title: Sensory sparing patterns and the sensory ratio in acute inflammatory demyelinating polyneuropathy.
abstract: The relative preservation (sparing) of sural sensory nerve action potentials (SNAPs) is a useful diagnostic finding in patients with acute inflammatory demyelinating polyneuropathy (AIDP). However, recording of sural SNAPs is not always technically feasible, especially in obese, edematous, or elderly individuals. Hence, we systematically evaluated the predictive values of the commonly employed SNAPs in the diagnosis of AIDP within 2 weeks from onset of symptoms. Sensory sparing patterns and sensory ratios of the sural, radial, median, and ulnar SNAPs of AIDP patients were included in a retrospective and blinded analysis, and compared to patients with diabetic polyneuropathy (DPN) and controls. Logistic regression models for the sural plus radial SNAPs/median plus ulnar SNAPs (sensory ratio) were constructed. A sural sparing pattern was present only in the AIDP group (34.4%, P < 0.001). A radial sparing pattern did not discriminate the AIDP from the DPN groups. The sural/radial sensory ratio was useful to ascertain DPN, but did not discriminate AIDP from controls. The sensory ratio was higher in AIDP compared to DPN and controls and was an independent predictor for AIDP. This study implies that the sensory ratio is a useful predictor for the diagnosis of AIDP and may substitute for sural sparing in technically difficult situations.
authors.affiliation: The Neurologic Institute, University Hospitals of Cleveland, Case School of Medicine, Cleveland, Ohio 44106-5040, USA. amer.alshekhlee@uhhs.com
authors.forename: Amer
authors.initials: A
authors.lastname: Al-Shekhlee
authors.forename: Jenice
authors.initials: J
authors.lastname: Robinson
authors.forename: Bashar
authors.initials: B
authors.lastname: Katirji
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D004558:Electric Stimulation / Q000379:methods; D005260:Female; D020275:Guillain-Barre Syndrome / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology; D012372:ROC Curve; D011930:Reaction Time / Q000502:physiology; D012189:Retrospective Studies; D013127:Spinal Nerves / Q000473:pathology / Q000503:physiopathology*