Quantitative cardiovascular autonomic function study in Fisher syndrome.

Quantitative cardiovascular autonomic function tests were performed longitudinally in nine patients with Fisher syndrome (FS). Parasympathetic autonomic function was evaluated by the Valsalva ratio and RR interval variation during rest and deep breathing. Sympathetic autonomic function was evaluate by blood pressure responses to sustained handgrip and to active standing. None of the patients with FS had clinical signs of autonomic dysfunction during the course of their illness. However, autonomic function abnormalities were seen in up to 83% of patients with FS. Thus, bedside clinical signs of autonomic dysfunctions are inadequate for the assessment of autonomic abnormality compared with quantitative autonomic function examination. Most autonomic function tests tended to improve after 4-12 weeks. Although parasympathetic and sympathetic functions were both involved at the height of FS, parasympathetic fibres were less vulnerable than the sympathetic fibres.