Diffuse neurogenic changes on electromyography and diagnosis of amyotrophic lateral sclerosis

Objective To explore the correlation between diffuse neurogenic changes on electromyography and diagnosis of amyotrophic lateral sclerosis (ALS). Methods Retrospective study was performed based on database of motor neuron disorders collected from January, 2002 to December, 2008. The category of disease with diffuse neurogenic changes at the first examination was summarized. The electromyography (EMG) manifestation in ALS patients at the first examination and the results after follow-up were reviewed. The factors affecting EMG manifestation in ALS were analyzed with binary Logistic regression. Results In 298 patients with diffuse neurogenic changes on EMG, 192 cases (64.4%) were diagnosed of ALS, 36(12.1%) progressive muscular atrophy, 13(4.4%) Kennedy’s disease, 10(3.4%) Hirayama disease, 9(3.0%) cervical spondylosis combined with lumbar spondylosis, 6(1.3%) spinal muscular disease, 5(1.7%) multifocal motor neuropathy, 5(1.7%)ALS-plus disease, 4(1.3%) myopathy, 3(1.0%) hereditary motor neuropathy, 3(1.0%) axonal motor neuropathy, 2(0.7%) post-polio syndrome, and 10 (3.4%) with no definite diagnosis. In total 213 patients who were diagnosed with ALS after follow-up, at their first examinations, 8(3.8%) had neurogenic changes in two regions and 13(6.1%) had neurogenic changes in one region, and they all developed to diffuse neurogenic changes after follow-up for 3 to 24 months. Logistic regression analysis showed that the EMG change at first examination was not related to duration from onset, symptom location at onset, age at onset and gender. Conclusion Diffuse neurogenic changes on EMG can present in many disease including ALS. Neurogenic changes in one or two regions on EMG can be the manifestation of ALS at early stage. Key words: Amyotrophic lateral sclerosis; Neuromuscular diseases; Electromyography