Electrophysiological characterisation in hereditary spastic paraplegia type 5

Objective: To assess in SPG5 hereditary spastic paraparesis (HSP) the involvement of the central (CNS) and the peripheral (PNS) nervous system by a multimodal electrophysiological approach. Methods: Four patients belonging to three HSP families, with a molecular diagnosis of SPG5, underwent electrophysiological evaluation including electromyography (EMG) and nerve conduction study (NCS), motor-evoked potentials (MEPs) by transcranial magnetic stimulation (TMS) and somatosensory evoked potentials (SEPs) at upper and lower limbs, visual (VEPs) and brainstem auditory evoked potentials (BAEPs). In one patient, electrophysiological evaluation was performed twice at the age of 12 and 31. years. Results: EMG and NCS were normal. MEPs and SEPs were abnormal in all patients along the central pathway for upper and/or lower limbs. VEPs revealed a damage of visual pathway and BAEPs showed the involvement of auditory pathway within the brainstem. In the patient who underwent electrophysiological follow-up, MEP and SEP findings were unmodified, whereas VEPs showed no reproducible responses. Conclusions: We report an extensive electrophysiological evaluation of SPG5 and we confirm that the SPG5 phenotype may be broader than pure presentation. Significance: Electrophysiological evaluation, showing diffuse CNS involvement with PNS sparing, could be very useful to address the molecular diagnosis and to follow-up a hypothetical treatment.