Primary lateral sclerosis: clinical, neurophysiological, and magnetic resonance findings

Objective-To describe the clinical, neurophysiological, and MRI findings in 10 patients with primary lateral sclerosis (PLS). Results-The course of the disease was very slowly progressive. Spasticity d ue to upper motor neuron dysfunction was the most prominent sign, but EMG s howed slight lower motor neuron signs, such as a mixed pattern on maximal v oluntary contraction and enlarged motor unit potentials. One patient had cl inically mild lower motor neuron involvement. Central motor conduction time s (CMCT) were more prolonged in PLS than is the case in ALS. Minor sensory signs were found on neurophysiological examination, comparable with those i n ALS. In four patients serum creatine kinase activity was raised. On MRI c ortical atrophy was seen, most pronounced in the precentral gyrus and expan ding into the parietal-occipital region. Conclusions-PLS is a distinct clinical syndrome, part of the range of motor neuron diseases. Besides pronounced upper motor neuron symptoms, mild lowe r motor neuron symptoms can also be found, as well as (subclinical) sensory symptoms. PLS can be distinguished from ALS by its slow clinical course, a severely prolonged MEP, and a more extensive focal cortical atrophy.