Familial spastic paraplegia: a clinical and electrodiagnostic evaluation.

Twenty members of a family with an autosomal dominant variety of a familial spastic paraplegia (FSP) underwent neurologic and electrodiagnostic examination. The degree of clinical involvement ranged from severe to none. This study investigated the presence of peroneal H reflex of Hoffmann along with other electrodiagnostic parameters in each family member and compared this with the presence of other neurologic findings. An H reflex in the peroneal nerve was found in all subjects with a definite diagnosis of FSP and in 4 of the 6 subjects with a diagnosis of probable FSP. It was not elicited in any subject with fewer than 3 neurologic signs or below the age of 25. The H reflex was found to have value as an indicator of upper motor neuron involvement when taken together with the neurologic findings, but its predictive value for individuals at risk to develop FSP has not been established.