The rostral to caudal gradient of clinical and electrophysiological features in sporadic amyotrophic lateral sclerosis with bulbar-onset

Objective Amyotrophic lateral sclerosis (ALS) with bulbar-onset (BO-ALS) tends to propagate to the adjacent anatomical regions symptomatically. However, the spreading pattern of clinical and electrophysiological features is not well documented. Methods This retrospective study enrolled consecutive patients with sporadic BO-ALS. The clinical progression and electrophysiological data by electromyography examination were retrospectively analysed based on information from the medical records. Results The study enrolled 57 patients: 43 presented with contiguous (37 of 57) or non-contiguous (6 of 57) progression clinically; and 14 patients did not present with symptomatic propagation to other spinal segments. Lower motor neuron dysfunction was more frequently involved in the bulbar and cervical segments and less in the thoracic and lumbosacral segments. As a result, a small proportion of patients had intact thoracic paraspinal or leg muscles or both by electromyography examination. Furthermore, the patients with diagnostic latency <= 6 months showed a significantly lower incidence of neurogenic changes in the lumbosacral spinal cord compared with those with diagnostic latency > 6 months. Conclusion This current study demonstrated a relative rostral-caudal descending gradient of lower motor neuron dysfunction in patients with BO-ALS. These results suggest that follow-up EMG might be necessary for a proportion of patients.