[Evaluating the sensitivity of sternocleidomastoid muscle electromyography in differential diagnosis of amyotrophic lateral sclerosis from cervical spondylotic myelopathy]

ABSTRACT

Differentiation between amyotrophic lateral sclerosis [ALS] and cervical spondylotic myelopathy [CSM] not only for those similar clinical features but also for different handling is very important in clinical practice. Considering that EMG of the sternocleidomastoid muscle [SCM] is using for differential diagnosis of these diseases in Iran, present study was aimed to evaluate the sensitivity of sternocleidomastoid muscle electromyography in differential diagnosis of ALS from CSM. We conducted a retrospective cohort study. Subjects [34patients] were identified from suspected ALS or CSM patients who referred to Loqhman hospital and evaluated with using of the sternocleidomastoid muscle electromyography [SCM-EMG] between March 2006 and February 2008 as part of the diagnostic workup. Clinical characteristics and MRI results were derived from subject's medical records. Follow-up clinical evaluation during two years after initial diagnostic evaluation was available as a gold standard for confirmation the EMG results. We used two way tables for calculating sensitivity. SCM-EMG was abnormal in 10 [29.4%] patients, all of whom were subsequently diagnosed with ALS. The sensitivity of SCM-EMG was 0.71 [95% CI, 0.42 +/- 0.91] for the diagnosis of ALS. Although our findings suggest that SCM-EMG is an extremely useful adjunct for the diagnosis of ALS, but further studies with larger sample size is needed for its application as a useful test "Ruling in" for the diagnosis of ALS