Electrophysiological evaluation of the peripheral and central pathways in patients with achondroplasia before and during a lower-limb lengthening procedure

In this paper we review the spectrum of spinal and peripheral nerve involvement secondary to achon- droplasia. Alongside conventional and computerised imaging techniques, electrophysiological investiga- tion may represent a useful, non-invasive approach in this clinical setting. Somatosensory evoked poten- tials (SEPs) and magnetic stimulation are valuable tools for studying spinal cord function. Neurophysio- logical abnormalities show a good correlation with the lesion level. Imaging techniques indicate that multiple malformation can affect the patient at the same time and SEPs help to determine the main site of involvement. Interestingly, these techniques are more sensitive than clinical evaluation in document- ing neurological impairment in patients with achon- droplasia prior to the manifestation of unmistakable signs. Callotasi has became a widely used and accept- ed procedure for limb lengthening. Extensive length- ening can be safely performed in patients with achon- droplasia once neurological impairment has been ruled out. In our experience, the presence of elec- trophysiological abnormalities calls for a compre- hensive surgical re-evaluation of the traditional pro- cedure, and sometimes exclusion of patients. Peripheral nerve involvement may occur during limb lengthening, and continuous nerve monitoring pro- vides useful insights into the pathophysiology of nerve damage.