Clinical application of triple stimulation technique in amyotrophic lateral sclerosis

Abstract

Objective: Although upper motor neuron (UMN) signs are essential components in diagnosis of Amyotrophic lateral sclerosis (ALS), it is difficult to measure UMN loss. New collision test called triple stimulation technique (TST) is capable of quantification of UMN loss. The purpose of this study is to identify diagnostic usefulness of TST in ALS patients and to investigate the correlation between TST findings and clinical features. Methods: Forty six patients who were suspected motor neuron disease and eight age-matched healthy controls were enrolled in this study. Transcranial magnetic stimulation (TMS) and TST were performed in all subjects. Correlation between TST findings and clinical parameters were investigated. After six months all patients were re-examined clinically. Results: Among forty six patients, clinically divided into 24 ALS patients, 9 pure lower motor neuron syndrome, 1 kennedy disease and 1 cervical cord lesion. 11 ALS patients were excluded due to conduction block or muscle atrophy. Mean TST amplitude ratio was 51.58 (±26.7) in ALS patients and 92.2 (±4.8) in healthy controls. Among 9 patients with lower motor neuron disease, 4 patients showed abnormal TST amplitude ratio. TST amplitude ratio was decreased in bulbar-onset ALS onset than limb-onset. Six months later, 4 of 9 patients presented without UMN signs at the first examination, were diagnosed as ALS with presence of UMN signs. Conclusions: TST provides considerable information for early prediction of ALS in suspected MND patients. Bulbar-onset ALS showed lower TST amplitude ratio than limb-onset ALS. TST might be potential candidate for electrodiagnostic marker in diagnosis of ALS.