title: Patterns of sensory nerve conduction abnormalities in Fisher syndrome: more predominant involvement of group Ia afferents than skin afferents.
abstract: OBJECTIVE
  To elucidate the features of sensory nerve involvement in Fisher syndrome (FS), this study extensively investigated sensory electrophysiology.
  
  
  METHODS
  In 47 consecutive FS patients, results of sensory nerve conduction studies in the median, ulnar and sural nerves, soleus H-reflexes, and median or tibial somatosensory-evoked potentials (SEP) were reviewed. Because of the large effects of age on amplitude of sensory nerve action potentials (SNAP), we strictly defined reduction of SNAP amplitudes by using a nomogram which age and amplitude obtained from 87 normal subjects.
  
  
  RESULTS
  In routine nerve conduction studies, SNAP amplitude was reduced only in 32% of the patients, and conduction velocity was decreased in 2%. In contrast, soleus H-reflexes were frequently absent or reduced (67%). SEPs were abnormal only in 17%.
  
  
  CONCLUSIONS
  In FS, absent soleus H-reflexes are the most frequent electrophysiologic abnormalities, whereas SNAPs amplitudes are rarely affected. The pattern is characterized by predominant involvement of group Ia afferents with relatively preserved cutaneous afferents without evidence suggestive of demyelination.
  
  
  CONCLUSIONS
  The major targets of immune attack by anti-GQ1b antibodies in FS appear to be group Ia neurons in the dorsal root ganglia, and this is presumably responsible for ataxia and areflexia in FS.
authors.affiliation: Department of Neurology, Graduate School of Medicine, Chiba University, 1-8-1, Inohana, Chuo-ku, Chiba 260-8670, Japan.
authors.forename: Yukari
authors.initials: Y
authors.lastname: Sekiguchi
authors.forename: Sonoko
authors.initials: S
authors.lastname: Misawa
authors.forename: Kazumoto
authors.initials: K
authors.lastname: Shibuya
authors.forename: Satsuki
authors.initials: S
authors.lastname: Mitsuma
authors.forename: Shigeki
authors.initials: S
authors.lastname: Hirano
authors.forename: Shigeki
authors.initials: S
authors.lastname: Ohmori
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Koga
authors.forename: Yuta
authors.initials: Y
authors.lastname: Iwai
authors.forename: Minako
authors.initials: M
authors.lastname: Beppu
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kuwabara
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D004558:Electric Stimulation; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D006181:H-Reflex / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D019846:Miller Fisher Syndrome / Q000473:pathology* / Q000503:physiopathology*; D009413:Nerve Fibers, Myelinated / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology*; D012867:Skin / Q000294:innervation*; D018709:Statistics, Nonparametric; D055815:Young Adult