The objective of this study is to discuss the possible role of cervical posterior epidural plexus engorgement during cervical flexion in the pathogenesis of Hirayama myelopathy. In Hirayama disease, MRI during neck flexion often shows that the posterior dura detaches from the posterior arches compressing the spinal cord. Autopsies demonstrated asymmetric changes in the anterior horns consistent with chronic ischemic damage, attributed to arterial insufficiency during flexion or to microcirculatory changes due to compression by the tight dura. In a 15-year-old patient with 5-year history of distal upper limbs weakness, MRI demonstrated marked venous engorgement of the posterior epidural plexus in cervical flexion, confirmed by angiography. Laminectomy from C3 to C6 with duraplasty was performed. At one-year follow-up, the clinical condition of the patient remained stable. In Hirayama myelopathy, compression of the spinal cord by the tight dura is probably the most important pathogenetic factor. However, venous congestion in flexion might play an additional role in determining spinal cord ischemic changes.