 ± 1.11 vs. 3.09 ± 1.01 ms, mean ± SEM; p < 0.001), while superexcitability was significantly less prominent in the AMSAN group (-6.80 ± 10.30 vs. -26.48 ± 1.17%, mean ± SEM; p < 0.001). Our study identified that both AIDP and AMSAN were associated with subtle changes in excitability properties. Nonetheless, the prominent increase in refractoriness in AMSAN suggests the presence of a nodal conduction block.
authors.affiliation: Department of Neurology, National Police Hospital, Seoul, Korea.
authors.forename: So Young
authors.initials: SY
authors.lastname: Pyun
authors.affiliation: Department of Neurology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Mi-Ri
authors.initials: MR
authors.lastname: Kang
authors.affiliation: Department of Neurology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Ju Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Neurology, Dong-A University College of Medicine, Busan, Korea.
authors.forename: Kim Jong
authors.initials: KJ
authors.lastname: Kuk
authors.affiliation: Department of Neurology, Busan Paik Hospital, Inje University College of Medicine, Busan, Korea.
authors.forename: Seong-Il
authors.initials: SI
authors.lastname: Oh
authors.affiliation: Department of Neurology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.
authors.forename: Jong Seok
authors.initials: JS
authors.lastname: Bae
mesh_terms: D000328:Adult; D000368:Aged; D001369:Axons / Q000473:pathology* / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D020275:Guillain-Barre Syndrome / Q000145:classification / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D009431:Neural Conduction; D011115:Polyneuropathies / Q000175:diagnosis*; D011930:Reaction Time; D012189:Retrospective Studies; D012684:Sensory Thresholds / Q000502:physiology
keywords: Guillain-Barré syndrome; acute motor sensory axonal neuropathy; nerve excitability; pathophysiology; threshold tracking