SEGMENTAL HYPERHIDROSIS IN 2 SIBLINGS WITH CHIARI TYPE-I MALFORMATION

A marked, left-sided segmental hyperhidrosis, verified by quantitative evaporimetry, corresponded to an area of dissociated sensory loss in 2 siblings (male 49 years old, female 47 years old). MRI scans of the head and whole cord demonstrated a Chiari type I malformation in both. In the male, there was a syrinx of the neck. The level of this did no t correspond to the hyperhidrosis and dissociated sensory loss areas o f the trunk and thigh. The female, who had no syrinx, had hyperhidrosi s and dissociated sensory loss of the head, neck, upper trunk, and arm , and anisocoria with the larger pupil ipsilateral to the sweating. Th is rare disorder may be due to a disinhibition of the preganglionic sy mpathetic neurons caused by cord lesion(s) interrupting inhibitory des cending and spinal pathways which are important for the normal thermor egulatory sweating.