[Progression patterns of lower motor neuron involvement in the lower medulla oblongata and cervical spinal cord of amyotrophic lateral sclerosis patients].

Objective: To investigate the lower motor neuron (LMN) involvement patterns in the lower medulla oblongata and cervical spinal cord in amyotrophic lateral sclerosis (ALS) patients. Methods: The needle electromyography (EMG) data of 200 patients with non-thoracic onset sporadic ALS, hospitalized in the Neurology Department of the First Medical Center of the Chinese PLA General Hospital from September 2022 to December 2023, were retropectively analyzed. All participants met the EI Escorial-Revised diagnostic criteria. According to the onset site, the patients were divided into the lower medulla oblongata onset group(34 cases), the spinal cord onset group(166 cases) [including the lower cervical spinal cord onset group (92 cases) and the lumbosacral spinal cord onset group (74 cases)]. Electromyography (EMG) abnormalities in the muscles innervated by the lower medulla oblongata and cervical cord were counted, and the characteristics of LMN involvement were analyzed. The binomial distribution test was used to determine whether the progression of LMN involvement to the second central nervous system segment was random. Results: Among 200 ALS patients, there were 111 males (55.5%) and 89 females (44.5%), with an age onset of 28-86 (56±11) years. 20 (10.0%) cases with normal sternocleidomastoid (SCM)-EMG or trapezius (TRA)-EMG results, and 7 (3.5%) cases with normal SCM-EMG and TRA-EMG results were observed in patients with LMN involvement in both the lower medulla oblongata and lower cervical spinal cord. The abnormal rates of EMG at the onset of lower cervical spinal cord were tongue muscle (GEN)-EMG (88.2%, 30/34), TRA-EMG (70.6%, 24/34) and SCM-EMG (67.6%, 23/34), respectively. The abnormal rates of EMG at the onset of lower cervical spinal cord were TRA-EMG (72.8%, 67/92), SCM-EMG (38.0%, 35/92) and GEN-EMG (32.6%, 30/92), respectively. The binomial distribution test showed that the progression of LMN involvement to the second segment of the central nervous system was not random (all P<0.05). In low bulbar onset patients, the abnormal rate of LMN involvement was higher in the lower cervical spinal cord segment [100.0% (34/34)], and lower in the lumbosacral spinal cord segment[91.2% (31/34)]. In the lower cervical spinal cord onset group, the abnormal rate of LMN involvement was lower in the the low medulla obliterum[32.6% (30/92)] and high in the lumbosacral spinal cord [96.7% (89/92)].In the lumbosacral spinal cord onset group, the abnormal rate of LMN involvement was low in the low medulla oblata [27.0% (20/74)] and high in the lower cervical spinal cord [94.6% (70/74)]. Conclusions: The progression of LMN involvement in the lower medulla oblongata and cervical spinal cord is primarily continuous, while a discontinuous progression pattern was also observed. The lower medulla oblongata of ALS patients with spinal onset is relatively less involved in disease progression.