The features or mechanisms of dyshidrosis have not been sufficiently clarif
ied. Neither has the difference between hyperhidrosis and hypohidrosis. To
clarify the features and mechanisms of dyshidrosis (hyperhidrosis and hypoh
idrosis) in syringomyelia, the clinical features focusing on hidrosis of 30
patients with syringomyelia and Chiari malformation located from a syringo
myelia database were prospectively analysed. The patients were classified i
nto three groups: eight patients (26.7%) had segmental hypohidrosis, 10 (33
.3%) had segmental hyperhidrosis, and 12 (40.0%) had normohidrosis. We foun
d that the Karnofsky functional status for the hyperhydrosis and normohidro
sis groups were significantly higher than for the hypohidrosis group (p=0.0
012), with no significant differences between the hyperhidrosis and normohi
drosis groups. The duration from the onset of syringomyelia to the current
dyshidrosis was significantly longer in the hypohidrosis group than in the
hyperhidrosis group (p=0.0027). A significant correlation was identified be
tween the duration from the onset of syringomyelia to the time at study and
the performance score (r=-0.599, p=0.0003). The results substantiate previ
ous hypotheses that in its early stage syringomyelia causes segmental hyper
activity of the sympathetic preganglionic neurons, and hyperactivity of the
se gradually subsides as tissue damage progresses. Focal hyperhidrosis may
be regarded as a hallmark of a relatively intact spinal cord, as well as no
rmohidrosis.