1·Bulbar muscles are often involved the whole body can affect other muscle groups, vulnerable to upper respiratory tract infection and other reasons, induced myasthenic crisis.
延髓肌受累者常可累及全身其它骨骼肌群，极易因上呼吸道感染等原因而诱发肌无力危象。
2·Bulbar symptoms, however, were infrequent at onset and two symptomatic patients had an almost pure pyramidal involvement. Two subjects were asymptomatic.
然而，延髓症状在发病初期并不常见，两位有症状的患者几乎完全为锥体系受累表现另外两位患者无症状。