Quantitative studies of ciliary and sphenopalatine ganglia in familial dysautonomia.

In 3 patients with familial dysautonomia (FD) sphenopalatine ganglia were less than one fifth normal in volume and their total neuronal content was reduced to a mean of 1,510 (control mean 56,500). Parasympathetic denervation accounts for absence of overflow tears in FD. Ciliary ganglia were not reduced in volume and in 4 patients the mean neuron total was only slightly diminished to 2,900 (control 3,670, P less than or equal to 0.05). This does not appear sufficient to account for pupillary supersensitivity to methacholine in FD on the basis of denervation. Temporal differences in the embryogenesis of sphenopalatine and ciliary ganglia may underlie the observed differences in neuronal populations and suggest that the developmental anomaly in FD does not occur early in gestation.