Apparent diffusion coefficients distinguish amyotrophic lateral sclerosis from cervical spondylotic myelopathy

• It is sometimes difficult to distinguish ALS patients from CSM patients at onset.
• We determined whether ADC assessed from brain MRI is useful for differentiation ALS from CSM.
• ALS patients showed significantly higher ADCs than CSM patients in the corticospinal tracts.
• ALS patients without bulbar symptoms also showed significantly high ADCs.
• Evaluating ADCs by brain MRI might be useful for distinguishing ALS from CSM.

ObjectiveFifty percent of patients with amyotrophic lateral sclerosis (ALS) have cervical spondylotic myelopathy (CSM) as a complication. Because patients with ALS do not develop bulbar signs and symptoms at onset, differentiating them from patients with CSM is sometimes difficult. We aimed to determine whether the apparent diffusion coefficients (ADCs) of intracranial corticospinal tracts can be used to distinguish between patients with ALS and those with CSM.MethodsWe evaluated 19 consecutive patients with ALS who did not have CSM by cervical MRI, 16 patients with CSM, and 11 healthy controls. We examined the mean ADCs in the precentral gyrus, the corona radiata, the posterior limbs of the internal capsule (PLIC), and the cerebral peduncle by 3 T magnetic resonance imaging (MRI). The mean ADCs in the intracranial corticospinal tracts in patients with ALS were compared with those in patients with CSM.ResultsThe mean ADCs in the intracranial corticospinal tracts in patients with ALS were compared with those in patients with CSM (p < 0.05). Additionally, the mean ADCs in the precentral gyrus, the PLIC, and the cerebral peduncle in the patients with ALS, including the patients who were initially diagnosed as having clinically possible ALS on the basis of the revised El Escorial criteria and did not develop bulbar symptoms at onset, were also higher than those in patients with CSM (p < 0.05).ConclusionsElevated ADCs in the intracranial corticospinal tracts might be useful for distinguishing ALS from CSM in the early stage of the disease.