Abstract Background Hirayama disease (HD) is a rare, self-limiting cervical myelopathy predominantly affecting adolescent and young adult males. It presents with asymmetric distal upper-limb weakness and wasting due to dynamic spinal cord compression during neck flexion and may be misdiagnosed as motor neuron disease. Aim The aim of this case series was to highlight the diagnostic utility of dynamic flexion magnetic resonance imaging in Hirayama disease, correlate radiological and clinical findings in four young male patients, and emphasize the role of early diagnosis in limiting neurological progression. Cases presentation Four male patients aged 18–22 years presented with progressive upper-limb weakness. A detailed clinical evaluation was conducted, assessing signs such as oblique amyotrophy and reverse split hand sign. The patients underwent cervical spine magnetic resonance imaging (MRI), including additional imaging in the flexion position. All patients demonstrated lower motor neuron-type weakness in the C7–T1 distribution, without sensory or bulbar involvement. Flexion MRI revealed anterior displacement of the posterior dural sac in all cases. Two patients had bilateral hand involvement, while another showed the “snake-eye” sign, indicating chronic anterior horn cell damage. All patients were managed conservatively. Conclusions Dynamic MRI performed in neck flexion is essential for the diagnosis of Hirayama disease and its differentiation from ALS and other mimics. Recognition of atypical features such as bilateral involvement and chronic MRI changes is important for timely diagnosis. Early conservative management may help prevent progression.
Dogra et al. (Thu,) studied this question.