Cervical spondylotic amyotrophy presenting as dropped head syndrome.

We report a case of acute-onset dropped head syndrome in a 65-year-old patient in whom the diagnosis of amyotrophic lateral sclerosis (ALS) was initially proposed based on electromyographic signs of neck and shoulder muscle denervation. There were no signs of pyramidal involvement and the clinical and electromyographic signs of motor denervation never evolved beyond the neck and shoulder girdle muscles after a 6-year follow-up period, which argued against ALS. Other causes of dropped head syndrome were carefully ruled out based on clinical findings, electrodiagnostic studies and blood investigations. The restriction of muscle denervation to a few cervical myotomes, the presence of C3-C4 spondylotic changes without associated root or spinal cord compression, and the absence of an alternative explanation to the patient's symptoms strongly supported the diagnosis of cervical spondylotic amyotrophy (CSA). CSA is thought to result from spinal cord microcirculatory disturbances and secondary anterior horn cell degeneration due to ischemia. Our case enlarges the clinical spectrum of focal cervical anterior horn disease, which classically results in more distal monomelic atrophy affecting one or both upper limbs.