Troyer syndrome: a combination of central brain abnormality and motor neuron disease?

Hereditary spastic paraplegia is a group of clinically and genetically hete rogeneous disorders consisting of pure and complicated forms. A variant wit h the additional features of severe atrophy of the small hand muscles, dysa rthria, mental retardation, and short stature has been termed Troyer syndro me (MIM#275900) after the name of Old Order Amish families suffering from t hese symptoms. We report here an Austrian family with two individuals who e xhibit all the features of Troyer syndrome, and provide additional data on this disorder. Electrophysiological studies showed chronic denervation and reduced motor nerve conduction velocities but normal sensory potentials. Mu scle biopsy revealed a neurogenic pattern while the sural nerve was normal on histological examination. Brain abnormalities on magnetic resonance imag ing consisted of a thin corpus callosum with a poorly developed cingulate g yrus and mild periventricular signal hyperintensities. These findings chara cterize the Troyer syndrome as a disorder of the first and second motor neu ron with additional damage in the brain. The morphological features observe d in this family may contribute to the grouping and subsequent understandin g of complicated forms of hereditary spastic paraplegia, together with simi lar observations in other, more recently reported families.