Trapezius vs. Tongue EMG for ALS Diagnosis

Demonstration of denervation and reinnervation in craniobulbar muscles by electromyography (EMG) is particularly useful for the diagnosis of amyotrophic lateral sclerosis (ALS), because few other pathologic processes can explain these findings. However, EMG in these muscles has a low diagnostic sensitivity, partly caused by difficulty achieving adequate relaxation. To compare the diagnostic utility of EMG in various muscles in ALS, the authors prospectively examined EMG of the upper trapezius, sternocleidomastoid (SCM), and tongue muscles in 104 patients with ALS (including 59 with possible or suspected ALS) and in 32 patients with limb weakness secondary to cervical spondylosis (controls).

The sensitivities of trapezius EMG were 63% for det…